Rewrite and revert some code to build in pre-C++11

Rewerite and revert some code that this library can be built in pre-C++11 and C++11 env.
Main Change List:
1. using -> typedef
2. not using auto & decltype
3. not using raw string literals
4. ..., other c++11 features will be chosen to compile, depending on env.

Author: dota17

example/readFromStream/readFromStream.cpp

@@ -1,4 +1,5 @@
 #include "json/json.h"
+#include <cstdlib>
 #include <fstream>
 #include <iostream>
 /** \brief Parse from stream, collect comments and capture error info.

example/readFromString/readFromString.cpp

@@ -1,4 +1,5 @@
 #include "json/json.h"
+#include <cstdlib>
 #include <iostream>
 /**
  * \brief Parse a raw string into Value object using the CharReaderBuilder
@@ -10,9 +11,9 @@
  * 20
  */
 int main() {
-  const std::string rawJson = R"({"Age": 20, "Name": "colin"})";
-  const auto rawJsonLength = static_cast<int>(rawJson.length());
-  constexpr bool shouldUseOldWay = false;
+  const std::string rawJson = "{\"Age\": 20, \"Name\": \"colin\"}";
+  const int rawJsonLength = static_cast<int>(rawJson.length());
+  JSONCPP_CONST bool shouldUseOldWay = false;
   JSONCPP_STRING err;
   Json::Value root;
 
@@ -21,12 +22,13 @@ int main() {
     reader.parse(rawJson, root);
   } else {
     Json::CharReaderBuilder builder;
-    const std::unique_ptr<Json::CharReader> reader(builder.newCharReader());
+    Json::CharReader* reader(builder.newCharReader());
     if (!reader->parse(rawJson.c_str(), rawJson.c_str() + rawJsonLength, &root,
                        &err)) {
       std::cout << "error" << std::endl;
       return EXIT_FAILURE;
     }
+    delete reader;
   }
   const std::string name = root["Name"].asString();
   const int age = root["Age"].asInt();

example/streamWrite/streamWrite.cpp

@@ -12,11 +12,11 @@
 int main() {
   Json::Value root;
   Json::StreamWriterBuilder builder;
-  const std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
+  Json::StreamWriter* writer(builder.newStreamWriter());
 
   root["Name"] = "robin";
   root["Age"] = 20;
   writer->write(root, &std::cout);
-
+  delete writer;
   return EXIT_SUCCESS;
 }

example/stringWrite/stringWrite.cpp

@@ -1,4 +1,5 @@
 #include "json/json.h"
+#include <cstdlib>
 #include <iostream>
 /** \brief Write a Value object to a string.
  * Example Usage:
@@ -15,7 +16,7 @@
 int main() {
   Json::Value root;
   Json::Value data;
-  constexpr bool shouldUseOldWay = false;
+  JSONCPP_CONST bool shouldUseOldWay = false;
   root["action"] = "run";
   data["number"] = 1;
   root["data"] = data;

include/json/assertions.h

@@ -58,4 +58,10 @@
     }                                                                          \
   } while (0)
 
+#if JSONCPP_CXX_STD_11
+#define JSONCPP_STATIC_ASSERT static_assert
+#else
+#define JSONCPP_STATIC_ASSERT JSON_ASSERT_MESSAGE
+#endif
+
 #endif // JSON_ASSERTIONS_H_INCLUDED

include/json/config.h

@@ -5,14 +5,20 @@
 
 #ifndef JSON_CONFIG_H_INCLUDED
 #define JSON_CONFIG_H_INCLUDED
-#include <cstddef>
-#include <cstdint>
+
 #include <istream>
 #include <memory>
 #include <ostream>
 #include <sstream>
 #include <string>
-#include <type_traits>
+
+#if JSONCPP_CXX_STD_11
+#include <cstddef> // typedef ptrdiff_t
+#include <cstdint> // typedef int64_t, uint64_t
+#else
+#include <stddef.h>
+#include <stdint.h>
+#endif
 
 // If non-zero, the library uses exceptions to report bad input instead of C
 // assertion macros. The default is to use exceptions.
@@ -50,11 +56,6 @@
 #define JSON_API
 #endif
 
-#if defined(_MSC_VER) && _MSC_VER < 1800
-#error                                                                         \
-    "ERROR:  Visual Studio 12 (2013) with _MSC_VER=1800 is the oldest supported compiler with sufficient C++11 capabilities"
-#endif
-
 #if defined(_MSC_VER) && _MSC_VER < 1900
 // As recommended at
 // https://stackoverflow.com/questions/2915672/snprintf-and-visual-studio-2010
@@ -70,10 +71,41 @@ extern JSON_API int msvc_pre1900_c99_snprintf(char* outBuf, size_t size,
 // Storages, and 64 bits integer support is disabled.
 // #define JSON_NO_INT64 1
 
