rapidjson/include/rapidjson/reader.h

#ifndef RAPIDJSON_READER_H_
#define RAPIDJSON_READER_H_

// Copyright (c) 2011 Milo Yip (miloyip@gmail.com)
// Version 0.1

#include "rapidjson.h"
#include "encodings.h"
#include "internal/pow10.h"
#include "internal/stack.h"

#ifdef RAPIDJSON_SSE42
#include <nmmintrin.h>
#elif defined(RAPIDJSON_SSE2)
#include <emmintrin.h>
#endif

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4127) // conditional expression is constant
#endif

#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; \
	RAPIDJSON_MULTILINEMACRO_END
#endif

#ifndef RAPIDJSON_PARSE_ERROR
#define RAPIDJSON_PARSE_ERROR(parseErrorCode, offset) \
	RAPIDJSON_MULTILINEMACRO_BEGIN \
	RAPIDJSON_PARSE_ERROR_NORETURN(parseErrorCode, offset); \
	return; \
	RAPIDJSON_MULTILINEMACRO_END
#endif

namespace rapidjson {

///////////////////////////////////////////////////////////////////////////////
// ParseFlag

//! Combination of parseFlags
enum ParseFlag {
	kParseDefaultFlags = 0,			//!< Default parse flags. Non-destructive parsing. Text strings are decoded into allocated buffer.
	kParseInsituFlag = 1,			//!< In-situ(destructive) parsing.
	kParseValidateEncodingFlag = 2,	//!< Validate encoding of JSON strings.
	kParseIterativeFlag = 4			//!< Iterative(constant complexity in terms of function call stack size) parsing.
};

//! 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 encoding in string.

	kParseErrorNumberTooBig,					//!< Number too big to be stored in double.
	kParseErrorNumberMissFraction,				//!< Miss fraction part in number.
	kParseErrorNumberMissExponent				//!< Miss exponent in number.
};

///////////////////////////////////////////////////////////////////////////////
// Handler

/*!	\class rapidjson::Handler
	\brief Concept for receiving events from GenericReader upon parsing.
\code
concept Handler {
	typename Ch;

	void Null();
	void Bool(bool b);
	void Int(int i);
	void Uint(unsigned i);
	void Int64(int64_t i);
	void Uint64(uint64_t i);
	void Double(double d);
	void String(const Ch* str, SizeType length, bool copy);
	void StartObject();
	void EndObject(SizeType memberCount);
	void StartArray();
	void EndArray(SizeType elementCount);
};
\endcode
*/
///////////////////////////////////////////////////////////////////////////////
// BaseReaderHandler

//! Default implementation of Handler.
/*! This can be used as base class of any reader handler.
	\note implements Handler concept
*/
template<typename Encoding = UTF8<> >
struct BaseReaderHandler {
	typedef typename Encoding::Ch Ch;

	void Default() {}
	void Null() { Default(); }
	void Bool(bool) { Default(); }
	void Int(int) { Default(); }
	void Uint(unsigned) { Default(); }
	void Int64(int64_t) { Default(); }
	void Uint64(uint64_t) { Default(); }
	void Double(double) { Default(); }
	void String(const Ch*, SizeType, bool) { Default(); }
	void StartObject() { Default(); }
	void EndObject(SizeType) { Default(); }
	void StartArray() { Default(); }
	void EndArray(SizeType) { Default(); }
};

///////////////////////////////////////////////////////////////////////////////
// StreamLocalCopy

namespace internal {

template<typename Stream, int = StreamTraits<Stream>::copyOptimization>
class StreamLocalCopy;

//! Do copy optimization.
template<typename Stream>
class StreamLocalCopy<Stream, 1> {
public:
	StreamLocalCopy(Stream& original) : s(original), original_(original) {}
	~StreamLocalCopy() { original_ = s; }

	Stream s;

private:
	StreamLocalCopy& operator=(const StreamLocalCopy&) /* = delete */;

	Stream& original_;
};

//! Keep reference.
template<typename Stream>
class StreamLocalCopy<Stream, 0> {
public:
	StreamLocalCopy(Stream& original) : s(original) {}

	Stream& s;

private:
	StreamLocalCopy& operator=(const StreamLocalCopy&) /* = delete */;
};

} // namespace internal

///////////////////////////////////////////////////////////////////////////////
// SkipWhitespace

