move ctors

* Add move constructor to Value::CZString
* Add unit test for Value move constructor
* Allow includer to specify in advance the value for
JSON_HAS_RVALUE_REFERENCES

Author: lanzkron

include/json/config.h

@@ -56,30 +56,59 @@
 // Storages, and 64 bits integer support is disabled.
 // #define JSON_NO_INT64 1
 
-#if defined(_MSC_VER) && _MSC_VER <= 1200 // MSVC 6
-// Microsoft Visual Studio 6 only support conversion from __int64 to double
-// (no conversion from unsigned __int64).
-#define JSON_USE_INT64_DOUBLE_CONVERSION 1
-// Disable warning 4786 for VS6 caused by STL (identifier was truncated to '255'
-// characters in the debug information)
-// All projects I've ever seen with VS6 were using this globally (not bothering
-// with pragma push/pop).
-#pragma warning(disable : 4786)
-#endif // if defined(_MSC_VER)  &&  _MSC_VER < 1200 // MSVC 6
-
-#if defined(_MSC_VER) && _MSC_VER >= 1500 // MSVC 2008
-/// Indicates that the following function is deprecated.
-#define JSONCPP_DEPRECATED(message) __declspec(deprecated(message))
-#elif defined(__clang__) && defined(__has_feature)
-#if __has_feature(attribute_deprecated_with_message)
-#define JSONCPP_DEPRECATED(message)  __attribute__ ((deprecated(message)))
-#endif
-#elif defined(__GNUC__) &&  (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
-#define JSONCPP_DEPRECATED(message)  __attribute__ ((deprecated(message)))
-#elif defined(__GNUC__) &&  (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
-#define JSONCPP_DEPRECATED(message)  __attribute__((__deprecated__))
+#if defined(_MSC_VER) // MSVC
+#  if _MSC_VER <= 1200 // MSVC 6
+    // Microsoft Visual Studio 6 only support conversion from __int64 to double
+    // (no conversion from unsigned __int64).
+#    define JSON_USE_INT64_DOUBLE_CONVERSION 1
+    // Disable warning 4786 for VS6 caused by STL (identifier was truncated to '255'
+    // characters in the debug information)
+    // All projects I've ever seen with VS6 were using this globally (not bothering
+    // with pragma push/pop).
+#    pragma warning(disable : 4786)
+#  endif // MSVC 6
+
+#  if _MSC_VER >= 1500 // MSVC 2008
+    /// Indicates that the following function is deprecated.
+#    define JSONCPP_DEPRECATED(message) __declspec(deprecated(message))
+#  endif
+
+#endif // defined(_MSC_VER)
+
+
+#ifndef JSON_HAS_RVALUE_REFERENCES
+
+#if defined(_MSC_VER) && _MSC_VER >= 1600 // MSVC >= 2010
+#define JSON_HAS_RVALUE_REFERENCES 1
+#endif // MSVC >= 2010
+
+#ifdef __clang__
+#if __has_feature(cxx_rvalue_references)
+#define JSON_HAS_RVALUE_REFERENCES 1
+#endif  // has_feature
+
+#elif defined __GNUC__ // not clang (gcc comes later since clang emulates gcc)
+#if defined(__GXX_EXPERIMENTAL_CXX0X__) || (__cplusplus >= 201103L)
+#define JSON_HAS_RVALUE_REFERENCES 1
+#endif  // GXX_EXPERIMENTAL
+
+#endif // __clang__ || __GNUC__
+
+#endif // not defined JSON_HAS_RVALUE_REFERENCES
+
+#ifndef JSON_HAS_RVALUE_REFERENCES
+#define JSON_HAS_RVALUE_REFERENCES 0
 #endif
 
+#ifdef __clang__
+#elif defined __GNUC__ // not clang (gcc comes later since clang emulates gcc)
+#  if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))
+#    define JSONCPP_DEPRECATED(message)  __attribute__ ((deprecated(message)))
+#  elif (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
+#    define JSONCPP_DEPRECATED(message)  __attribute__((__deprecated__))
+#  endif  // GNUC version
+#endif // __clang__ || __GNUC__
+
 #if !defined(JSONCPP_DEPRECATED)
 #define JSONCPP_DEPRECATED(message)
 #endif // if !defined(JSONCPP_DEPRECATED)

include/json/value.h

@@ -197,6 +197,9 @@ class JSON_API Value {
     CZString(ArrayIndex index);
     CZString(char const* str, unsigned length, DuplicationPolicy allocate);
     CZString(CZString const& other);
+#if JSON_HAS_RVALUE_REFERENCES
+    CZString(CZString&& other);
+#endif
     ~CZString();
     CZString& operator=(CZString other);
     bool operator<(CZString const& other) const;
@@ -279,6 +282,10 @@ Json::Value obj_value(Json::objectValue); // {}
   Value(bool value);
   /// Deep copy.
   Value(const Value& other);
+#if JSON_HAS_RVALUE_REFERENCES
+  /// Move constructor
+  Value(Value&& other);
+#endif
   ~Value();
 
   /// Deep copy, then swap(other).

src/lib_json/json_value.cpp

@@ -254,6 +254,15 @@ Value::CZString::CZString(const CZString& other)
   storage_.length_ = other.storage_.length_;
 }
 
+#if JSON_HAS_RVALUE_REFERENCES
+Value::CZString::CZString(CZString&& other)
+  : cstr_(other.cstr_),
+  index_(other.index_)
+{
+  other.cstr_ = 0;
+}
+#endif
+
 Value::CZString::~CZString() {
   if (cstr_ && storage_.policy_ == duplicate)
     releaseStringValue(const_cast<char*>(cstr_));
@@ -442,6 +451,15 @@ Value::Value(Value const& other)
   }
 }
 
+#if JSON_HAS_RVALUE_REFERENCES
+// Move constructor
+Value::Value(Value&& other)
+{
+	initBasic(nullValue);
+	swap(other);
+}
+#endif
+
 Value::~Value() {
   switch (type_) {
   case nullValue:

src/test_lib_json/main.cpp

@@ -2334,6 +2334,19 @@ JSONTEST_FIXTURE(IteratorTest, indexes) {
   JSONTEST_ASSERT(it == json.end());
 }
 
+struct RValueTest : JsonTest::TestCase {};
+
+JSONTEST_FIXTURE(RValueTest, moveConstruction) {
+#if JSON_HAS_RVALUE_REFERENCES
+  Json::Value json;
+  json["key"] = "value";
+  Json::Value moved = std::move(json);
+  JSONTEST_ASSERT(moved != json); // Possibly not nullValue; definitely not equal.
+  JSONTEST_ASSERT_EQUAL(Json::objectValue, moved.type());
+  JSONTEST_ASSERT_EQUAL(Json::stringValue, moved["key"].type());
+#endif
+}
+
 int main(int argc, const char* argv[]) {
   JsonTest::Runner runner;
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, checkNormalizeFloatingPointStr);
@@ -2402,5 +2415,7 @@ int main(int argc, const char* argv[]) {
   JSONTEST_REGISTER_FIXTURE(runner, IteratorTest, names);
   JSONTEST_REGISTER_FIXTURE(runner, IteratorTest, indexes);
 
+  JSONTEST_REGISTER_FIXTURE(runner, RValueTest, moveConstruction);
+
   return runner.runCommandLine(argc, argv);
 }