-// JSONCPP_OVERRIDE is maintained for backwards compatibility of external tools.
-// C++11 should be used directly in JSONCPP.
+#if __cplusplus >= 201103L || defined(_MSC_VER)
+#define JSONCPP_OP_EXPLICIT explicit
+#else
+#define JSONCPP_OP_EXPLICIT
+#endif
+
+// These Macros are maintained for backwards compatibility of external tools.
+#if (defined(_MSC_VER) && _MSC_VER >= 1900) ||                                 \
+    (defined(__GNUC__) && __cplusplus >= 201103L) ||                           \
+    (defined(__clang__) && __clang_major__ == 3 && __clang_minor__ >= 3)
+
+#define JSONCPP_CXX_STD_11 1
+#else
+#define JSONCPP_CXX_STD_11 0
+#endif
+
+#if JSONCPP_CXX_STD_11
+#define JSONCPP_NULL nullptr
+#define JSONCPP_CONST constexpr
+#define JSONCPP_CTOR_DELETE = delete
+#define JSONCPP_NOEXCEPT noexcept
 #define JSONCPP_OVERRIDE override
+#define JSONCPP_MOVE(value) std::move(value)
+#else
+#define JSONCPP_NULL NULL
+#define JSONCPP_CONST const
+#define JSONCPP_CTOR_DELETE
+#define JSONCPP_NOEXCEPT throw()
+#define JSONCPP_OVERRIDE
+#define JSONCPP_MOVE(value) value
+#endif
 
+// Define *deprecated* attribute
+// [[deprecated]] is in C++14 or in Visual Studio 2015 and later
+// For compatibility, [[deprecated]] is not used
 #ifdef __clang__
 #if __has_extension(attribute_deprecated_with_message)
 #define JSONCPP_DEPRECATED(message) __attribute__((deprecated(message)))
@@ -98,33 +130,36 @@ extern JSON_API int msvc_pre1900_c99_snprintf(char* outBuf, size_t size,
 #endif
 
 #if !defined(JSON_IS_AMALGAMATION)
-
+#if JSONCPP_CXX_STD_11
 #include "allocator.h"
+#endif
 #include "version.h"
 
 #endif // if !defined(JSON_IS_AMALGAMATION)
 
 namespace Json {
-using Int = int;
-using UInt = unsigned int;
+
+typedef int Int;
+typedef unsigned int UInt;
 #if defined(JSON_NO_INT64)
-using LargestInt = int;
-using LargestUInt = unsigned int;
+typedef int LargestInt;
+typedef unsigned int LargestUInt;
 #undef JSON_HAS_INT64
 #else                 // if defined(JSON_NO_INT64)
 // For Microsoft Visual use specific types as long long is not supported
 #if defined(_MSC_VER) // Microsoft Visual Studio
-using Int64 = __int64;
-using UInt64 = unsigned __int64;
+typedef __int64 Int64;
+typedef unsigned __int64 UInt64;
 #else                 // if defined(_MSC_VER) // Other platforms, use long long
-using Int64 = int64_t;
-using UInt64 = uint64_t;
+typedef int64_t Int64;
+typedef uint64_t UInt64;
 #endif                // if defined(_MSC_VER)
-using LargestInt = Int64;
-using LargestUInt = UInt64;
+typedef Int64 LargestInt;
+typedef UInt64 LargestUInt;
 #define JSON_HAS_INT64
 #endif // if defined(JSON_NO_INT64)
 
+#if JSONCPP_CXX_STD_11
 template <typename T>
 using Allocator =
     typename std::conditional<JSONCPP_USING_SECURE_MEMORY, SecureAllocator<T>,
@@ -138,13 +173,20 @@ using OStringStream =
                              String::allocator_type>;
 using IStream = std::istream;
 using OStream = std::ostream;
+#else
+typedef std::string String;
+typedef std::istringstream IStringStream;
+typedef std::ostringstream OStringStream;
+typedef std::istream IStream;
+typedef std::ostream OStream;
+#endif // JSONCPP_CXX_STD_11
 } // namespace Json
 
 // Legacy names (formerly macros).
-using JSONCPP_STRING = Json::String;
-using JSONCPP_ISTRINGSTREAM = Json::IStringStream;
-using JSONCPP_OSTRINGSTREAM = Json::OStringStream;
-using JSONCPP_ISTREAM = Json::IStream;
-using JSONCPP_OSTREAM = Json::OStream;
+typedef Json::String JSONCPP_STRING;
+typedef Json::IStringStream JSONCPP_ISTRINGSTREAM;
+typedef Json::OStringStream JSONCPP_OSTRINGSTREAM;
+typedef Json::IStream JSONCPP_ISTREAM;
+typedef Json::OStream JSONCPP_OSTREAM;
 