//! Skip the JSON white spaces in a stream.
/*! \param is A input stream for skipping white spaces.
	\note This function has SSE2/SSE4.2 specialization.
*/
template<typename InputStream>
void SkipWhitespace(InputStream& is) {
	internal::StreamLocalCopy<InputStream> copy(is);
	InputStream& s(copy.s);

	while (s.Peek() == ' ' || s.Peek() == '\n' || s.Peek() == '\r' || s.Peek() == '\t')
		s.Take();
}

#ifdef RAPIDJSON_SSE42
//! Skip whitespace with SSE 4.2 pcmpistrm instruction, testing 16 8-byte characters at once.
inline const char *SkipWhitespace_SIMD(const char* p) {
	static const char whitespace[16] = " \n\r\t";
	__m128i w = _mm_loadu_si128((const __m128i *)&whitespace[0]);

	for (;;) {
		__m128i s = _mm_loadu_si128((const __m128i *)p);
		unsigned r = _mm_cvtsi128_si32(_mm_cmpistrm(w, s, _SIDD_UBYTE_OPS | _SIDD_CMP_EQUAL_ANY | _SIDD_BIT_MASK | _SIDD_NEGATIVE_POLARITY));
		if (r == 0)	// all 16 characters are whitespace
			p += 16;
		else {		// some of characters may be non-whitespace
#ifdef _MSC_VER		// Find the index of first non-whitespace
			unsigned long offset;
			if (_BitScanForward(&offset, r))
				return p + offset;
#else
			if (r != 0)
				return p + __builtin_ffs(r) - 1;
#endif
		}
	}
}

#elif defined(RAPIDJSON_SSE2)

//! Skip whitespace with SSE2 instructions, testing 16 8-byte characters at once.
inline const char *SkipWhitespace_SIMD(const char* p) {
	static const char whitespaces[4][17] = {
		"                ",
		"\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n",
		"\r\r\r\r\r\r\r\r\r\r\r\r\r\r\r\r",
		"\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"};

	__m128i w0 = _mm_loadu_si128((const __m128i *)&whitespaces[0][0]);
	__m128i w1 = _mm_loadu_si128((const __m128i *)&whitespaces[1][0]);
	__m128i w2 = _mm_loadu_si128((const __m128i *)&whitespaces[2][0]);
	__m128i w3 = _mm_loadu_si128((const __m128i *)&whitespaces[3][0]);

	for (;;) {
		__m128i s = _mm_loadu_si128((const __m128i *)p);
		__m128i x = _mm_cmpeq_epi8(s, w0);
		x = _mm_or_si128(x, _mm_cmpeq_epi8(s, w1));
		x = _mm_or_si128(x, _mm_cmpeq_epi8(s, w2));
		x = _mm_or_si128(x, _mm_cmpeq_epi8(s, w3));
		unsigned short r = (unsigned short)~_mm_movemask_epi8(x);
		if (r == 0)	// all 16 characters are whitespace
			p += 16;
		else {		// some of characters may be non-whitespace
#ifdef _MSC_VER		// Find the index of first non-whitespace
			unsigned long offset;
			if (_BitScanForward(&offset, r))
				return p + offset;
#else
			if (r != 0)
				return p + __builtin_ffs(r) - 1;
#endif
		}
	}
}

#endif // RAPIDJSON_SSE2

#ifdef RAPIDJSON_SIMD
//! Template function specialization for InsituStringStream
template<> inline void SkipWhitespace(InsituStringStream& is) { 
	is.src_ = const_cast<char*>(SkipWhitespace_SIMD(is.src_));
}

//! Template function specialization for StringStream
template<> inline void SkipWhitespace(StringStream& is) {
	is.src_ = SkipWhitespace_SIMD(is.src_);
}
#endif // RAPIDJSON_SIMD

///////////////////////////////////////////////////////////////////////////////
// GenericReader

//! SAX-style JSON parser. Use Reader for UTF8 encoding and default allocator.
/*! GenericReader parses JSON text from a stream, and send events synchronously to an 
    object implementing Handler concept.

    It needs to allocate a stack for storing a single decoded string during 
    non-destructive parsing.

    For in-situ parsing, the decoded string is directly written to the source 
    text string, no temporary buffer is required.

    A GenericReader object can be reused for parsing multiple JSON text.
    
