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Posted to commits@marmotta.apache.org by ss...@apache.org on 2018/04/29 19:35:56 UTC

[27/51] [partial] marmotta git commit: * Replace gtest with upstream version, including LICENSE header. * Include absl library for faster and safer string operations. * Update license headers where needed. * Removed custom code replaced by absl.

http://git-wip-us.apache.org/repos/asf/marmotta/blob/0eb556da/libraries/ostrich/backend/3rdparty/abseil/absl/strings/str_split_test.cc
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diff --git a/libraries/ostrich/backend/3rdparty/abseil/absl/strings/str_split_test.cc b/libraries/ostrich/backend/3rdparty/abseil/absl/strings/str_split_test.cc
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+// Copyright 2017 The Abseil Authors.
+//
+// Licensed 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.
+
+#include "absl/strings/str_split.h"
+
+#include <deque>
+#include <initializer_list>
+#include <list>
+#include <map>
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "absl/base/dynamic_annotations.h"  // for RunningOnValgrind
+#include "absl/base/macros.h"
+#include "absl/strings/numbers.h"
+
+namespace {
+
+using ::testing::ElementsAre;
+using ::testing::Pair;
+using ::testing::UnorderedElementsAre;
+
+// This tests the overall split API, which is made up of the absl::StrSplit()
+// function and the Delimiter objects in the absl:: namespace.
+// This TEST macro is outside of any namespace to require full specification of
+// namespaces just like callers will need to use.
+TEST(Split, APIExamples) {
+  {
+    // Passes std::string delimiter. Assumes the default of Literal.
+    std::vector<std::string> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+
+    // Equivalent to...
+    using absl::ByString;
+    v = absl::StrSplit("a,b,c", ByString(","));
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+
+    // Equivalent to...
+    EXPECT_THAT(absl::StrSplit("a,b,c", ByString(",")),
+                ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Same as above, but using a single character as the delimiter.
+    std::vector<std::string> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+
+    // Equivalent to...
+    using absl::ByChar;
+    v = absl::StrSplit("a,b,c", ByChar(','));
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Same as above, but using std::string
+    std::vector<std::string> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+
+    // Equivalent to...
+    using absl::ByChar;
+    v = absl::StrSplit("a,b,c", ByChar(','));
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Uses the Literal std::string "=>" as the delimiter.
+    const std::vector<std::string> v = absl::StrSplit("a=>b=>c", "=>");
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // The substrings are returned as string_views, eliminating copying.
+    std::vector<absl::string_view> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Leading and trailing empty substrings.
+    std::vector<std::string> v = absl::StrSplit(",a,b,c,", ',');
+    EXPECT_THAT(v, ElementsAre("", "a", "b", "c", ""));
+  }
+
+  {
+    // Splits on a delimiter that is not found.
+    std::vector<std::string> v = absl::StrSplit("abc", ',');
+    EXPECT_THAT(v, ElementsAre("abc"));
+  }
+
+  {
+    // Splits the input std::string into individual characters by using an empty
+    // std::string as the delimiter.
+    std::vector<std::string> v = absl::StrSplit("abc", "");
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Splits std::string data with embedded NUL characters, using NUL as the
+    // delimiter. A simple delimiter of "\0" doesn't work because strlen() will
+    // say that's the empty std::string when constructing the absl::string_view
+    // delimiter. Instead, a non-empty std::string containing NUL can be used as the
+    // delimiter.
+    std::string embedded_nulls("a\0b\0c", 5);
+    std::string null_delim("\0", 1);
+    std::vector<std::string> v = absl::StrSplit(embedded_nulls, null_delim);
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Stores first two split strings as the members in a std::pair.
+    std::pair<std::string, std::string> p = absl::StrSplit("a,b,c", ',');
+    EXPECT_EQ("a", p.first);
+    EXPECT_EQ("b", p.second);
+    // "c" is omitted because std::pair can hold only two elements.
+  }
+
+  {
+    // Results stored in std::set<std::string>
+    std::set<std::string> v = absl::StrSplit("a,b,c,a,b,c,a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Uses a non-const char* delimiter.
+    char a[] = ",";
+    char* d = a + 0;
+    std::vector<std::string> v = absl::StrSplit("a,b,c", d);
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Results split using either of , or ;
+    using absl::ByAnyChar;
+    std::vector<std::string> v = absl::StrSplit("a,b;c", ByAnyChar(",;"));
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Uses the SkipWhitespace predicate.
+    using absl::SkipWhitespace;
+    std::vector<std::string> v = absl::StrSplit(" a , ,,b,", ',', SkipWhitespace());
+    EXPECT_THAT(v, ElementsAre(" a ", "b"));
+  }
+
+  {
+    // Uses the ByLength delimiter.
+    using absl::ByLength;
+    std::vector<std::string> v = absl::StrSplit("abcdefg", ByLength(3));
+    EXPECT_THAT(v, ElementsAre("abc", "def", "g"));
+  }
+
+  {
+    // Different forms of initialization / conversion.
+    std::vector<std::string> v1 = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v1, ElementsAre("a", "b", "c"));
+    std::vector<std::string> v2(absl::StrSplit("a,b,c", ','));
+    EXPECT_THAT(v2, ElementsAre("a", "b", "c"));
+    auto v3 = std::vector<std::string>(absl::StrSplit("a,b,c", ','));
+    EXPECT_THAT(v3, ElementsAre("a", "b", "c"));
+    v3 = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v3, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Results stored in a std::map.
+    std::map<std::string, std::string> m = absl::StrSplit("a,1,b,2,a,3", ',');
+    EXPECT_EQ(2, m.size());
+    EXPECT_EQ("3", m["a"]);
+    EXPECT_EQ("2", m["b"]);
+  }
+
+  {
+    // Results stored in a std::multimap.
+    std::multimap<std::string, std::string> m = absl::StrSplit("a,1,b,2,a,3", ',');
+    EXPECT_EQ(3, m.size());
+    auto it = m.find("a");
+    EXPECT_EQ("1", it->second);
+    ++it;
+    EXPECT_EQ("3", it->second);
+    it = m.find("b");
+    EXPECT_EQ("2", it->second);
+  }
+
+  {
+    // Demonstrates use in a range-based for loop in C++11.
+    std::string s = "x,x,x,x,x,x,x";
+    for (absl::string_view sp : absl::StrSplit(s, ',')) {
+      EXPECT_EQ("x", sp);
+    }
+  }
+
+  {
+    // Demonstrates use with a Predicate in a range-based for loop.
+    using absl::SkipWhitespace;
+    std::string s = " ,x,,x,,x,x,x,,";
+    for (absl::string_view sp : absl::StrSplit(s, ',', SkipWhitespace())) {
+      EXPECT_EQ("x", sp);
+    }
+  }
+
+  {
+    // Demonstrates a "smart" split to std::map using two separate calls to
+    // absl::StrSplit. One call to split the records, and another call to split
+    // the keys and values. This also uses the Limit delimiter so that the
+    // std::string "a=b=c" will split to "a" -> "b=c".
+    std::map<std::string, std::string> m;
+    for (absl::string_view sp : absl::StrSplit("a=b=c,d=e,f=,g", ',')) {
+      m.insert(absl::StrSplit(sp, absl::MaxSplits('=', 1)));
+    }
+    EXPECT_EQ("b=c", m.find("a")->second);
+    EXPECT_EQ("e", m.find("d")->second);
+    EXPECT_EQ("", m.find("f")->second);
+    EXPECT_EQ("", m.find("g")->second);
+  }
+}
+
+//
+// Tests for SplitIterator
+//
+
+TEST(SplitIterator, Basics) {
+  auto splitter = absl::StrSplit("a,b", ',');
+  auto it = splitter.begin();
+  auto end = splitter.end();
+
+  EXPECT_NE(it, end);
+  EXPECT_EQ("a", *it);  // tests dereference
+  ++it;                 // tests preincrement
+  EXPECT_NE(it, end);
+  EXPECT_EQ("b", std::string(it->data(), it->size()));  // tests dereference as ptr
+  it++;                                            // tests postincrement
+  EXPECT_EQ(it, end);
+}
+
+// Simple Predicate to skip a particular std::string.