 #endif // JSON_CONFIG_H_INCLUDED

include/json/forwards.h

@@ -29,7 +29,7 @@ class CharReaderBuilder;
 class Features;
 
 // value.h
-using ArrayIndex = unsigned int;
+typedef unsigned int ArrayIndex;
 class StaticString;
 class Path;
 class PathArgument;

include/json/json_features.h

@@ -41,17 +41,17 @@ class JSON_API Features {
   Features();
 
   /// \c true if comments are allowed. Default: \c true.
-  bool allowComments_{true};
+  bool allowComments_;
 
   /// \c true if root must be either an array or an object value. Default: \c
   /// false.
-  bool strictRoot_{false};
+  bool strictRoot_;
 
   /// \c true if dropped null placeholders are allowed. Default: \c false.
-  bool allowDroppedNullPlaceholders_{false};
+  bool allowDroppedNullPlaceholders_;
 
   /// \c true if numeric object key are allowed. Default: \c false.
-  bool allowNumericKeys_{false};
+  bool allowNumericKeys_;
 };
 
 } // namespace Json

include/json/reader.h

@@ -36,8 +36,8 @@ namespace Json {
 class JSONCPP_DEPRECATED(
     "Use CharReader and CharReaderBuilder instead.") JSON_API Reader {
 public:
-  using Char = char;
-  using Location = const Char*;
+  typedef char Char;
+  typedef const Char* Location;
 
   /** \brief An error tagged with where in the JSON text it was encountered.
    *
@@ -187,7 +187,7 @@ class JSONCPP_DEPRECATED(
     Location extra_;
   };
 
-  using Errors = std::deque<ErrorInfo>;
+  typedef std::deque<ErrorInfo> Errors;
 
   bool readToken(Token& token);
   void skipSpaces();
@@ -210,7 +210,8 @@ class JSONCPP_DEPRECATED(
                               unsigned int& unicode);
   bool decodeUnicodeEscapeSequence(Token& token, Location& current,
                                    Location end, unsigned int& unicode);
-  bool addError(const String& message, Token& token, Location extra = nullptr);
+  bool addError(const String& message, Token& token,
+                Location extra = JSONCPP_NULL);
   bool recoverFromError(TokenType skipUntilToken);
   bool addErrorAndRecover(const String& message, Token& token,
                           TokenType skipUntilToken);
@@ -226,25 +227,25 @@ class JSONCPP_DEPRECATED(
   static bool containsNewLine(Location begin, Location end);
   static String normalizeEOL(Location begin, Location end);
 
-  using Nodes = std::stack<Value*>;
+  typedef std::stack<Value*> Nodes;
   Nodes nodes_;
   Errors errors_;
   String document_;
-  Location begin_{};
-  Location end_{};
-  Location current_{};
-  Location lastValueEnd_{};
-  Value* lastValue_{};
+  Location begin_;
+  Location end_;
+  Location current_;
+  Location lastValueEnd_;
+  Value* lastValue_;
   String commentsBefore_;
   Features features_;
-  bool collectComments_{};
+  bool collectComments_;
 }; // Reader
 
 /** Interface for reading JSON from a char array.
  */
 class JSON_API CharReader {
 public:
-  virtual ~CharReader() = default;
+  virtual ~CharReader() {}
   /** \brief Read a Value from a <a HREF="http://www.json.org">JSON</a>
    * document. The document must be a UTF-8 encoded string containing the
    * document to read.
@@ -266,7 +267,7 @@ class JSON_API CharReader {
 
   class JSON_API Factory {
   public:
-    virtual ~Factory() = default;
+    virtual ~Factory() {}
     /** \brief Allocate a CharReader via operator new().
      * \throw std::exception if something goes wrong (e.g. invalid settings)
      */
@@ -332,9 +333,9 @@ class JSON_API CharReaderBuilder : public CharReader::Factory {
   Json::Value settings_;
 
   CharReaderBuilder();
-  ~CharReaderBuilder() override;
+  ~CharReaderBuilder() JSONCPP_OVERRIDE;
 
-  CharReader* newCharReader() const override;
+  CharReader* newCharReader() const JSONCPP_OVERRIDE;
 
   /** \return true if 'settings' are legal and consistent;
    *   otherwise, indicate bad settings via 'invalid'.