    \tparam SourceEncoding Encoding of the input stream.
	\tparam TargetEncoding Encoding of the parse output.
    \tparam Allocator Allocator type for stack.
*/
template <typename SourceEncoding, typename TargetEncoding, typename Allocator = MemoryPoolAllocator<> >
class GenericReader {
public:
	typedef typename SourceEncoding::Ch Ch;

	//! Constructor.
	/*! \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) {}

	//! Parse JSON text.
	/*! \tparam parseFlags Combination of ParseFlag. 
		 \tparam InputStream Type of input stream.
		 \tparam Handler Type of handler which must implement Handler concept.
		 \param is Input stream to be parsed.
		 \param handler The handler to receive events.
		 \return Whether the parsing is successful.
	*/
	template <unsigned parseFlags, typename InputStream, typename Handler>
	bool Parse(InputStream& is, Handler& handler) {
		parseErrorCode_ = kParseErrorNone;
		errorOffset_ = 0;

		if (parseFlags & kParseIterativeFlag)
			return IterativeParse<parseFlags>(is, handler);

		SkipWhitespace(is);

		if (is.Peek() == '\0')
			RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentEmpty, is.Tell());
		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;

			SkipWhitespace(is);

			if (is.Peek() != '\0')
				RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentRootNotSingular, is.Tell());
		}

	out:
		stack_.Clear();
		return !HasParseError();
	}

	template <typename InputStream, typename Handler>
	bool Parse(InputStream& is, Handler& handler) {
		return Parse<kParseDefaultFlags>(is, handler);
	}

	bool HasParseError() const { return parseErrorCode_ != kParseErrorNone; }
	
	ParseErrorCode GetParseErrorCode() const { return parseErrorCode_; }

	size_t GetErrorOffset() const { return errorOffset_; }

private:
	// Prohibit copy constructor & assignment operator.
	GenericReader(const GenericReader&);
	GenericReader& operator=(const GenericReader&);

	// Parse object: { string : value, ... }
	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseObject(InputStream& is, Handler& handler) {
		RAPIDJSON_ASSERT(is.Peek() == '{');
		is.Take();	// Skip '{'
		handler.StartObject();
		SkipWhitespace(is);

		if (is.Peek() == '}') {
			is.Take();
			handler.EndObject(0);	// empty object
			return;
		}

		for (SizeType memberCount = 0;;) {
			if (is.Peek() != '"')
				RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissName, is.Tell());

			ParseString<parseFlags>(is, handler);
			if (HasParseError())
				return;

			SkipWhitespace(is);

			if (is.Take() != ':')
				RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissColon, is.Tell());

			SkipWhitespace(is);

			ParseValue<parseFlags>(is, handler);
			if (HasParseError())
				return;

			SkipWhitespace(is);

			++memberCount;

			switch(is.Take()) {
				case ',': SkipWhitespace(is); break;
				case '}': handler.EndObject(memberCount); return;
				default:  RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissCommaOrCurlyBracket, is.Tell());
			}
		}
	}

	// Parse array: [ value, ... ]
	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseArray(InputStream& is, Handler& handler) {
		RAPIDJSON_ASSERT(is.Peek() == '[');
		is.Take();	// Skip '['
		handler.StartArray();
		SkipWhitespace(is);

		if (is.Peek() == ']') {
			is.Take();
			handler.EndArray(0); // empty array
			return;
		}

		for (SizeType elementCount = 0;;) {
			ParseValue<parseFlags>(is, handler);
			if (HasParseError())
				return;

			++elementCount;
			SkipWhitespace(is);

			switch (is.Take()) {
				case ',': SkipWhitespace(is); break;
				case ']': handler.EndArray(elementCount); return;
				default:  RAPIDJSON_PARSE_ERROR(kParseErrorArrayMissCommaOrSquareBracket, is.Tell());
			}
		}
	}

	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseNull(InputStream& is, Handler& handler) {
		RAPIDJSON_ASSERT(is.Peek() == 'n');
		is.Take();

		if (is.Take() == 'u' && is.Take() == 'l' && is.Take() == 'l')
			handler.Null();
		else
			RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell() - 1);
	}

	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseTrue(InputStream& is, Handler& handler) {
		RAPIDJSON_ASSERT(is.Peek() == 't');
		is.Take();

		if (is.Take() == 'r' && is.Take() == 'u' && is.Take() == 'e')
			handler.Bool(true);
		else
			RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell());
	}

	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseFalse(InputStream& is, Handler& handler) {
		RAPIDJSON_ASSERT(is.Peek() == 'f');
		is.Take();

		if (is.Take() == 'a' && is.Take() == 'l' && is.Take() == 's' && is.Take() == 'e')
			handler.Bool(false);
		else
			RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell() - 1);
	}

