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Posted to notifications@skywalking.apache.org by wu...@apache.org on 2021/02/09 07:02:15 UTC

[skywalking-infra-e2e] branch main updated: Implement the verification of the actual data file (#7)

This is an automated email from the ASF dual-hosted git repository.

wusheng pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/skywalking-infra-e2e.git


The following commit(s) were added to refs/heads/main by this push:
     new 8856938  Implement the verification of the actual data file (#7)
8856938 is described below

commit 8856938617a8f07ba49b32dc6ed8fb2b0fe3b9e8
Author: Hoshea Jiang <fg...@gmail.com>
AuthorDate: Tue Feb 9 15:02:06 2021 +0800

    Implement the verification of the actual data file (#7)
---
 .golangci.yml                            |    2 +
 .licenserc.yaml                          |    1 +
 LICENSE                                  |    9 +
 Makefile                                 |    4 +-
 commands/root.go                         |   20 +-
 commands/setup/setup.go                  |   23 +-
 commands/verify/verify.go                |   21 +-
 dist/LICENSE                             |    8 +-
 dist/licenses/LICENSE-go-cmp.txt         |   27 +
 dist/licenses/LICENSE-golang.txt         |   27 +
 go.mod                                   |    2 +
 internal/components/verifier/funcs.go    |   71 ++
 internal/components/verifier/verifier.go |  104 +++
 internal/config/e2eConfig.go             |    9 +-
 internal/config/globalConfig.go          |   33 +-
 internal/util/utils.go                   |   14 +
 test/verify/1.actual.yaml                |   41 ++
 test/verify/1.expected.yaml              |   41 ++
 third-party/go/internal/fmtsort/sort.go  |  220 ++++++
 third-party/go/template/exec.go          | 1079 ++++++++++++++++++++++++++++++
 third-party/go/template/funcs.go         |  769 +++++++++++++++++++++
 third-party/go/template/helper.go        |  130 ++++
 third-party/go/template/option.go        |   74 ++
 third-party/go/template/parse/lex.go     |  667 ++++++++++++++++++
 third-party/go/template/parse/node.go    |  957 ++++++++++++++++++++++++++
 third-party/go/template/parse/parse.go   |  740 ++++++++++++++++++++
 third-party/go/template/template.go      |  229 +++++++
 27 files changed, 5269 insertions(+), 53 deletions(-)

diff --git a/.golangci.yml b/.golangci.yml
index 4535951..617deaf 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -18,6 +18,8 @@
 
 run:
   tests: false
+  skip-dirs:
+    - third-party
 
 linters-settings:
   govet:
diff --git a/.licenserc.yaml b/.licenserc.yaml
index 45f9a41..9c7b73f 100644
--- a/.licenserc.yaml
+++ b/.licenserc.yaml
@@ -69,5 +69,6 @@ header: # `header` section is configurations for source codes license header.
     - '**/go.sum'
     - 'LICENSE'
     - 'NOTICE'
+    - 'third-party'
 
   comment: on-failure # on what condition license-eye will comment on the pull request, `on-failure`, `always`, `never`.
diff --git a/LICENSE b/LICENSE
index 6a4bacd..be17a52 100644
--- a/LICENSE
+++ b/LICENSE
@@ -235,3 +235,12 @@ The following components are provided under the MIT license. See project link fo
 The text of each license is also included at licenses/LICENSE-[project].txt.
 
     logrus 1.7.0: https://github.com/sirupsen/logrus MIT
+
+========================================================================
+BSD licenses
+========================================================================
+
+The following components are provided under a BSD license. See project link for details.
+The text of each license is also included at licenses/LICENSE-[project].txt.
+
+   third-party/go files from golang/go: https://github.com/golang/go/tree/master/src  BSD-3-Clause
\ No newline at end of file
diff --git a/Makefile b/Makefile
index c1db858..1eee4be 100644
--- a/Makefile
+++ b/Makefile
@@ -36,7 +36,7 @@ ARCH = amd64
 RELEASE_BIN = skywalking-$(PROJECT)-$(VERSION)-bin
 RELEASE_SRC = skywalking-$(PROJECT)-$(VERSION)-src
 
-all: clean lint license test build
+all: clean lint test build
 
 .PHONY: lint
 lint:
@@ -68,7 +68,7 @@ clean:
 	-rm -rf "$(RELEASE_SRC)"*
 
 .PHONY: verify
-verify: clean license lint test
+verify: clean lint test
 
 release-src: clean
 	-mkdir $(RELEASE_SRC)
diff --git a/commands/root.go b/commands/root.go
index 3843d61..8493e0d 100644
--- a/commands/root.go
+++ b/commands/root.go
@@ -20,16 +20,13 @@ package commands
 import (
 	"github.com/spf13/cobra"
 
-	"github.com/apache/skywalking-infra-e2e/internal/util"
-
-	"github.com/apache/skywalking-infra-e2e/internal/config"
-	"github.com/apache/skywalking-infra-e2e/internal/constant"
-
 	"github.com/apache/skywalking-infra-e2e/commands/cleanup"
 	"github.com/apache/skywalking-infra-e2e/commands/run"
 	"github.com/apache/skywalking-infra-e2e/commands/setup"
 	"github.com/apache/skywalking-infra-e2e/commands/trigger"
 	"github.com/apache/skywalking-infra-e2e/commands/verify"
+	"github.com/apache/skywalking-infra-e2e/internal/config"
+	"github.com/apache/skywalking-infra-e2e/internal/constant"
 )
 
 // Root represents the base command when called without any subcommands
@@ -39,17 +36,8 @@ var Root = &cobra.Command{
 	Version:       version,
 	SilenceErrors: true,
 	SilenceUsage:  true,
-	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
-		err := util.CheckDockerDaemon()
-		if err != nil {
-			return err
-		}
-
-		err = config.ReadGlobalConfigFile(constant.E2EDefaultFile)
-		if err != nil {
-			return err
-		}
-		return nil
+	PersistentPreRun: func(cmd *cobra.Command, args []string) {
+		config.ReadGlobalConfigFile(constant.E2EDefaultFile)
 	},
 }
 
diff --git a/commands/setup/setup.go b/commands/setup/setup.go
index b1f9f7c..a3eb3b9 100644
--- a/commands/setup/setup.go
+++ b/commands/setup/setup.go
@@ -21,30 +21,37 @@ package setup
 import (
 	"fmt"
 
+	"github.com/apache/skywalking-infra-e2e/internal/components/setup"
 	"github.com/apache/skywalking-infra-e2e/internal/config"
-
 	"github.com/apache/skywalking-infra-e2e/internal/constant"
+	"github.com/apache/skywalking-infra-e2e/internal/logger"
+	"github.com/apache/skywalking-infra-e2e/internal/util"
 
 	"github.com/spf13/cobra"
-
-	"github.com/apache/skywalking-infra-e2e/internal/components/setup"
-	"github.com/apache/skywalking-infra-e2e/internal/logger"
 )
 
 var Setup = &cobra.Command{
 	Use:   "setup",
 	Short: "",
-	RunE: func(cmd *cobra.Command, args []string) error {
-		err := setupAccordingE2E()
-		if err != nil {
-			err = fmt.Errorf("[Setup] %s", err)
+	PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
+		if err := util.CheckDockerDaemon(); err != nil {
 			return err
 		}
 		return nil
 	},
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := setupAccordingE2E(); err != nil {
+			return fmt.Errorf("[Setup] %s", err)
+		}
+		return nil
+	},
 }
 
 func setupAccordingE2E() error {
+	if config.GlobalConfig.Error != nil {
+		return config.GlobalConfig.Error
+	}
+
 	e2eConfig := config.GlobalConfig.E2EConfig
 
 	if e2eConfig.Setup.Env == constant.Kind {
diff --git a/commands/verify/verify.go b/commands/verify/verify.go
index 34c122c..91f37bf 100644
--- a/commands/verify/verify.go
+++ b/commands/verify/verify.go
@@ -1,4 +1,3 @@
-//
 // Licensed to Apache Software Foundation (ASF) under one or more contributor
 // license agreements. See the NOTICE file distributed with
 // this work for additional information regarding copyright
@@ -15,18 +14,36 @@
 // KIND, either express or implied.  See the License for the
 // specific language governing permissions and limitations
 // under the License.
+
 package verify
 
 import (
 	"fmt"
 
+	"github.com/apache/skywalking-infra-e2e/internal/components/verifier"
+
 	"github.com/spf13/cobra"
 )
 
+var (
+	query    string
+	actual   string
+	expected string
+)
+
+func init() {
+	Verify.Flags().StringVarP(&query, "query", "q", "", "the query to get the actual data, the result of the query should in YAML format")
+	Verify.Flags().StringVarP(&actual, "actual", "a", "", "the actual data file, only YAML file format is supported")
+	Verify.Flags().StringVarP(&expected, "expected", "e", "", "the expected data file, only YAML file format is supported")
+}
+
 var Verify = &cobra.Command{
 	Use:   "verify",
-	Short: "",
+	Short: "verify if the actual data match the expected data",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		if actual != "" && expected != "" {
+			return verifier.VerifyDataFile(actual, expected)
+		}
 		fmt.Println("Not implemented.")
 		return nil
 	},
diff --git a/dist/LICENSE b/dist/LICENSE
index 6ffc5bd..de2e629 100644
--- a/dist/LICENSE
+++ b/dist/LICENSE
@@ -244,11 +244,13 @@ The text of each license is also included at licenses/LICENSE-[project].txt.
     aec v1.0.0: https://github.com/morikuni/aec MIT
 
 ========================================================================
-BSD 3-Clause licenses
+BSD licenses
 ========================================================================
 
-The following components are provided under the BSD 3-Clause license. See project link for details.
+The following components are provided under the BSD license. See project link for details.
 The text of each license is also included at licenses/LICENSE-[project].txt.
 
     mergo v0.3.11: https://github.com/imdario/mergo BSD-3-Clause
-    gorilla/mux v1.8.0: https://github.com/gorilla/mux BSD-3-Clause
\ No newline at end of file
+    gorilla/mux v1.8.0: https://github.com/gorilla/mux BSD-3-Clause
+    third-party/go files from golang/go: https://github.com/golang/go/tree/master/src  BSD-3-Clause
+    go-cmp v0.4.0 https://github.com/google/go-cmp BSD-3-Clause
\ No newline at end of file
diff --git a/dist/licenses/LICENSE-go-cmp.txt b/dist/licenses/LICENSE-go-cmp.txt
new file mode 100644
index 0000000..d9b732c
--- /dev/null
+++ b/dist/licenses/LICENSE-go-cmp.txt
@@ -0,0 +1,27 @@
+Copyright (c) 2017 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
diff --git a/dist/licenses/LICENSE-golang.txt b/dist/licenses/LICENSE-golang.txt
new file mode 100644
index 0000000..ea5ea89
--- /dev/null
+++ b/dist/licenses/LICENSE-golang.txt
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
\ No newline at end of file
diff --git a/go.mod b/go.mod
index 30c2d57..1430167 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/docker/docker v20.10.3+incompatible
 	github.com/docker/go-connections v0.4.0 // indirect
 	github.com/docker/go-units v0.4.0 // indirect
+	github.com/google/go-cmp v0.4.0
 	github.com/gorilla/mux v1.8.0 // indirect
 	github.com/imdario/mergo v0.3.11 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
@@ -15,6 +16,7 @@ require (
 	github.com/sirupsen/logrus v1.7.0
 	github.com/spf13/cobra v1.1.1
 	gopkg.in/yaml.v2 v2.3.0
+	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776
 	k8s.io/api v0.19.0
 	k8s.io/apimachinery v0.19.0
 	k8s.io/cli-runtime v0.19.0
diff --git a/internal/components/verifier/funcs.go b/internal/components/verifier/funcs.go
new file mode 100644
index 0000000..af8a0ea
--- /dev/null
+++ b/internal/components/verifier/funcs.go
@@ -0,0 +1,71 @@
+// Licensed to Apache Software Foundation (ASF) under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Apache Software Foundation (ASF) licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package verifier
+
+import (
+	"encoding/base64"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/apache/skywalking-infra-e2e/third-party/go/template"
+)
+
+// funcMap produces the custom function map.
+// Use this to pass the functions into the template engine:
+// 	tpl := template.New("foo").Funcs(funcMap()))
+func funcMap() template.FuncMap {
+	fm := make(map[string]interface{}, len(customFuncMap))
+	for k, v := range customFuncMap {
+		fm[k] = v
+	}
+	return template.FuncMap(fm)
+}
+
+var customFuncMap = map[string]interface{}{
+	// Basic:
+	"notEmpty": notEmpty,
+
+	// Encoding:
+	"b64enc": base64encode,
+
+	// Regex:
+	"regexp": regexpMatch,
+}
+
+func base64encode(s string) string {
+	return base64.StdEncoding.EncodeToString([]byte(s))
+}
+
+func notEmpty(s string) string {
+	if len(strings.TrimSpace(s)) > 0 {
+		return s
+	}
+	return fmt.Sprintf(`<"%s" is empty, wanted is not empty>`, s)
+}
+
+func regexpMatch(s, pattern string) string {
+	matched, err := regexp.MatchString(pattern, s)
+	if err != nil {
+		return fmt.Sprintf(`<"%s">`, err)
+	}
+	if !matched {
+		return fmt.Sprintf(`<"%s" does not match the pattern %s">`, s, pattern)
+	}
+	return s
+}
diff --git a/internal/components/verifier/verifier.go b/internal/components/verifier/verifier.go
new file mode 100644
index 0000000..84150c1
--- /dev/null
+++ b/internal/components/verifier/verifier.go
@@ -0,0 +1,104 @@
+// Licensed to Apache Software Foundation (ASF) under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Apache Software Foundation (ASF) licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+package verifier
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+
+	"github.com/apache/skywalking-infra-e2e/internal/logger"
+	"github.com/apache/skywalking-infra-e2e/internal/util"
+	"github.com/apache/skywalking-infra-e2e/third-party/go/template"
+
+	"github.com/google/go-cmp/cmp"
+	"gopkg.in/yaml.v2"
+)
+
+// MismatchError is the error type returned by the verify functions.
+// Then the caller will know if there is a mismatch.
+type MismatchError struct {
+	Err error
+}
+
+func (e *MismatchError) Unwrap() error { return e.Err }
+
+func (e *MismatchError) Error() string {
+	if e == nil {
+		return "<nil>"
+	}
+	return "the actual data does not match the expected data"
+}
+
+// VerifyDataFile reads the actual data from the file and verifies.
+func VerifyDataFile(actualFile, expectedFile string) error {
+	actualData, err := util.ReadFileContent(actualFile)
+	if err != nil {
+		logger.Log.Error("failed to read the actual data file")
+		return err
+	}
+
+	expectedTemplate, err := util.ReadFileContent(expectedFile)
+	if err != nil {
+		logger.Log.Error("failed to read the expected data file")
+		return err
+	}
+
+	return verify(actualData, expectedTemplate)
+}
+
+// VerifyQuery gets the actual data from the query and then verifies.
+func VerifyQuery(query, expectedFile string) error {
+	return errors.New("not implemented")
+}
+
+// verify checks if the actual data match the expected template.
+// It will print the diff if the actual data does not match.
+func verify(actualData, expectedTemplate string) error {
+	var actual interface{}
+	if err := yaml.Unmarshal([]byte(actualData), &actual); err != nil {
+		logger.Log.Error("failed to unmarshal actual data")
+		return err
+	}
+
+	tmpl, err := template.New("test").Funcs(funcMap()).Parse(expectedTemplate)
+	if err != nil {
+		logger.Log.Error("failed to parse template")
+		return err
+	}
+
+	var b bytes.Buffer
+	if err := tmpl.Execute(&b, actual); err != nil {
+		logger.Log.Error("failed to execute template")
+		return err
+	}
+
+	var expected interface{}
+	if err := yaml.Unmarshal(b.Bytes(), &expected); err != nil {
+		logger.Log.Error("failed to unmarshal expected data")
+		return err
+	}
+
+	if !cmp.Equal(expected, actual) {
+		diff := cmp.Diff(expected, actual)
+		fmt.Println(diff)
+		return &MismatchError{}
+	}
+
+	logger.Log.Info("the actual data matches the expected data")
+	return nil
+}
diff --git a/internal/config/e2eConfig.go b/internal/config/e2eConfig.go
index 836e582..c242947 100644
--- a/internal/config/e2eConfig.go
+++ b/internal/config/e2eConfig.go
@@ -20,7 +20,8 @@ package config
 
 // E2EConfig corresponds to configuration file e2e.yaml.
 type E2EConfig struct {
-	Setup Setup `yaml:"setup"`
+	Setup  Setup        `yaml:"setup"`
+	Verify []VerifyCase `yaml:"verify"`
 }
 
 type Setup struct {
@@ -48,3 +49,9 @@ type Wait struct {
 	LabelSelector string `yaml:"label-selector"`
 	For           string `yaml:"for"`
 }
+
+type VerifyCase struct {
+	Query    string `yaml:"query"`
+	Actual   string `yaml:"actual"`
+	Expected string `yaml:"expected"`
+}
diff --git a/internal/config/globalConfig.go b/internal/config/globalConfig.go
index 91afdcb..f8c1334 100644
--- a/internal/config/globalConfig.go
+++ b/internal/config/globalConfig.go
@@ -22,8 +22,6 @@ import (
 	"fmt"
 	"io/ioutil"
 
-	"github.com/apache/skywalking-infra-e2e/internal/logger"
-
 	"gopkg.in/yaml.v2"
 
 	"github.com/apache/skywalking-infra-e2e/internal/util"
@@ -31,39 +29,32 @@ import (
 
 // GlobalE2EConfig store E2EConfig which can be used globally.
 type GlobalE2EConfig struct {
-	Ready     bool
+	Error     error
 	E2EConfig E2EConfig
 }
 
 var GlobalConfig GlobalE2EConfig
 
-func ReadGlobalConfigFile(configFilePath string) error {
-	if GlobalConfig.Ready {
-		logger.Log.Info("e2e config has been initialized")
-		return nil
-	}
-
+func ReadGlobalConfigFile(configFilePath string) {
 	e2eFile := configFilePath
 
 	if !util.PathExist(e2eFile) {
-		return fmt.Errorf("e2e config file %s not exist", e2eFile)
+		GlobalConfig.Error = fmt.Errorf("e2e config file %s not exist", e2eFile)
+		return
 	}
 
 	data, err := ioutil.ReadFile(e2eFile)
 	if err != nil {
-		return fmt.Errorf("read e2e config file %s error: %s", e2eFile, err)
+		GlobalConfig.Error = fmt.Errorf("read e2e config file %s error: %s", e2eFile, err)
+		return
 	}
-	e2eConfigObject := E2EConfig{}
-	err = yaml.Unmarshal(data, &e2eConfigObject)
-	if err != nil {
-		return fmt.Errorf("unmarshal e2e config file %s error: %s", e2eFile, err)
-	}
-	GlobalConfig.E2EConfig = e2eConfigObject
-	GlobalConfig.Ready = true
 
-	if !GlobalConfig.Ready {
-		return fmt.Errorf("e2e config read failed")
+	e2eConfigObject := E2EConfig{}
+	if err := yaml.Unmarshal(data, &e2eConfigObject); err != nil {
+		GlobalConfig.Error = fmt.Errorf("unmarshal e2e config file %s error: %s", e2eFile, err)
+		return
 	}
 
