Merge pull request #64 from pah/feature/exception-support

Improve exception safety and add support for swtiching error handling to exceptions

include/rapidjson/document.h

@@ -1211,7 +1211,7 @@ public:
 	/*! \param allocator		Optional allocator for allocating stack memory.
 		\param stackCapacity	Initial capacity of stack in bytes.
 	*/
-	GenericDocument(Allocator* allocator = 0, size_t stackCapacity = kDefaultStackCapacity) : stack_(allocator, stackCapacity), parseErrorCode_(kParseErrorNone), errorOffset_(0) {}
+	GenericDocument(Allocator* allocator = 0, size_t stackCapacity = kDefaultStackCapacity) : stack_(allocator, stackCapacity), parseResult_() {}
 
 	//!@name Parse from stream
 	//!@{
@@ -1227,16 +1227,11 @@ public:
 	GenericDocument& ParseStream(InputStream& is) {
 		ValueType::SetNull(); // Remove existing root if exist
 		GenericReader<SourceEncoding, Encoding, Allocator> reader(&GetAllocator());
-		if (reader.template Parse<parseFlags>(is, *this)) {
+		ClearStackOnExit scope(*this);
+		parseResult_ = reader.template Parse<parseFlags>(is, *this);
+		if (parseResult_) {
 			RAPIDJSON_ASSERT(stack_.GetSize() == sizeof(ValueType)); // Got one and only one root object
 			this->RawAssign(*stack_.template Pop<ValueType>(1));	// Add this-> to prevent issue 13.
-			parseErrorCode_ = kParseErrorNone;
-			errorOffset_ = 0;
-		}
-		else {
-			parseErrorCode_ = reader.GetParseErrorCode();
-			errorOffset_ = reader.GetErrorOffset();
-			ClearStack();
 		}
 		return *this;
 	}
@@ -1332,14 +1327,14 @@ public:
 	//!@name Handling parse errors
 	//!@{
 
-	//! Whether a parse error was occured in the last parsing.
-	bool HasParseError() const { return parseErrorCode_ != kParseErrorNone; }
+	//! Whether a parse error has occured in the last parsing.
+	bool HasParseError() const { return parseResult_.IsError(); }
 
-	//! Get the message of parsing error.
-	ParseErrorCode GetParseError() const { return parseErrorCode_; }
+	//! Get the \ref ParseErrorCode of last parsing.
+	ParseErrorCode GetParseError() const { return parseResult_.Code(); }
 
-	//! Get the offset in character of the parsing error.
-	size_t GetErrorOffset() const { return errorOffset_; }
+	//! Get the position of last parsing error in input, 0 otherwise.
+	size_t GetErrorOffset() const { return parseResult_.Offset(); }
 
 	//!@}
 
@@ -1350,6 +1345,14 @@ public:
 	size_t GetStackCapacity() const { return stack_.GetCapacity(); }
 
 private:
+	// clear stack on any exit from ParseStream, e.g. due to exception
+	struct ClearStackOnExit {
+		explicit ClearStackOnExit(GenericDocument& d) : d_(d) {}
+		~ClearStackOnExit() { d_.ClearStack(); }
+	private:
+		GenericDocument& d_;
+	};
+
 	// callers of the following private Handler functions
 	template <typename,typename,typename> friend class GenericReader; // for parsing
 	friend class GenericValue<Encoding,Allocator>; // for deep copying
@@ -1401,8 +1404,7 @@ private:
 
 	static const size_t kDefaultStackCapacity = 1024;
 	internal::Stack<Allocator> stack_;
-	ParseErrorCode parseErrorCode_;
-	size_t errorOffset_;
+	ParseResult parseResult_;
 };
 
