Added float Json::Value::asFloat() to obtain a floating point value as a float (avoid lost of precision warning caused by used of asDouble() to initialize a float).

blep · blep · commit b96aed0f3e8e · 2010-12-24T19:30:06.000Z
diff --git a/NEWS.txt b/NEWS.txt
@@ -38,6 +38,10 @@
 	array.append( 1234 );
 	int value = array[0].asInt();  // did not compile previously
 
+  - Added float Json::Value::asFloat() to obtain a floating point value as a
+    float (avoid lost of precision warning caused by used of asDouble() 
+    to initialize a float).
+
 * Tests
 
   - Added test to ensure that the escape sequence "\/" is corrected handled 
diff --git a/include/json/value.h b/include/json/value.h
@@ -240,6 +240,7 @@ namespace Json {
 # endif
       Int asInt() const;
       UInt asUInt() const;
+      float asFloat() const;
       double asDouble() const;
       bool asBool() const;
 
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
@@ -772,6 +772,35 @@ Value::asDouble() const
    return 0; // unreachable;
 }
 
+float
+Value::asFloat() const
+{
+   switch ( type_ )
+   {
+   case nullValue:
+      return 0.0f;
+   case intValue:
+      return static_cast<float>( value_.int_ );
+   case uintValue:
+#if !defined(JSON_USE_INT64_DOUBLE_CONVERSION)
+      return static_cast<float>( value_.uint_ );
+#else // if !defined(JSON_USE_INT64_DOUBLE_CONVERSION)
+      return static_cast<float>( Int(value_.uint_/2) ) * 2 + Int(value_.uint_ & 1);
+#endif // if !defined(JSON_USE_INT64_DOUBLE_CONVERSION)
+   case realValue:
+      return static_cast<float>( value_.real_ );
+   case booleanValue:
+      return value_.bool_ ? 1.0f : 0.0f;
+   case stringValue:
+   case arrayValue:
+   case objectValue:
+      JSON_ASSERT_MESSAGE( false, "Type is not convertible to float" );
+   default:
+      JSON_ASSERT_UNREACHABLE;
+   }
+   return 0.0f; // unreachable;
+}
+
 bool 
 Value::asBool() const
 {
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
@@ -28,6 +28,7 @@ struct ValueTest : JsonTest::TestCase
    Json::Value unsignedInteger_;
    Json::Value smallUnsignedInteger_;
    Json::Value real_;
+   Json::Value float_;
    Json::Value array1_;
    Json::Value object1_;
    Json::Value emptyString_;
@@ -43,6 +44,7 @@ struct ValueTest : JsonTest::TestCase
       , smallUnsignedInteger_( Json::Value::UInt( Json::Value::maxInt ) )
       , unsignedInteger_( 34567890u )
       , real_( 1234.56789 )
+	  , float_( 0.00390625f )
       , emptyString_( "" )
       , string1_( "a" )
       , string_( "sometext with space" )
@@ -184,6 +186,11 @@ JSONTEST_FIXTURE( ValueTest, accessArray )
 }
 
 
+JSONTEST_FIXTURE( ValueTest, asFloat )
+{
+	JSONTEST_ASSERT_EQUAL( 0.00390625f, float_.asFloat() ) << "Json::Value::asFloat()";
+}
+
 void
 ValueTest::checkConstMemberCount( const Json::Value &value, unsigned int expectedCount )
 {
@@ -259,5 +266,6 @@ int main( int argc, const char *argv[] )
    JSONTEST_REGISTER_FIXTURE( runner, ValueTest, isNull );
    JSONTEST_REGISTER_FIXTURE( runner, ValueTest, isNull );
    JSONTEST_REGISTER_FIXTURE( runner, ValueTest, accessArray );
+   JSONTEST_REGISTER_FIXTURE( runner, ValueTest, asFloat );
    return runner.runCommandLine( argc, argv );
 }