-	return nil
+	GlobalConfig.E2EConfig = e2eConfigObject
+	GlobalConfig.Error = nil
 }
diff --git a/internal/util/utils.go b/internal/util/utils.go
index 50030d7..0c2a2f0 100644
--- a/internal/util/utils.go
+++ b/internal/util/utils.go
@@ -19,6 +19,8 @@
 package util
 
 import (
+	"errors"
+	"io/ioutil"
 	"os"
 	"os/exec"
 )
@@ -38,3 +40,15 @@ func PathExist(_path string) bool {
 	}
 	return true
 }
+
+// ReadFileContent reads the file content.
+func ReadFileContent(filename string) (string, error) {
+	if PathExist(filename) {
+		content, err := ioutil.ReadFile(filename)
+		if err != nil {
+			return "", err
+		}
+		return string(content), nil
+	}
+	return "", errors.New("the file does not exist")
+}
diff --git a/test/verify/1.actual.yaml b/test/verify/1.actual.yaml
new file mode 100644
index 0000000..b236877
--- /dev/null
+++ b/test/verify/1.actual.yaml
@@ -0,0 +1,41 @@
+# Licensed to Apache Software Foundation (ASF) under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Apache Software Foundation (ASF) licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+nodes:
+  - id: VXNlcg==.0
+    name: User
+    type: USER
+    isReal: false
+  - id: WW91cl9BcHBsaWNhdGlvbk5hbWU=.1
+    name: Your_ApplicationName
+    type: Tomcat
+    isReal: true
+  - id: bG9jYWxob3N0Oi0x.0
+    name: localhost:-1
+    type: H2
+    isReal: false
+calls:
+  - id: WW91cl9BcHBsaWNhdGlvbk5hbWU=.1-bG9jYWxob3N0Oi0x.0
+    source: WW91cl9BcHBsaWNhdGlvbk5hbWU=.1
+    detectPoints:
+      - CLIENT
+    target: bG9jYWxob3N0Oi0x.0
+  - id: VXNlcg==.0-WW91cl9BcHBsaWNhdGlvbk5hbWU=.1
+    source: VXNlcg==.0
+    detectPoints:
+      - SERVER
+    target: WW91cl9BcHBsaWNhdGlvbk5hbWU=.1
\ No newline at end of file
diff --git a/test/verify/1.expected.yaml b/test/verify/1.expected.yaml
new file mode 100644
index 0000000..796dfde
--- /dev/null
+++ b/test/verify/1.expected.yaml
@@ -0,0 +1,41 @@
+# Licensed to Apache Software Foundation (ASF) under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Apache Software Foundation (ASF) licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+nodes:
+  - id: {{ b64enc "User" }}.0
+    name: User
+    type: USER
+    isReal: false
+  - id: {{ b64enc "Your_ApplicationName" }}.1
+    name: Your_ApplicationName
+    type: Tomcat
+    isReal: true
+  - id: {{ $h2ID := (index .nodes 2).id }}{{ notEmpty $h2ID }}
+    name: localhost:-1
+    type: H2
+    isReal: false
+calls:
+  - id: {{ notEmpty (index .calls 0).id }}
+    source: {{ b64enc "Your_ApplicationName" }}.1
+    target: {{ $h2ID }}
+    detectPoints:
+      - CLIENT
+  - id: {{ b64enc "User" }}.0-{{ b64enc "Your_ApplicationName" }}.1
+    source: {{ b64enc "User" }}.0
+    target: {{ b64enc "Your_ApplicationName" }}.1
+    detectPoints:
+      - SERVER
\ No newline at end of file
diff --git a/third-party/go/internal/fmtsort/sort.go b/third-party/go/internal/fmtsort/sort.go
new file mode 100644
index 0000000..b01229b
--- /dev/null
+++ b/third-party/go/internal/fmtsort/sort.go
@@ -0,0 +1,220 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package fmtsort provides a general stable ordering mechanism
+// for maps, on behalf of the fmt and text/template packages.
+// It is not guaranteed to be efficient and works only for types
+// that are valid map keys.
+package fmtsort
+
+import (
+	"reflect"
+	"sort"
+)
+
+// Note: Throughout this package we avoid calling reflect.Value.Interface as
+// it is not always legal to do so and it's easier to avoid the issue than to face it.
+
+// SortedMap represents a map's keys and values. The keys and values are
+// aligned in index order: Value[i] is the value in the map corresponding to Key[i].
+type SortedMap struct {
+	Key   []reflect.Value
+	Value []reflect.Value
+}
+
+func (o *SortedMap) Len() int           { return len(o.Key) }
+func (o *SortedMap) Less(i, j int) bool { return compare(o.Key[i], o.Key[j]) < 0 }
+func (o *SortedMap) Swap(i, j int) {
+	o.Key[i], o.Key[j] = o.Key[j], o.Key[i]
+	o.Value[i], o.Value[j] = o.Value[j], o.Value[i]
+}
+
+// Sort accepts a map and returns a SortedMap that has the same keys and
+// values but in a stable sorted order according to the keys, modulo issues
+// raised by unorderable key values such as NaNs.
+//
+// The ordering rules are more general than with Go's < operator:
+//
+//  - when applicable, nil compares low
+//  - ints, floats, and strings order by <
+//  - NaN compares less than non-NaN floats
+//  - bool compares false before true
+//  - complex compares real, then imag
+//  - pointers compare by machine address
+//  - channel values compare by machine address
+//  - structs compare each field in turn
+//  - arrays compare each element in turn.
+//    Otherwise identical arrays compare by length.
+//  - interface values compare first by reflect.Type describing the concrete type
+//    and then by concrete value as described in the previous rules.
+//
+func Sort(mapValue reflect.Value) *SortedMap {
+	if mapValue.Type().Kind() != reflect.Map {
+		return nil
+	}
+	// Note: this code is arranged to not panic even in the presence
+	// of a concurrent map update. The runtime is responsible for
+	// yelling loudly if that happens. See issue 33275.
+	n := mapValue.Len()
+	key := make([]reflect.Value, 0, n)
+	value := make([]reflect.Value, 0, n)
+	iter := mapValue.MapRange()
+	for iter.Next() {
+		key = append(key, iter.Key())
+		value = append(value, iter.Value())
+	}
+	sorted := &SortedMap{
+		Key:   key,
+		Value: value,
+	}
+	sort.Stable(sorted)
+	return sorted
+}
+
+// compare compares two values of the same type. It returns -1, 0, 1
+// according to whether a > b (1), a == b (0), or a < b (-1).
+// If the types differ, it returns -1.
+// See the comment on Sort for the comparison rules.
+func compare(aVal, bVal reflect.Value) int {
+	aType, bType := aVal.Type(), bVal.Type()
+	if aType != bType {
+		return -1 // No good answer possible, but don't return 0: they're not equal.
+	}
+	switch aVal.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		a, b := aVal.Int(), bVal.Int()
+		switch {
+		case a < b:
+			return -1
+		case a > b:
+			return 1
+		default:
+			return 0
+		}
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		a, b := aVal.Uint(), bVal.Uint()
+		switch {
+		case a < b:
+			return -1
+		case a > b:
+			return 1
+		default:
+			return 0
+		}
+	case reflect.String:
+		a, b := aVal.String(), bVal.String()
+		switch {
+		case a < b:
+			return -1
+		case a > b:
+			return 1
+		default:
+			return 0
+		}
+	case reflect.Float32, reflect.Float64:
+		return floatCompare(aVal.Float(), bVal.Float())
+	case reflect.Complex64, reflect.Complex128:
+		a, b := aVal.Complex(), bVal.Complex()
+		if c := floatCompare(real(a), real(b)); c != 0 {
+			return c
+		}
+		return floatCompare(imag(a), imag(b))
+	case reflect.Bool:
+		a, b := aVal.Bool(), bVal.Bool()
+		switch {
+		case a == b:
+			return 0
+		case a:
+			return 1
+		default:
+			return -1
+		}
+	case reflect.Ptr:
+		a, b := aVal.Pointer(), bVal.Pointer()
+		switch {
+		case a < b:
+			return -1
+		case a > b:
+			return 1
+		default:
+			return 0
+		}
+	case reflect.Chan:
+		if c, ok := nilCompare(aVal, bVal); ok {
+			return c
+		}
+		ap, bp := aVal.Pointer(), bVal.Pointer()
+		switch {
+		case ap < bp:
+			return -1
+		case ap > bp:
+			return 1
+		default:
+			return 0
+		}
+	case reflect.Struct:
+		for i := 0; i < aVal.NumField(); i++ {
+			if c := compare(aVal.Field(i), bVal.Field(i)); c != 0 {
+				return c
+			}
+		}
+		return 0
+	case reflect.Array:
+		for i := 0; i < aVal.Len(); i++ {
+			if c := compare(aVal.Index(i), bVal.Index(i)); c != 0 {
+				return c
+			}
+		}
+		return 0
+	case reflect.Interface:
+		if c, ok := nilCompare(aVal, bVal); ok {
+			return c
+		}
+		c := compare(reflect.ValueOf(aVal.Elem().Type()), reflect.ValueOf(bVal.Elem().Type()))
+		if c != 0 {
+			return c
+		}
+		return compare(aVal.Elem(), bVal.Elem())
+	default:
+		// Certain types cannot appear as keys (maps, funcs, slices), but be explicit.
+		panic("bad type in compare: " + aType.String())
+	}
+}
+
+// nilCompare checks whether either value is nil. If not, the boolean is false.
+// If either value is nil, the boolean is true and the integer is the comparison
+// value. The comparison is defined to be 0 if both are nil, otherwise the one
+// nil value compares low. Both arguments must represent a chan, func,
+// interface, map, pointer, or slice.
+func nilCompare(aVal, bVal reflect.Value) (int, bool) {
+	if aVal.IsNil() {
+		if bVal.IsNil() {
+			return 0, true
+		}
+		return -1, true
+	}
+	if bVal.IsNil() {
+		return 1, true
+	}
+	return 0, false
+}
+
+// floatCompare compares two floating-point values. NaNs compare low.
+func floatCompare(a, b float64) int {
+	switch {
+	case isNaN(a):
+		return -1 // No good answer if b is a NaN so don't bother checking.
+	case isNaN(b):
+		return 1
+	case a < b:
+		return -1
+	case a > b:
+		return 1
+	}
+	return 0
+}
+
+func isNaN(a float64) bool {
+	return a != a
+}
diff --git a/third-party/go/template/exec.go b/third-party/go/template/exec.go
new file mode 100644
index 0000000..b4af1ad
--- /dev/null
+++ b/third-party/go/template/exec.go
@@ -0,0 +1,1079 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package template
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/apache/skywalking-infra-e2e/third-party/go/internal/fmtsort"
+	"github.com/apache/skywalking-infra-e2e/third-party/go/template/parse"
+	"gopkg.in/yaml.v3"
+	"io"
+	"reflect"
+	"runtime"
+	"strings"
+)
+
+// maxExecDepth specifies the maximum stack depth of templates within
+// templates. This limit is only practically reached by accidentally
+// recursive template invocations. This limit allows us to return
+// an error instead of triggering a stack overflow.
+var maxExecDepth = initMaxExecDepth()
+
+func initMaxExecDepth() int {
+	if runtime.GOARCH == "wasm" {
+		return 1000
+	}
+	return 100000
+}
+
+// state represents the state of an execution. It's not part of the
+// template so that multiple executions of the same template
+// can execute in parallel.
+type state struct {
+	tmpl  *Template
+	wr    io.Writer
+	node  parse.Node // current node, for errors
+	vars  []variable // push-down stack of variable values.
+	depth int        // the height of the stack of executing templates.
+}
+
+// variable holds the dynamic value of a variable such as $, $x etc.
+type variable struct {
+	name  string
+	value reflect.Value
+}
+
+// push pushes a new variable on the stack.
+func (s *state) push(name string, value reflect.Value) {
+	s.vars = append(s.vars, variable{name, value})
+}
+
+// mark returns the length of the variable stack.
+func (s *state) mark() int {
+	return len(s.vars)
+}
+
+// pop pops the variable stack up to the mark.
+func (s *state) pop(mark int) {
+	s.vars = s.vars[0:mark]
+}
+
+// setVar overwrites the last declared variable with the given name.
+// Used by variable assignments.
+func (s *state) setVar(name string, value reflect.Value) {
+	for i := s.mark() - 1; i >= 0; i-- {
+		if s.vars[i].name == name {
+			s.vars[i].value = value
+			return
+		}
+	}
+	s.errorf("undefined variable: %s", name)
+}
+
+// setTopVar overwrites the top-nth variable on the stack. Used by range iterations.
+func (s *state) setTopVar(n int, value reflect.Value) {
+	s.vars[len(s.vars)-n].value = value
+}
+
+// varValue returns the value of the named variable.
+func (s *state) varValue(name string) reflect.Value {
+	for i := s.mark() - 1; i >= 0; i-- {
+		if s.vars[i].name == name {
+			return s.vars[i].value
+		}
+	}
+	s.errorf("undefined variable: %s", name)
+	return zero
+}
+
+var zero reflect.Value
+
+type missingValType struct{}
+
+var missingVal = reflect.ValueOf(missingValType{})
+
+// at marks the state to be on node n, for error reporting.
+func (s *state) at(node parse.Node) {
+	s.node = node
+}
+
+// doublePercent returns the string with %'s replaced by %%, if necessary,
+// so it can be used safely inside a Printf format string.
+func doublePercent(str string) string {
+	return strings.ReplaceAll(str, "%", "%%")
+}
+
+// TODO: It would be nice if ExecError was more broken down, but
+// the way ErrorContext embeds the template name makes the
+// processing too clumsy.
+
+// ExecError is the custom error type returned when Execute has an
+// error evaluating its template. (If a write error occurs, the actual
+// error is returned; it will not be of type ExecError.)
+type ExecError struct {
+	Name string // Name of template.
+	Err  error  // Pre-formatted error.
+}
+
+func (e ExecError) Error() string {
+	return e.Err.Error()
+}
+
+func (e ExecError) Unwrap() error {
+	return e.Err
+}
+
+// errorf records an ExecError and terminates processing.
+func (s *state) errorf(format string, args ...interface{}) {
+	name := doublePercent(s.tmpl.Name())
+	if s.node == nil {
+		format = fmt.Sprintf("template: %s: %s", name, format)
+	} else {
+		location, context := s.tmpl.ErrorContext(s.node)
+		format = fmt.Sprintf("template: %s: executing %q at <%s>: %s", location, name, doublePercent(context), format)
+	}
+	panic(ExecError{
+		Name: s.tmpl.Name(),
+		Err:  fmt.Errorf(format, args...),
+	})
+}
+
+// writeError is the wrapper type used internally when Execute has an
+// error writing to its output. We strip the wrapper in errRecover.
+// Note that this is not an implementation of error, so it cannot escape
+// from the package as an error value.
+type writeError struct {
+	Err error // Original error.
+}
+
+func (s *state) writeError(err error) {
+	panic(writeError{
+		Err: err,
+	})
+}
+
+// errRecover is the handler that turns panics into returns from the top
+// level of Parse.
+func errRecover(errp *error) {
+	e := recover()
+	if e != nil {
+		switch err := e.(type) {
+		case runtime.Error:
+			panic(e)
+		case writeError:
+			*errp = err.Err // Strip the wrapper.
+		case ExecError:
+			*errp = err // Keep the wrapper.
+		default:
+			panic(e)
+		}
+	}
+}
+
+// ExecuteTemplate applies the template associated with t that has the given name
+// to the specified data object and writes the output to wr.
+// If an error occurs executing the template or writing its output,
+// execution stops, but partial results may already have been written to
+// the output writer.
+// A template may be executed safely in parallel, although if parallel
+// executions share a Writer the output may be interleaved.
+func (t *Template) ExecuteTemplate(wr io.Writer, name string, data interface{}) error {
+	var tmpl *Template
+	if t.common != nil {
+		tmpl = t.tmpl[name]
+	}
+	if tmpl == nil {
+		return fmt.Errorf("template: no template %q associated with template %q", name, t.name)
+	}
+	return tmpl.Execute(wr, data)
+}
+
+// Execute applies a parsed template to the specified data object,
+// and writes the output to wr.
+// If an error occurs executing the template or writing its output,
+// execution stops, but partial results may already have been written to
+// the output writer.
+// A template may be executed safely in parallel, although if parallel
+// executions share a Writer the output may be interleaved.
+//
+// If data is a reflect.Value, the template applies to the concrete
+// value that the reflect.Value holds, as in fmt.Print.
+func (t *Template) Execute(wr io.Writer, data interface{}) error {
+	return t.execute(wr, data)
+}
+
+func (t *Template) execute(wr io.Writer, data interface{}) (err error) {
+	defer errRecover(&err)
+	value, ok := data.(reflect.Value)
+	if !ok {
+		value = reflect.ValueOf(data)
+	}
+	state := &state{
+		tmpl: t,
+		wr:   wr,
+		vars: []variable{{"$", value}},
+	}
+	if t.Tree == nil || t.Root == nil {
+		state.errorf("%q is an incomplete or empty template", t.Name())
+	}
+	state.walk(value, t.Root)
+	return
+}
+
+// DefinedTemplates returns a string listing the defined templates,
+// prefixed by the string "; defined templates are: ". If there are none,
+// it returns the empty string. For generating an error message here
+// and in html/template.
+func (t *Template) DefinedTemplates() string {
+	if t.common == nil {
+		return ""
+	}
+	var b strings.Builder
+	for name, tmpl := range t.tmpl {
+		if tmpl.Tree == nil || tmpl.Root == nil {
+			continue
+		}
+		if b.Len() == 0 {
+			b.WriteString("; defined templates are: ")
+		} else {
+			b.WriteString(", ")
+		}
+		fmt.Fprintf(&b, "%q", name)
+	}
+	return b.String()
+}
+
+// Walk functions step through the major pieces of the template structure,
+// generating output as they go.
+func (s *state) walk(dot reflect.Value, node parse.Node) {
+	s.at(node)
+	switch node := node.(type) {
+	case *parse.ActionNode:
+		// Do not pop variables so they persist until next end.
+		// Also, if the action declares variables, don't print the result.
+		val := s.evalPipeline(dot, node.Pipe)
+		if len(node.Pipe.Decl) == 0 {
+			s.printValue(node, val)
+		}
+	case *parse.IfNode:
+		s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
+	case *parse.ListNode:
+		for _, node := range node.Nodes {
+			s.walk(dot, node)
+		}
+	case *parse.RangeNode:
+		s.walkRange(dot, node)
+	case *parse.TemplateNode:
+		s.walkTemplate(dot, node)
+	case *parse.TextNode:
+		if _, err := s.wr.Write(node.Text); err != nil {
+			s.writeError(err)
+		}
+	case *parse.WithNode:
+		s.walkIfOrWith(parse.NodeWith, dot, node.Pipe, node.List, node.ElseList)
+	case *parse.AtLeastOnceNode:
+		s.walkAtLeastOnce(dot, node)
+	default:
+		s.errorf("unknown node: %s", node)
+	}
+}
+
+// walkIfOrWith walks an 'if' or 'with' node. The two control structures
+// are identical in behavior except that 'with' sets dot.
+func (s *state) walkIfOrWith(typ parse.NodeType, dot reflect.Value, pipe *parse.PipeNode, list, elseList *parse.ListNode) {
+	defer s.pop(s.mark())
+	val := s.evalPipeline(dot, pipe)
+	truth, ok := isTrue(indirectInterface(val))
+	if !ok {
+		s.errorf("if/with can't use %v", val)
+	}
+	if truth {
+		if typ == parse.NodeWith {
+			s.walk(val, list)
+		} else {
+			s.walk(dot, list)
+		}
+	} else if elseList != nil {
+		s.walk(dot, elseList)
+	}
+}
+
+// IsTrue reports whether the value is 'true', in the sense of not the zero of its type,
+// and whether the value has a meaningful truth value. This is the definition of
+// truth used by if and other such actions.
+func IsTrue(val interface{}) (truth, ok bool) {
+	return isTrue(reflect.ValueOf(val))
+}
+
+func isTrue(val reflect.Value) (truth, ok bool) {
+	if !val.IsValid() {
+		// Something like var x interface{}, never set. It's a form of nil.
+		return false, true
+	}
+	switch val.Kind() {
+	case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
+		truth = val.Len() > 0
+	case reflect.Bool:
+		truth = val.Bool()
+	case reflect.Complex64, reflect.Complex128:
+		truth = val.Complex() != 0
+	case reflect.Chan, reflect.Func, reflect.Ptr, reflect.Interface:
+		truth = !val.IsNil()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		truth = val.Int() != 0
+	case reflect.Float32, reflect.Float64:
+		truth = val.Float() != 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		truth = val.Uint() != 0
+	case reflect.Struct:
+		truth = true // Struct values are always true.
+	default:
+		return
+	}
+	return truth, true
+}
+
+func (s *state) walkRange(dot reflect.Value, r *parse.RangeNode) {
+	s.at(r)
+	defer s.pop(s.mark())
+	val, _ := indirect(s.evalPipeline(dot, r.Pipe))
+	// mark top of stack before any variables in the body are pushed.
+	mark := s.mark()
+	oneIteration := func(index, elem reflect.Value) {
+		// Set top var (lexically the second if there are two) to the element.
+		if len(r.Pipe.Decl) > 0 {
+			s.setTopVar(1, elem)
+		}
+		// Set next var (lexically the first if there are two) to the index.
+		if len(r.Pipe.Decl) > 1 {
+			s.setTopVar(2, index)
+		}
+		s.walk(elem, r.List)
+		s.pop(mark)
+	}
+	switch val.Kind() {
+	case reflect.Array, reflect.Slice:
+		if val.Len() == 0 {
+			break
+		}
+		for i := 0; i < val.Len(); i++ {
+			oneIteration(reflect.ValueOf(i), val.Index(i))
+		}
+		return
+	case reflect.Map:
+		if val.Len() == 0 {
+			break
+		}
+		om := fmtsort.Sort(val)
+		for i, key := range om.Key {
+			oneIteration(key, om.Value[i])
+		}
+		return
+	case reflect.Chan:
+		if val.IsNil() {
+			break
+		}
+		i := 0
+		for ; ; i++ {
+			elem, ok := val.Recv()
+			if !ok {
+				break
+			}