 //! GenericDocument with UTF8 encoding

include/rapidjson/error/en.h

@@ -32,12 +32,14 @@ inline const RAPIDJSON_ERROR_CHARTYPE* GetParseError_En(ParseErrorCode parseErro
 		case kParseErrorStringUnicodeSurrogateInvalid:	return RAPIDJSON_ERROR_STRING("The surrogate pair in string is invalid.");
 		case kParseErrorStringEscapeInvalid:			return RAPIDJSON_ERROR_STRING("Invalid escape character in string.");
 		case kParseErrorStringMissQuotationMark:		return RAPIDJSON_ERROR_STRING("Missing a closing quotation mark in string.");
-		case kParseErrorStringInvalidEncoding:			return RAPIDJSON_ERROR_STRING("Invalid encoidng in string.");
+		case kParseErrorStringInvalidEncoding:			return RAPIDJSON_ERROR_STRING("Invalid encoding in string.");
 
 		case kParseErrorNumberTooBig:					return RAPIDJSON_ERROR_STRING("Number too big to be stored in double.");
 		case kParseErrorNumberMissFraction:				return RAPIDJSON_ERROR_STRING("Miss fraction part in number.");
 		case kParseErrorNumberMissExponent:				return RAPIDJSON_ERROR_STRING("Miss exponent in number.");
 
+		case kParseErrorTermination:					return RAPIDJSON_ERROR_STRING("Terminate parsing due to Handler error.");
+
 		default:
 			return RAPIDJSON_ERROR_STRING("Unknown error.");
 	}

include/rapidjson/error/error.h

 #ifndef RAPIDJSON_ERROR_ERROR_H__
 #define RAPIDJSON_ERROR_ERROR_H__
 
-#include "../reader.h"	// ParseErrorCode
-
 ///////////////////////////////////////////////////////////////////////////////
 // RAPIDJSON_ERROR_CHARTYPE
 
@@ -29,6 +27,84 @@
 
 namespace rapidjson {
 
+///////////////////////////////////////////////////////////////////////////////
+// ParseErrorCode
+
+//! Error code of parsing.
+/*! \see GenericReader::Parse, GenericReader::GetParseErrorCode
+*/
+enum ParseErrorCode {
+	kParseErrorNone = 0,						//!< No error.
+
+	kParseErrorDocumentEmpty,					//!< The document is empty.
+	kParseErrorDocumentRootNotObjectOrArray,	//!< The document root must be either object or array.
+	kParseErrorDocumentRootNotSingular,			//!< The document root must not follow by other values.
+
+	kParseErrorValueInvalid,					//!< Invalid value.
+
+	kParseErrorObjectMissName,					//!< Missing a name for object member.
+	kParseErrorObjectMissColon,					//!< Missing a colon after a name of object member.
+	kParseErrorObjectMissCommaOrCurlyBracket,	//!< Missing a comma or '}' after an object member.
+
+	kParseErrorArrayMissCommaOrSquareBracket,	//!< Missing a comma or ']' after an array element.
+
+	kParseErrorStringUnicodeEscapeInvalidHex,	//!< Incorrect hex digit after \\u escape in string.
+	kParseErrorStringUnicodeSurrogateInvalid,	//!< The surrogate pair in string is invalid.
+	kParseErrorStringEscapeInvalid,				//!< Invalid escape character in string.
+	kParseErrorStringMissQuotationMark,			//!< Missing a closing quotation mark in string.
+	kParseErrorStringInvalidEncoding,			//!< Invalid encoding in string.
+
+	kParseErrorNumberTooBig,					//!< Number too big to be stored in double.
+	kParseErrorNumberMissFraction,				//!< Miss fraction part in number.
+	kParseErrorNumberMissExponent,				//!< Miss exponent in number.
+
+	kParseErrorTermination						//!< Parsing was terminated.
+};
+
+//! Result of parsing (wraps ParseErrorCode)
+/*!
+	\code
+		Document doc;
+		ParseResult ok = doc.Parse("[42]");
+		if (!ok) {
+			fprintf(stderr, "JSON parse error: %s (%u)",
+					GetParseError_En(ok.Code()), ok.Offset());
+			exit(EXIT_FAILURE);
+		}
+	\endcode
+	\see GenericReader::Parse, GenericDocument::Parse
+*/
+struct ParseResult {
+
+	//! Default constructor, no error.
+	ParseResult() : code_(kParseErrorNone), offset_(0) {}
+	//! Constructor to set an error.
+	ParseResult(ParseErrorCode code, size_t offset) : code_(code), offset_(offset) {}
+
+	//! Get the error code.
+	ParseErrorCode Code() const { return code_; }
+	//! Get the error offset, if \ref IsError(), 0 otherwise.
+	size_t Offset() const { return offset_; }
+
+	//! Conversion to \c bool, returns \c true, iff !\ref IsError().
+	operator bool() const { return !IsError(); }
+	//! Whether the result is an error.
+	bool IsError() const { return code_ != kParseErrorNone; }
+
+	bool operator==(const ParseResult& that) const { return code_ == that.code_; }
+	bool operator==(ParseErrorCode code) const { return code_ == code; }
+	friend bool operator==(ParseErrorCode code, const ParseResult & err) { return code == err.code_; }
+
+	//! Reset error code.
+	void Clear() { Set(kParseErrorNone); }
+	//! Update error code and offset.
+	void Set(ParseErrorCode code, size_t offset = 0) { code_ = code; offset_ = offset; }
+
+private:
+	ParseErrorCode code_;
+	size_t offset_;
+};
+
 //! Function pointer type of GetParseError().
 /*! This is the prototype for GetParseError_X(), where X is a locale.
 	User can dynamically change locale in runtime, e.g.:

include/rapidjson/reader.h

@@ -24,12 +24,21 @@ RAPIDJSON_DIAG_PUSH
 RAPIDJSON_DIAG_OFF(4127)  // conditional expression is constant
 #endif
 
+#define RAPIDJSON_NOTHING /* deliberately empty */
+#ifndef RAPIDJSON_PARSE_ERROR_EARLY_RETURN
+#define RAPIDJSON_PARSE_ERROR_EARLY_RETURN(value) \
+	RAPIDJSON_MULTILINEMACRO_BEGIN \
+	if (HasParseError()) { return value; } \
+	RAPIDJSON_MULTILINEMACRO_END
+#endif
+#define RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID \
+	RAPIDJSON_PARSE_ERROR_EARLY_RETURN(RAPIDJSON_NOTHING)
+
 #ifndef RAPIDJSON_PARSE_ERROR_NORETURN
 #define RAPIDJSON_PARSE_ERROR_NORETURN(parseErrorCode, offset) \
 	RAPIDJSON_MULTILINEMACRO_BEGIN \
 	RAPIDJSON_ASSERT(!HasParseError()); /* Error can only be assigned once */ \
-	parseErrorCode_ = parseErrorCode; \
-	errorOffset_ = offset; \
+	parseResult_.Set(parseErrorCode,offset); \
 	RAPIDJSON_MULTILINEMACRO_END
 #endif
 
@@ -37,10 +46,12 @@ RAPIDJSON_DIAG_OFF(4127)  // conditional expression is constant
 #define RAPIDJSON_PARSE_ERROR(parseErrorCode, offset) \
 	RAPIDJSON_MULTILINEMACRO_BEGIN \
 	RAPIDJSON_PARSE_ERROR_NORETURN(parseErrorCode, offset); \
-	return; \
+	RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID; \
 	RAPIDJSON_MULTILINEMACRO_END
 #endif
 
+#include "error/error.h" // ParseErrorCode, ParseResult
+
 namespace rapidjson {
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -55,35 +66,6 @@ enum ParseFlag {
 	kParseValidateEncodingFlag = 2	//!< Validate encoding of JSON strings.
 };
 