+class Skip {
+ public:
+  explicit Skip(const std::string& s) : s_(s) {}
+  bool operator()(absl::string_view sp) { return sp != s_; }
+
+ private:
+  std::string s_;
+};
+
+TEST(SplitIterator, Predicate) {
+  auto splitter = absl::StrSplit("a,b,c", ',', Skip("b"));
+  auto it = splitter.begin();
+  auto end = splitter.end();
+
+  EXPECT_NE(it, end);
+  EXPECT_EQ("a", *it);  // tests dereference
+  ++it;                 // tests preincrement -- "b" should be skipped here.
+  EXPECT_NE(it, end);
+  EXPECT_EQ("c", std::string(it->data(), it->size()));  // tests dereference as ptr
+  it++;                                            // tests postincrement
+  EXPECT_EQ(it, end);
+}
+
+TEST(SplitIterator, EdgeCases) {
+  // Expected input and output, assuming a delimiter of ','
+  struct {
+    std::string in;
+    std::vector<std::string> expect;
+  } specs[] = {
+      {"", {""}},
+      {"foo", {"foo"}},
+      {",", {"", ""}},
+      {",foo", {"", "foo"}},
+      {"foo,", {"foo", ""}},
+      {",foo,", {"", "foo", ""}},
+      {"foo,bar", {"foo", "bar"}},
+  };
+
+  for (const auto& spec : specs) {
+    SCOPED_TRACE(spec.in);
+    auto splitter = absl::StrSplit(spec.in, ',');
+    auto it = splitter.begin();
+    auto end = splitter.end();
+    for (const auto& expected : spec.expect) {
+      EXPECT_NE(it, end);
+      EXPECT_EQ(expected, *it++);
+    }
+    EXPECT_EQ(it, end);
+  }
+}
+
+TEST(Splitter, Const) {
+  const auto splitter = absl::StrSplit("a,b,c", ',');
+  EXPECT_THAT(splitter, ElementsAre("a", "b", "c"));
+}
+
+TEST(Split, EmptyAndNull) {
+  // Attention: Splitting a null absl::string_view is different than splitting
+  // an empty absl::string_view even though both string_views are considered
+  // equal. This behavior is likely surprising and undesirable. However, to
+  // maintain backward compatibility, there is a small "hack" in
+  // str_split_internal.h that preserves this behavior. If that behavior is ever
+  // changed/fixed, this test will need to be updated.
+  EXPECT_THAT(absl::StrSplit(absl::string_view(""), '-'), ElementsAre(""));
+  EXPECT_THAT(absl::StrSplit(absl::string_view(), '-'), ElementsAre());
+}
+
+TEST(SplitIterator, EqualityAsEndCondition) {
+  auto splitter = absl::StrSplit("a,b,c", ',');
+  auto it = splitter.begin();
+  auto it2 = it;
+
+  // Increments it2 twice to point to "c" in the input text.
+  ++it2;
+  ++it2;
+  EXPECT_EQ("c", *it2);
+
+  // This test uses a non-end SplitIterator as the terminating condition in a
+  // for loop. This relies on SplitIterator equality for non-end SplitIterators
+  // working correctly. At this point it2 points to "c", and we use that as the
+  // "end" condition in this test.
+  std::vector<absl::string_view> v;
+  for (; it != it2; ++it) {
+    v.push_back(*it);
+  }
+  EXPECT_THAT(v, ElementsAre("a", "b"));
+}
+
+//
+// Tests for Splitter
+//
+
+TEST(Splitter, RangeIterators) {
+  auto splitter = absl::StrSplit("a,b,c", ',');
+  std::vector<absl::string_view> output;
+  for (const absl::string_view p : splitter) {
+    output.push_back(p);
+  }
+  EXPECT_THAT(output, ElementsAre("a", "b", "c"));
+}
+
+// Some template functions for use in testing conversion operators
+template <typename ContainerType, typename Splitter>
+void TestConversionOperator(const Splitter& splitter) {
+  ContainerType output = splitter;
+  EXPECT_THAT(output, UnorderedElementsAre("a", "b", "c", "d"));
+}
+
+template <typename MapType, typename Splitter>
+void TestMapConversionOperator(const Splitter& splitter) {
+  MapType m = splitter;
+  EXPECT_THAT(m, UnorderedElementsAre(Pair("a", "b"), Pair("c", "d")));
+}
+
+template <typename FirstType, typename SecondType, typename Splitter>
+void TestPairConversionOperator(const Splitter& splitter) {
+  std::pair<FirstType, SecondType> p = splitter;
+  EXPECT_EQ(p, (std::pair<FirstType, SecondType>("a", "b")));
+}
+
+TEST(Splitter, ConversionOperator) {
+  auto splitter = absl::StrSplit("a,b,c,d", ',');
+
+  TestConversionOperator<std::vector<absl::string_view>>(splitter);
+  TestConversionOperator<std::vector<std::string>>(splitter);
+  TestConversionOperator<std::list<absl::string_view>>(splitter);
+  TestConversionOperator<std::list<std::string>>(splitter);
+  TestConversionOperator<std::deque<absl::string_view>>(splitter);
+  TestConversionOperator<std::deque<std::string>>(splitter);
+  TestConversionOperator<std::set<absl::string_view>>(splitter);
+  TestConversionOperator<std::set<std::string>>(splitter);
+  TestConversionOperator<std::multiset<absl::string_view>>(splitter);
+  TestConversionOperator<std::multiset<std::string>>(splitter);
+  TestConversionOperator<std::unordered_set<std::string>>(splitter);
+
+  // Tests conversion to map-like objects.
+
+  TestMapConversionOperator<std::map<absl::string_view, absl::string_view>>(
+      splitter);
+  TestMapConversionOperator<std::map<absl::string_view, std::string>>(splitter);
+  TestMapConversionOperator<std::map<std::string, absl::string_view>>(splitter);
+  TestMapConversionOperator<std::map<std::string, std::string>>(splitter);
+  TestMapConversionOperator<
+      std::multimap<absl::string_view, absl::string_view>>(splitter);
+  TestMapConversionOperator<std::multimap<absl::string_view, std::string>>(splitter);
+  TestMapConversionOperator<std::multimap<std::string, absl::string_view>>(splitter);
+  TestMapConversionOperator<std::multimap<std::string, std::string>>(splitter);
+  TestMapConversionOperator<std::unordered_map<std::string, std::string>>(splitter);
+
+  // Tests conversion to std::pair
+
+  TestPairConversionOperator<absl::string_view, absl::string_view>(splitter);
+  TestPairConversionOperator<absl::string_view, std::string>(splitter);
+  TestPairConversionOperator<std::string, absl::string_view>(splitter);
+  TestPairConversionOperator<std::string, std::string>(splitter);
+}
+
+// A few additional tests for conversion to std::pair. This conversion is
+// different from others because a std::pair always has exactly two elements:
+// .first and .second. The split has to work even when the split has
+// less-than, equal-to, and more-than 2 strings.
+TEST(Splitter, ToPair) {
+  {
+    // Empty std::string
+    std::pair<std::string, std::string> p = absl::StrSplit("", ',');
+    EXPECT_EQ("", p.first);
+    EXPECT_EQ("", p.second);
+  }
+
+  {
+    // Only first
+    std::pair<std::string, std::string> p = absl::StrSplit("a", ',');
+    EXPECT_EQ("a", p.first);
+    EXPECT_EQ("", p.second);
+  }
+
+  {
+    // Only second
+    std::pair<std::string, std::string> p = absl::StrSplit(",b", ',');
+    EXPECT_EQ("", p.first);
+    EXPECT_EQ("b", p.second);
+  }
+
+  {
+    // First and second.