	// Helper function to parse four hexidecimal digits in \uXXXX in ParseString().
	template<typename InputStream>
	unsigned ParseHex4(InputStream& is) {
		unsigned codepoint = 0;
		for (int i = 0; i < 4; i++) {
			Ch c = is.Take();
			codepoint <<= 4;
			codepoint += static_cast<unsigned>(c);
			if (c >= '0' && c <= '9')
				codepoint -= '0';
			else if (c >= 'A' && c <= 'F')
				codepoint -= 'A' - 10;
			else if (c >= 'a' && c <= 'f')
				codepoint -= 'a' - 10;
			else {
				RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorStringUnicodeEscapeInvalidHex, is.Tell() - 1);
				return 0;
			}
		}
		return codepoint;
	}

	class StackStream {
	public:
		typedef typename TargetEncoding::Ch Ch;

		StackStream(internal::Stack<Allocator>& stack) : stack_(stack), length_(0) {}
		void Put(Ch c) {
			*stack_.template Push<Ch>() = c;
			++length_;
		}
		internal::Stack<Allocator>& stack_;
		SizeType length_;

	private:
		StackStream(const StackStream&);
		StackStream& operator=(const StackStream&);
	};

	// Parse string and generate String event. Different code paths for kParseInsituFlag.
	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseString(InputStream& is, Handler& handler) {
		internal::StreamLocalCopy<InputStream> copy(is);
		InputStream& s(copy.s);

		if (parseFlags & kParseInsituFlag) {
			typename InputStream::Ch *head = s.PutBegin();
			ParseStringToStream<parseFlags, SourceEncoding, SourceEncoding>(s, s);
			if (HasParseError())
				return;
			size_t length = s.PutEnd(head) - 1;
			RAPIDJSON_ASSERT(length <= 0xFFFFFFFF);
			handler.String((typename TargetEncoding::Ch*)head, SizeType(length), false);
		}
		else {
			StackStream stackStream(stack_);
			ParseStringToStream<parseFlags, SourceEncoding, TargetEncoding>(s, stackStream);
			if (HasParseError())
				return;
			handler.String(stack_.template Pop<typename TargetEncoding::Ch>(stackStream.length_), stackStream.length_ - 1, true);
		}
	}

	// Parse string to an output is
	// This function handles the prefix/suffix double quotes, escaping, and optional encoding validation.
	template<unsigned parseFlags, typename SEncoding, typename TEncoding, typename InputStream, typename OutputStream>
	RAPIDJSON_FORCEINLINE void ParseStringToStream(InputStream& is, OutputStream& os) {
#define Z16 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
		static const char escape[256] = {
			Z16, Z16, 0, 0,'\"', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,'/', 
			Z16, Z16, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,'\\', 0, 0, 0, 
			0, 0,'\b', 0, 0, 0,'\f', 0, 0, 0, 0, 0, 0, 0,'\n', 0, 
			0, 0,'\r', 0,'\t', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 
			Z16, Z16, Z16, Z16, Z16, Z16, Z16, Z16
		};
#undef Z16

		RAPIDJSON_ASSERT(is.Peek() == '\"');
		is.Take();	// Skip '\"'

		for (;;) {
			Ch c = is.Peek();
			if (c == '\\') {	// Escape
				is.Take();
				Ch e = is.Take();
				if ((sizeof(Ch) == 1 || unsigned(e) < 256) && escape[(unsigned char)e])
					os.Put(escape[(unsigned char)e]);
				else if (e == 'u') {	// Unicode
					unsigned codepoint = ParseHex4(is);
					if (codepoint >= 0xD800 && codepoint <= 0xDBFF) {
						// Handle UTF-16 surrogate pair
						if (is.Take() != '\\' || is.Take() != 'u')
							RAPIDJSON_PARSE_ERROR(kParseErrorStringUnicodeSurrogateInvalid, is.Tell() - 2);
						unsigned codepoint2 = ParseHex4(is);
						if (codepoint2 < 0xDC00 || codepoint2 > 0xDFFF)
							RAPIDJSON_PARSE_ERROR(kParseErrorStringUnicodeSurrogateInvalid, is.Tell() - 2);
						codepoint = (((codepoint - 0xD800) << 10) | (codepoint2 - 0xDC00)) + 0x10000;
					}
					TEncoding::Encode(os, codepoint);
				}
				else
					RAPIDJSON_PARSE_ERROR(kParseErrorStringEscapeInvalid, is.Tell() - 1);
			}
			else if (c == '"') {	// Closing double quote
				is.Take();
				os.Put('\0');	// null-terminate the string
				return;
			}
			else if (c == '\0')
				RAPIDJSON_PARSE_ERROR(kParseErrorStringMissQuotationMark, is.Tell() - 1);
			else if ((unsigned)c < 0x20) // RFC 4627: unescaped = %x20-21 / %x23-5B / %x5D-10FFFF
				RAPIDJSON_PARSE_ERROR(kParseErrorStringEscapeInvalid, is.Tell() - 1);
			else {
				if (parseFlags & kParseValidateEncodingFlag ? 
					!Transcoder<SEncoding, TEncoding>::Validate(is, os) : 
					!Transcoder<SEncoding, TEncoding>::Transcode(is, os))
					RAPIDJSON_PARSE_ERROR(kParseErrorStringInvalidEncoding, is.Tell());
			}
		}
	}