-//! Error code of parsing.
-enum ParseErrorCode {
-	kParseErrorNone = 0,						//!< No error.
-	
-	kParseErrorDocumentEmpty,					//!< The document is empty.
-	kParseErrorDocumentRootNotObjectOrArray,	//!< The document root must be either object or array.
-	kParseErrorDocumentRootNotSingular,			//!< The document root must not follow by other values.
-	
-	kParseErrorValueInvalid,					//!< Invalid value.
-	
-	kParseErrorObjectMissName,					//!< Missing a name for object member.
-	kParseErrorObjectMissColon,					//!< Missing a colon after a name of object member.
-	kParseErrorObjectMissCommaOrCurlyBracket,	//!< Missing a comma or '}' after an object member.
-	
-	kParseErrorArrayMissCommaOrSquareBracket,	//!< Missing a comma or ']' after an array element.
-
-	kParseErrorStringUnicodeEscapeInvalidHex,	//!< Incorrect hex digit after \\u escape in string.
-	kParseErrorStringUnicodeSurrogateInvalid,	//!< The surrogate pair in string is invalid.
-	kParseErrorStringEscapeInvalid,				//!< Invalid escape character in string.
-	kParseErrorStringMissQuotationMark,			//!< Missing a closing quotation mark in string.
-	kParseErrorStringInvalidEncoding,			//!< Invalid encoidng in string.
-
-	kParseErrorNumberTooBig,					//!< Number too big to be stored in double.
-	kParseErrorNumberMissFraction,				//!< Miss fraction part in number.
-	kParseErrorNumberMissExponent,				//!< Miss exponent in number.
-
-	kParseErrorTermination						//!< Parsing was terminated.
-};
-
 ///////////////////////////////////////////////////////////////////////////////
 // Handler
 
@@ -292,7 +274,7 @@ public:
 	/*! \param allocator Optional allocator for allocating stack memory. (Only use for non-destructive parsing)
 		\param stackCapacity stack capacity in bytes for storing a single decoded string.  (Only use for non-destructive parsing)
 	*/
-	GenericReader(Allocator* allocator = 0, size_t stackCapacity = kDefaultStackCapacity) : stack_(allocator, stackCapacity), parseErrorCode_(kParseErrorNone), errorOffset_(0) {}
+	GenericReader(Allocator* allocator = 0, size_t stackCapacity = kDefaultStackCapacity) : stack_(allocator, stackCapacity), parseResult_() {}
 
 	//! Parse JSON text.
 	/*! \tparam parseFlags Combination of \ref ParseFlag.
@@ -303,32 +285,33 @@ public:
 		\return Whether the parsing is successful.
 	*/
 	template <unsigned parseFlags, typename InputStream, typename Handler>
-	bool Parse(InputStream& is, Handler& handler) {
-		parseErrorCode_ = kParseErrorNone;
-		errorOffset_ = 0;
+	ParseResult Parse(InputStream& is, Handler& handler) {
+		parseResult_.Clear();
 
+		ClearStackOnExit scope(*this);
 		SkipWhitespace(is);
 
-		if (is.Peek() == '\0')
+		if (is.Peek() == '\0') {
 			RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentEmpty, is.Tell());
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
+		}
 		else {
 			switch (is.Peek()) {
 				case '{': ParseObject<parseFlags>(is, handler); break;
 				case '[': ParseArray<parseFlags>(is, handler); break;
 				default: RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentRootNotObjectOrArray, is.Tell());
 			}
-			if (HasParseError())
-				goto out;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
 
 			SkipWhitespace(is);
 
-			if (is.Peek() != '\0')
+			if (is.Peek() != '\0') {
 				RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentRootNotSingular, is.Tell());
+				RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
+			}
 		}
 
-	out:
-		stack_.Clear();
-		return !HasParseError();
+		return parseResult_;
 	}
 
 	//! Parse JSON text (with \ref kParseDefaultFlags)
@@ -339,21 +322,34 @@ public:
 		\return Whether the parsing is successful.
 	*/
 	template <typename InputStream, typename Handler>
-	bool Parse(InputStream& is, Handler& handler) {
+	ParseResult Parse(InputStream& is, Handler& handler) {
 		return Parse<kParseDefaultFlags>(is, handler);
 	}
 