+    std::pair<std::string, std::string> p = absl::StrSplit("a,b", ',');
+    EXPECT_EQ("a", p.first);
+    EXPECT_EQ("b", p.second);
+  }
+
+  {
+    // First and second and then more stuff that will be ignored.
+    std::pair<std::string, std::string> p = absl::StrSplit("a,b,c", ',');
+    EXPECT_EQ("a", p.first);
+    EXPECT_EQ("b", p.second);
+    // "c" is omitted.
+  }
+}
+
+TEST(Splitter, Predicates) {
+  static const char kTestChars[] = ",a, ,b,";
+  using absl::AllowEmpty;
+  using absl::SkipEmpty;
+  using absl::SkipWhitespace;
+
+  {
+    // No predicate. Does not skip empties.
+    auto splitter = absl::StrSplit(kTestChars, ',');
+    std::vector<std::string> v = splitter;
+    EXPECT_THAT(v, ElementsAre("", "a", " ", "b", ""));
+  }
+
+  {
+    // Allows empty strings. Same behavior as no predicate at all.
+    auto splitter = absl::StrSplit(kTestChars, ',', AllowEmpty());
+    std::vector<std::string> v_allowempty = splitter;
+    EXPECT_THAT(v_allowempty, ElementsAre("", "a", " ", "b", ""));
+
+    // Ensures AllowEmpty equals the behavior with no predicate.
+    auto splitter_nopredicate = absl::StrSplit(kTestChars, ',');
+    std::vector<std::string> v_nopredicate = splitter_nopredicate;
+    EXPECT_EQ(v_allowempty, v_nopredicate);
+  }
+
+  {
+    // Skips empty strings.
+    auto splitter = absl::StrSplit(kTestChars, ',', SkipEmpty());
+    std::vector<std::string> v = splitter;
+    EXPECT_THAT(v, ElementsAre("a", " ", "b"));
+  }
+
+  {
+    // Skips empty and all-whitespace strings.
+    auto splitter = absl::StrSplit(kTestChars, ',', SkipWhitespace());
+    std::vector<std::string> v = splitter;
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+}
+
+//
+// Tests for StrSplit()
+//
+
+TEST(Split, Basics) {
+  {
+    // Doesn't really do anything useful because the return value is ignored,
+    // but it should work.
+    absl::StrSplit("a,b,c", ',');
+  }
+
+  {
+    std::vector<absl::string_view> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    std::vector<std::string> v = absl::StrSplit("a,b,c", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+  }
+
+  {
+    // Ensures that assignment works. This requires a little extra work with
+    // C++11 because of overloads with initializer_list.
+    std::vector<std::string> v;
+    v = absl::StrSplit("a,b,c", ',');
+
+    EXPECT_THAT(v, ElementsAre("a", "b", "c"));
+    std::map<std::string, std::string> m;
+    m = absl::StrSplit("a,b,c", ',');
+    EXPECT_EQ(2, m.size());
+    std::unordered_map<std::string, std::string> hm;
+    hm = absl::StrSplit("a,b,c", ',');
+    EXPECT_EQ(2, hm.size());
+  }
+}
+
+absl::string_view ReturnStringView() { return "Hello World"; }
+const char* ReturnConstCharP() { return "Hello World"; }
+char* ReturnCharP() { return const_cast<char*>("Hello World"); }
+
+TEST(Split, AcceptsCertainTemporaries) {
+  std::vector<std::string> v;
+  v = absl::StrSplit(ReturnStringView(), ' ');
+  EXPECT_THAT(v, ElementsAre("Hello", "World"));
+  v = absl::StrSplit(ReturnConstCharP(), ' ');
+  EXPECT_THAT(v, ElementsAre("Hello", "World"));
+  v = absl::StrSplit(ReturnCharP(), ' ');
+  EXPECT_THAT(v, ElementsAre("Hello", "World"));
+}
+
+TEST(Split, Temporary) {
+  // Use a std::string longer than the small-std::string-optimization length, so that when
+  // the temporary is destroyed, if the splitter keeps a reference to the
+  // std::string's contents, it'll reference freed memory instead of just dead
+  // on-stack memory.
+  const char input[] = "a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u";
+  EXPECT_LT(sizeof(std::string), ABSL_ARRAYSIZE(input))
+      << "Input should be larger than fits on the stack.";
+
+  // This happens more often in C++11 as part of a range-based for loop.
+  auto splitter = absl::StrSplit(std::string(input), ',');
+  std::string expected = "a";
+  for (absl::string_view letter : splitter) {
+    EXPECT_EQ(expected, letter);
+    ++expected[0];
+  }
+  EXPECT_EQ("v", expected);
+
+  // This happens more often in C++11 as part of a range-based for loop.
+  auto std_splitter = absl::StrSplit(std::string(input), ',');
+  expected = "a";
+  for (absl::string_view letter : std_splitter) {
+    EXPECT_EQ(expected, letter);
+    ++expected[0];
+  }
+  EXPECT_EQ("v", expected);
+}
+
+template <typename T>
+static std::unique_ptr<T> CopyToHeap(const T& value) {
+  return std::unique_ptr<T>(new T(value));
+}
+
+TEST(Split, LvalueCaptureIsCopyable) {
+  std::string input = "a,b";
+  auto heap_splitter = CopyToHeap(absl::StrSplit(input, ','));
+  auto stack_splitter = *heap_splitter;
+  heap_splitter.reset();
+  std::vector<std::string> result = stack_splitter;
+  EXPECT_THAT(result, testing::ElementsAre("a", "b"));
+}
+
+TEST(Split, TemporaryCaptureIsCopyable) {
+  auto heap_splitter = CopyToHeap(absl::StrSplit(std::string("a,b"), ','));
+  auto stack_splitter = *heap_splitter;
+  heap_splitter.reset();
+  std::vector<std::string> result = stack_splitter;
+  EXPECT_THAT(result, testing::ElementsAre("a", "b"));
+}
+
+TEST(Split, SplitterIsCopyableAndMoveable) {
+  auto a = absl::StrSplit("foo", '-');
+
+  // Ensures that the following expressions compile.
+  auto b = a;             // Copy construct
+  auto c = std::move(a);  // Move construct
+  b = c;                  // Copy assign
+  c = std::move(b);       // Move assign
+
+  EXPECT_THAT(c, ElementsAre("foo"));
+}
+
+TEST(Split, StringDelimiter) {
+  {
+    std::vector<absl::string_view> v = absl::StrSplit("a,b", ',');
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+
+  {
+    std::vector<absl::string_view> v = absl::StrSplit("a,b", std::string(","));
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+
+  {
+    std::vector<absl::string_view> v =
+        absl::StrSplit("a,b", absl::string_view(","));
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+}
+
+TEST(Split, UTF8) {
+  // Tests splitting utf8 strings and utf8 delimiters.
+  std::string utf8_string = u8"\u03BA\u1F79\u03C3\u03BC\u03B5";
+  {
+    // A utf8 input std::string with an ascii delimiter.
+    std::string to_split = "a," + utf8_string;
+    std::vector<absl::string_view> v = absl::StrSplit(to_split, ',');
+    EXPECT_THAT(v, ElementsAre("a", utf8_string));
+  }
+
+  {
+    // A utf8 input std::string and a utf8 delimiter.
+    std::string to_split = "a," + utf8_string + ",b";
+    std::string unicode_delimiter = "," + utf8_string + ",";
+    std::vector<absl::string_view> v =
+        absl::StrSplit(to_split, unicode_delimiter);
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+
+  {
+    // A utf8 input std::string and ByAnyChar with ascii chars.