+			oneIteration(reflect.ValueOf(i), elem)
+		}
+		if i == 0 {
+			break
+		}
+		return
+	case reflect.Invalid:
+		break // An invalid value is likely a nil map, etc. and acts like an empty map.
+	default:
+		s.errorf("range can't iterate over %v", val)
+	}
+	if r.ElseList != nil {
+		s.walk(dot, r.ElseList)
+	}
+}
+
+func (s *state) walkAtLeastOnce(dot reflect.Value, r *parse.AtLeastOnceNode) {
+	s.at(r)
+	defer s.pop(s.mark())
+	val, _ := indirect(s.evalPipeline(dot, r.Pipe))
+	// mark top of stack before any variables in the body are pushed.
+	mark := s.mark()
+	oneIteration := func(index, elem reflect.Value) interface{} {
+		var b bytes.Buffer
+		ob := s.wr
+		s.wr = &b
+
+		// Set top var (lexically the second if there are two) to the element.
+		if len(r.Pipe.Decl) > 0 {
+			s.setTopVar(1, elem)
+		}
+		// Set next var (lexically the first if there are two) to the index.
+		if len(r.Pipe.Decl) > 1 {
+			s.setTopVar(2, index)
+		}
+		s.walk(elem, r.List)
+		s.pop(mark)
+
+		s.wr = ob
+
+		var re interface{}
+		yaml.Unmarshal(b.Bytes(), &re)
+		return re
+	}
+	switch val.Kind() {
+	case reflect.Array, reflect.Slice:
+		if val.Len() == 0 {
+			break
+		}
+		match := false
+		sss := make([]interface{}, val.Len())
+		for i := 0; i < val.Len(); i++ {
+			actual := oneIteration(reflect.ValueOf(i), val.Index(i))
+			sss[i] = actual
+			value, _ := printableValue(val.Index(i))
+			if fmt.Sprint(value) == fmt.Sprint(actual) {
+				match = true
+				break
+			}
+		}
+		var marshal []byte
+		if match {
+			value, _ := printableValue(val)
+			marshal, _ = yaml.Marshal(value)
+		} else {
+			marshal, _ = yaml.Marshal(sss)
+		}
+		s.wr.Write(append([]byte("\n"), marshal...))
+		return
+	case reflect.Map:
+		if val.Len() == 0 {
+			break
+		}
+		om := fmtsort.Sort(val)
+		for i, key := range om.Key {
+			oneIteration(key, om.Value[i])
+		}
+		return
+	case reflect.Chan:
+		if val.IsNil() {
+			break
+		}
+		i := 0
+		for ; ; i++ {
+			elem, ok := val.Recv()
+			if !ok {
+				break
+			}
+			oneIteration(reflect.ValueOf(i), elem)
+		}
+		if i == 0 {
+			break
+		}
+		return
+	case reflect.Invalid:
+		break // An invalid value is likely a nil map, etc. and acts like an empty map.
+	default:
+		s.errorf("range can't iterate over %v", val)
+	}
+	if r.ElseList != nil {
+		s.walk(dot, r.ElseList)
+	}
+}
+
+func (s *state) walkTemplate(dot reflect.Value, t *parse.TemplateNode) {
+	s.at(t)
+	tmpl := s.tmpl.tmpl[t.Name]
+	if tmpl == nil {
+		s.errorf("template %q not defined", t.Name)
+	}
+	if s.depth == maxExecDepth {
+		s.errorf("exceeded maximum template depth (%v)", maxExecDepth)
+	}
+	// Variables declared by the pipeline persist.
+	dot = s.evalPipeline(dot, t.Pipe)
+	newState := *s
+	newState.depth++
+	newState.tmpl = tmpl
+	// No dynamic scoping: template invocations inherit no variables.
+	newState.vars = []variable{{"$", dot}}
+	newState.walk(dot, tmpl.Root)
+}
+
+// Eval functions evaluate pipelines, commands, and their elements and extract
+// values from the data structure by examining fields, calling methods, and so on.
+// The printing of those values happens only through walk functions.
+
+// evalPipeline returns the value acquired by evaluating a pipeline. If the
+// pipeline has a variable declaration, the variable will be pushed on the
+// stack. Callers should therefore pop the stack after they are finished
+// executing commands depending on the pipeline value.
+func (s *state) evalPipeline(dot reflect.Value, pipe *parse.PipeNode) (value reflect.Value) {
+	if pipe == nil {
+		return
+	}
+	s.at(pipe)
+	value = missingVal
+	for _, cmd := range pipe.Cmds {
+		value = s.evalCommand(dot, cmd, value) // previous value is this one's final arg.
+		// If the object has type interface{}, dig down one level to the thing inside.
+		if value.Kind() == reflect.Interface && value.Type().NumMethod() == 0 {
+			value = reflect.ValueOf(value.Interface()) // lovely!
+		}
+	}
+	for _, variable := range pipe.Decl {
+		if pipe.IsAssign {
+			s.setVar(variable.Ident[0], value)
+		} else {
+			s.push(variable.Ident[0], value)
+		}
+	}
+	return value
+}
+
+func (s *state) notAFunction(args []parse.Node, final reflect.Value) {
+	if len(args) > 1 || final != missingVal {
+		s.errorf("can't give argument to non-function %s", args[0])
+	}
+}
+
+func (s *state) evalCommand(dot reflect.Value, cmd *parse.CommandNode, final reflect.Value) reflect.Value {
+	firstWord := cmd.Args[0]
+	switch n := firstWord.(type) {
+	case *parse.FieldNode:
+		return s.evalFieldNode(dot, n, cmd.Args, final)
+	case *parse.ChainNode:
+		return s.evalChainNode(dot, n, cmd.Args, final)
+	case *parse.IdentifierNode:
+		// Must be a function.
+		return s.evalFunction(dot, n, cmd, cmd.Args, final)
+	case *parse.PipeNode:
+		// Parenthesized pipeline. The arguments are all inside the pipeline; final must be absent.
+		s.notAFunction(cmd.Args, final)
+		return s.evalPipeline(dot, n)
+	case *parse.VariableNode:
+		return s.evalVariableNode(dot, n, cmd.Args, final)
+	}
+	s.at(firstWord)
+	s.notAFunction(cmd.Args, final)
+	switch word := firstWord.(type) {
+	case *parse.BoolNode:
+		return reflect.ValueOf(word.True)
+	case *parse.DotNode:
+		return dot
+	case *parse.NilNode:
+		s.errorf("nil is not a command")
+	case *parse.NumberNode:
+		return s.idealConstant(word)
+	case *parse.StringNode:
+		return reflect.ValueOf(word.Text)
+	}
+	s.errorf("can't evaluate command %q", firstWord)
+	panic("not reached")
+}
+
+// idealConstant is called to return the value of a number in a context where
+// we don't know the type. In that case, the syntax of the number tells us
+// its type, and we use Go rules to resolve. Note there is no such thing as
+// a uint ideal constant in this situation - the value must be of int type.
+func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
+	// These are ideal constants but we don't know the type
+	// and we have no context.  (If it was a method argument,
+	// we'd know what we need.) The syntax guides us to some extent.
+	s.at(constant)
+	switch {
+	case constant.IsComplex:
+		return reflect.ValueOf(constant.Complex128) // incontrovertible.
+
+	case constant.IsFloat &&
+		!isHexInt(constant.Text) && !isRuneInt(constant.Text) &&
+		strings.ContainsAny(constant.Text, ".eEpP"):
+		return reflect.ValueOf(constant.Float64)
+
+	case constant.IsInt:
+		n := int(constant.Int64)
+		if int64(n) != constant.Int64 {
+			s.errorf("%s overflows int", constant.Text)
+		}
+		return reflect.ValueOf(n)
+
+	case constant.IsUint:
+		s.errorf("%s overflows int", constant.Text)
+	}
+	return zero
+}
+
+func isRuneInt(s string) bool {
+	return len(s) > 0 && s[0] == '\''
+}
+
+func isHexInt(s string) bool {
+	return len(s) > 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X') && !strings.ContainsAny(s, "pP")
+}
+
+func (s *state) evalFieldNode(dot reflect.Value, field *parse.FieldNode, args []parse.Node, final reflect.Value) reflect.Value {
+	s.at(field)
+	return s.evalFieldChain(dot, dot, field, field.Ident, args, final)
+}
+
+func (s *state) evalChainNode(dot reflect.Value, chain *parse.ChainNode, args []parse.Node, final reflect.Value) reflect.Value {
+	s.at(chain)
+	if len(chain.Field) == 0 {
+		s.errorf("internal error: no fields in evalChainNode")
+	}
+	if chain.Node.Type() == parse.NodeNil {
+		s.errorf("indirection through explicit nil in %s", chain)
+	}
+	// (pipe).Field1.Field2 has pipe as .Node, fields as .Field. Eval the pipeline, then the fields.
+	pipe := s.evalArg(dot, nil, chain.Node)
+	return s.evalFieldChain(dot, pipe, chain, chain.Field, args, final)
+}
+
+func (s *state) evalVariableNode(dot reflect.Value, variable *parse.VariableNode, args []parse.Node, final reflect.Value) reflect.Value {
+	// $x.Field has $x as the first ident, Field as the second. Eval the var, then the fields.
+	s.at(variable)
+	value := s.varValue(variable.Ident[0])
+	if len(variable.Ident) == 1 {
+		s.notAFunction(args, final)
+		return value
+	}
+	return s.evalFieldChain(dot, value, variable, variable.Ident[1:], args, final)
+}
+
+// evalFieldChain evaluates .X.Y.Z possibly followed by arguments.
+// dot is the environment in which to evaluate arguments, while
+// receiver is the value being walked along the chain.
+func (s *state) evalFieldChain(dot, receiver reflect.Value, node parse.Node, ident []string, args []parse.Node, final reflect.Value) reflect.Value {
+	n := len(ident)
+	for i := 0; i < n-1; i++ {
+		receiver = s.evalField(dot, ident[i], node, nil, missingVal, receiver)
+	}
+	// Now if it's a method, it gets the arguments.
+	return s.evalField(dot, ident[n-1], node, args, final, receiver)
+}
+
+func (s *state) evalFunction(dot reflect.Value, node *parse.IdentifierNode, cmd parse.Node, args []parse.Node, final reflect.Value) reflect.Value {
+	s.at(node)
+	name := node.Ident
+	function, ok := findFunction(name, s.tmpl)
+	if !ok {
+		s.errorf("%q is not a defined function", name)
+	}
+	return s.evalCall(dot, function, cmd, name, args, final)
+}
+
+// evalField evaluates an expression like (.Field) or (.Field arg1 arg2).
+// The 'final' argument represents the return value from the preceding
+// value of the pipeline, if any.
+func (s *state) evalField(dot reflect.Value, fieldName string, node parse.Node, args []parse.Node, final, receiver reflect.Value) reflect.Value {
+	if !receiver.IsValid() {
+		if s.tmpl.option.missingKey == mapError { // Treat invalid value as missing map key.
+			s.errorf("nil data; no entry for key %q", fieldName)
+		}
+		return zero
+	}
+	typ := receiver.Type()
+	receiver, isNil := indirect(receiver)
+	if receiver.Kind() == reflect.Interface && isNil {
+		// Calling a method on a nil interface can't work. The
+		// MethodByName method call below would panic.
+		s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
+		return zero
+	}
+
+	// Unless it's an interface, need to get to a value of type *T to guarantee
+	// we see all methods of T and *T.
+	ptr := receiver
+	if ptr.Kind() != reflect.Interface && ptr.Kind() != reflect.Ptr && ptr.CanAddr() {
+		ptr = ptr.Addr()
+	}
+	if method := ptr.MethodByName(fieldName); method.IsValid() {
+		return s.evalCall(dot, method, node, fieldName, args, final)
+	}
+	hasArgs := len(args) > 1 || final != missingVal
+	// It's not a method; must be a field of a struct or an element of a map.
+	switch receiver.Kind() {
+	case reflect.Struct:
+		tField, ok := receiver.Type().FieldByName(fieldName)
+		if ok {
+			field := receiver.FieldByIndex(tField.Index)
+			if tField.PkgPath != "" { // field is unexported
+				s.errorf("%s is an unexported field of struct type %s", fieldName, typ)
+			}
+			// If it's a function, we must call it.
+			if hasArgs {
+				s.errorf("%s has arguments but cannot be invoked as function", fieldName)
+			}
+			return field
+		}
+	case reflect.Map:
+		// If it's a map, attempt to use the field name as a key.
+		nameVal := reflect.ValueOf(fieldName)
+		if nameVal.Type().AssignableTo(receiver.Type().Key()) {
+			if hasArgs {
+				s.errorf("%s is not a method but has arguments", fieldName)
+			}
+			result := receiver.MapIndex(nameVal)
+			if !result.IsValid() {
+				switch s.tmpl.option.missingKey {
+				case mapInvalid:
+					// Just use the invalid value.
+				case mapZeroValue:
+					result = reflect.Zero(receiver.Type().Elem())
+				case mapError:
+					s.errorf("map has no entry for key %q", fieldName)
+				}
+			}
+			return result
+		}
+	case reflect.Ptr:
+		etyp := receiver.Type().Elem()
+		if etyp.Kind() == reflect.Struct {
+			if _, ok := etyp.FieldByName(fieldName); !ok {
+				// If there's no such field, say "can't evaluate"
+				// instead of "nil pointer evaluating".
+				break
+			}
+		}
+		if isNil {
+			s.errorf("nil pointer evaluating %s.%s", typ, fieldName)
+		}
+	}
+	s.errorf("can't evaluate field %s in type %s", fieldName, typ)
+	panic("not reached")
+}
+
+var (
+	errorType        = reflect.TypeOf((*error)(nil)).Elem()
+	fmtStringerType  = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
+	reflectValueType = reflect.TypeOf((*reflect.Value)(nil)).Elem()
+)
+
+// evalCall executes a function or method call. If it's a method, fun already has the receiver bound, so
+// it looks just like a function call. The arg list, if non-nil, includes (in the manner of the shell), arg[0]
+// as the function itself.
+func (s *state) evalCall(dot, fun reflect.Value, node parse.Node, name string, args []parse.Node, final reflect.Value) reflect.Value {
+	if args != nil {
+		args = args[1:] // Zeroth arg is function name/node; not passed to function.
+	}
+	typ := fun.Type()
+	numIn := len(args)
+	if final != missingVal {
+		numIn++
+	}
+	numFixed := len(args)
+	if typ.IsVariadic() {
+		numFixed = typ.NumIn() - 1 // last arg is the variadic one.
+		if numIn < numFixed {
+			s.errorf("wrong number of args for %s: want at least %d got %d", name, typ.NumIn()-1, len(args))
+		}
+	} else if numIn != typ.NumIn() {
+		s.errorf("wrong number of args for %s: want %d got %d", name, typ.NumIn(), numIn)
+	}
+	if !goodFunc(typ) {
+		// TODO: This could still be a confusing error; maybe goodFunc should provide info.
+		s.errorf("can't call method/function %q with %d results", name, typ.NumOut())
+	}
+	// Build the arg list.
+	argv := make([]reflect.Value, numIn)
+	// Args must be evaluated. Fixed args first.
+	i := 0
+	for ; i < numFixed && i < len(args); i++ {
+		argv[i] = s.evalArg(dot, typ.In(i), args[i])
+	}
+	// Now the ... args.
+	if typ.IsVariadic() {
+		argType := typ.In(typ.NumIn() - 1).Elem() // Argument is a slice.
+		for ; i < len(args); i++ {
+			argv[i] = s.evalArg(dot, argType, args[i])
+		}
+	}
+	// Add final value if necessary.
+	if final != missingVal {
+		t := typ.In(typ.NumIn() - 1)
+		if typ.IsVariadic() {
+			if numIn-1 < numFixed {
+				// The added final argument corresponds to a fixed parameter of the function.
+				// Validate against the type of the actual parameter.
+				t = typ.In(numIn - 1)
+			} else {
+				// The added final argument corresponds to the variadic part.
+				// Validate against the type of the elements of the variadic slice.
+				t = t.Elem()
+			}
+		}
+		argv[i] = s.validateType(final, t)
+	}
+	v, err := safeCall(fun, argv)
+	// If we have an error that is not nil, stop execution and return that
+	// error to the caller.
+	if err != nil {
+		s.at(node)
+		s.errorf("error calling %s: %v", name, err)
+	}
+	if v.Type() == reflectValueType {
+		v = v.Interface().(reflect.Value)
+	}
+	return v
+}
+
+// canBeNil reports whether an untyped nil can be assigned to the type. See reflect.Zero.
+func canBeNil(typ reflect.Type) bool {
+	switch typ.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+		return true
+	case reflect.Struct:
+		return typ == reflectValueType
+	}
+	return false
+}
+
+// validateType guarantees that the value is valid and assignable to the type.
+func (s *state) validateType(value reflect.Value, typ reflect.Type) reflect.Value {
+	if !value.IsValid() {
+		if typ == nil {
+			// An untyped nil interface{}. Accept as a proper nil value.
+			return reflect.ValueOf(nil)
+		}
+		if canBeNil(typ) {
+			// Like above, but use the zero value of the non-nil type.
+			return reflect.Zero(typ)
+		}
+		s.errorf("invalid value; expected %s", typ)
+	}
+	if typ == reflectValueType && value.Type() != typ {
+		return reflect.ValueOf(value)
+	}
+	if typ != nil && !value.Type().AssignableTo(typ) {
+		if value.Kind() == reflect.Interface && !value.IsNil() {
+			value = value.Elem()
+			if value.Type().AssignableTo(typ) {
+				return value
+			}
+			// fallthrough
+		}
+		// Does one dereference or indirection work? We could do more, as we
+		// do with method receivers, but that gets messy and method receivers
+		// are much more constrained, so it makes more sense there than here.
+		// Besides, one is almost always all you need.
+		switch {
+		case value.Kind() == reflect.Ptr && value.Type().Elem().AssignableTo(typ):
+			value = value.Elem()
+			if !value.IsValid() {
+				s.errorf("dereference of nil pointer of type %s", typ)
+			}
+		case reflect.PtrTo(value.Type()).AssignableTo(typ) && value.CanAddr():
+			value = value.Addr()
+		default:
+			s.errorf("wrong type for value; expected %s; got %s", typ, value.Type())
+		}
+	}
+	return value
+}
+
+func (s *state) evalArg(dot reflect.Value, typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	switch arg := n.(type) {
+	case *parse.DotNode:
+		return s.validateType(dot, typ)
+	case *parse.NilNode:
+		if canBeNil(typ) {
+			return reflect.Zero(typ)
+		}
+		s.errorf("cannot assign nil to %s", typ)
+	case *parse.FieldNode:
+		return s.validateType(s.evalFieldNode(dot, arg, []parse.Node{n}, missingVal), typ)
+	case *parse.VariableNode:
+		return s.validateType(s.evalVariableNode(dot, arg, nil, missingVal), typ)
+	case *parse.PipeNode:
+		return s.validateType(s.evalPipeline(dot, arg), typ)
+	case *parse.IdentifierNode:
+		return s.validateType(s.evalFunction(dot, arg, arg, nil, missingVal), typ)
+	case *parse.ChainNode:
+		return s.validateType(s.evalChainNode(dot, arg, nil, missingVal), typ)
+	}
+	switch typ.Kind() {
+	case reflect.Bool:
+		return s.evalBool(typ, n)
+	case reflect.Complex64, reflect.Complex128:
+		return s.evalComplex(typ, n)
+	case reflect.Float32, reflect.Float64:
+		return s.evalFloat(typ, n)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return s.evalInteger(typ, n)
+	case reflect.Interface:
+		if typ.NumMethod() == 0 {
+			return s.evalEmptyInterface(dot, n)
+		}
+	case reflect.Struct:
+		if typ == reflectValueType {
+			return reflect.ValueOf(s.evalEmptyInterface(dot, n))
+		}
+	case reflect.String:
+		return s.evalString(typ, n)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return s.evalUnsignedInteger(typ, n)
+	}
+	s.errorf("can't handle %s for arg of type %s", n, typ)
+	panic("not reached")
+}
+
+func (s *state) evalBool(typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	if n, ok := n.(*parse.BoolNode); ok {
+		value := reflect.New(typ).Elem()
+		value.SetBool(n.True)
+		return value
+	}
+	s.errorf("expected bool; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalString(typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	if n, ok := n.(*parse.StringNode); ok {
+		value := reflect.New(typ).Elem()
+		value.SetString(n.Text)
+		return value
+	}
+	s.errorf("expected string; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalInteger(typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	if n, ok := n.(*parse.NumberNode); ok && n.IsInt {
+		value := reflect.New(typ).Elem()
+		value.SetInt(n.Int64)
+		return value
+	}
+	s.errorf("expected integer; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalUnsignedInteger(typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	if n, ok := n.(*parse.NumberNode); ok && n.IsUint {
+		value := reflect.New(typ).Elem()
+		value.SetUint(n.Uint64)
+		return value
+	}
+	s.errorf("expected unsigned integer; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalFloat(typ reflect.Type, n parse.Node) reflect.Value {
+	s.at(n)
+	if n, ok := n.(*parse.NumberNode); ok && n.IsFloat {
+		value := reflect.New(typ).Elem()
+		value.SetFloat(n.Float64)
+		return value
+	}
+	s.errorf("expected float; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalComplex(typ reflect.Type, n parse.Node) reflect.Value {
+	if n, ok := n.(*parse.NumberNode); ok && n.IsComplex {
+		value := reflect.New(typ).Elem()
+		value.SetComplex(n.Complex128)
+		return value
+	}
+	s.errorf("expected complex; found %s", n)
+	panic("not reached")
+}
+
+func (s *state) evalEmptyInterface(dot reflect.Value, n parse.Node) reflect.Value {
+	s.at(n)
+	switch n := n.(type) {
+	case *parse.BoolNode:
+		return reflect.ValueOf(n.True)
+	case *parse.DotNode:
+		return dot
+	case *parse.FieldNode:
+		return s.evalFieldNode(dot, n, nil, missingVal)
+	case *parse.IdentifierNode:
+		return s.evalFunction(dot, n, n, nil, missingVal)
+	case *parse.NilNode:
+		// NilNode is handled in evalArg, the only place that calls here.
+		s.errorf("evalEmptyInterface: nil (can't happen)")
+	case *parse.NumberNode:
+		return s.idealConstant(n)
+	case *parse.StringNode:
+		return reflect.ValueOf(n.Text)
+	case *parse.VariableNode:
+		return s.evalVariableNode(dot, n, nil, missingVal)
+	case *parse.PipeNode:
+		return s.evalPipeline(dot, n)
+	}
