- Moved definition of Json::Int and Json::UInt to config.h which compiler detection logic to define them to 64 bits integer if JSON_NO_INT64 is not defined.

- Added Json::ArrayIndex as an unsigned int to forwards.h
- Modified Json::Value to consistently use Json::ArrayIndex.
- Added int/unsigned int constructor overload to Json::Value to avoid ambiguous constructor call.
- Modified jsontestrunner/main.cpp to use Json::valueToString for Value::asInt() conversion to string.
- Modified Json::Reader to only overflow to double when the number is too large (previous code relied on the fact that an int fitted in a double without precision loss).
- Generalized uintToString() helpers and buffer size to automatically adapt to the precision of Json::UInt.
- Added specific conversion logic for UInt to double conversion on Microsoft Visual Studio 6 which only support __int64 to double conversion (unsigned __int64 conversion is not supported)
- Added test for 64 bits parsing/writing. Notes: those will fail when compiled with JSON_NO_INT64 (more dev required to adapt).

src/lib_json/json_reader.cpp

@@ -555,21 +555,36 @@ Reader::decodeNumber( Token &token )
    }
    if ( isDouble )
       return decodeDouble( token );
+   // Attempts to parse the number as an integer. If the number is
+   // larger than the maximum supported value of an integer then
+   // we decode the number as a double.
    Location current = token.start_;
    bool isNegative = *current == '-';
    if ( isNegative )
       ++current;
-   Value::UInt threshold = (isNegative ? Value::UInt(-Value::minInt) 
-                                       : Value::maxUInt) / 10;
+   Value::UInt maxIntegerValue = isNegative ? Value::UInt(-Value::minInt) 
+                                            : Value::maxUInt;
+   Value::UInt threshold = maxIntegerValue / 10;
+   Value::UInt lastDigitThreshold = maxIntegerValue % 10;
+   assert( lastDigitThreshold >=0  &&  lastDigitThreshold <= 9 );
    Value::UInt value = 0;
    while ( current < token.end_ )
    {
       Char c = *current++;
       if ( c < '0'  ||  c > '9' )
          return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );
+      Value::UInt digit(c - '0');
       if ( value >= threshold )
-         return decodeDouble( token );
-      value = value * 10 + Value::UInt(c - '0');
+      {
+         // If the current digit is not the last one, or if it is
+         // greater than the last digit of the maximum integer value,
+         // the parse the number as a double.
+         if ( current != token.end_  ||  digit > lastDigitThreshold )
+         {
+            return decodeDouble( token );
+         }
+      }
+      value = value * 10 + digit;
    }
    if ( isNegative )
       currentValue() = -Value::Int( value );