+    std::vector<absl::string_view> v =
+        absl::StrSplit(u8"Foo h\u00E4llo th\u4E1Ere", absl::ByAnyChar(" \t"));
+    EXPECT_THAT(v, ElementsAre("Foo", u8"h\u00E4llo", u8"th\u4E1Ere"));
+  }
+}
+
+TEST(Split, EmptyStringDelimiter) {
+  {
+    std::vector<std::string> v = absl::StrSplit("", "");
+    EXPECT_THAT(v, ElementsAre(""));
+  }
+
+  {
+    std::vector<std::string> v = absl::StrSplit("a", "");
+    EXPECT_THAT(v, ElementsAre("a"));
+  }
+
+  {
+    std::vector<std::string> v = absl::StrSplit("ab", "");
+    EXPECT_THAT(v, ElementsAre("a", "b"));
+  }
+
+  {
+    std::vector<std::string> v = absl::StrSplit("a b", "");
+    EXPECT_THAT(v, ElementsAre("a", " ", "b"));
+  }
+}
+
+TEST(Split, SubstrDelimiter) {
+  std::vector<absl::string_view> results;
+  absl::string_view delim("//");
+
+  results = absl::StrSplit("", delim);
+  EXPECT_THAT(results, ElementsAre(""));
+
+  results = absl::StrSplit("//", delim);
+  EXPECT_THAT(results, ElementsAre("", ""));
+
+  results = absl::StrSplit("ab", delim);
+  EXPECT_THAT(results, ElementsAre("ab"));
+
+  results = absl::StrSplit("ab//", delim);
+  EXPECT_THAT(results, ElementsAre("ab", ""));
+
+  results = absl::StrSplit("ab/", delim);
+  EXPECT_THAT(results, ElementsAre("ab/"));
+
+  results = absl::StrSplit("a/b", delim);
+  EXPECT_THAT(results, ElementsAre("a/b"));
+
+  results = absl::StrSplit("a//b", delim);
+  EXPECT_THAT(results, ElementsAre("a", "b"));
+
+  results = absl::StrSplit("a///b", delim);
+  EXPECT_THAT(results, ElementsAre("a", "/b"));
+
+  results = absl::StrSplit("a////b", delim);
+  EXPECT_THAT(results, ElementsAre("a", "", "b"));
+}
+
+TEST(Split, EmptyResults) {
+  std::vector<absl::string_view> results;
+
+  results = absl::StrSplit("", '#');
+  EXPECT_THAT(results, ElementsAre(""));
+
+  results = absl::StrSplit("#", '#');
+  EXPECT_THAT(results, ElementsAre("", ""));
+
+  results = absl::StrSplit("#cd", '#');
+  EXPECT_THAT(results, ElementsAre("", "cd"));
+
+  results = absl::StrSplit("ab#cd#", '#');
+  EXPECT_THAT(results, ElementsAre("ab", "cd", ""));
+
+  results = absl::StrSplit("ab##cd", '#');
+  EXPECT_THAT(results, ElementsAre("ab", "", "cd"));
+
+  results = absl::StrSplit("ab##", '#');
+  EXPECT_THAT(results, ElementsAre("ab", "", ""));
+
+  results = absl::StrSplit("ab#ab#", '#');
+  EXPECT_THAT(results, ElementsAre("ab", "ab", ""));
+
+  results = absl::StrSplit("aaaa", 'a');
+  EXPECT_THAT(results, ElementsAre("", "", "", "", ""));
+
+  results = absl::StrSplit("", '#', absl::SkipEmpty());
+  EXPECT_THAT(results, ElementsAre());
+}
+
+template <typename Delimiter>
+static bool IsFoundAtStartingPos(absl::string_view text, Delimiter d,
+                                 size_t starting_pos, int expected_pos) {
+  absl::string_view found = d.Find(text, starting_pos);
+  return found.data() != text.end() &&
+         expected_pos == found.data() - text.data();
+}
+
+// Helper function for testing Delimiter objects. Returns true if the given
+// Delimiter is found in the given std::string at the given position. This function
+// tests two cases:
+//   1. The actual text given, staring at position 0
+//   2. The text given with leading padding that should be ignored
+template <typename Delimiter>
+static bool IsFoundAt(absl::string_view text, Delimiter d, int expected_pos) {
+  const std::string leading_text = ",x,y,z,";
+  return IsFoundAtStartingPos(text, d, 0, expected_pos) &&
+         IsFoundAtStartingPos(leading_text + std::string(text), d,
+                              leading_text.length(),
+                              expected_pos + leading_text.length());
+}
+
+//
+// Tests for Literal
+//
+
+// Tests using any delimiter that represents a single comma.
+template <typename Delimiter>
+void TestComma(Delimiter d) {
+  EXPECT_TRUE(IsFoundAt(",", d, 0));
+  EXPECT_TRUE(IsFoundAt("a,", d, 1));
+  EXPECT_TRUE(IsFoundAt(",b", d, 0));
+  EXPECT_TRUE(IsFoundAt("a,b", d, 1));
+  EXPECT_TRUE(IsFoundAt("a,b,", d, 1));
+  EXPECT_TRUE(IsFoundAt("a,b,c", d, 1));
+  EXPECT_FALSE(IsFoundAt("", d, -1));
+  EXPECT_FALSE(IsFoundAt(" ", d, -1));
+  EXPECT_FALSE(IsFoundAt("a", d, -1));
+  EXPECT_FALSE(IsFoundAt("a b c", d, -1));
+  EXPECT_FALSE(IsFoundAt("a;b;c", d, -1));
+  EXPECT_FALSE(IsFoundAt(";", d, -1));
+}
+
+TEST(Delimiter, Literal) {
+  using absl::ByString;
+  TestComma(ByString(","));
+
+  // Works as named variable.
+  ByString comma_string(",");
+  TestComma(comma_string);
+
+  // The first occurrence of empty std::string ("") in a std::string is at position 0.
+  // There is a test below that demonstrates this for absl::string_view::find().
+  // If the ByString delimiter returned position 0 for this, there would
+  // be an infinite loop in the SplitIterator code. To avoid this, empty std::string
+  // is a special case in that it always returns the item at position 1.
+  absl::string_view abc("abc");
+  EXPECT_EQ(0, abc.find(""));  // "" is found at position 0
+  ByString empty("");
+  EXPECT_FALSE(IsFoundAt("", empty, 0));
+  EXPECT_FALSE(IsFoundAt("a", empty, 0));
+  EXPECT_TRUE(IsFoundAt("ab", empty, 1));
+  EXPECT_TRUE(IsFoundAt("abc", empty, 1));
+}
+
+TEST(Split, ByChar) {
+  using absl::ByChar;
+  TestComma(ByChar(','));
+
+  // Works as named variable.
+  ByChar comma_char(',');
+  TestComma(comma_char);
+}
+
+//
+// Tests for ByAnyChar
+//
+
+TEST(Delimiter, ByAnyChar) {
+  using absl::ByAnyChar;
+  ByAnyChar one_delim(",");
+  // Found
+  EXPECT_TRUE(IsFoundAt(",", one_delim, 0));
+  EXPECT_TRUE(IsFoundAt("a,", one_delim, 1));
+  EXPECT_TRUE(IsFoundAt("a,b", one_delim, 1));
+  EXPECT_TRUE(IsFoundAt(",b", one_delim, 0));
+  // Not found
+  EXPECT_FALSE(IsFoundAt("", one_delim, -1));
+  EXPECT_FALSE(IsFoundAt(" ", one_delim, -1));
+  EXPECT_FALSE(IsFoundAt("a", one_delim, -1));
+  EXPECT_FALSE(IsFoundAt("a;b;c", one_delim, -1));
+  EXPECT_FALSE(IsFoundAt(";", one_delim, -1));
+
+  ByAnyChar two_delims(",;");
+  // Found
+  EXPECT_TRUE(IsFoundAt(",", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt(";", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt(",;", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt(";,", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt(",;b", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt(";,b", two_delims, 0));
+  EXPECT_TRUE(IsFoundAt("a;,", two_delims, 1));
+  EXPECT_TRUE(IsFoundAt("a,;", two_delims, 1));
+  EXPECT_TRUE(IsFoundAt("a;,b", two_delims, 1));
+  EXPECT_TRUE(IsFoundAt("a,;b", two_delims, 1));
+  // Not found
+  EXPECT_FALSE(IsFoundAt("", two_delims, -1));
+  EXPECT_FALSE(IsFoundAt(" ", two_delims, -1));
+  EXPECT_FALSE(IsFoundAt("a", two_delims, -1));
+  EXPECT_FALSE(IsFoundAt("a=b=c", two_delims, -1));
+  EXPECT_FALSE(IsFoundAt("=", two_delims, -1));
+
+  // ByAnyChar behaves just like ByString when given a delimiter of empty
+  // std::string. That is, it always returns a zero-length absl::string_view
+  // referring to the item at position 1, not position 0.