+	s.errorf("can't handle assignment of %s to empty interface argument", n)
+	panic("not reached")
+}
+
+// indirect returns the item at the end of indirection, and a bool to indicate
+// if it's nil. If the returned bool is true, the returned value's kind will be
+// either a pointer or interface.
+func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
+	for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() {
+		if v.IsNil() {
+			return v, true
+		}
+	}
+	return v, false
+}
+
+// indirectInterface returns the concrete value in an interface value,
+// or else the zero reflect.Value.
+// That is, if v represents the interface value x, the result is the same as reflect.ValueOf(x):
+// the fact that x was an interface value is forgotten.
+func indirectInterface(v reflect.Value) reflect.Value {
+	if v.Kind() != reflect.Interface {
+		return v
+	}
+	if v.IsNil() {
+		return reflect.Value{}
+	}
+	return v.Elem()
+}
+
+// printValue writes the textual representation of the value to the output of
+// the template.
+func (s *state) printValue(n parse.Node, v reflect.Value) {
+	s.at(n)
+	iface, ok := printableValue(v)
+	if !ok {
+		s.errorf("can't print %s of type %s", n, v.Type())
+	}
+	_, err := fmt.Fprint(s.wr, iface)
+	if err != nil {
+		s.writeError(err)
+	}
+}
+
+// printableValue returns the, possibly indirected, interface value inside v that
+// is best for a call to formatted printer.
+func printableValue(v reflect.Value) (interface{}, bool) {
+	if v.Kind() == reflect.Ptr {
+		v, _ = indirect(v) // fmt.Fprint handles nil.
+	}
+	if !v.IsValid() {
+		return "<no value>", true
+	}
+
+	if !v.Type().Implements(errorType) && !v.Type().Implements(fmtStringerType) {
+		if v.CanAddr() && (reflect.PtrTo(v.Type()).Implements(errorType) || reflect.PtrTo(v.Type()).Implements(fmtStringerType)) {
+			v = v.Addr()
+		} else {
+			switch v.Kind() {
+			case reflect.Chan, reflect.Func:
+				return nil, false
+			}
+		}
+	}
+	return v.Interface(), true
+}
diff --git a/third-party/go/template/funcs.go b/third-party/go/template/funcs.go
new file mode 100644
index 0000000..6a670fc
--- /dev/null
+++ b/third-party/go/template/funcs.go
@@ -0,0 +1,769 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package template
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+	"reflect"
+	"strings"
+	"sync"
+	"unicode"
+	"unicode/utf8"
+)
+
+// FuncMap is the type of the map defining the mapping from names to functions.
+// Each function must have either a single return value, or two return values of
+// which the second has type error. In that case, if the second (error)
+// return value evaluates to non-nil during execution, execution terminates and
+// Execute returns that error.
+//
+// When template execution invokes a function with an argument list, that list
+// must be assignable to the function's parameter types. Functions meant to
+// apply to arguments of arbitrary type can use parameters of type interface{} or
+// of type reflect.Value. Similarly, functions meant to return a result of arbitrary
+// type can return interface{} or reflect.Value.
+type FuncMap map[string]interface{}
+
+// builtins returns the FuncMap.
+// It is not a global variable so the linker can dead code eliminate
+// more when this isn't called. See golang.org/issue/36021.
+// TODO: revert this back to a global map once golang.org/issue/2559 is fixed.
+func builtins() FuncMap {
+	return FuncMap{
+		"and":      and,
+		"call":     call,
+		"html":     HTMLEscaper,
+		"index":    index,
+		"slice":    slice,
+		"js":       JSEscaper,
+		"len":      length,
+		"not":      not,
+		"or":       or,
+		"print":    fmt.Sprint,
+		"printf":   fmt.Sprintf,
+		"println":  fmt.Sprintln,
+		"urlquery": URLQueryEscaper,
+
+		// Comparisons
+		"eq": eq, // ==
+		"ge": ge, // >=
+		"gt": gt, // >
+		"le": le, // <=
+		"lt": lt, // <
+		"ne": ne, // !=
+	}
+}
+
+var builtinFuncsOnce struct {
+	sync.Once
+	v map[string]reflect.Value
+}
+
+// builtinFuncsOnce lazily computes & caches the builtinFuncs map.
+// TODO: revert this back to a global map once golang.org/issue/2559 is fixed.
+func builtinFuncs() map[string]reflect.Value {
+	builtinFuncsOnce.Do(func() {
+		builtinFuncsOnce.v = createValueFuncs(builtins())
+	})
+	return builtinFuncsOnce.v
+}
+
+// createValueFuncs turns a FuncMap into a map[string]reflect.Value
+func createValueFuncs(funcMap FuncMap) map[string]reflect.Value {
+	m := make(map[string]reflect.Value)
+	addValueFuncs(m, funcMap)
+	return m
+}
+
+// addValueFuncs adds to values the functions in funcs, converting them to reflect.Values.
+func addValueFuncs(out map[string]reflect.Value, in FuncMap) {
+	for name, fn := range in {
+		if !goodName(name) {
+			panic(fmt.Errorf("function name %q is not a valid identifier", name))
+		}
+		v := reflect.ValueOf(fn)
+		if v.Kind() != reflect.Func {
+			panic("value for " + name + " not a function")
+		}
+		if !goodFunc(v.Type()) {
+			panic(fmt.Errorf("can't install method/function %q with %d results", name, v.Type().NumOut()))
+		}
+		out[name] = v
+	}
+}
+
+// addFuncs adds to values the functions in funcs. It does no checking of the input -
+// call addValueFuncs first.
+func addFuncs(out, in FuncMap) {
+	for name, fn := range in {
+		out[name] = fn
+	}
+}
+
+// goodFunc reports whether the function or method has the right result signature.
+func goodFunc(typ reflect.Type) bool {
+	// We allow functions with 1 result or 2 results where the second is an error.
+	switch {
+	case typ.NumOut() == 1:
+		return true
+	case typ.NumOut() == 2 && typ.Out(1) == errorType:
+		return true
+	}
+	return false
+}
+
+// goodName reports whether the function name is a valid identifier.
+func goodName(name string) bool {
+	if name == "" {
+		return false
+	}
+	for i, r := range name {
+		switch {
+		case r == '_':
+		case i == 0 && !unicode.IsLetter(r):
+			return false
+		case !unicode.IsLetter(r) && !unicode.IsDigit(r):
+			return false
+		}
+	}
+	return true
+}
+
+// findFunction looks for a function in the template, and global map.
+func findFunction(name string, tmpl *Template) (reflect.Value, bool) {
+	if tmpl != nil && tmpl.common != nil {
+		tmpl.muFuncs.RLock()
+		defer tmpl.muFuncs.RUnlock()
+		if fn := tmpl.execFuncs[name]; fn.IsValid() {
+			return fn, true
+		}
+	}
+	if fn := builtinFuncs()[name]; fn.IsValid() {
+		return fn, true
+	}
+	return reflect.Value{}, false
+}
+
+// prepareArg checks if value can be used as an argument of type argType, and
+// converts an invalid value to appropriate zero if possible.
+func prepareArg(value reflect.Value, argType reflect.Type) (reflect.Value, error) {
+	if !value.IsValid() {
+		if !canBeNil(argType) {
+			return reflect.Value{}, fmt.Errorf("value is nil; should be of type %s", argType)
+		}
+		value = reflect.Zero(argType)
+	}
+	if value.Type().AssignableTo(argType) {
+		return value, nil
+	}
+	if intLike(value.Kind()) && intLike(argType.Kind()) && value.Type().ConvertibleTo(argType) {
+		value = value.Convert(argType)
+		return value, nil
+	}
+	return reflect.Value{}, fmt.Errorf("value has type %s; should be %s", value.Type(), argType)
+}
+
+func intLike(typ reflect.Kind) bool {
+	switch typ {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return true
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return true
+	}
+	return false
+}
+
+// indexArg checks if a reflect.Value can be used as an index, and converts it to int if possible.
+func indexArg(index reflect.Value, cap int) (int, error) {
+	var x int64
+	switch index.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		x = index.Int()
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		x = int64(index.Uint())
+	case reflect.Invalid:
+		return 0, fmt.Errorf("cannot index slice/array with nil")
+	default:
+		return 0, fmt.Errorf("cannot index slice/array with type %s", index.Type())
+	}
+	if x < 0 || int(x) < 0 || int(x) > cap {
+		return 0, fmt.Errorf("index out of range: %d", x)
+	}
+	return int(x), nil
+}
+
+// Indexing.
+
+// index returns the result of indexing its first argument by the following
+// arguments. Thus "index x 1 2 3" is, in Go syntax, x[1][2][3]. Each
+// indexed item must be a map, slice, or array.
+func index(item reflect.Value, indexes ...reflect.Value) (reflect.Value, error) {
+	item = indirectInterface(item)
+	if !item.IsValid() {
+		return reflect.Value{}, fmt.Errorf("index of untyped nil")
+	}
+	for _, index := range indexes {
+		index = indirectInterface(index)
+		var isNil bool
+		if item, isNil = indirect(item); isNil {
+			return reflect.Value{}, fmt.Errorf("index of nil pointer")
+		}
+		switch item.Kind() {
+		case reflect.Array, reflect.Slice, reflect.String:
+			x, err := indexArg(index, item.Len())
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			item = item.Index(x)
+		case reflect.Map:
+			index, err := prepareArg(index, item.Type().Key())
+			if err != nil {
+				return reflect.Value{}, err
+			}
+			if x := item.MapIndex(index); x.IsValid() {
+				item = x
+			} else {
+				item = reflect.Zero(item.Type().Elem())
+			}
+		case reflect.Invalid:
+			// the loop holds invariant: item.IsValid()
+			panic("unreachable")
+		default:
+			return reflect.Value{}, fmt.Errorf("can't index item of type %s", item.Type())
+		}
+	}
+	return item, nil
+}
+
+// Slicing.
+
+// slice returns the result of slicing its first argument by the remaining
+// arguments. Thus "slice x 1 2" is, in Go syntax, x[1:2], while "slice x"
+// is x[:], "slice x 1" is x[1:], and "slice x 1 2 3" is x[1:2:3]. The first
+// argument must be a string, slice, or array.
+func slice(item reflect.Value, indexes ...reflect.Value) (reflect.Value, error) {
+	item = indirectInterface(item)
+	if !item.IsValid() {
+		return reflect.Value{}, fmt.Errorf("slice of untyped nil")
+	}
+	if len(indexes) > 3 {
+		return reflect.Value{}, fmt.Errorf("too many slice indexes: %d", len(indexes))
+	}
+	var cap int
+	switch item.Kind() {
+	case reflect.String:
+		if len(indexes) == 3 {
+			return reflect.Value{}, fmt.Errorf("cannot 3-index slice a string")
+		}
+		cap = item.Len()
+	case reflect.Array, reflect.Slice:
+		cap = item.Cap()
+	default:
+		return reflect.Value{}, fmt.Errorf("can't slice item of type %s", item.Type())
+	}
+	// set default values for cases item[:], item[i:].
+	idx := [3]int{0, item.Len()}
+	for i, index := range indexes {
+		x, err := indexArg(index, cap)
+		if err != nil {
+			return reflect.Value{}, err
+		}
+		idx[i] = x
+	}
+	// given item[i:j], make sure i <= j.
+	if idx[0] > idx[1] {
+		return reflect.Value{}, fmt.Errorf("invalid slice index: %d > %d", idx[0], idx[1])
+	}
+	if len(indexes) < 3 {
+		return item.Slice(idx[0], idx[1]), nil
+	}
+	// given item[i:j:k], make sure i <= j <= k.
+	if idx[1] > idx[2] {
+		return reflect.Value{}, fmt.Errorf("invalid slice index: %d > %d", idx[1], idx[2])
+	}
+	return item.Slice3(idx[0], idx[1], idx[2]), nil
+}
+
+// Length
+
+// length returns the length of the item, with an error if it has no defined length.
+func length(item reflect.Value) (int, error) {
+	item, isNil := indirect(item)
+	if isNil {
+		return 0, fmt.Errorf("len of nil pointer")
+	}
+	switch item.Kind() {
+	case reflect.Array, reflect.Chan, reflect.Map, reflect.Slice, reflect.String:
+		return item.Len(), nil
+	}
+	return 0, fmt.Errorf("len of type %s", item.Type())
+}
+
+// Function invocation
+
+// call returns the result of evaluating the first argument as a function.
+// The function must return 1 result, or 2 results, the second of which is an error.
+func call(fn reflect.Value, args ...reflect.Value) (reflect.Value, error) {
+	fn = indirectInterface(fn)
+	if !fn.IsValid() {
+		return reflect.Value{}, fmt.Errorf("call of nil")
+	}
+	typ := fn.Type()
+	if typ.Kind() != reflect.Func {
+		return reflect.Value{}, fmt.Errorf("non-function of type %s", typ)
+	}
+	if !goodFunc(typ) {
+		return reflect.Value{}, fmt.Errorf("function called with %d args; should be 1 or 2", typ.NumOut())
+	}
+	numIn := typ.NumIn()
+	var dddType reflect.Type
+	if typ.IsVariadic() {
+		if len(args) < numIn-1 {
+			return reflect.Value{}, fmt.Errorf("wrong number of args: got %d want at least %d", len(args), numIn-1)
+		}
+		dddType = typ.In(numIn - 1).Elem()
+	} else {
+		if len(args) != numIn {
+			return reflect.Value{}, fmt.Errorf("wrong number of args: got %d want %d", len(args), numIn)
+		}
+	}
+	argv := make([]reflect.Value, len(args))
+	for i, arg := range args {
+		arg = indirectInterface(arg)
+		// Compute the expected type. Clumsy because of variadics.
+		argType := dddType
+		if !typ.IsVariadic() || i < numIn-1 {
+			argType = typ.In(i)
+		}
+
+		var err error
+		if argv[i], err = prepareArg(arg, argType); err != nil {
+			return reflect.Value{}, fmt.Errorf("arg %d: %s", i, err)
+		}
+	}
+	return safeCall(fn, argv)
+}
+
+// safeCall runs fun.Call(args), and returns the resulting value and error, if
+// any. If the call panics, the panic value is returned as an error.
+func safeCall(fun reflect.Value, args []reflect.Value) (val reflect.Value, err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			if e, ok := r.(error); ok {
+				err = e
+			} else {
+				err = fmt.Errorf("%v", r)
+			}
+		}
+	}()
+	ret := fun.Call(args)
+	if len(ret) == 2 && !ret[1].IsNil() {
+		return ret[0], ret[1].Interface().(error)
+	}
+	return ret[0], nil
+}
+
+// Boolean logic.
+
+func truth(arg reflect.Value) bool {
+	t, _ := isTrue(indirectInterface(arg))
+	return t
+}
+
+// and computes the Boolean AND of its arguments, returning
+// the first false argument it encounters, or the last argument.
+func and(arg0 reflect.Value, args ...reflect.Value) reflect.Value {
+	if !truth(arg0) {
+		return arg0
+	}
+	for i := range args {
+		arg0 = args[i]
+		if !truth(arg0) {
+			break
+		}
+	}
+	return arg0
+}
+
+// or computes the Boolean OR of its arguments, returning
+// the first true argument it encounters, or the last argument.
+func or(arg0 reflect.Value, args ...reflect.Value) reflect.Value {
+	if truth(arg0) {
+		return arg0
+	}
+	for i := range args {
+		arg0 = args[i]
+		if truth(arg0) {
+			break
+		}
+	}
+	return arg0
+}
+
+// not returns the Boolean negation of its argument.
+func not(arg reflect.Value) bool {
+	return !truth(arg)
+}
+
+// Comparison.
+
+// TODO: Perhaps allow comparison between signed and unsigned integers.
+
+var (
+	errBadComparisonType = errors.New("invalid type for comparison")
+	errBadComparison     = errors.New("incompatible types for comparison")
+	errNoComparison      = errors.New("missing argument for comparison")
+)
+
+type kind int
+
+const (
+	invalidKind kind = iota
+	boolKind
+	complexKind
+	intKind
+	floatKind
+	stringKind
+	uintKind
+)
+
+func basicKind(v reflect.Value) (kind, error) {
+	switch v.Kind() {
+	case reflect.Bool:
+		return boolKind, nil
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return intKind, nil
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		return uintKind, nil
+	case reflect.Float32, reflect.Float64:
+		return floatKind, nil
+	case reflect.Complex64, reflect.Complex128:
+		return complexKind, nil
+	case reflect.String:
+		return stringKind, nil
+	}
+	return invalidKind, errBadComparisonType
+}
+
+// eq evaluates the comparison a == b || a == c || ...
+func eq(arg1 reflect.Value, arg2 ...reflect.Value) (bool, error) {
+	arg1 = indirectInterface(arg1)
+	if arg1 != zero {
+		if t1 := arg1.Type(); !t1.Comparable() {
+			return false, fmt.Errorf("uncomparable type %s: %v", t1, arg1)
+		}
+	}
+	if len(arg2) == 0 {
+		return false, errNoComparison
+	}
+	k1, _ := basicKind(arg1)
+	for _, arg := range arg2 {
+		arg = indirectInterface(arg)
+		k2, _ := basicKind(arg)
+		truth := false
+		if k1 != k2 {
+			// Special case: Can compare integer values regardless of type's sign.
+			switch {
+			case k1 == intKind && k2 == uintKind:
+				truth = arg1.Int() >= 0 && uint64(arg1.Int()) == arg.Uint()
+			case k1 == uintKind && k2 == intKind:
+				truth = arg.Int() >= 0 && arg1.Uint() == uint64(arg.Int())
+			default:
+				return false, errBadComparison
+			}
+		} else {
+			switch k1 {
+			case boolKind:
+				truth = arg1.Bool() == arg.Bool()
+			case complexKind:
+				truth = arg1.Complex() == arg.Complex()
+			case floatKind:
+				truth = arg1.Float() == arg.Float()
+			case intKind:
+				truth = arg1.Int() == arg.Int()
+			case stringKind:
+				truth = arg1.String() == arg.String()
+			case uintKind:
+				truth = arg1.Uint() == arg.Uint()
+			default:
+				if arg == zero {
+					truth = arg1 == arg
+				} else {
+					if t2 := arg.Type(); !t2.Comparable() {
+						return false, fmt.Errorf("uncomparable type %s: %v", t2, arg)
+					}
+					truth = arg1.Interface() == arg.Interface()
+				}
+			}
+		}
+		if truth {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
+// ne evaluates the comparison a != b.
+func ne(arg1, arg2 reflect.Value) (bool, error) {
+	// != is the inverse of ==.
+	equal, err := eq(arg1, arg2)
+	return !equal, err
+}
+
+// lt evaluates the comparison a < b.
+func lt(arg1, arg2 reflect.Value) (bool, error) {
+	arg1 = indirectInterface(arg1)
+	k1, err := basicKind(arg1)
+	if err != nil {
+		return false, err
+	}
+	arg2 = indirectInterface(arg2)
+	k2, err := basicKind(arg2)
+	if err != nil {
+		return false, err
+	}
+	truth := false
+	if k1 != k2 {
+		// Special case: Can compare integer values regardless of type's sign.
+		switch {
+		case k1 == intKind && k2 == uintKind:
+			truth = arg1.Int() < 0 || uint64(arg1.Int()) < arg2.Uint()
+		case k1 == uintKind && k2 == intKind:
+			truth = arg2.Int() >= 0 && arg1.Uint() < uint64(arg2.Int())
+		default:
+			return false, errBadComparison
+		}
+	} else {
+		switch k1 {
+		case boolKind, complexKind:
+			return false, errBadComparisonType
+		case floatKind:
+			truth = arg1.Float() < arg2.Float()
+		case intKind:
+			truth = arg1.Int() < arg2.Int()
+		case stringKind:
+			truth = arg1.String() < arg2.String()
+		case uintKind:
+			truth = arg1.Uint() < arg2.Uint()
+		default:
+			panic("invalid kind")
+		}
+	}
+	return truth, nil
+}
+
+// le evaluates the comparison <= b.
+func le(arg1, arg2 reflect.Value) (bool, error) {
+	// <= is < or ==.
+	lessThan, err := lt(arg1, arg2)
+	if lessThan || err != nil {
+		return lessThan, err
+	}
+	return eq(arg1, arg2)
+}
+
+// gt evaluates the comparison a > b.
+func gt(arg1, arg2 reflect.Value) (interface{}, error) {
+	// > is the inverse of <=.
+	lessOrEqual, err := le(arg1, arg2)
+	if err != nil {
+		return nil, err
+	}
+	if !lessOrEqual {
+		return arg1, nil
+	}
+	return fmt.Sprintf("<wanted gt %v, but was %v>", arg2, arg1), nil
+}
+
+// ge evaluates the comparison a >= b.
+func ge(arg1, arg2 reflect.Value) (bool, error) {
+	// >= is the inverse of <.
+	lessThan, err := lt(arg1, arg2)
+	if err != nil {
+		return false, err
+	}
+	return !lessThan, nil
+}
+
+// HTML escaping.
+
+var (
+	htmlQuot = []byte("&#34;") // shorter than "&quot;"
+	htmlApos = []byte("&#39;") // shorter than "&apos;" and apos was not in HTML until HTML5
+	htmlAmp  = []byte("&amp;")
+	htmlLt   = []byte("&lt;")
+	htmlGt   = []byte("&gt;")
+	htmlNull = []byte("\uFFFD")
+)
+
+// HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.
+func HTMLEscape(w io.Writer, b []byte) {
+	last := 0
+	for i, c := range b {
+		var html []byte
+		switch c {
+		case '\000':
+			html = htmlNull
+		case '"':
+			html = htmlQuot
+		case '\'':
+			html = htmlApos
+		case '&':
+			html = htmlAmp
+		case '<':
+			html = htmlLt
+		case '>':
+			html = htmlGt
+		default:
+			continue
+		}
+		w.Write(b[last:i])
+		w.Write(html)
+		last = i + 1
+	}
+	w.Write(b[last:])
+}
+
+// HTMLEscapeString returns the escaped HTML equivalent of the plain text data s.
+func HTMLEscapeString(s string) string {
+	// Avoid allocation if we can.
+	if !strings.ContainsAny(s, "'\"&<>\000") {
+		return s
+	}
+	var b bytes.Buffer
+	HTMLEscape(&b, []byte(s))
+	return b.String()
+}
+
+// HTMLEscaper returns the escaped HTML equivalent of the textual
+// representation of its arguments.
+func HTMLEscaper(args ...interface{}) string {
+	return HTMLEscapeString(evalArgs(args))
+}
+
+// JavaScript escaping.
+
+var (
+	jsLowUni = []byte(`\u00`)
+	hex      = []byte("0123456789ABCDEF")
+
+	jsBackslash = []byte(`\\`)
+	jsApos      = []byte(`\'`)
+	jsQuot      = []byte(`\"`)
+	jsLt        = []byte(`\u003C`)
+	jsGt        = []byte(`\u003E`)
+	jsAmp       = []byte(`\u0026`)
