[GitHub] [incubator-kvrocks] caipengbo commented on a diff in pull request #787: Add newly designed `ParseInt`

[GitBox <gi...@apache.org>]

caipengbo commented on code in PR #787:
URL: https://github.com/apache/incubator-kvrocks/pull/787#discussion_r952062710


##########
src/parse_util.h:
##########
@@ -0,0 +1,130 @@
+/*
+ * Licensed to the 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.  The 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.
+ *
+ */
+
+#pragma once
+
+#include <cstdlib>
+#include <limits>
+#include <string>
+#include <tuple>
+#include <status.h>
+
+namespace details {
+
+template <typename>
+struct ParseIntFunc;
+
+template <>
+struct ParseIntFunc<short> { // NOLINT
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<int> {
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<long> { // NOLINT
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<long long> { // NOLINT
+  constexpr static const auto value = std::strtoll;
+};
+
+template <>
+struct ParseIntFunc<unsigned short> { // NOLINT
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned> {
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned long> { // NOLINT
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned long long> { // NOLINT
+  constexpr static const auto value = std::strtoull;
+};
+
+}  // namespace details
+
+template <typename T>
+using ParseResultAndPos = std::tuple<T, const char *>;
+
+template <typename T = long long> // NOLINT
+StatusOr<ParseResultAndPos<T>> TryParseInt(const char *v, int base = 0) {

Review Comment:
   Should we put TryParseInt under ParseInt?  Normal first, then special, which I think is logical.
   
   And write a few simple comments on TryParseInt to explain the difference between TryParseInt and ParseInt?
   It was in the test cases that I learned the difference.



##########
src/parse_util.h:
##########
@@ -0,0 +1,130 @@
+/*
+ * Licensed to the 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.  The 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.
+ *
+ */
+
+#pragma once
+
+#include <cstdlib>
+#include <limits>
+#include <string>
+#include <tuple>
+#include <status.h>
+
+namespace details {
+
+template <typename>
+struct ParseIntFunc;
+
+template <>
+struct ParseIntFunc<short> { // NOLINT
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<int> {
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<long> { // NOLINT
+  constexpr static const auto value = std::strtol;
+};
+
+template <>
+struct ParseIntFunc<long long> { // NOLINT
+  constexpr static const auto value = std::strtoll;
+};
+
+template <>
+struct ParseIntFunc<unsigned short> { // NOLINT
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned> {
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned long> { // NOLINT
+  constexpr static const auto value = std::strtoul;
+};
+
+template <>
+struct ParseIntFunc<unsigned long long> { // NOLINT
+  constexpr static const auto value = std::strtoull;
+};
+
+}  // namespace details
+
+template <typename T>
+using ParseResultAndPos = std::tuple<T, const char *>;
+
+template <typename T = long long> // NOLINT
+StatusOr<ParseResultAndPos<T>> TryParseInt(const char *v, int base = 0) {
+  char *end;
+
+  errno = 0;
+  auto res = details::ParseIntFunc<T>::value(v, &end, base);
+
+  if (v == end) {
+    return {Status::NotOK, "TryParseInt: not started as an integer"};
+  }
+
+  if (errno) {
+    return {Status::NotOK, std::string {"TryParseInt: "} + std::strerror(errno)};
+  }
+
+  if (!std::is_same<T, decltype(res)>::value &&
+    (res < std::numeric_limits<T>::min() || res > std::numeric_limits<T>::max())) {
+    return {Status::NotOK, "TryParseInt: out of range of integer type"};

Review Comment:
   Personally, I don't think you need to prefix the function name in the Status information returned, which is probably a little redundant. 
   This is what the caller needs to add, he knows what function he is using.



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