+  ByAnyChar empty("");
+  EXPECT_FALSE(IsFoundAt("", empty, 0));
+  EXPECT_FALSE(IsFoundAt("a", empty, 0));
+  EXPECT_TRUE(IsFoundAt("ab", empty, 1));
+  EXPECT_TRUE(IsFoundAt("abc", empty, 1));
+}
+
+//
+// Tests for ByLength
+//
+
+TEST(Delimiter, ByLength) {
+  using absl::ByLength;
+
+  ByLength four_char_delim(4);
+
+  // Found
+  EXPECT_TRUE(IsFoundAt("abcde", four_char_delim, 4));
+  EXPECT_TRUE(IsFoundAt("abcdefghijklmnopqrstuvwxyz", four_char_delim, 4));
+  EXPECT_TRUE(IsFoundAt("a b,c\nd", four_char_delim, 4));
+  // Not found
+  EXPECT_FALSE(IsFoundAt("", four_char_delim, 0));
+  EXPECT_FALSE(IsFoundAt("a", four_char_delim, 0));
+  EXPECT_FALSE(IsFoundAt("ab", four_char_delim, 0));
+  EXPECT_FALSE(IsFoundAt("abc", four_char_delim, 0));
+  EXPECT_FALSE(IsFoundAt("abcd", four_char_delim, 0));
+}
+
+TEST(Split, WorksWithLargeStrings) {
+  if (sizeof(size_t) > 4) {
+    std::string s((uint32_t{1} << 31) + 1, 'x');  // 2G + 1 byte
+    s.back() = '-';
+    std::vector<absl::string_view> v = absl::StrSplit(s, '-');
+    EXPECT_EQ(2, v.size());
+    // The first element will contain 2G of 'x's.
+    // testing::StartsWith is too slow with a 2G std::string.
+    EXPECT_EQ('x', v[0][0]);
+    EXPECT_EQ('x', v[0][1]);
+    EXPECT_EQ('x', v[0][3]);
+    EXPECT_EQ("", v[1]);
+  }
+}
+
+TEST(SplitInternalTest, TypeTraits) {
+  EXPECT_FALSE(absl::strings_internal::HasMappedType<int>::value);
+  EXPECT_TRUE(
+      (absl::strings_internal::HasMappedType<std::map<int, int>>::value));
+  EXPECT_FALSE(absl::strings_internal::HasValueType<int>::value);
+  EXPECT_TRUE(
+      (absl::strings_internal::HasValueType<std::map<int, int>>::value));
+  EXPECT_FALSE(absl::strings_internal::HasConstIterator<int>::value);
+  EXPECT_TRUE(
+      (absl::strings_internal::HasConstIterator<std::map<int, int>>::value));
+  EXPECT_FALSE(absl::strings_internal::IsInitializerList<int>::value);
+  EXPECT_TRUE((absl::strings_internal::IsInitializerList<
+               std::initializer_list<int>>::value));
+}
+
+}  // namespace

http://git-wip-us.apache.org/repos/asf/marmotta/blob/0eb556da/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.cc
----------------------------------------------------------------------
diff --git a/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.cc b/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.cc
new file mode 100644
index 0000000..0e17295
--- /dev/null
+++ b/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.cc
@@ -0,0 +1,247 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed 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.
+
+#include "absl/strings/string_view.h"
+
+#ifndef ABSL_HAVE_STD_STRING_VIEW
+
+#include <algorithm>
+#include <climits>
+#include <cstring>
+#include <ostream>
+
+#include "absl/strings/internal/memutil.h"
+#include "absl/strings/internal/resize_uninitialized.h"
+#include "absl/strings/match.h"
+
+namespace absl {
+
+namespace {
+void WritePadding(std::ostream& o, size_t pad) {
+  char fill_buf[32];
+  memset(fill_buf, o.fill(), sizeof(fill_buf));
+  while (pad) {
+    size_t n = std::min(pad, sizeof(fill_buf));
+    o.write(fill_buf, n);
+    pad -= n;
+  }
+}
+
+class LookupTable {
+ public:
+  // For each character in wanted, sets the index corresponding
+  // to the ASCII code of that character. This is used by
+  // the find_.*_of methods below to tell whether or not a character is in
+  // the lookup table in constant time.
+  explicit LookupTable(string_view wanted) {
+    for (char c : wanted) {
+      table_[Index(c)] = true;
+    }
+  }
+  bool operator[](char c) const { return table_[Index(c)]; }
+
+ private:
+  static unsigned char Index(char c) { return static_cast<unsigned char>(c); }
+  bool table_[UCHAR_MAX + 1] = {};
+};
+
+}  // namespace
+
+std::ostream& operator<<(std::ostream& o, string_view piece) {
+  std::ostream::sentry sentry(o);
+  if (sentry) {
+    size_t lpad = 0;
+    size_t rpad = 0;
+    if (static_cast<size_t>(o.width()) > piece.size()) {
+      size_t pad = o.width() - piece.size();
+      if ((o.flags() & o.adjustfield) == o.left) {
+        rpad = pad;
+      } else {
+        lpad = pad;
+      }
+    }
+    if (lpad) WritePadding(o, lpad);
+    o.write(piece.data(), piece.size());
+    if (rpad) WritePadding(o, rpad);
+    o.width(0);
+  }
+  return o;
+}
+
+string_view::size_type string_view::copy(char* buf, size_type n,
+                                         size_type pos) const {
+  size_type ulen = length_;
+  assert(pos <= ulen);
+  size_type rlen = std::min(ulen - pos, n);
+  if (rlen > 0) {
+    const char* start = ptr_ + pos;
+    std::copy(start, start + rlen, buf);
+  }
+  return rlen;
+}
+
+string_view::size_type string_view::find(string_view s, size_type pos) const
+    noexcept {
+  if (empty() || pos > length_) {
+    if (empty() && pos == 0 && s.empty()) return 0;
+    return npos;
+  }
+  const char* result =
+      strings_internal::memmatch(ptr_ + pos, length_ - pos, s.ptr_, s.length_);
+  return result ? result - ptr_ : npos;
+}
+
+string_view::size_type string_view::find(char c, size_type pos) const noexcept {
+  if (empty() || pos >= length_) {
+    return npos;
+  }
+  const char* result =
+      static_cast<const char*>(memchr(ptr_ + pos, c, length_ - pos));
+  return result != nullptr ? result - ptr_ : npos;
+}
+
+string_view::size_type string_view::rfind(string_view s, size_type pos) const
+    noexcept {
+  if (length_ < s.length_) return npos;
+  if (s.empty()) return std::min(length_, pos);
+  const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_;
+  const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_);
+  return result != last ? result - ptr_ : npos;
+}
+
+// Search range is [0..pos] inclusive.  If pos == npos, search everything.
+string_view::size_type string_view::rfind(char c, size_type pos) const
+    noexcept {
+  // Note: memrchr() is not available on Windows.
+  if (empty()) return npos;
+  for (size_type i = std::min(pos, length_ - 1);; --i) {
+    if (ptr_[i] == c) {
+      return i;
+    }
+    if (i == 0) break;
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_first_of(string_view s,
+                                                  size_type pos) const
+    noexcept {
+  if (empty() || s.empty()) {
+    return npos;
+  }
+  // Avoid the cost of LookupTable() for a single-character search.