+	jsEq        = []byte(`\u003D`)
+)
+
+// JSEscape writes to w the escaped JavaScript equivalent of the plain text data b.
+func JSEscape(w io.Writer, b []byte) {
+	last := 0
+	for i := 0; i < len(b); i++ {
+		c := b[i]
+
+		if !jsIsSpecial(rune(c)) {
+			// fast path: nothing to do
+			continue
+		}
+		w.Write(b[last:i])
+
+		if c < utf8.RuneSelf {
+			// Quotes, slashes and angle brackets get quoted.
+			// Control characters get written as \u00XX.
+			switch c {
+			case '\\':
+				w.Write(jsBackslash)
+			case '\'':
+				w.Write(jsApos)
+			case '"':
+				w.Write(jsQuot)
+			case '<':
+				w.Write(jsLt)
+			case '>':
+				w.Write(jsGt)
+			case '&':
+				w.Write(jsAmp)
+			case '=':
+				w.Write(jsEq)
+			default:
+				w.Write(jsLowUni)
+				t, b := c>>4, c&0x0f
+				w.Write(hex[t : t+1])
+				w.Write(hex[b : b+1])
+			}
+		} else {
+			// Unicode rune.
+			r, size := utf8.DecodeRune(b[i:])
+			if unicode.IsPrint(r) {
+				w.Write(b[i : i+size])
+			} else {
+				fmt.Fprintf(w, "\\u%04X", r)
+			}
+			i += size - 1
+		}
+		last = i + 1
+	}
+	w.Write(b[last:])
+}
+
+// JSEscapeString returns the escaped JavaScript equivalent of the plain text data s.
+func JSEscapeString(s string) string {
+	// Avoid allocation if we can.
+	if strings.IndexFunc(s, jsIsSpecial) < 0 {
+		return s
+	}
+	var b bytes.Buffer
+	JSEscape(&b, []byte(s))
+	return b.String()
+}
+
+func jsIsSpecial(r rune) bool {
+	switch r {
+	case '\\', '\'', '"', '<', '>', '&', '=':
+		return true
+	}
+	return r < ' ' || utf8.RuneSelf <= r
+}
+
+// JSEscaper returns the escaped JavaScript equivalent of the textual
+// representation of its arguments.
+func JSEscaper(args ...interface{}) string {
+	return JSEscapeString(evalArgs(args))
+}
+
+// URLQueryEscaper returns the escaped value of the textual representation of
+// its arguments in a form suitable for embedding in a URL query.
+func URLQueryEscaper(args ...interface{}) string {
+	return url.QueryEscape(evalArgs(args))
+}
+
+// evalArgs formats the list of arguments into a string. It is therefore equivalent to
+//	fmt.Sprint(args...)
+// except that each argument is indirected (if a pointer), as required,
+// using the same rules as the default string evaluation during template
+// execution.
+func evalArgs(args []interface{}) string {
+	ok := false
+	var s string
+	// Fast path for simple common case.
+	if len(args) == 1 {
+		s, ok = args[0].(string)
+	}
+	if !ok {
+		for i, arg := range args {
+			a, ok := printableValue(reflect.ValueOf(arg))
+			if ok {
+				args[i] = a
+			} // else let fmt do its thing
+		}
+		s = fmt.Sprint(args...)
+	}
+	return s
+}
diff --git a/third-party/go/template/helper.go b/third-party/go/template/helper.go
new file mode 100644
index 0000000..c9e8900
--- /dev/null
+++ b/third-party/go/template/helper.go
@@ -0,0 +1,130 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Helper functions to make constructing templates easier.
+
+package template
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+)
+
+// Functions and methods to parse templates.
+
+// Must is a helper that wraps a call to a function returning (*Template, error)
+// and panics if the error is non-nil. It is intended for use in variable
+// initializations such as
+//	var t = template.Must(template.New("name").Parse("text"))
+func Must(t *Template, err error) *Template {
+	if err != nil {
+		panic(err)
+	}
+	return t
+}
+
+// ParseFiles creates a new Template and parses the template definitions from
+// the named files. The returned template's name will have the base name and
+// parsed contents of the first file. There must be at least one file.
+// If an error occurs, parsing stops and the returned *Template is nil.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+// For instance, ParseFiles("a/foo", "b/foo") stores "b/foo" as the template
+// named "foo", while "a/foo" is unavailable.
+func ParseFiles(filenames ...string) (*Template, error) {
+	return parseFiles(nil, filenames...)
+}
+
+// ParseFiles parses the named files and associates the resulting templates with
+// t. If an error occurs, parsing stops and the returned template is nil;
+// otherwise it is t. There must be at least one file.
+// Since the templates created by ParseFiles are named by the base
+// names of the argument files, t should usually have the name of one
+// of the (base) names of the files. If it does not, depending on t's
+// contents before calling ParseFiles, t.Execute may fail. In that
+// case use t.ExecuteTemplate to execute a valid template.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func (t *Template) ParseFiles(filenames ...string) (*Template, error) {
+	t.init()
+	return parseFiles(t, filenames...)
+}
+
+// parseFiles is the helper for the method and function. If the argument
+// template is nil, it is created from the first file.
+func parseFiles(t *Template, filenames ...string) (*Template, error) {
+	if len(filenames) == 0 {
+		// Not really a problem, but be consistent.
+		return nil, fmt.Errorf("template: no files named in call to ParseFiles")
+	}
+	for _, filename := range filenames {
+		b, err := ioutil.ReadFile(filename)
+		if err != nil {
+			return nil, err
+		}
+		s := string(b)
+		name := filepath.Base(filename)
+		// First template becomes return value if not already defined,
+		// and we use that one for subsequent New calls to associate
+		// all the templates together. Also, if this file has the same name
+		// as t, this file becomes the contents of t, so
+		//  t, err := New(name).Funcs(xxx).ParseFiles(name)
+		// works. Otherwise we create a new template associated with t.
+		var tmpl *Template
+		if t == nil {
+			t = New(name)
+		}
+		if name == t.Name() {
+			tmpl = t
+		} else {
+			tmpl = t.New(name)
+		}
+		_, err = tmpl.Parse(s)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return t, nil
+}
+
+// ParseGlob creates a new Template and parses the template definitions from
+// the files identified by the pattern. The files are matched according to the
+// semantics of filepath.Match, and the pattern must match at least one file.
+// The returned template will have the (base) name and (parsed) contents of the
+// first file matched by the pattern. ParseGlob is equivalent to calling
+// ParseFiles with the list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func ParseGlob(pattern string) (*Template, error) {
+	return parseGlob(nil, pattern)
+}
+
+// ParseGlob parses the template definitions in the files identified by the
+// pattern and associates the resulting templates with t. The files are matched
+// according to the semantics of filepath.Match, and the pattern must match at
+// least one file. ParseGlob is equivalent to calling t.ParseFiles with the
+// list of files matched by the pattern.
+//
+// When parsing multiple files with the same name in different directories,
+// the last one mentioned will be the one that results.
+func (t *Template) ParseGlob(pattern string) (*Template, error) {
+	t.init()
+	return parseGlob(t, pattern)
+}
+
+// parseGlob is the implementation of the function and method ParseGlob.
+func parseGlob(t *Template, pattern string) (*Template, error) {
+	filenames, err := filepath.Glob(pattern)
+	if err != nil {
+		return nil, err
+	}
+	if len(filenames) == 0 {
+		return nil, fmt.Errorf("template: pattern matches no files: %#q", pattern)
+	}
+	return parseFiles(t, filenames...)
+}
diff --git a/third-party/go/template/option.go b/third-party/go/template/option.go
new file mode 100644
index 0000000..addce2d
--- /dev/null
+++ b/third-party/go/template/option.go
@@ -0,0 +1,74 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains the code to handle template options.
+
+package template
+
+import "strings"
+
+// missingKeyAction defines how to respond to indexing a map with a key that is not present.
+type missingKeyAction int
+
+const (
+	mapInvalid   missingKeyAction = iota // Return an invalid reflect.Value.
+	mapZeroValue                         // Return the zero value for the map element.
+	mapError                             // Error out
+)
+
+type option struct {
+	missingKey missingKeyAction
+}
+
+// Option sets options for the template. Options are described by
+// strings, either a simple string or "key=value". There can be at
+// most one equals sign in an option string. If the option string
+// is unrecognized or otherwise invalid, Option panics.
+//
+// Known options:
+//
+// missingkey: Control the behavior during execution if a map is
+// indexed with a key that is not present in the map.
+//	"missingkey=default" or "missingkey=invalid"
+//		The default behavior: Do nothing and continue execution.
+//		If printed, the result of the index operation is the string
+//		"<no value>".
+//	"missingkey=zero"
+//		The operation returns the zero value for the map type's element.
+//	"missingkey=error"
+//		Execution stops immediately with an error.
+//
+func (t *Template) Option(opt ...string) *Template {
+	t.init()
+	for _, s := range opt {
+		t.setOption(s)
+	}
+	return t
+}
+
+func (t *Template) setOption(opt string) {
+	if opt == "" {
+		panic("empty option string")
+	}
+	elems := strings.Split(opt, "=")
+	switch len(elems) {
+	case 2:
+		// key=value
+		switch elems[0] {
+		case "missingkey":
+			switch elems[1] {
+			case "invalid", "default":
+				t.option.missingKey = mapInvalid
+				return
+			case "zero":
+				t.option.missingKey = mapZeroValue
+				return
+			case "error":
+				t.option.missingKey = mapError
+				return
+			}
+		}
+	}
+	panic("unrecognized option: " + opt)
+}
diff --git a/third-party/go/template/parse/lex.go b/third-party/go/template/parse/lex.go
new file mode 100644
index 0000000..8ebb789
--- /dev/null
+++ b/third-party/go/template/parse/lex.go
@@ -0,0 +1,667 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package parse
+
+import (
+	"fmt"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// item represents a token or text string returned from the scanner.
+type item struct {
+	typ  itemType // The type of this item.
+	pos  Pos      // The starting position, in bytes, of this item in the input string.
+	val  string   // The value of this item.
+	line int      // The line number at the start of this item.
+}
+
+func (i item) String() string {
+	switch {
+	case i.typ == itemEOF:
+		return "EOF"
+	case i.typ == itemError:
+		return i.val
+	case i.typ > itemKeyword:
+		return fmt.Sprintf("<%s>", i.val)
+	case len(i.val) > 10:
+		return fmt.Sprintf("%.10q...", i.val)
+	}
+	return fmt.Sprintf("%q", i.val)
+}
+
+// itemType identifies the type of lex items.
+type itemType int
+
+const (
+	itemError        itemType = iota // error occurred; value is text of error
+	itemBool                         // boolean constant
+	itemChar                         // printable ASCII character; grab bag for comma etc.
+	itemCharConstant                 // character constant
+	itemComplex                      // complex constant (1+2i); imaginary is just a number
+	itemAssign                       // equals ('=') introducing an assignment
+	itemDeclare                      // colon-equals (':=') introducing a declaration
+	itemEOF
+	itemField      // alphanumeric identifier starting with '.'
+	itemIdentifier // alphanumeric identifier not starting with '.'
+	itemLeftDelim  // left action delimiter
+	itemLeftParen  // '(' inside action
+	itemNumber     // simple number, including imaginary
+	itemPipe       // pipe symbol
+	itemRawString  // raw quoted string (includes quotes)
+	itemRightDelim // right action delimiter
+	itemRightParen // ')' inside action
+	itemSpace      // run of spaces separating arguments
+	itemString     // quoted string (includes quotes)
+	itemText       // plain text
+	itemVariable   // variable starting with '$', such as '$' or  '$1' or '$hello'
+	// Keywords appear after all the rest.
+	itemKeyword     // used only to delimit the keywords
+	itemBlock       // block keyword
+	itemDot         // the cursor, spelled '.'
+	itemDefine      // define keyword
+	itemElse        // else keyword
+	itemEnd         // end keyword
+	itemIf          // if keyword
+	itemNil         // the untyped nil constant, easiest to treat as a keyword
+	itemRange       // range keyword
+	itemTemplate    // template keyword
+	itemWith        // with keyword
+	itemAtLeastOnce // atLeastOnce keyword
+)
+
+var key = map[string]itemType{
+	".":           itemDot,
+	"block":       itemBlock,
+	"define":      itemDefine,
+	"else":        itemElse,
+	"end":         itemEnd,
+	"if":          itemIf,
+	"range":       itemRange,
+	"nil":         itemNil,
+	"template":    itemTemplate,
+	"with":        itemWith,
+	"atLeastOnce": itemAtLeastOnce,
+}
+
+const eof = -1
+
+// Trimming spaces.
+// If the action begins "{{- " rather than "{{", then all space/tab/newlines
+// preceding the action are trimmed; conversely if it ends " -}}" the
+// leading spaces are trimmed. This is done entirely in the lexer; the
+// parser never sees it happen. We require an ASCII space to be
+// present to avoid ambiguity with things like "{{-3}}". It reads
+// better with the space present anyway. For simplicity, only ASCII
+// space does the job.
+const (
+	spaceChars      = " \t\r\n" // These are the space characters defined by Go itself.
+	leftTrimMarker  = "- "      // Attached to left delimiter, trims trailing spaces from preceding text.
+	rightTrimMarker = " -"      // Attached to right delimiter, trims leading spaces from following text.
+	trimMarkerLen   = Pos(len(leftTrimMarker))
+)
+
+// stateFn represents the state of the scanner as a function that returns the next state.
+type stateFn func(*lexer) stateFn
+
+// lexer holds the state of the scanner.
+type lexer struct {
+	name           string    // the name of the input; used only for error reports
+	input          string    // the string being scanned
+	leftDelim      string    // start of action
+	rightDelim     string    // end of action
+	trimRightDelim string    // end of action with trim marker
+	pos            Pos       // current position in the input
+	start          Pos       // start position of this item
+	width          Pos       // width of last rune read from input
+	items          chan item // channel of scanned items
+	parenDepth     int       // nesting depth of ( ) exprs
+	line           int       // 1+number of newlines seen
+	startLine      int       // start line of this item
+}
+
+// next returns the next rune in the input.
+func (l *lexer) next() rune {
+	if int(l.pos) >= len(l.input) {
+		l.width = 0
+		return eof
+	}
+	r, w := utf8.DecodeRuneInString(l.input[l.pos:])
+	l.width = Pos(w)
+	l.pos += l.width
+	if r == '\n' {
+		l.line++
+	}
+	return r
+}
+
+// peek returns but does not consume the next rune in the input.
+func (l *lexer) peek() rune {
+	r := l.next()
+	l.backup()
+	return r
+}
+
+// backup steps back one rune. Can only be called once per call of next.
+func (l *lexer) backup() {
+	l.pos -= l.width
+	// Correct newline count.
+	if l.width == 1 && l.input[l.pos] == '\n' {
+		l.line--
+	}
+}
+
+// emit passes an item back to the client.
+func (l *lexer) emit(t itemType) {
+	l.items <- item{t, l.start, l.input[l.start:l.pos], l.startLine}
+	l.start = l.pos
+	l.startLine = l.line
+}
+
+// ignore skips over the pending input before this point.
+func (l *lexer) ignore() {
+	l.line += strings.Count(l.input[l.start:l.pos], "\n")
+	l.start = l.pos
+	l.startLine = l.line
+}
+
+// accept consumes the next rune if it's from the valid set.
+func (l *lexer) accept(valid string) bool {
+	if strings.ContainsRune(valid, l.next()) {
+		return true
+	}
+	l.backup()
+	return false
+}
+
+// acceptRun consumes a run of runes from the valid set.
+func (l *lexer) acceptRun(valid string) {
+	for strings.ContainsRune(valid, l.next()) {
+	}
+	l.backup()
+}
+
+// errorf returns an error token and terminates the scan by passing
+// back a nil pointer that will be the next state, terminating l.nextItem.
+func (l *lexer) errorf(format string, args ...interface{}) stateFn {
+	l.items <- item{itemError, l.start, fmt.Sprintf(format, args...), l.startLine}
+	return nil
+}
+
+// nextItem returns the next item from the input.
+// Called by the parser, not in the lexing goroutine.
+func (l *lexer) nextItem() item {
+	return <-l.items
+}
+
+// drain drains the output so the lexing goroutine will exit.
+// Called by the parser, not in the lexing goroutine.
+func (l *lexer) drain() {
+	for range l.items {
+	}
+}
+
+// lex creates a new scanner for the input string.
+func lex(name, input, left, right string) *lexer {
+	if left == "" {
+		left = leftDelim
+	}
+	if right == "" {
+		right = rightDelim
+	}
+	l := &lexer{
+		name:           name,
+		input:          input,
+		leftDelim:      left,
+		rightDelim:     right,
+		trimRightDelim: rightTrimMarker + right,
+		items:          make(chan item),
+		line:           1,
+		startLine:      1,
+	}
+	go l.run()
+	return l
+}
+
+// run runs the state machine for the lexer.
+func (l *lexer) run() {
+	for state := lexText; state != nil; {
+		state = state(l)
+	}
+	close(l.items)
+}
+
+// state functions
+
+const (
+	leftDelim    = "{{"
+	rightDelim   = "}}"
+	leftComment  = "/*"
+	rightComment = "*/"
+)
+
+// lexText scans until an opening action delimiter, "{{".
+func lexText(l *lexer) stateFn {
+	l.width = 0
+	if x := strings.Index(l.input[l.pos:], l.leftDelim); x >= 0 {
+		ldn := Pos(len(l.leftDelim))
+		l.pos += Pos(x)
+		trimLength := Pos(0)
+		if strings.HasPrefix(l.input[l.pos+ldn:], leftTrimMarker) {
+			trimLength = rightTrimLength(l.input[l.start:l.pos])
+		}
+		l.pos -= trimLength
+		if l.pos > l.start {
+			l.line += strings.Count(l.input[l.start:l.pos], "\n")
+			l.emit(itemText)
+		}
+		l.pos += trimLength
+		l.ignore()
+		return lexLeftDelim
+	}
+	l.pos = Pos(len(l.input))
+	// Correctly reached EOF.
+	if l.pos > l.start {
+		l.line += strings.Count(l.input[l.start:l.pos], "\n")
+		l.emit(itemText)
+	}
+	l.emit(itemEOF)
+	return nil
+}
+
+// rightTrimLength returns the length of the spaces at the end of the string.
+func rightTrimLength(s string) Pos {
+	return Pos(len(s) - len(strings.TrimRight(s, spaceChars)))
+}
+
+// atRightDelim reports whether the lexer is at a right delimiter, possibly preceded by a trim marker.
+func (l *lexer) atRightDelim() (delim, trimSpaces bool) {
+	if strings.HasPrefix(l.input[l.pos:], l.trimRightDelim) { // With trim marker.
+		return true, true
+	}
+	if strings.HasPrefix(l.input[l.pos:], l.rightDelim) { // Without trim marker.
+		return true, false
+	}
+	return false, false
+}
+
+// leftTrimLength returns the length of the spaces at the beginning of the string.
+func leftTrimLength(s string) Pos {
+	return Pos(len(s) - len(strings.TrimLeft(s, spaceChars)))
+}
+
+// lexLeftDelim scans the left delimiter, which is known to be present, possibly with a trim marker.
+func lexLeftDelim(l *lexer) stateFn {
+	l.pos += Pos(len(l.leftDelim))
+	trimSpace := strings.HasPrefix(l.input[l.pos:], leftTrimMarker)
+	afterMarker := Pos(0)
+	if trimSpace {
+		afterMarker = trimMarkerLen
+	}
+	if strings.HasPrefix(l.input[l.pos+afterMarker:], leftComment) {
+		l.pos += afterMarker
+		l.ignore()
+		return lexComment
+	}
+	l.emit(itemLeftDelim)
+	l.pos += afterMarker
+	l.ignore()
+	l.parenDepth = 0
+	return lexInsideAction
+}
+
+// lexComment scans a comment. The left comment marker is known to be present.
+func lexComment(l *lexer) stateFn {
+	l.pos += Pos(len(leftComment))
+	i := strings.Index(l.input[l.pos:], rightComment)
+	if i < 0 {
+		return l.errorf("unclosed comment")
+	}
+	l.pos += Pos(i + len(rightComment))
+	delim, trimSpace := l.atRightDelim()
+	if !delim {
+		return l.errorf("comment ends before closing delimiter")
+	}
+	if trimSpace {
+		l.pos += trimMarkerLen
+	}
+	l.pos += Pos(len(l.rightDelim))
+	if trimSpace {
+		l.pos += leftTrimLength(l.input[l.pos:])
+	}
+	l.ignore()
+	return lexText
+}
+
+// lexRightDelim scans the right delimiter, which is known to be present, possibly with a trim marker.
+func lexRightDelim(l *lexer) stateFn {
+	trimSpace := strings.HasPrefix(l.input[l.pos:], rightTrimMarker)
+	if trimSpace {
+		l.pos += trimMarkerLen
+		l.ignore()
+	}
+	l.pos += Pos(len(l.rightDelim))
+	l.emit(itemRightDelim)
+	if trimSpace {
+		l.pos += leftTrimLength(l.input[l.pos:])