-	bool HasParseError() const { return parseErrorCode_ != kParseErrorNone; }
+	//! Whether a parse error has occured in the last parsing.
+	bool HasParseError() const { return parseResult_.IsError(); }
 	
-	ParseErrorCode GetParseErrorCode() const { return parseErrorCode_; }
+	//! Get the \ref ParseErrorCode of last parsing.
+	ParseErrorCode GetParseErrorCode() const { return parseResult_.Code(); }
 
-	size_t GetErrorOffset() const { return errorOffset_; }
+	//! Get the position of last parsing error in input, 0 otherwise.
+	size_t GetErrorOffset() const { return parseResult_.Offset(); }
 
 private:
 	// Prohibit copy constructor & assignment operator.
 	GenericReader(const GenericReader&);
 	GenericReader& operator=(const GenericReader&);
 
+	void ClearStack() { stack_.Clear(); }
+
+	// clear stack on any exit from ParseStream, e.g. due to exception
+	struct ClearStackOnExit {
+		explicit ClearStackOnExit(GenericReader& r) : r_(r) {}
+		~ClearStackOnExit() { r_.ClearStack(); }
+	private:
+		GenericReader& r_;
+	};
+
 	// Parse object: { string : value, ... }
 	template<unsigned parseFlags, typename InputStream, typename Handler>
 	void ParseObject(InputStream& is, Handler& handler) {
@@ -377,8 +373,7 @@ private:
 				RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissName, is.Tell());
 
 			ParseString<parseFlags>(is, handler);
-			if (HasParseError())
-				return;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
 
 			SkipWhitespace(is);
 
@@ -388,8 +383,7 @@ private:
 			SkipWhitespace(is);
 
 			ParseValue<parseFlags>(is, handler);
-			if (HasParseError())
-				return;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
 
 			SkipWhitespace(is);
 
@@ -427,8 +421,7 @@ private:
 
 		for (SizeType elementCount = 0;;) {
 			ParseValue<parseFlags>(is, handler);
-			if (HasParseError())
-				return;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
 
 			++elementCount;
 			SkipWhitespace(is);
@@ -500,7 +493,7 @@ private:
 				codepoint -= 'a' - 10;
 			else {
 				RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorStringUnicodeEscapeInvalidHex, is.Tell() - 1);
-				return 0;
+				RAPIDJSON_PARSE_ERROR_EARLY_RETURN(0);
 			}
 		}
 		return codepoint;
@@ -532,8 +525,7 @@ private:
 		if (parseFlags & kParseInsituFlag) {
 			typename InputStream::Ch *head = s.PutBegin();
 			ParseStringToStream<parseFlags, SourceEncoding, SourceEncoding>(s, s);
-			if (HasParseError())
-				return;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
 			size_t length = s.PutEnd(head) - 1;
 			RAPIDJSON_ASSERT(length <= 0xFFFFFFFF);
 			if (!handler.String((typename TargetEncoding::Ch*)head, SizeType(length), false))
@@ -542,8 +534,7 @@ private:
 		else {
 			StackStream stackStream(stack_);
 			ParseStringToStream<parseFlags, SourceEncoding, TargetEncoding>(s, stackStream);
-			if (HasParseError())
-				return;
+			RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
 			if (!handler.String(stack_.template Pop<typename TargetEncoding::Ch>(stackStream.length_), stackStream.length_ - 1, true))
 				RAPIDJSON_PARSE_ERROR(kParseErrorTermination, s.Tell());
 		}
@@ -794,8 +785,7 @@ private:
 
 	static const size_t kDefaultStackCapacity = 256;	//!< Default stack capacity in bytes for storing a single decoded string. 
 	internal::Stack<Allocator> stack_;	//!< A stack for storing decoded string temporarily during non-destructive parsing.
-	ParseErrorCode parseErrorCode_;
-	size_t errorOffset_;
+	ParseResult parseResult_;
 }; // class GenericReader
 
 //! Reader with UTF8 encoding and default allocator.