+  if (s.length_ == 1) return find_first_of(s.ptr_[0], pos);
+  LookupTable tbl(s);
+  for (size_type i = pos; i < length_; ++i) {
+    if (tbl[ptr_[i]]) {
+      return i;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_first_not_of(string_view s,
+                                                      size_type pos) const
+    noexcept {
+  if (empty()) return npos;
+  // Avoid the cost of LookupTable() for a single-character search.
+  if (s.length_ == 1) return find_first_not_of(s.ptr_[0], pos);
+  LookupTable tbl(s);
+  for (size_type i = pos; i < length_; ++i) {
+    if (!tbl[ptr_[i]]) {
+      return i;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_first_not_of(char c,
+                                                      size_type pos) const
+    noexcept {
+  if (empty()) return npos;
+  for (; pos < length_; ++pos) {
+    if (ptr_[pos] != c) {
+      return pos;
+    }
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_last_of(string_view s,
+                                                 size_type pos) const noexcept {
+  if (empty() || s.empty()) return npos;
+  // Avoid the cost of LookupTable() for a single-character search.
+  if (s.length_ == 1) return find_last_of(s.ptr_[0], pos);
+  LookupTable tbl(s);
+  for (size_type i = std::min(pos, length_ - 1);; --i) {
+    if (tbl[ptr_[i]]) {
+      return i;
+    }
+    if (i == 0) break;
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_last_not_of(string_view s,
+                                                     size_type pos) const
+    noexcept {
+  if (empty()) return npos;
+  size_type i = std::min(pos, length_ - 1);
+  if (s.empty()) return i;
+  // Avoid the cost of LookupTable() for a single-character search.
+  if (s.length_ == 1) return find_last_not_of(s.ptr_[0], pos);
+  LookupTable tbl(s);
+  for (;; --i) {
+    if (!tbl[ptr_[i]]) {
+      return i;
+    }
+    if (i == 0) break;
+  }
+  return npos;
+}
+
+string_view::size_type string_view::find_last_not_of(char c,
+                                                     size_type pos) const
+    noexcept {
+  if (empty()) return npos;
+  size_type i = std::min(pos, length_ - 1);
+  for (;; --i) {
+    if (ptr_[i] != c) {
+      return i;
+    }
+    if (i == 0) break;
+  }
+  return npos;
+}
+
+// MSVC has non-standard behavior that implicitly creates definitions for static
+// const members. These implicit definitions conflict with explicit out-of-class
+// member definitions that are required by the C++ standard, resulting in
+// LNK1169 "multiply defined" errors at link time. __declspec(selectany) asks
+// MSVC to choose only one definition for the symbol it decorates. See details
+// at http://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx
+#ifdef _MSC_VER
+#define ABSL_STRING_VIEW_SELECTANY __declspec(selectany)
+#else
+#define ABSL_STRING_VIEW_SELECTANY
+#endif
+
+ABSL_STRING_VIEW_SELECTANY
+constexpr string_view::size_type string_view::npos;
+ABSL_STRING_VIEW_SELECTANY
+constexpr string_view::size_type string_view::kMaxSize;
+
+}  // namespace absl
+
+#endif  // ABSL_HAVE_STD_STRING_VIEW

http://git-wip-us.apache.org/repos/asf/marmotta/blob/0eb556da/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.h
----------------------------------------------------------------------
diff --git a/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.h b/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.h
new file mode 100644
index 0000000..9162bb3
--- /dev/null
+++ b/libraries/ostrich/backend/3rdparty/abseil/absl/strings/string_view.h
@@ -0,0 +1,570 @@
+//
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed 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.
+//
+// -----------------------------------------------------------------------------
+// File: string_view.h
+// -----------------------------------------------------------------------------
+//
+// This file contains the definition of the `absl::string_view` class. A
+// `string_view` points to a contiguous span of characters, often part or all of
+// another `std::string`, double-quoted std::string literal, character array, or even
+// another `string_view`.
+//
+// This `absl::string_view` abstraction is designed to be a drop-in
+// replacement for the C++17 `std::string_view` abstraction.
+#ifndef ABSL_STRINGS_STRING_VIEW_H_
+#define ABSL_STRINGS_STRING_VIEW_H_
+
+#include <algorithm>
+#include "absl/base/config.h"
+
+#ifdef ABSL_HAVE_STD_STRING_VIEW
+
+#include <string_view>
+
+namespace absl {
+using std::string_view;
+};
+
+#else  // ABSL_HAVE_STD_STRING_VIEW
+
+#include <cassert>
+#include <cstddef>
+#include <cstring>
+#include <iosfwd>
+#include <iterator>
+#include <limits>
+#include <string>
+
+#include "absl/base/internal/throw_delegate.h"
+#include "absl/base/macros.h"
+#include "absl/base/port.h"
+
+namespace absl {
+
+// absl::string_view
+//
+// A `string_view` provides a lightweight view into the std::string data provided by
+// a `std::string`, double-quoted std::string literal, character array, or even
+// another `string_view`. A `string_view` does *not* own the std::string to which it
+// points, and that data cannot be modified through the view.
+//
+// You can use `string_view` as a function or method parameter anywhere a
+// parameter can receive a double-quoted std::string literal, `const char*`,
+// `std::string`, or another `absl::string_view` argument with no need to copy
+// the std::string data. Systematic use of `string_view` within function arguments
+// reduces data copies and `strlen()` calls.
+//
+// Because of its small size, prefer passing `string_view` by value:
+//
+//   void MyFunction(absl::string_view arg);
+//
+// If circumstances require, you may also pass one by const reference:
+//
+//   void MyFunction(const absl::string_view& arg);  // not preferred
+//
+// Passing by value generates slightly smaller code for many architectures.
+//
+// In either case, the source data of the `string_view` must outlive the
+// `string_view` itself.
+//
+// A `string_view` is also suitable for local variables if you know that the
+// lifetime of the underlying object is longer than the lifetime of your
+// `string_view` variable. However, beware of binding a `string_view` to a
+// temporary value:
+//
+//   // BAD use of string_view: lifetime problem
+//   absl::string_view sv = obj.ReturnAString();
+//
+//   // GOOD use of string_view: str outlives sv
+//   std::string str = obj.ReturnAString();
+//   absl::string_view sv = str;
+//
+// Due to lifetime issues, a `string_view` is sometimes a poor choice for a
+// return value and usually a poor choice for a data member. If you do use a
+// `string_view` this way, it is your responsibility to ensure that the object
+// pointed to by the `string_view` outlives the `string_view`.
+//
+// A `string_view` may represent a whole std::string or just part of a std::string. For
+// example, when splitting a std::string, `std::vector<absl::string_view>` is a
+// natural data type for the output.
+//
+//
+// When constructed from a source which is nul-terminated, the `string_view`
+// itself will not include the nul-terminator unless a specific size (including
+// the nul) is passed to the constructor. As a result, common idioms that work
+// on nul-terminated strings do not work on `string_view` objects. If you write
+// code that scans a `string_view`, you must check its length rather than test
+// for nul, for example. Note, however, that nuls may still be embedded within
+// a `string_view` explicitly.
+//
+// You may create a null `string_view` in two ways:
+//
+//   absl::string_view sv();
+//   absl::string_view sv(nullptr, 0);
+//
+// For the above, `sv.data() == nullptr`, `sv.length() == 0`, and
+// `sv.empty() == true`. Also, if you create a `string_view` with a non-null
+// pointer then `sv.data() != nullptr`. Thus, you can use `string_view()` to
+// signal an undefined value that is different from other `string_view` values
+// in a similar fashion to how `const char* p1 = nullptr;` is different from
+// `const char* p2 = "";`. However, in practice, it is not recommended to rely
+// on this behavior.
+//
+// Be careful not to confuse a null `string_view` with an empty one. A null
+// `string_view` is an empty `string_view`, but some empty `string_view`s are
+// not null. Prefer checking for emptiness over checking for null.
+//
+// There are many ways to create an empty string_view:
+//
+//   const char* nullcp = nullptr;
+//   // string_view.size() will return 0 in all cases.