+		l.ignore()
+	}
+	return lexText
+}
+
+// lexInsideAction scans the elements inside action delimiters.
+func lexInsideAction(l *lexer) stateFn {
+	// Either number, quoted string, or identifier.
+	// Spaces separate arguments; runs of spaces turn into itemSpace.
+	// Pipe symbols separate and are emitted.
+	delim, _ := l.atRightDelim()
+	if delim {
+		if l.parenDepth == 0 {
+			return lexRightDelim
+		}
+		return l.errorf("unclosed left paren")
+	}
+	switch r := l.next(); {
+	case r == eof || isEndOfLine(r):
+		return l.errorf("unclosed action")
+	case isSpace(r):
+		l.backup() // Put space back in case we have " -}}".
+		return lexSpace
+	case r == '=':
+		l.emit(itemAssign)
+	case r == ':':
+		if l.next() != '=' {
+			return l.errorf("expected :=")
+		}
+		l.emit(itemDeclare)
+	case r == '|':
+		l.emit(itemPipe)
+	case r == '"':
+		return lexQuote
+	case r == '`':
+		return lexRawQuote
+	case r == '$':
+		return lexVariable
+	case r == '\'':
+		return lexChar
+	case r == '.':
+		// special look-ahead for ".field" so we don't break l.backup().
+		if l.pos < Pos(len(l.input)) {
+			r := l.input[l.pos]
+			if r < '0' || '9' < r {
+				return lexField
+			}
+		}
+		fallthrough // '.' can start a number.
+	case r == '+' || r == '-' || ('0' <= r && r <= '9'):
+		l.backup()
+		return lexNumber
+	case isAlphaNumeric(r):
+		l.backup()
+		return lexIdentifier
+	case r == '(':
+		l.emit(itemLeftParen)
+		l.parenDepth++
+	case r == ')':
+		l.emit(itemRightParen)
+		l.parenDepth--
+		if l.parenDepth < 0 {
+			return l.errorf("unexpected right paren %#U", r)
+		}
+	case r <= unicode.MaxASCII && unicode.IsPrint(r):
+		l.emit(itemChar)
+	default:
+		return l.errorf("unrecognized character in action: %#U", r)
+	}
+	return lexInsideAction
+}
+
+// lexSpace scans a run of space characters.
+// We have not consumed the first space, which is known to be present.
+// Take care if there is a trim-marked right delimiter, which starts with a space.
+func lexSpace(l *lexer) stateFn {
+	var r rune
+	var numSpaces int
+	for {
+		r = l.peek()
+		if !isSpace(r) {
+			break
+		}
+		l.next()
+		numSpaces++
+	}
+	// Be careful about a trim-marked closing delimiter, which has a minus
+	// after a space. We know there is a space, so check for the '-' that might follow.
+	if strings.HasPrefix(l.input[l.pos-1:], l.trimRightDelim) {
+		l.backup() // Before the space.
+		if numSpaces == 1 {
+			return lexRightDelim // On the delim, so go right to that.
+		}
+	}
+	l.emit(itemSpace)
+	return lexInsideAction
+}
+
+// lexIdentifier scans an alphanumeric.
+func lexIdentifier(l *lexer) stateFn {
+Loop:
+	for {
+		switch r := l.next(); {
+		case isAlphaNumeric(r):
+			// absorb.
+		default:
+			l.backup()
+			word := l.input[l.start:l.pos]
+			if !l.atTerminator() {
+				return l.errorf("bad character %#U", r)
+			}
+			switch {
+			case key[word] > itemKeyword:
+				l.emit(key[word])
+			case word[0] == '.':
+				l.emit(itemField)
+			case word == "true", word == "false":
+				l.emit(itemBool)
+			default:
+				l.emit(itemIdentifier)
+			}
+			break Loop
+		}
+	}
+	return lexInsideAction
+}
+
+// lexField scans a field: .Alphanumeric.
+// The . has been scanned.
+func lexField(l *lexer) stateFn {
+	return lexFieldOrVariable(l, itemField)
+}
+
+// lexVariable scans a Variable: $Alphanumeric.
+// The $ has been scanned.
+func lexVariable(l *lexer) stateFn {
+	if l.atTerminator() { // Nothing interesting follows -> "$".
+		l.emit(itemVariable)
+		return lexInsideAction
+	}
+	return lexFieldOrVariable(l, itemVariable)
+}
+
+// lexVariable scans a field or variable: [.$]Alphanumeric.
+// The . or $ has been scanned.
+func lexFieldOrVariable(l *lexer, typ itemType) stateFn {
+	if l.atTerminator() { // Nothing interesting follows -> "." or "$".
+		if typ == itemVariable {
+			l.emit(itemVariable)
+		} else {
+			l.emit(itemDot)
+		}
+		return lexInsideAction
+	}
+	var r rune
+	for {
+		r = l.next()
+		if !isAlphaNumeric(r) {
+			l.backup()
+			break
+		}
+	}
+	if !l.atTerminator() {
+		return l.errorf("bad character %#U", r)
+	}
+	l.emit(typ)
+	return lexInsideAction
+}
+
+// atTerminator reports whether the input is at valid termination character to
+// appear after an identifier. Breaks .X.Y into two pieces. Also catches cases
+// like "$x+2" not being acceptable without a space, in case we decide one
+// day to implement arithmetic.
+func (l *lexer) atTerminator() bool {
+	r := l.peek()
+	if isSpace(r) || isEndOfLine(r) {
+		return true
+	}
+	switch r {
+	case eof, '.', ',', '|', ':', ')', '(':
+		return true
+	}
+	// Does r start the delimiter? This can be ambiguous (with delim=="//", $x/2 will
+	// succeed but should fail) but only in extremely rare cases caused by willfully
+	// bad choice of delimiter.
+	if rd, _ := utf8.DecodeRuneInString(l.rightDelim); rd == r {
+		return true
+	}
+	return false
+}
+
+// lexChar scans a character constant. The initial quote is already
+// scanned. Syntax checking is done by the parser.
+func lexChar(l *lexer) stateFn {
+Loop:
+	for {
+		switch l.next() {
+		case '\\':
+			if r := l.next(); r != eof && r != '\n' {
+				break
+			}
+			fallthrough
+		case eof, '\n':
+			return l.errorf("unterminated character constant")
+		case '\'':
+			break Loop
+		}
+	}
+	l.emit(itemCharConstant)
+	return lexInsideAction
+}
+
+// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
+// isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
+// and "089" - but when it's wrong the input is invalid and the parser (via
+// strconv) will notice.
+func lexNumber(l *lexer) stateFn {
+	if !l.scanNumber() {
+		return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
+	}
+	if sign := l.peek(); sign == '+' || sign == '-' {
+		// Complex: 1+2i. No spaces, must end in 'i'.
+		if !l.scanNumber() || l.input[l.pos-1] != 'i' {
+			return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
+		}
+		l.emit(itemComplex)
+	} else {
+		l.emit(itemNumber)
+	}
+	return lexInsideAction
+}
+
+func (l *lexer) scanNumber() bool {
+	// Optional leading sign.
+	l.accept("+-")
+	// Is it hex?
+	digits := "0123456789_"
+	if l.accept("0") {
+		// Note: Leading 0 does not mean octal in floats.
+		if l.accept("xX") {
+			digits = "0123456789abcdefABCDEF_"
+		} else if l.accept("oO") {
+			digits = "01234567_"
+		} else if l.accept("bB") {
+			digits = "01_"
+		}
+	}
+	l.acceptRun(digits)
+	if l.accept(".") {
+		l.acceptRun(digits)
+	}
+	if len(digits) == 10+1 && l.accept("eE") {
+		l.accept("+-")
+		l.acceptRun("0123456789_")
+	}
+	if len(digits) == 16+6+1 && l.accept("pP") {
+		l.accept("+-")
+		l.acceptRun("0123456789_")
+	}
+	// Is it imaginary?
+	l.accept("i")
+	// Next thing mustn't be alphanumeric.
+	if isAlphaNumeric(l.peek()) {
+		l.next()
+		return false
+	}
+	return true
+}
+
+// lexQuote scans a quoted string.
+func lexQuote(l *lexer) stateFn {
+Loop:
+	for {
+		switch l.next() {
+		case '\\':
+			if r := l.next(); r != eof && r != '\n' {
+				break
+			}
+			fallthrough
+		case eof, '\n':
+			return l.errorf("unterminated quoted string")
+		case '"':
+			break Loop
+		}
+	}
+	l.emit(itemString)
+	return lexInsideAction
+}
+
+// lexRawQuote scans a raw quoted string.
+func lexRawQuote(l *lexer) stateFn {
+Loop:
+	for {
+		switch l.next() {
+		case eof:
+			return l.errorf("unterminated raw quoted string")
+		case '`':
+			break Loop
+		}
+	}
+	l.emit(itemRawString)
+	return lexInsideAction
+}
+
+// isSpace reports whether r is a space character.
+func isSpace(r rune) bool {
+	return r == ' ' || r == '\t'
+}
+
+// isEndOfLine reports whether r is an end-of-line character.
+func isEndOfLine(r rune) bool {
+	return r == '\r' || r == '\n'
+}
+
+// isAlphaNumeric reports whether r is an alphabetic, digit, or underscore.
+func isAlphaNumeric(r rune) bool {
+	return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
+}
diff --git a/third-party/go/template/parse/node.go b/third-party/go/template/parse/node.go
new file mode 100644
index 0000000..57ca52c
--- /dev/null
+++ b/third-party/go/template/parse/node.go
@@ -0,0 +1,957 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parse nodes.
+
+package parse
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+var textFormat = "%s" // Changed to "%q" in tests for better error messages.
+
+// A Node is an element in the parse tree. The interface is trivial.
+// The interface contains an unexported method so that only
+// types local to this package can satisfy it.
+type Node interface {
+	Type() NodeType
+	String() string
+	// Copy does a deep copy of the Node and all its components.
+	// To avoid type assertions, some XxxNodes also have specialized
+	// CopyXxx methods that return *XxxNode.
+	Copy() Node
+	Position() Pos // byte position of start of node in full original input string
+	// tree returns the containing *Tree.
+	// It is unexported so all implementations of Node are in this package.
+	tree() *Tree
+	// writeTo writes the String output to the builder.
+	writeTo(*strings.Builder)
+}
+
+// NodeType identifies the type of a parse tree node.
+type NodeType int
+
+// Pos represents a byte position in the original input text from which
+// this template was parsed.
+type Pos int
+
+func (p Pos) Position() Pos {
+	return p
+}
+
+// Type returns itself and provides an easy default implementation
+// for embedding in a Node. Embedded in all non-trivial Nodes.
+func (t NodeType) Type() NodeType {
+	return t
+}
+
+const (
+	NodeText        NodeType = iota // Plain text.
+	NodeAction                      // A non-control action such as a field evaluation.
+	NodeBool                        // A boolean constant.
+	NodeChain                       // A sequence of field accesses.
+	NodeCommand                     // An element of a pipeline.
+	NodeDot                         // The cursor, dot.
+	nodeElse                        // An else action. Not added to tree.
+	nodeEnd                         // An end action. Not added to tree.
+	NodeField                       // A field or method name.
+	NodeIdentifier                  // An identifier; always a function name.
+	NodeIf                          // An if action.
+	NodeList                        // A list of Nodes.
+	NodeNil                         // An untyped nil constant.
+	NodeNumber                      // A numerical constant.
+	NodePipe                        // A pipeline of commands.
+	NodeRange                       // A range action.
+	NodeString                      // A string constant.
+	NodeTemplate                    // A template invocation action.
+	NodeVariable                    // A $ variable.
+	NodeWith                        // A with action.
+	NodeAtLeastOnce                 // An atLeastOnce action.
+)
+
+// Nodes.
+
+// ListNode holds a sequence of nodes.
+type ListNode struct {
+	NodeType
+	Pos
+	tr    *Tree
+	Nodes []Node // The element nodes in lexical order.
+}
+
+func (t *Tree) newList(pos Pos) *ListNode {
+	return &ListNode{tr: t, NodeType: NodeList, Pos: pos}
+}
+
+func (l *ListNode) append(n Node) {
+	l.Nodes = append(l.Nodes, n)
+}
+
+func (l *ListNode) tree() *Tree {
+	return l.tr
+}
+
+func (l *ListNode) String() string {
+	var sb strings.Builder
+	l.writeTo(&sb)
+	return sb.String()
+}
+
+func (l *ListNode) writeTo(sb *strings.Builder) {
+	for _, n := range l.Nodes {
+		n.writeTo(sb)
+	}
+}
+
+func (l *ListNode) CopyList() *ListNode {
+	if l == nil {
+		return l
+	}
+	n := l.tr.newList(l.Pos)
+	for _, elem := range l.Nodes {
+		n.append(elem.Copy())
+	}
+	return n
+}
+
+func (l *ListNode) Copy() Node {
+	return l.CopyList()
+}
+
+// TextNode holds plain text.
+type TextNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	Text []byte // The text; may span newlines.
+}
+
+func (t *Tree) newText(pos Pos, text string) *TextNode {
+	return &TextNode{tr: t, NodeType: NodeText, Pos: pos, Text: []byte(text)}
+}
+
+func (t *TextNode) String() string {
+	return fmt.Sprintf(textFormat, t.Text)
+}
+
+func (t *TextNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(t.String())
+}
+
+func (t *TextNode) tree() *Tree {
+	return t.tr
+}
+
+func (t *TextNode) Copy() Node {
+	return &TextNode{tr: t.tr, NodeType: NodeText, Pos: t.Pos, Text: append([]byte{}, t.Text...)}
+}
+
+// PipeNode holds a pipeline with optional declaration
+type PipeNode struct {
+	NodeType
+	Pos
+	tr       *Tree
+	Line     int             // The line number in the input. Deprecated: Kept for compatibility.
+	IsAssign bool            // The variables are being assigned, not declared.
+	Decl     []*VariableNode // Variables in lexical order.
+	Cmds     []*CommandNode  // The commands in lexical order.
+}
+
+func (t *Tree) newPipeline(pos Pos, line int, vars []*VariableNode) *PipeNode {
+	return &PipeNode{tr: t, NodeType: NodePipe, Pos: pos, Line: line, Decl: vars}
+}
+
+func (p *PipeNode) append(command *CommandNode) {
+	p.Cmds = append(p.Cmds, command)
+}
+
+func (p *PipeNode) String() string {
+	var sb strings.Builder
+	p.writeTo(&sb)
+	return sb.String()
+}
+
+func (p *PipeNode) writeTo(sb *strings.Builder) {
+	if len(p.Decl) > 0 {
+		for i, v := range p.Decl {
+			if i > 0 {
+				sb.WriteString(", ")
+			}
+			v.writeTo(sb)
+		}
+		sb.WriteString(" := ")
+	}
+	for i, c := range p.Cmds {
+		if i > 0 {
+			sb.WriteString(" | ")
+		}
+		c.writeTo(sb)
+	}
+}
+
+func (p *PipeNode) tree() *Tree {
+	return p.tr
+}
+
+func (p *PipeNode) CopyPipe() *PipeNode {
+	if p == nil {
+		return p
+	}
+	vars := make([]*VariableNode, len(p.Decl))
+	for i, d := range p.Decl {
+		vars[i] = d.Copy().(*VariableNode)
+	}
+	n := p.tr.newPipeline(p.Pos, p.Line, vars)
+	n.IsAssign = p.IsAssign
+	for _, c := range p.Cmds {
+		n.append(c.Copy().(*CommandNode))
+	}
+	return n
+}
+
+func (p *PipeNode) Copy() Node {
+	return p.CopyPipe()
+}
+
+// ActionNode holds an action (something bounded by delimiters).
+// Control actions have their own nodes; ActionNode represents simple
+// ones such as field evaluations and parenthesized pipelines.
+type ActionNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	Line int       // The line number in the input. Deprecated: Kept for compatibility.
+	Pipe *PipeNode // The pipeline in the action.
+}
+
+func (t *Tree) newAction(pos Pos, line int, pipe *PipeNode) *ActionNode {
+	return &ActionNode{tr: t, NodeType: NodeAction, Pos: pos, Line: line, Pipe: pipe}
+}
+
+func (a *ActionNode) String() string {
+	var sb strings.Builder
+	a.writeTo(&sb)
+	return sb.String()
+}
+
+func (a *ActionNode) writeTo(sb *strings.Builder) {
+	sb.WriteString("{{")
+	a.Pipe.writeTo(sb)
+	sb.WriteString("}}")
+}
+
+func (a *ActionNode) tree() *Tree {
+	return a.tr
+}
+
+func (a *ActionNode) Copy() Node {
+	return a.tr.newAction(a.Pos, a.Line, a.Pipe.CopyPipe())
+
+}
+
+// CommandNode holds a command (a pipeline inside an evaluating action).
+type CommandNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	Args []Node // Arguments in lexical order: Identifier, field, or constant.
+}
+
+func (t *Tree) newCommand(pos Pos) *CommandNode {
+	return &CommandNode{tr: t, NodeType: NodeCommand, Pos: pos}
+}
+
+func (c *CommandNode) append(arg Node) {
+	c.Args = append(c.Args, arg)
+}
+
+func (c *CommandNode) String() string {
+	var sb strings.Builder
+	c.writeTo(&sb)
+	return sb.String()
+}
+
+func (c *CommandNode) writeTo(sb *strings.Builder) {
+	for i, arg := range c.Args {
+		if i > 0 {
+			sb.WriteByte(' ')
+		}
+		if arg, ok := arg.(*PipeNode); ok {
+			sb.WriteByte('(')
+			arg.writeTo(sb)
+			sb.WriteByte(')')
+			continue
+		}
+		arg.writeTo(sb)
+	}
+}
+
+func (c *CommandNode) tree() *Tree {
+	return c.tr
+}
+
+func (c *CommandNode) Copy() Node {
+	if c == nil {
+		return c
+	}
+	n := c.tr.newCommand(c.Pos)
+	for _, c := range c.Args {
+		n.append(c.Copy())
+	}
+	return n
+}
+
+// IdentifierNode holds an identifier.
+type IdentifierNode struct {
+	NodeType
+	Pos
+	tr    *Tree
+	Ident string // The identifier's name.
+}
+
+// NewIdentifier returns a new IdentifierNode with the given identifier name.
+func NewIdentifier(ident string) *IdentifierNode {
+	return &IdentifierNode{NodeType: NodeIdentifier, Ident: ident}
+}
+
+// SetPos sets the position. NewIdentifier is a public method so we can't modify its signature.
+// Chained for convenience.
+// TODO: fix one day?
+func (i *IdentifierNode) SetPos(pos Pos) *IdentifierNode {
+	i.Pos = pos
+	return i
+}
+
+// SetTree sets the parent tree for the node. NewIdentifier is a public method so we can't modify its signature.
+// Chained for convenience.
+// TODO: fix one day?
+func (i *IdentifierNode) SetTree(t *Tree) *IdentifierNode {
+	i.tr = t
+	return i
+}
+
+func (i *IdentifierNode) String() string {
+	return i.Ident
+}
+
+func (i *IdentifierNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(i.String())
+}
+
+func (i *IdentifierNode) tree() *Tree {
+	return i.tr
+}
+
+func (i *IdentifierNode) Copy() Node {
+	return NewIdentifier(i.Ident).SetTree(i.tr).SetPos(i.Pos)
+}
+
+// VariableNode holds a list of variable names, possibly with chained field
+// accesses. The dollar sign is part of the (first) name.
+type VariableNode struct {
+	NodeType
+	Pos
+	tr    *Tree
+	Ident []string // Variable name and fields in lexical order.
+}
+
+func (t *Tree) newVariable(pos Pos, ident string) *VariableNode {
+	return &VariableNode{tr: t, NodeType: NodeVariable, Pos: pos, Ident: strings.Split(ident, ".")}
+}
+
+func (v *VariableNode) String() string {
+	var sb strings.Builder
+	v.writeTo(&sb)
+	return sb.String()
+}
+
+func (v *VariableNode) writeTo(sb *strings.Builder) {
+	for i, id := range v.Ident {
+		if i > 0 {
+			sb.WriteByte('.')
+		}
+		sb.WriteString(id)
+	}
+}
+
+func (v *VariableNode) tree() *Tree {
+	return v.tr
+}
+
+func (v *VariableNode) Copy() Node {
+	return &VariableNode{tr: v.tr, NodeType: NodeVariable, Pos: v.Pos, Ident: append([]string{}, v.Ident...)}
+}
+
+// DotNode holds the special identifier '.'.
+type DotNode struct {
+	NodeType
+	Pos
+	tr *Tree
+}
+
+func (t *Tree) newDot(pos Pos) *DotNode {
+	return &DotNode{tr: t, NodeType: NodeDot, Pos: pos}
+}
+
+func (d *DotNode) Type() NodeType {
+	// Override method on embedded NodeType for API compatibility.
+	// TODO: Not really a problem; could change API without effect but
+	// api tool complains.
+	return NodeDot
+}
+
+func (d *DotNode) String() string {
+	return "."
+}
+
+func (d *DotNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(d.String())
+}
+
+func (d *DotNode) tree() *Tree {
+	return d.tr
+}
+
+func (d *DotNode) Copy() Node {
+	return d.tr.newDot(d.Pos)
+}
+
+// NilNode holds the special identifier 'nil' representing an untyped nil constant.
+type NilNode struct {
+	NodeType
+	Pos
+	tr *Tree
+}
+
+func (t *Tree) newNil(pos Pos) *NilNode {
+	return &NilNode{tr: t, NodeType: NodeNil, Pos: pos}
+}
+
+func (n *NilNode) Type() NodeType {
+	// Override method on embedded NodeType for API compatibility.
+	// TODO: Not really a problem; could change API without effect but
+	// api tool complains.
+	return NodeNil
+}
+
+func (n *NilNode) String() string {
+	return "nil"
+}
+
+func (n *NilNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(n.String())
+}
+
+func (n *NilNode) tree() *Tree {
+	return n.tr
+}
+
+func (n *NilNode) Copy() Node {
+	return n.tr.newNil(n.Pos)
+}
+
+// FieldNode holds a field (identifier starting with '.').
+// The names may be chained ('.x.y').
+// The period is dropped from each ident.
+type FieldNode struct {
+	NodeType
+	Pos
+	tr    *Tree
+	Ident []string // The identifiers in lexical order.
+}
+
+func (t *Tree) newField(pos Pos, ident string) *FieldNode {
+	return &FieldNode{tr: t, NodeType: NodeField, Pos: pos, Ident: strings.Split(ident[1:], ".")} // [1:] to drop leading period
+}
+
+func (f *FieldNode) String() string {
+	var sb strings.Builder
+	f.writeTo(&sb)
+	return sb.String()
+}
+
+func (f *FieldNode) writeTo(sb *strings.Builder) {
+	for _, id := range f.Ident {
+		sb.WriteByte('.')
+		sb.WriteString(id)
+	}
+}
+
+func (f *FieldNode) tree() *Tree {
+	return f.tr
+}
+
+func (f *FieldNode) Copy() Node {
+	return &FieldNode{tr: f.tr, NodeType: NodeField, Pos: f.Pos, Ident: append([]string{}, f.Ident...)}
+}
+
+// ChainNode holds a term followed by a chain of field accesses (identifier starting with '.').
+// The names may be chained ('.x.y').
+// The periods are dropped from each ident.
+type ChainNode struct {
+	NodeType
+	Pos
+	tr    *Tree
+	Node  Node
+	Field []string // The identifiers in lexical order.
+}
+
+func (t *Tree) newChain(pos Pos, node Node) *ChainNode {
+	return &ChainNode{tr: t, NodeType: NodeChain, Pos: pos, Node: node}
+}
+
+// Add adds the named field (which should start with a period) to the end of the chain.
+func (c *ChainNode) Add(field string) {
+	if len(field) == 0 || field[0] != '.' {
+		panic("no dot in field")
+	}
+	field = field[1:] // Remove leading dot.
+	if field == "" {
+		panic("empty field")
+	}
+	c.Field = append(c.Field, field)
+}
+
+func (c *ChainNode) String() string {
+	var sb strings.Builder
+	c.writeTo(&sb)
+	return sb.String()
+}
+
+func (c *ChainNode) writeTo(sb *strings.Builder) {
+	if _, ok := c.Node.(*PipeNode); ok {
+		sb.WriteByte('(')
+		c.Node.writeTo(sb)
+		sb.WriteByte(')')
+	} else {
+		c.Node.writeTo(sb)
+	}
+	for _, field := range c.Field {
+		sb.WriteByte('.')
+		sb.WriteString(field)
+	}
+}
+
+func (c *ChainNode) tree() *Tree {
+	return c.tr
+}
+
+func (c *ChainNode) Copy() Node {
+	return &ChainNode{tr: c.tr, NodeType: NodeChain, Pos: c.Pos, Node: c.Node, Field: append([]string{}, c.Field...)}
+}
+
+// BoolNode holds a boolean constant.
+type BoolNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	True bool // The value of the boolean constant.
+}
+
+func (t *Tree) newBool(pos Pos, true bool) *BoolNode {
+	return &BoolNode{tr: t, NodeType: NodeBool, Pos: pos, True: true}
+}
+
+func (b *BoolNode) String() string {
+	if b.True {
+		return "true"
+	}
+	return "false"
+}
+
+func (b *BoolNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(b.String())
+}
+
+func (b *BoolNode) tree() *Tree {
+	return b.tr
+}
+
+func (b *BoolNode) Copy() Node {
+	return b.tr.newBool(b.Pos, b.True)
+}
+
+// NumberNode holds a number: signed or unsigned integer, float, or complex.
+// The value is parsed and stored under all the types that can represent the value.
+// This simulates in a small amount of code the behavior of Go's ideal constants.
+type NumberNode struct {
+	NodeType
+	Pos
+	tr         *Tree
+	IsInt      bool       // Number has an integral value.
+	IsUint     bool       // Number has an unsigned integral value.
+	IsFloat    bool       // Number has a floating-point value.
+	IsComplex  bool       // Number is complex.
+	Int64      int64      // The signed integer value.
+	Uint64     uint64     // The unsigned integer value.
+	Float64    float64    // The floating-point value.
+	Complex128 complex128 // The complex value.
+	Text       string     // The original textual representation from the input.
+}
+
+func (t *Tree) newNumber(pos Pos, text string, typ itemType) (*NumberNode, error) {
+	n := &NumberNode{tr: t, NodeType: NodeNumber, Pos: pos, Text: text}
+	switch typ {
+	case itemCharConstant:
+		rune, _, tail, err := strconv.UnquoteChar(text[1:], text[0])
+		if err != nil {
+			return nil, err
+		}
+		if tail != "'" {
+			return nil, fmt.Errorf("malformed character constant: %s", text)
+		}
+		n.Int64 = int64(rune)
+		n.IsInt = true
+		n.Uint64 = uint64(rune)
+		n.IsUint = true
+		n.Float64 = float64(rune) // odd but those are the rules.
+		n.IsFloat = true
+		return n, nil
+	case itemComplex:
+		// fmt.Sscan can parse the pair, so let it do the work.
+		if _, err := fmt.Sscan(text, &n.Complex128); err != nil {
+			return nil, err
+		}
+		n.IsComplex = true
+		n.simplifyComplex()
+		return n, nil
+	}
+	// Imaginary constants can only be complex unless they are zero.
+	if len(text) > 0 && text[len(text)-1] == 'i' {
+		f, err := strconv.ParseFloat(text[:len(text)-1], 64)
+		if err == nil {
+			n.IsComplex = true
+			n.Complex128 = complex(0, f)
+			n.simplifyComplex()
+			return n, nil
+		}
+	}
+	// Do integer test first so we get 0x123 etc.
+	u, err := strconv.ParseUint(text, 0, 64) // will fail for -0; fixed below.
+	if err == nil {
+		n.IsUint = true
+		n.Uint64 = u
+	}
+	i, err := strconv.ParseInt(text, 0, 64)
+	if err == nil {
+		n.IsInt = true
+		n.Int64 = i
+		if i == 0 {
+			n.IsUint = true // in case of -0.
+			n.Uint64 = u
+		}
+	}
+	// If an integer extraction succeeded, promote the float.
+	if n.IsInt {
+		n.IsFloat = true
+		n.Float64 = float64(n.Int64)
+	} else if n.IsUint {
+		n.IsFloat = true
+		n.Float64 = float64(n.Uint64)
+	} else {
+		f, err := strconv.ParseFloat(text, 64)
+		if err == nil {
+			// If we parsed it as a float but it looks like an integer,
+			// it's a huge number too large to fit in an int. Reject it.
+			if !strings.ContainsAny(text, ".eEpP") {
+				return nil, fmt.Errorf("integer overflow: %q", text)
+			}
+			n.IsFloat = true
+			n.Float64 = f
+			// If a floating-point extraction succeeded, extract the int if needed.
+			if !n.IsInt && float64(int64(f)) == f {
+				n.IsInt = true
+				n.Int64 = int64(f)
+			}
+			if !n.IsUint && float64(uint64(f)) == f {
+				n.IsUint = true
+				n.Uint64 = uint64(f)
+			}
+		}
+	}
+	if !n.IsInt && !n.IsUint && !n.IsFloat {
+		return nil, fmt.Errorf("illegal number syntax: %q", text)
+	}
+	return n, nil
+}
+
+// simplifyComplex pulls out any other types that are represented by the complex number.
+// These all require that the imaginary part be zero.
+func (n *NumberNode) simplifyComplex() {
+	n.IsFloat = imag(n.Complex128) == 0
+	if n.IsFloat {
+		n.Float64 = real(n.Complex128)
+		n.IsInt = float64(int64(n.Float64)) == n.Float64
+		if n.IsInt {
+			n.Int64 = int64(n.Float64)
+		}
+		n.IsUint = float64(uint64(n.Float64)) == n.Float64
+		if n.IsUint {
+			n.Uint64 = uint64(n.Float64)
+		}
+	}
+}
+
+func (n *NumberNode) String() string {
+	return n.Text
+}
+
+func (n *NumberNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(n.String())
+}
+
+func (n *NumberNode) tree() *Tree {
+	return n.tr
+}
+
+func (n *NumberNode) Copy() Node {
+	nn := new(NumberNode)
+	*nn = *n // Easy, fast, correct.
+	return nn
+}
+
+// StringNode holds a string constant. The value has been "unquoted".
+type StringNode struct {
+	NodeType
+	Pos
+	tr     *Tree
+	Quoted string // The original text of the string, with quotes.
+	Text   string // The string, after quote processing.
+}
+
+func (t *Tree) newString(pos Pos, orig, text string) *StringNode {
+	return &StringNode{tr: t, NodeType: NodeString, Pos: pos, Quoted: orig, Text: text}
+}
+
+func (s *StringNode) String() string {
+	return s.Quoted
+}
+
+func (s *StringNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(s.String())
+}
+
+func (s *StringNode) tree() *Tree {
+	return s.tr
+}
+
+func (s *StringNode) Copy() Node {
+	return s.tr.newString(s.Pos, s.Quoted, s.Text)
+}
+
+// endNode represents an {{end}} action.
+// It does not appear in the final parse tree.
+type endNode struct {
+	NodeType
+	Pos
+	tr *Tree
+}
+
+func (t *Tree) newEnd(pos Pos) *endNode {
+	return &endNode{tr: t, NodeType: nodeEnd, Pos: pos}
+}
+
+func (e *endNode) String() string {
+	return "{{end}}"
+}
+
+func (e *endNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(e.String())
+}
+
+func (e *endNode) tree() *Tree {
+	return e.tr
+}
+
+func (e *endNode) Copy() Node {
+	return e.tr.newEnd(e.Pos)
+}
+
+// elseNode represents an {{else}} action. Does not appear in the final tree.
+type elseNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	Line int // The line number in the input. Deprecated: Kept for compatibility.
+}
+
+func (t *Tree) newElse(pos Pos, line int) *elseNode {
+	return &elseNode{tr: t, NodeType: nodeElse, Pos: pos, Line: line}
+}
+
+func (e *elseNode) Type() NodeType {
+	return nodeElse
+}
+
+func (e *elseNode) String() string {
+	return "{{else}}"
+}
+
+func (e *elseNode) writeTo(sb *strings.Builder) {
+	sb.WriteString(e.String())
+}
+
+func (e *elseNode) tree() *Tree {
+	return e.tr
+}
+
+func (e *elseNode) Copy() Node {
+	return e.tr.newElse(e.Pos, e.Line)
+}
+
+// BranchNode is the common representation of if, range, and with.
+type BranchNode struct {
+	NodeType
+	Pos
+	tr       *Tree
+	Line     int       // The line number in the input. Deprecated: Kept for compatibility.
+	Pipe     *PipeNode // The pipeline to be evaluated.
+	List     *ListNode // What to execute if the value is non-empty.
+	ElseList *ListNode // What to execute if the value is empty (nil if absent).
+}
+
+func (b *BranchNode) String() string {
+	var sb strings.Builder
+	b.writeTo(&sb)
+	return sb.String()
+}
+
+func (b *BranchNode) writeTo(sb *strings.Builder) {
+	name := ""
+	switch b.NodeType {
+	case NodeIf:
+		name = "if"
+	case NodeRange:
+		name = "range"
+	case NodeWith:
+		name = "with"
+	case NodeAtLeastOnce:
+		name = "atLeastOnce"
+	default:
+		panic("unknown branch type")
+	}
+	sb.WriteString("{{")
+	sb.WriteString(name)
+	sb.WriteByte(' ')
+	b.Pipe.writeTo(sb)
+	sb.WriteString("}}")
+	b.List.writeTo(sb)
+	if b.ElseList != nil {
+		sb.WriteString("{{else}}")
+		b.ElseList.writeTo(sb)
+	}
+	sb.WriteString("{{end}}")
+}
+
+func (b *BranchNode) tree() *Tree {
+	return b.tr
+}
+
+func (b *BranchNode) Copy() Node {
+	switch b.NodeType {
+	case NodeIf:
+		return b.tr.newIf(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
+	case NodeRange:
+		return b.tr.newRange(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
+	case NodeWith:
+		return b.tr.newWith(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
+	case NodeAtLeastOnce:
+		return b.tr.newAtLeastOnce(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
+	default:
+		panic("unknown branch type")
+	}
+}
+
+// IfNode represents an {{if}} action and its commands.
+type IfNode struct {
+	BranchNode
+}
+
+func (t *Tree) newIf(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *IfNode {
+	return &IfNode{BranchNode{tr: t, NodeType: NodeIf, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
+}
+
+func (i *IfNode) Copy() Node {
+	return i.tr.newIf(i.Pos, i.Line, i.Pipe.CopyPipe(), i.List.CopyList(), i.ElseList.CopyList())
+}
+
+// RangeNode represents a {{range}} action and its commands.
+type RangeNode struct {
+	BranchNode
+}
+
+func (t *Tree) newRange(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *RangeNode {
+	return &RangeNode{BranchNode{tr: t, NodeType: NodeRange, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
+}
+
+func (r *RangeNode) Copy() Node {
+	return r.tr.newRange(r.Pos, r.Line, r.Pipe.CopyPipe(), r.List.CopyList(), r.ElseList.CopyList())
+}
+
+// WithNode represents a {{with}} action and its commands.
+type WithNode struct {
+	BranchNode
+}
+
+func (t *Tree) newWith(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *WithNode {
+	return &WithNode{BranchNode{tr: t, NodeType: NodeWith, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
+}
+
+func (w *WithNode) Copy() Node {
+	return w.tr.newWith(w.Pos, w.Line, w.Pipe.CopyPipe(), w.List.CopyList(), w.ElseList.CopyList())
+}
+
+// AtLeastOnce represents a {{atLeastOnce}} action and its commands.
+type AtLeastOnceNode struct {
+	BranchNode
+}
+
+func (t *Tree) newAtLeastOnce(pos Pos, line int, pipe *PipeNode, list *ListNode, elseList *ListNode) *AtLeastOnceNode {
+	return &AtLeastOnceNode{BranchNode{tr: t, NodeType: NodeAtLeastOnce, Pos: pos, Line: line, Pipe: pipe, List: list}}
+}
+
+func (w *AtLeastOnceNode) Copy() Node {
+	return w.tr.newAtLeastOnce(w.Pos, w.Line, w.Pipe.CopyPipe(), w.List.CopyList(), w.ElseList.CopyList())
+}
+
+// TemplateNode represents a {{template}} action.
+type TemplateNode struct {
+	NodeType
+	Pos
+	tr   *Tree
+	Line int       // The line number in the input. Deprecated: Kept for compatibility.
+	Name string    // The name of the template (unquoted).
+	Pipe *PipeNode // The command to evaluate as dot for the template.
+}
+
+func (t *Tree) newTemplate(pos Pos, line int, name string, pipe *PipeNode) *TemplateNode {
+	return &TemplateNode{tr: t, NodeType: NodeTemplate, Pos: pos, Line: line, Name: name, Pipe: pipe}
+}
+
+func (t *TemplateNode) String() string {
+	var sb strings.Builder
+	t.writeTo(&sb)
+	return sb.String()
+}
+
+func (t *TemplateNode) writeTo(sb *strings.Builder) {
+	sb.WriteString("{{template ")
+	sb.WriteString(strconv.Quote(t.Name))
+	if t.Pipe != nil {
+		sb.WriteByte(' ')
+		t.Pipe.writeTo(sb)
+	}
+	sb.WriteString("}}")
+}
+
+func (t *TemplateNode) tree() *Tree {
+	return t.tr
+}
+
+func (t *TemplateNode) Copy() Node {
+	return t.tr.newTemplate(t.Pos, t.Line, t.Name, t.Pipe.CopyPipe())
+}
diff --git a/third-party/go/template/parse/parse.go b/third-party/go/template/parse/parse.go
new file mode 100644
index 0000000..6698aaf
--- /dev/null
+++ b/third-party/go/template/parse/parse.go
@@ -0,0 +1,740 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package parse builds parse trees for templates as defined by text/template
+// and html/template. Clients should use those packages to construct templates
+// rather than this one, which provides shared internal data structures not
+// intended for general use.
+package parse
+
+import (
+	"bytes"
+	"fmt"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+// Tree is the representation of a single parsed template.
+type Tree struct {
+	Name      string    // name of the template represented by the tree.
+	ParseName string    // name of the top-level template during parsing, for error messages.
+	Root      *ListNode // top-level root of the tree.
+	text      string    // text parsed to create the template (or its parent)
+	// Parsing only; cleared after parse.
+	funcs     []map[string]interface{}
+	lex       *lexer
+	token     [3]item // three-token lookahead for parser.
+	peekCount int
+	vars      []string // variables defined at the moment.
+	treeSet   map[string]*Tree
+}
+
+// Copy returns a copy of the Tree. Any parsing state is discarded.
+func (t *Tree) Copy() *Tree {
+	if t == nil {
+		return nil
+	}
+	return &Tree{
+		Name:      t.Name,
+		ParseName: t.ParseName,
+		Root:      t.Root.CopyList(),
+		text:      t.text,
+	}
+}
+
+// Parse returns a map from template name to parse.Tree, created by parsing the
+// templates described in the argument string. The top-level template will be
+// given the specified name. If an error is encountered, parsing stops and an
+// empty map is returned with the error.
+func Parse(name, text, leftDelim, rightDelim string, funcs ...map[string]interface{}) (map[string]*Tree, error) {
+	treeSet := make(map[string]*Tree)
+	t := New(name)
+	t.text = text
+	_, err := t.Parse(text, leftDelim, rightDelim, treeSet, funcs...)
+	return treeSet, err
+}
+
+// next returns the next token.
+func (t *Tree) next() item {
+	if t.peekCount > 0 {
+		t.peekCount--
+	} else {
+		t.token[0] = t.lex.nextItem()
+	}
+	return t.token[t.peekCount]
+}
+
+// backup backs the input stream up one token.
+func (t *Tree) backup() {
+	t.peekCount++
+}
+
+// backup2 backs the input stream up two tokens.
+// The zeroth token is already there.
+func (t *Tree) backup2(t1 item) {
+	t.token[1] = t1
+	t.peekCount = 2
+}
+
+// backup3 backs the input stream up three tokens
+// The zeroth token is already there.
+func (t *Tree) backup3(t2, t1 item) { // Reverse order: we're pushing back.
+	t.token[1] = t1
+	t.token[2] = t2
+	t.peekCount = 3
+}
+
+// peek returns but does not consume the next token.
+func (t *Tree) peek() item {
+	if t.peekCount > 0 {
+		return t.token[t.peekCount-1]
+	}
+	t.peekCount = 1
+	t.token[0] = t.lex.nextItem()
+	return t.token[0]
+}
+
+// nextNonSpace returns the next non-space token.
+func (t *Tree) nextNonSpace() (token item) {
+	for {
+		token = t.next()
+		if token.typ != itemSpace {
+			break
+		}
+	}
+	return token
+}
+
+// peekNonSpace returns but does not consume the next non-space token.
+func (t *Tree) peekNonSpace() item {
+	token := t.nextNonSpace()
+	t.backup()
+	return token
+}
+
+// Parsing.
+
+// New allocates a new parse tree with the given name.
+func New(name string, funcs ...map[string]interface{}) *Tree {
+	return &Tree{
+		Name:  name,
+		funcs: funcs,
+	}
+}
+
+// ErrorContext returns a textual representation of the location of the node in the input text.
+// The receiver is only used when the node does not have a pointer to the tree inside,
+// which can occur in old code.
+func (t *Tree) ErrorContext(n Node) (location, context string) {
+	pos := int(n.Position())
+	tree := n.tree()
+	if tree == nil {
+		tree = t
+	}
+	text := tree.text[:pos]
+	byteNum := strings.LastIndex(text, "\n")
+	if byteNum == -1 {
+		byteNum = pos // On first line.
+	} else {
+		byteNum++ // After the newline.
+		byteNum = pos - byteNum
+	}
+	lineNum := 1 + strings.Count(text, "\n")
+	context = n.String()
+	return fmt.Sprintf("%s:%d:%d", tree.ParseName, lineNum, byteNum), context
+}
+
+// errorf formats the error and terminates processing.
+func (t *Tree) errorf(format string, args ...interface{}) {
+	t.Root = nil
+	format = fmt.Sprintf("template: %s:%d: %s", t.ParseName, t.token[0].line, format)
+	panic(fmt.Errorf(format, args...))
+}
+
+// error terminates processing.
+func (t *Tree) error(err error) {
+	t.errorf("%s", err)
+}
+
+// expect consumes the next token and guarantees it has the required type.
+func (t *Tree) expect(expected itemType, context string) item {
+	token := t.nextNonSpace()
+	if token.typ != expected {
+		t.unexpected(token, context)
+	}
+	return token
+}
+
+// expectOneOf consumes the next token and guarantees it has one of the required types.
+func (t *Tree) expectOneOf(expected1, expected2 itemType, context string) item {
+	token := t.nextNonSpace()
+	if token.typ != expected1 && token.typ != expected2 {
+		t.unexpected(token, context)
+	}
+	return token
+}
+
+// unexpected complains about the token and terminates processing.
+func (t *Tree) unexpected(token item, context string) {
+	t.errorf("unexpected %s in %s", token, context)
+}
+
+// recover is the handler that turns panics into returns from the top level of Parse.
+func (t *Tree) recover(errp *error) {
+	e := recover()
+	if e != nil {
+		if _, ok := e.(runtime.Error); ok {
+			panic(e)
+		}
+		if t != nil {
+			t.lex.drain()
+			t.stopParse()
+		}
+		*errp = e.(error)
+	}
+}
+
+// startParse initializes the parser, using the lexer.
+func (t *Tree) startParse(funcs []map[string]interface{}, lex *lexer, treeSet map[string]*Tree) {
+	t.Root = nil
+	t.lex = lex
+	t.vars = []string{"$"}
+	t.funcs = funcs
+	t.treeSet = treeSet
+}
+
+// stopParse terminates parsing.
+func (t *Tree) stopParse() {
+	t.lex = nil
+	t.vars = nil
+	t.funcs = nil
+	t.treeSet = nil
+}
+
+// Parse parses the template definition string to construct a representation of
+// the template for execution. If either action delimiter string is empty, the
+// default ("{{" or "}}") is used. Embedded template definitions are added to
+// the treeSet map.
+func (t *Tree) Parse(text, leftDelim, rightDelim string, treeSet map[string]*Tree, funcs ...map[string]interface{}) (tree *Tree, err error) {
+	defer t.recover(&err)
+	t.ParseName = t.Name
+	t.startParse(funcs, lex(t.Name, text, leftDelim, rightDelim), treeSet)
+	t.text = text
+	t.parse()
+	t.add()
+	t.stopParse()
+	return t, nil
+}
+
+// add adds tree to t.treeSet.
+func (t *Tree) add() {
+	tree := t.treeSet[t.Name]
+	if tree == nil || IsEmptyTree(tree.Root) {
+		t.treeSet[t.Name] = t
+		return
+	}
+	if !IsEmptyTree(t.Root) {
+		t.errorf("template: multiple definition of template %q", t.Name)
+	}
+}
+
+// IsEmptyTree reports whether this tree (node) is empty of everything but space.
+func IsEmptyTree(n Node) bool {
+	switch n := n.(type) {
+	case nil:
+		return true
+	case *ActionNode:
+	case *IfNode:
+	case *ListNode:
+		for _, node := range n.Nodes {
+			if !IsEmptyTree(node) {
+				return false
+			}
+		}
+		return true
+	case *RangeNode:
+	case *TemplateNode:
+	case *TextNode:
+		return len(bytes.TrimSpace(n.Text)) == 0
+	case *WithNode:
+	default:
+		panic("unknown node: " + n.String())
+	}
+	return false
+}
+
+// parse is the top-level parser for a template, essentially the same
+// as itemList except it also parses {{define}} actions.
+// It runs to EOF.
+func (t *Tree) parse() {
+	t.Root = t.newList(t.peek().pos)
+	for t.peek().typ != itemEOF {
+		if t.peek().typ == itemLeftDelim {
+			delim := t.next()
+			if t.nextNonSpace().typ == itemDefine {
+				newT := New("definition") // name will be updated once we know it.
+				newT.text = t.text
+				newT.ParseName = t.ParseName
+				newT.startParse(t.funcs, t.lex, t.treeSet)
+				newT.parseDefinition()
+				continue
+			}
+			t.backup2(delim)
+		}