+//   absl::string_view();
+//   absl::string_view(nullcp, 0);
+//   absl::string_view("");
+//   absl::string_view("", 0);
+//   absl::string_view("abcdef", 0);
+//   absl::string_view("abcdef" + 6, 0);
+//
+// All empty `string_view` objects whether null or not, are equal:
+//
+//   absl::string_view() == absl::string_view("", 0)
+//   absl::string_view(nullptr, 0) == absl:: string_view("abcdef"+6, 0)
+class string_view {
+ public:
+  using traits_type = std::char_traits<char>;
+  using value_type = char;
+  using pointer = char*;
+  using const_pointer = const char*;
+  using reference = char&;
+  using const_reference = const char&;
+  using const_iterator = const char*;
+  using iterator = const_iterator;
+  using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+  using reverse_iterator = const_reverse_iterator;
+  using size_type = size_t;
+  using difference_type = std::ptrdiff_t;
+
+  static constexpr size_type npos = static_cast<size_type>(-1);
+
+  // Null `string_view` constructor
+  constexpr string_view() noexcept : ptr_(nullptr), length_(0) {}
+
+  // Implicit constructors
+
+  template <typename Allocator>
+  string_view(  // NOLINT(runtime/explicit)
+      const std::basic_string<char, std::char_traits<char>, Allocator>&
+          str) noexcept
+      : ptr_(str.data()), length_(CheckLengthInternal(str.size())) {}
+
+  // Implicit constructor of a `string_view` from nul-terminated `str`. When
+  // accepting possibly null strings, use `absl::NullSafeStringView(str)`
+  // instead (see below).
+  constexpr string_view(const char* str)  // NOLINT(runtime/explicit)
+      : ptr_(str), length_(CheckLengthInternal(StrLenInternal(str))) {}
+
+  // Implicit constructor of a `string_view` from a `const char*` and length.
+  constexpr string_view(const char* data, size_type len)
+      : ptr_(data), length_(CheckLengthInternal(len)) {}
+
+  // NOTE: Harmlessly omitted to work around gdb bug.
+  //   constexpr string_view(const string_view&) noexcept = default;
+  //   string_view& operator=(const string_view&) noexcept = default;
+
+  // Iterators
+
+  // string_view::begin()
+  //
+  // Returns an iterator pointing to the first character at the beginning of the
+  // `string_view`, or `end()` if the `string_view` is empty.
+  constexpr const_iterator begin() const noexcept { return ptr_; }
+
+  // string_view::end()
+  //
+  // Returns an iterator pointing just beyond the last character at the end of
+  // the `string_view`. This iterator acts as a placeholder; attempting to
+  // access it results in undefined behavior.
+  constexpr const_iterator end() const noexcept { return ptr_ + length_; }
+
+  // string_view::cbegin()
+  //
+  // Returns a const iterator pointing to the first character at the beginning
+  // of the `string_view`, or `end()` if the `string_view` is empty.
+  constexpr const_iterator cbegin() const noexcept { return begin(); }
+
+  // string_view::cend()
+  //
+  // Returns a const iterator pointing just beyond the last character at the end
+  // of the `string_view`. This pointer acts as a placeholder; attempting to
+  // access its element results in undefined behavior.
+  constexpr const_iterator cend() const noexcept { return end(); }
+
+  // string_view::rbegin()
+  //
+  // Returns a reverse iterator pointing to the last character at the end of the
+  // `string_view`, or `rend()` if the `string_view` is empty.
+  const_reverse_iterator rbegin() const noexcept {
+    return const_reverse_iterator(end());
+  }
+
+  // string_view::rend()
+  //
+  // Returns a reverse iterator pointing just before the first character at the
+  // beginning of the `string_view`. This pointer acts as a placeholder;
+  // attempting to access its element results in undefined behavior.
+  const_reverse_iterator rend() const noexcept {
+    return const_reverse_iterator(begin());
+  }
+
+  // string_view::crbegin()
+  //
+  // Returns a const reverse iterator pointing to the last character at the end
+  // of the `string_view`, or `crend()` if the `string_view` is empty.
+  const_reverse_iterator crbegin() const noexcept { return rbegin(); }
+
+  // string_view::crend()
+  //
+  // Returns a const reverse iterator pointing just before the first character
+  // at the beginning of the `string_view`. This pointer acts as a placeholder;
+  // attempting to access its element results in undefined behavior.
+  const_reverse_iterator crend() const noexcept { return rend(); }
+
+  // Capacity Utilities
+
+  // string_view::size()
+  //
+  // Returns the number of characters in the `string_view`.
+  constexpr size_type size() const noexcept {
+    return length_;
+  }
+
+  // string_view::length()
+  //
+  // Returns the number of characters in the `string_view`. Alias for `size()`.
+  constexpr size_type length() const noexcept { return size(); }
+
+  // string_view::max_size()
+  //
+  // Returns the maximum number of characters the `string_view` can hold.
+  constexpr size_type max_size() const noexcept { return kMaxSize; }
+
+  // string_view::empty()
+  //
+  // Checks if the `string_view` is empty (refers to no characters).
+  constexpr bool empty() const noexcept { return length_ == 0; }
+
+  // std::string:view::operator[]
+  //
+  // Returns the ith element of an `string_view` using the array operator.
+  // Note that this operator does not perform any bounds checking.
+  constexpr const_reference operator[](size_type i) const { return ptr_[i]; }
+
+  // string_view::front()
+  //
+  // Returns the first element of a `string_view`.
+  constexpr const_reference front() const { return ptr_[0]; }
+
+  // string_view::back()
+  //
+  // Returns the last element of a `string_view`.
+  constexpr const_reference back() const { return ptr_[size() - 1]; }
+
+  // string_view::data()
+  //
+  // Returns a pointer to the underlying character array (which is of course
+  // stored elsewhere). Note that `string_view::data()` may contain embedded nul
+  // characters, but the returned buffer may or may not be nul-terminated;
+  // therefore, do not pass `data()` to a routine that expects a nul-terminated
+  // std::string.
+  constexpr const_pointer data() const noexcept { return ptr_; }
+
+  // Modifiers
+
+  // string_view::remove_prefix()
+  //
+  // Removes the first `n` characters from the `string_view`. Note that the
+  // underlying std::string is not changed, only the view.
+  void remove_prefix(size_type n) {
+    assert(n <= length_);
+    ptr_ += n;
+    length_ -= n;
+  }
+
+  // string_view::remove_suffix()
+  //
+  // Removes the last `n` characters from the `string_view`. Note that the
+  // underlying std::string is not changed, only the view.
+  void remove_suffix(size_type n) {
+    assert(n <= length_);
+    length_ -= n;
+  }
+
+  // string_view::swap()
+  //
+  // Swaps this `string_view` with another `string_view`.
+  void swap(string_view& s) noexcept {
+    auto t = *this;
+    *this = s;
+    s = t;
+  }
+
+  // Explicit conversion operators
+
+  // Converts to `std::basic_string`.
+  template <typename A>
+  explicit operator std::basic_string<char, traits_type, A>() const {
+    if (!data()) return {};
+    return std::basic_string<char, traits_type, A>(data(), size());
+  }
+
+  // string_view::copy()
+  //
+  // Copies the contents of the `string_view` at offset `pos` and length `n`
+  // into `buf`.
+  size_type copy(char* buf, size_type n, size_type pos = 0) const;
+
+  // string_view::substr()
+  //
+  // Returns a "substring" of the `string_view` (at offset `pos` and length
+  // `n`) as another string_view. This function throws `std::out_of_bounds` if
+  // `pos > size'.
+  string_view substr(size_type pos, size_type n = npos) const {
+    if (ABSL_PREDICT_FALSE(pos > length_))
+      base_internal::ThrowStdOutOfRange("absl::string_view::substr");
+    n = std::min(n, length_ - pos);
+    return string_view(ptr_ + pos, n);
+  }
+
+  // string_view::compare()
+  //
+  // Performs a lexicographical comparison between the `string_view` and
+  // another `absl::string_view), returning -1 if `this` is less than, 0 if
+  // `this` is equal to, and 1 if `this` is greater than the passed std::string
+  // view. Note that in the case of data equality, a further comparison is made
+  // on the respective sizes of the two `string_view`s to determine which is
+  // smaller, equal, or greater.