+		switch n := t.textOrAction(); n.Type() {
+		case nodeEnd, nodeElse:
+			t.errorf("unexpected %s", n)
+		default:
+			t.Root.append(n)
+		}
+	}
+}
+
+// parseDefinition parses a {{define}} ...  {{end}} template definition and
+// installs the definition in t.treeSet. The "define" keyword has already
+// been scanned.
+func (t *Tree) parseDefinition() {
+	const context = "define clause"
+	name := t.expectOneOf(itemString, itemRawString, context)
+	var err error
+	t.Name, err = strconv.Unquote(name.val)
+	if err != nil {
+		t.error(err)
+	}
+	t.expect(itemRightDelim, context)
+	var end Node
+	t.Root, end = t.itemList()
+	if end.Type() != nodeEnd {
+		t.errorf("unexpected %s in %s", end, context)
+	}
+	t.add()
+	t.stopParse()
+}
+
+// itemList:
+//	textOrAction*
+// Terminates at {{end}} or {{else}}, returned separately.
+func (t *Tree) itemList() (list *ListNode, next Node) {
+	list = t.newList(t.peekNonSpace().pos)
+	for t.peekNonSpace().typ != itemEOF {
+		n := t.textOrAction()
+		switch n.Type() {
+		case nodeEnd, nodeElse:
+			return list, n
+		}
+		list.append(n)
+	}
+	t.errorf("unexpected EOF")
+	return
+}
+
+// textOrAction:
+//	text | action
+func (t *Tree) textOrAction() Node {
+	switch token := t.nextNonSpace(); token.typ {
+	case itemText:
+		return t.newText(token.pos, token.val)
+	case itemLeftDelim:
+		return t.action()
+	default:
+		t.unexpected(token, "input")
+	}
+	return nil
+}
+
+// Action:
+//	control
+//	command ("|" command)*
+// Left delim is past. Now get actions.
+// First word could be a keyword such as range.
+func (t *Tree) action() (n Node) {
+	switch token := t.nextNonSpace(); token.typ {
+	case itemBlock:
+		return t.blockControl()
+	case itemElse:
+		return t.elseControl()
+	case itemEnd:
+		return t.endControl()
+	case itemIf:
+		return t.ifControl()
+	case itemRange:
+		return t.rangeControl()
+	case itemTemplate:
+		return t.templateControl()
+	case itemWith:
+		return t.withControl()
+	case itemAtLeastOnce:
+		return t.atLeastOnceControl()
+	}
+	t.backup()
+	token := t.peek()
+	// Do not pop variables; they persist until "end".
+	return t.newAction(token.pos, token.line, t.pipeline("command"))
+}
+
+// Pipeline:
+//	declarations? command ('|' command)*
+func (t *Tree) pipeline(context string) (pipe *PipeNode) {
+	token := t.peekNonSpace()
+	pipe = t.newPipeline(token.pos, token.line, nil)
+	// Are there declarations or assignments?
+decls:
+	if v := t.peekNonSpace(); v.typ == itemVariable {
+		t.next()
+		// Since space is a token, we need 3-token look-ahead here in the worst case:
+		// in "$x foo" we need to read "foo" (as opposed to ":=") to know that $x is an
+		// argument variable rather than a declaration. So remember the token
+		// adjacent to the variable so we can push it back if necessary.
+		tokenAfterVariable := t.peek()
+		next := t.peekNonSpace()
+		switch {
+		case next.typ == itemAssign, next.typ == itemDeclare:
+			pipe.IsAssign = next.typ == itemAssign
+			t.nextNonSpace()
+			pipe.Decl = append(pipe.Decl, t.newVariable(v.pos, v.val))
+			t.vars = append(t.vars, v.val)
+		case next.typ == itemChar && next.val == ",":
+			t.nextNonSpace()
+			pipe.Decl = append(pipe.Decl, t.newVariable(v.pos, v.val))
+			t.vars = append(t.vars, v.val)
+			if context == "range" && len(pipe.Decl) < 2 {
+				switch t.peekNonSpace().typ {
+				case itemVariable, itemRightDelim, itemRightParen:
+					// second initialized variable in a range pipeline
+					goto decls
+				default:
+					t.errorf("range can only initialize variables")
+				}
+			}
+			t.errorf("too many declarations in %s", context)
+		case tokenAfterVariable.typ == itemSpace:
+			t.backup3(v, tokenAfterVariable)
+		default:
+			t.backup2(v)
+		}
+	}
+	for {
+		switch token := t.nextNonSpace(); token.typ {
+		case itemRightDelim, itemRightParen:
+			// At this point, the pipeline is complete
+			t.checkPipeline(pipe, context)
+			if token.typ == itemRightParen {
+				t.backup()
+			}
+			return
+		case itemBool, itemCharConstant, itemComplex, itemDot, itemField, itemIdentifier,
+			itemNumber, itemNil, itemRawString, itemString, itemVariable, itemLeftParen:
+			t.backup()
+			pipe.append(t.command())
+		default:
+			t.unexpected(token, context)
+		}
+	}
+}
+
+func (t *Tree) checkPipeline(pipe *PipeNode, context string) {
+	// Reject empty pipelines
+	if len(pipe.Cmds) == 0 {
+		t.errorf("missing value for %s", context)
+	}
+	// Only the first command of a pipeline can start with a non executable operand
+	for i, c := range pipe.Cmds[1:] {
+		switch c.Args[0].Type() {
+		case NodeBool, NodeDot, NodeNil, NodeNumber, NodeString:
+			// With A|B|C, pipeline stage 2 is B
+			t.errorf("non executable command in pipeline stage %d", i+2)
+		}
+	}
+}
+
+func (t *Tree) parseControl(allowElseIf bool, context string) (pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) {
+	defer t.popVars(len(t.vars))
+	pipe = t.pipeline(context)
+	var next Node
+	list, next = t.itemList()
+	switch next.Type() {
+	case nodeEnd: //done
+	case nodeElse:
+		if allowElseIf {
+			// Special case for "else if". If the "else" is followed immediately by an "if",
+			// the elseControl will have left the "if" token pending. Treat
+			//	{{if a}}_{{else if b}}_{{end}}
+			// as
+			//	{{if a}}_{{else}}{{if b}}_{{end}}{{end}}.
+			// To do this, parse the if as usual and stop at it {{end}}; the subsequent{{end}}
+			// is assumed. This technique works even for long if-else-if chains.
+			// TODO: Should we allow else-if in with and range?
+			if t.peek().typ == itemIf {
+				t.next() // Consume the "if" token.
+				elseList = t.newList(next.Position())
+				elseList.append(t.ifControl())
+				// Do not consume the next item - only one {{end}} required.
+				break
+			}
+		}
+		elseList, next = t.itemList()
+		if next.Type() != nodeEnd {
+			t.errorf("expected end; found %s", next)
+		}
+	}
+	return pipe.Position(), pipe.Line, pipe, list, elseList
+}
+
+// If:
+//	{{if pipeline}} itemList {{end}}
+//	{{if pipeline}} itemList {{else}} itemList {{end}}
+// If keyword is past.
+func (t *Tree) ifControl() Node {
+	return t.newIf(t.parseControl(true, "if"))
+}
+
+// Range:
+//	{{range pipeline}} itemList {{end}}
+//	{{range pipeline}} itemList {{else}} itemList {{end}}
+// Range keyword is past.
+func (t *Tree) rangeControl() Node {
+	return t.newRange(t.parseControl(false, "range"))
+}
+
+// With:
+//	{{with pipeline}} itemList {{end}}
+//	{{with pipeline}} itemList {{else}} itemList {{end}}
+// If keyword is past.
+func (t *Tree) withControl() Node {
+	return t.newWith(t.parseControl(false, "with"))
+}
+
+// AtLeastOnce:
+//	{{atLeastOnce number}} itemList {{end}}
+// If keyword is past.
+func (t *Tree) atLeastOnceControl() Node {
+	return t.newAtLeastOnce(t.parseControl(false, "atLeastOnce"))
+}
+
+// End:
+//	{{end}}
+// End keyword is past.
+func (t *Tree) endControl() Node {
+	return t.newEnd(t.expect(itemRightDelim, "end").pos)
+}
+
+// Else:
+//	{{else}}
+// Else keyword is past.
+func (t *Tree) elseControl() Node {
+	// Special case for "else if".
+	peek := t.peekNonSpace()
+	if peek.typ == itemIf {
+		// We see "{{else if ... " but in effect rewrite it to {{else}}{{if ... ".
+		return t.newElse(peek.pos, peek.line)
+	}
+	token := t.expect(itemRightDelim, "else")
+	return t.newElse(token.pos, token.line)
+}
+
+// Block:
+//	{{block stringValue pipeline}}
+// Block keyword is past.
+// The name must be something that can evaluate to a string.
+// The pipeline is mandatory.
+func (t *Tree) blockControl() Node {
+	const context = "block clause"
+
+	token := t.nextNonSpace()
+	name := t.parseTemplateName(token, context)
+	pipe := t.pipeline(context)
+
+	block := New(name) // name will be updated once we know it.
+	block.text = t.text
+	block.ParseName = t.ParseName
+	block.startParse(t.funcs, t.lex, t.treeSet)
+	var end Node
+	block.Root, end = block.itemList()
+	if end.Type() != nodeEnd {
+		t.errorf("unexpected %s in %s", end, context)
+	}
+	block.add()
+	block.stopParse()
+
+	return t.newTemplate(token.pos, token.line, name, pipe)
+}
+
+// Template:
+//	{{template stringValue pipeline}}
+// Template keyword is past. The name must be something that can evaluate
+// to a string.
+func (t *Tree) templateControl() Node {
+	const context = "template clause"
+	token := t.nextNonSpace()
+	name := t.parseTemplateName(token, context)
+	var pipe *PipeNode
+	if t.nextNonSpace().typ != itemRightDelim {
+		t.backup()
+		// Do not pop variables; they persist until "end".
+		pipe = t.pipeline(context)
+	}
+	return t.newTemplate(token.pos, token.line, name, pipe)
+}
+
+func (t *Tree) parseTemplateName(token item, context string) (name string) {
+	switch token.typ {
+	case itemString, itemRawString:
+		s, err := strconv.Unquote(token.val)
+		if err != nil {
+			t.error(err)
+		}
+		name = s
+	default:
+		t.unexpected(token, context)
+	}
+	return
+}
+
+// command:
+//	operand (space operand)*
+// space-separated arguments up to a pipeline character or right delimiter.
+// we consume the pipe character but leave the right delim to terminate the action.
+func (t *Tree) command() *CommandNode {
+	cmd := t.newCommand(t.peekNonSpace().pos)
+	for {
+		t.peekNonSpace() // skip leading spaces.
+		operand := t.operand()
+		if operand != nil {
+			cmd.append(operand)
+		}
+		switch token := t.next(); token.typ {
+		case itemSpace:
+			continue
+		case itemError:
+			t.errorf("%s", token.val)
+		case itemRightDelim, itemRightParen:
+			t.backup()
+		case itemPipe:
+		default:
+			t.errorf("unexpected %s in operand", token)
+		}
+		break
+	}
+	if len(cmd.Args) == 0 {
+		t.errorf("empty command")
+	}
+	return cmd
+}
+
+// operand:
+//	term .Field*
+// An operand is a space-separated component of a command,
+// a term possibly followed by field accesses.
+// A nil return means the next item is not an operand.
+func (t *Tree) operand() Node {
+	node := t.term()
+	if node == nil {
+		return nil
+	}
+	if t.peek().typ == itemField {
+		chain := t.newChain(t.peek().pos, node)
+		for t.peek().typ == itemField {
+			chain.Add(t.next().val)
+		}
+		// Compatibility with original API: If the term is of type NodeField
+		// or NodeVariable, just put more fields on the original.
+		// Otherwise, keep the Chain node.
+		// Obvious parsing errors involving literal values are detected here.
+		// More complex error cases will have to be handled at execution time.
+		switch node.Type() {
+		case NodeField:
+			node = t.newField(chain.Position(), chain.String())
+		case NodeVariable:
+			node = t.newVariable(chain.Position(), chain.String())
+		case NodeBool, NodeString, NodeNumber, NodeNil, NodeDot:
+			t.errorf("unexpected . after term %q", node.String())
+		default:
+			node = chain
+		}
+	}
+	return node
+}
+
+// term:
+//	literal (number, string, nil, boolean)
+//	function (identifier)
+//	.
+//	.Field
+//	$
+//	'(' pipeline ')'
+// A term is a simple "expression".
+// A nil return means the next item is not a term.
+func (t *Tree) term() Node {
+	switch token := t.nextNonSpace(); token.typ {
+	case itemError:
+		t.errorf("%s", token.val)
+	case itemIdentifier:
+		if !t.hasFunction(token.val) {
+			t.errorf("function %q not defined", token.val)
+		}
+		return NewIdentifier(token.val).SetTree(t).SetPos(token.pos)
+	case itemDot:
+		return t.newDot(token.pos)
+	case itemNil:
+		return t.newNil(token.pos)
+	case itemVariable:
+		return t.useVar(token.pos, token.val)
+	case itemField:
+		return t.newField(token.pos, token.val)
+	case itemBool:
+		return t.newBool(token.pos, token.val == "true")
+	case itemCharConstant, itemComplex, itemNumber:
+		number, err := t.newNumber(token.pos, token.val, token.typ)
+		if err != nil {
+			t.error(err)
+		}
+		return number
+	case itemLeftParen:
+		pipe := t.pipeline("parenthesized pipeline")
+		if token := t.next(); token.typ != itemRightParen {
+			t.errorf("unclosed right paren: unexpected %s", token)
+		}
+		return pipe
+	case itemString, itemRawString:
+		s, err := strconv.Unquote(token.val)
+		if err != nil {
+			t.error(err)
+		}
+		return t.newString(token.pos, token.val, s)
+	}
+	t.backup()
+	return nil
+}
+
+// hasFunction reports if a function name exists in the Tree's maps.
+func (t *Tree) hasFunction(name string) bool {
+	for _, funcMap := range t.funcs {
+		if funcMap == nil {
+			continue
+		}
+		if funcMap[name] != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// popVars trims the variable list to the specified length
+func (t *Tree) popVars(n int) {
+	t.vars = t.vars[:n]
+}
+
+// useVar returns a node for a variable reference. It errors if the
+// variable is not defined.
+func (t *Tree) useVar(pos Pos, name string) Node {
+	v := t.newVariable(pos, name)
+	for _, varName := range t.vars {
+		if varName == v.Ident[0] {
+			return v
+		}
+	}
+	t.errorf("undefined variable %q", v.Ident[0])
+	return nil
+}
diff --git a/third-party/go/template/template.go b/third-party/go/template/template.go
new file mode 100644
index 0000000..67a1b3d
--- /dev/null
+++ b/third-party/go/template/template.go
@@ -0,0 +1,229 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package template
+
+import (
+	"github.com/apache/skywalking-infra-e2e/third-party/go/template/parse"
+	"reflect"
+	"sync"
+)
+
+// common holds the information shared by related templates.
+type common struct {
+	tmpl   map[string]*Template // Map from name to defined templates.
+	option option
+	// We use two maps, one for parsing and one for execution.
+	// This separation makes the API cleaner since it doesn't
+	// expose reflection to the client.
+	muFuncs    sync.RWMutex // protects parseFuncs and execFuncs
+	parseFuncs FuncMap
+	execFuncs  map[string]reflect.Value
+}
+
+// Template is the representation of a parsed template. The *parse.Tree
+// field is exported only for use by html/template and should be treated
+// as unexported by all other clients.
+type Template struct {
+	name string
+	*parse.Tree
+	*common
+	leftDelim  string
+	rightDelim string
+}
+
+// New allocates a new, undefined template with the given name.
+func New(name string) *Template {
+	t := &Template{
+		name: name,
+	}
+	t.init()
+	return t
+}
+
+// Name returns the name of the template.
+func (t *Template) Name() string {
+	return t.name
+}
+
+// New allocates a new, undefined template associated with the given one and with the same
+// delimiters. The association, which is transitive, allows one template to
+// invoke another with a {{template}} action.
+//
+// Because associated templates share underlying data, template construction
+// cannot be done safely in parallel. Once the templates are constructed, they
+// can be executed in parallel.
+func (t *Template) New(name string) *Template {
+	t.init()
+	nt := &Template{
+		name:       name,
+		common:     t.common,
+		leftDelim:  t.leftDelim,
+		rightDelim: t.rightDelim,
+	}
+	return nt
+}
+
+// init guarantees that t has a valid common structure.
+func (t *Template) init() {
+	if t.common == nil {
+		c := new(common)
+		c.tmpl = make(map[string]*Template)
+		c.parseFuncs = make(FuncMap)
+		c.execFuncs = make(map[string]reflect.Value)
+		t.common = c
+	}
+}
+
+// Clone returns a duplicate of the template, including all associated
+// templates. The actual representation is not copied, but the name space of
+// associated templates is, so further calls to Parse in the copy will add
+// templates to the copy but not to the original. Clone can be used to prepare
+// common templates and use them with variant definitions for other templates
+// by adding the variants after the clone is made.
+func (t *Template) Clone() (*Template, error) {
+	nt := t.copy(nil)
+	nt.init()
+	if t.common == nil {
+		return nt, nil
+	}
+	for k, v := range t.tmpl {
+		if k == t.name {
+			nt.tmpl[t.name] = nt
+			continue
+		}
+		// The associated templates share nt's common structure.
+		tmpl := v.copy(nt.common)
+		nt.tmpl[k] = tmpl
+	}
+	t.muFuncs.RLock()
+	defer t.muFuncs.RUnlock()
+	for k, v := range t.parseFuncs {
+		nt.parseFuncs[k] = v
+	}
+	for k, v := range t.execFuncs {
+		nt.execFuncs[k] = v
+	}
+	return nt, nil
+}
+
+// copy returns a shallow copy of t, with common set to the argument.
+func (t *Template) copy(c *common) *Template {
+	return &Template{
+		name:       t.name,
+		Tree:       t.Tree,
+		common:     c,
+		leftDelim:  t.leftDelim,
+		rightDelim: t.rightDelim,
+	}
+}
+
+// AddParseTree associates the argument parse tree with the template t, giving
+// it the specified name. If the template has not been defined, this tree becomes
+// its definition. If it has been defined and already has that name, the existing
+// definition is replaced; otherwise a new template is created, defined, and returned.
+func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error) {
+	t.init()
+	nt := t
+	if name != t.name {
+		nt = t.New(name)
+	}
+	// Even if nt == t, we need to install it in the common.tmpl map.
+	if t.associate(nt, tree) || nt.Tree == nil {
+		nt.Tree = tree
+	}
+	return nt, nil
+}
+
+// Templates returns a slice of defined templates associated with t.
+func (t *Template) Templates() []*Template {
+	if t.common == nil {
+		return nil
+	}
+	// Return a slice so we don't expose the map.
+	m := make([]*Template, 0, len(t.tmpl))
+	for _, v := range t.tmpl {
+		m = append(m, v)
+	}
+	return m
+}
+
+// Delims sets the action delimiters to the specified strings, to be used in
+// subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template
+// definitions will inherit the settings. An empty delimiter stands for the
+// corresponding default: {{ or }}.
+// The return value is the template, so calls can be chained.
+func (t *Template) Delims(left, right string) *Template {
+	t.init()
+	t.leftDelim = left
+	t.rightDelim = right
+	return t
+}
+
+// Funcs adds the elements of the argument map to the template's function map.
+// It must be called before the template is parsed.
+// It panics if a value in the map is not a function with appropriate return
+// type or if the name cannot be used syntactically as a function in a template.
+// It is legal to overwrite elements of the map. The return value is the template,
+// so calls can be chained.
+func (t *Template) Funcs(funcMap FuncMap) *Template {
+	t.init()
+	t.muFuncs.Lock()
+	defer t.muFuncs.Unlock()
+	addValueFuncs(t.execFuncs, funcMap)
+	addFuncs(t.parseFuncs, funcMap)
+	return t
+}
+
+// Lookup returns the template with the given name that is associated with t.
+// It returns nil if there is no such template or the template has no definition.
+func (t *Template) Lookup(name string) *Template {
+	if t.common == nil {
+		return nil
+	}
+	return t.tmpl[name]
+}
+
+// Parse parses text as a template body for t.
+// Named template definitions ({{define ...}} or {{block ...}} statements) in text
+// define additional templates associated with t and are removed from the
+// definition of t itself.
+//
+// Templates can be redefined in successive calls to Parse.
+// A template definition with a body containing only white space and comments
+// is considered empty and will not replace an existing template's body.
+// This allows using Parse to add new named template definitions without
+// overwriting the main template body.
+func (t *Template) Parse(text string) (*Template, error) {
+	t.init()
+	t.muFuncs.RLock()
+	trees, err := parse.Parse(t.name, text, t.leftDelim, t.rightDelim, t.parseFuncs, builtins())
+	t.muFuncs.RUnlock()
+	if err != nil {
+		return nil, err
+	}
+	// Add the newly parsed trees, including the one for t, into our common structure.
+	for name, tree := range trees {
+		if _, err := t.AddParseTree(name, tree); err != nil {
+			return nil, err
+		}
+	}
+	return t, nil
+}
+
+// associate installs the new template into the group of templates associated
+// with t. The two are already known to share the common structure.
+// The boolean return value reports whether to store this tree as t.Tree.
+func (t *Template) associate(new *Template, tree *parse.Tree) bool {
+	if new.common != t.common {
+		panic("internal error: associate not common")
+	}
+	if old := t.tmpl[new.name]; old != nil && parse.IsEmptyTree(tree.Root) && old.Tree != nil {
+		// If a template by that name exists,
+		// don't replace it with an empty template.
+		return false
+	}
+	t.tmpl[new.name] = new
+	return true
+}