+  int compare(string_view x) const noexcept {
+    auto min_length = std::min(length_, x.length_);
+    if (min_length > 0) {
+      int r = memcmp(ptr_, x.ptr_, min_length);
+      if (r < 0) return -1;
+      if (r > 0) return 1;
+    }
+    if (length_ < x.length_) return -1;
+    if (length_ > x.length_) return 1;
+    return 0;
+  }
+
+  // Overload of `string_view::compare()` for comparing a substring of the
+  // 'string_view` and another `absl::string_view`.
+  int compare(size_type pos1, size_type count1, string_view v) const {
+    return substr(pos1, count1).compare(v);
+  }
+
+  // Overload of `string_view::compare()` for comparing a substring of the
+  // `string_view` and a substring of another `absl::string_view`.
+  int compare(size_type pos1, size_type count1, string_view v, size_type pos2,
+              size_type count2) const {
+    return substr(pos1, count1).compare(v.substr(pos2, count2));
+  }
+
+  // Overload of `string_view::compare()` for comparing a `string_view` and a
+  // a different  C-style std::string `s`.
+  int compare(const char* s) const { return compare(string_view(s)); }
+
+  // Overload of `string_view::compare()` for comparing a substring of the
+  // `string_view` and a different std::string C-style std::string `s`.
+  int compare(size_type pos1, size_type count1, const char* s) const {
+    return substr(pos1, count1).compare(string_view(s));
+  }
+
+  // Overload of `string_view::compare()` for comparing a substring of the
+  // `string_view` and a substring of a different C-style std::string `s`.
+  int compare(size_type pos1, size_type count1, const char* s,
+              size_type count2) const {
+    return substr(pos1, count1).compare(string_view(s, count2));
+  }
+
+  // Find Utilities
+
+  // string_view::find()
+  //
+  // Finds the first occurrence of the substring `s` within the `string_view`,
+  // returning the position of the first character's match, or `npos` if no
+  // match was found.
+  size_type find(string_view s, size_type pos = 0) const noexcept;
+
+  // Overload of `string_view::find()` for finding the given character `c`
+  // within the `string_view`.
+  size_type find(char c, size_type pos = 0) const noexcept;
+
+  // string_view::rfind()
+  //
+  // Finds the last occurrence of a substring `s` within the `string_view`,
+  // returning the position of the first character's match, or `npos` if no
+  // match was found.
+  size_type rfind(string_view s, size_type pos = npos) const
+      noexcept;
+
+  // Overload of `string_view::rfind()` for finding the last given character `c`
+  // within the `string_view`.
+  size_type rfind(char c, size_type pos = npos) const noexcept;
+
+  // string_view::find_first_of()
+  //
+  // Finds the first occurrence of any of the characters in `s` within the
+  // `string_view`, returning the start position of the match, or `npos` if no
+  // match was found.
+  size_type find_first_of(string_view s, size_type pos = 0) const
+      noexcept;
+
+  // Overload of `string_view::find_first_of()` for finding a character `c`
+  // within the `string_view`.
+  size_type find_first_of(char c, size_type pos = 0) const
+      noexcept {
+    return find(c, pos);
+  }
+
+  // string_view::find_last_of()
+  //
+  // Finds the last occurrence of any of the characters in `s` within the
+  // `string_view`, returning the start position of the match, or `npos` if no
+  // match was found.
+  size_type find_last_of(string_view s, size_type pos = npos) const
+      noexcept;
+
+  // Overload of `string_view::find_last_of()` for finding a character `c`
+  // within the `string_view`.
+  size_type find_last_of(char c, size_type pos = npos) const
+      noexcept {
+    return rfind(c, pos);
+  }
+
+  // string_view::find_first_not_of()
+  //
+  // Finds the first occurrence of any of the characters not in `s` within the
+  // `string_view`, returning the start position of the first non-match, or
+  // `npos` if no non-match was found.
+  size_type find_first_not_of(string_view s, size_type pos = 0) const noexcept;
+
+  // Overload of `string_view::find_first_not_of()` for finding a character
+  // that is not `c` within the `string_view`.
+  size_type find_first_not_of(char c, size_type pos = 0) const noexcept;
+
+  // string_view::find_last_not_of()
+  //
+  // Finds the last occurrence of any of the characters not in `s` within the
+  // `string_view`, returning the start position of the last non-match, or
+  // `npos` if no non-match was found.
+  size_type find_last_not_of(string_view s,
+                                          size_type pos = npos) const noexcept;
+
+  // Overload of `string_view::find_last_not_of()` for finding a character
+  // that is not `c` within the `string_view`.
+  size_type find_last_not_of(char c, size_type pos = npos) const
+      noexcept;
+
+ private:
+  static constexpr size_type kMaxSize =
+      std::numeric_limits<difference_type>::max();
+
+  // check whether __builtin_strlen is provided by the compiler.
+  // GCC doesn't have __has_builtin()
+  // (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66970),
+  // but has __builtin_strlen according to
+  // https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Other-Builtins.html.
+#if ABSL_HAVE_BUILTIN(__builtin_strlen) || \
+    (defined(__GNUC__) && !defined(__clang__))
+  static constexpr size_type StrLenInternal(const char* str) {
+    return str ? __builtin_strlen(str) : 0;
+  }
+#else
+  static constexpr size_type StrLenInternal(const char* str) {
+    return str ? strlen(str) : 0;
+  }
+#endif
+
+  static constexpr size_type CheckLengthInternal(size_type len) {
+    return ABSL_ASSERT(len <= kMaxSize), len;
+  }
+
+  const char* ptr_;
+  size_type length_;
+};
+
+// This large function is defined inline so that in a fairly common case where
+// one of the arguments is a literal, the compiler can elide a lot of the
+// following comparisons.
+inline bool operator==(string_view x, string_view y) noexcept {
+  auto len = x.size();
+  if (len != y.size()) {
+    return false;
+  }
+  return x.data() == y.data() || len <= 0 ||
+         memcmp(x.data(), y.data(), len) == 0;
+}
+
+inline bool operator!=(string_view x, string_view y) noexcept {
+  return !(x == y);
+}
+
+inline bool operator<(string_view x, string_view y) noexcept {
+  auto min_size = std::min(x.size(), y.size());
+  const int r = min_size == 0 ? 0 : memcmp(x.data(), y.data(), min_size);
+  return (r < 0) || (r == 0 && x.size() < y.size());
+}
+
+inline bool operator>(string_view x, string_view y) noexcept { return y < x; }
+
+inline bool operator<=(string_view x, string_view y) noexcept {
+  return !(y < x);
+}
+
+inline bool operator>=(string_view x, string_view y) noexcept {
+  return !(x < y);
+}
+
+// IO Insertion Operator
+std::ostream& operator<<(std::ostream& o, string_view piece);
+
+}  // namespace absl
+
+#endif  // ABSL_HAVE_STD_STRING_VIEW
+
+namespace absl {
+
+// ClippedSubstr()
+//
+// Like `s.substr(pos, n)`, but clips `pos` to an upper bound of `s.size()`.
+// Provided because std::string_view::substr throws if `pos > size()`
+inline string_view ClippedSubstr(string_view s, size_t pos,
+                                 size_t n = string_view::npos) {
+  pos = std::min(pos, static_cast<size_t>(s.size()));
+  return s.substr(pos, n);
+}
+
+// NullSafeStringView()
+//
+// Creates an `absl::string_view` from a pointer `p` even if it's null-valued.
+// This function should be used where an `absl::string_view` can be created from
+// a possibly-null pointer.
+inline string_view NullSafeStringView(const char* p) {
+  return p ? string_view(p) : string_view();
+}
+
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_STRING_VIEW_H_