	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseNumber(InputStream& is, Handler& handler) {
		internal::StreamLocalCopy<InputStream> copy(is);
		InputStream& s(copy.s);

		// Parse minus
		bool minus = false;
		if (s.Peek() == '-') {
			minus = true;
			s.Take();
		}

		// Parse int: zero / ( digit1-9 *DIGIT )
		unsigned i;
		bool try64bit = false;
		if (s.Peek() == '0') {
			i = 0;
			s.Take();
		}
		else if (s.Peek() >= '1' && s.Peek() <= '9') {
			i = static_cast<unsigned>(s.Take() - '0');

			if (minus)
				while (s.Peek() >= '0' && s.Peek() <= '9') {
					if (i >= 214748364) { // 2^31 = 2147483648
						if (i != 214748364 || s.Peek() > '8') {
							try64bit = true;
							break;
						}
					}
					i = i * 10 + static_cast<unsigned>(s.Take() - '0');
				}
			else
				while (s.Peek() >= '0' && s.Peek() <= '9') {
					if (i >= 429496729) { // 2^32 - 1 = 4294967295
						if (i != 429496729 || s.Peek() > '5') {
							try64bit = true;
							break;
						}
					}
					i = i * 10 + static_cast<unsigned>(s.Take() - '0');
				}
		}
		else
			RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());

		// Parse 64bit int
		uint64_t i64 = 0;
		bool useDouble = false;
		if (try64bit) {
			i64 = i;
			if (minus) 
				while (s.Peek() >= '0' && s.Peek() <= '9') {					
					if (i64 >= UINT64_C(922337203685477580)) // 2^63 = 9223372036854775808
						if (i64 != UINT64_C(922337203685477580) || s.Peek() > '8') {
							useDouble = true;
							break;
						}
					i64 = i64 * 10 + static_cast<unsigned>(s.Take() - '0');
				}
			else
				while (s.Peek() >= '0' && s.Peek() <= '9') {					
					if (i64 >= UINT64_C(1844674407370955161)) // 2^64 - 1 = 18446744073709551615
						if (i64 != UINT64_C(1844674407370955161) || s.Peek() > '5') {
							useDouble = true;
							break;
						}
					i64 = i64 * 10 + static_cast<unsigned>(s.Take() - '0');
				}
		}

		// Force double for big integer
		double d = 0.0;
		if (useDouble) {
			d = (double)i64;
			while (s.Peek() >= '0' && s.Peek() <= '9') {
				if (d >= 1E307)
					RAPIDJSON_PARSE_ERROR(kParseErrorNumberTooBig, s.Tell());
				d = d * 10 + (s.Take() - '0');
			}
		}

		// Parse frac = decimal-point 1*DIGIT
		int expFrac = 0;
		if (s.Peek() == '.') {
			if (!useDouble) {
				d = try64bit ? (double)i64 : (double)i;
				useDouble = true;
			}
			s.Take();

			if (s.Peek() >= '0' && s.Peek() <= '9') {
				d = d * 10 + (s.Take() - '0');
				--expFrac;
			}
			else
				RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());

			while (s.Peek() >= '0' && s.Peek() <= '9') {
				if (expFrac > -16) {
					d = d * 10 + (s.Peek() - '0');
					--expFrac;
				}
				s.Take();
			}
		}

		// Parse exp = e [ minus / plus ] 1*DIGIT
		int exp = 0;
		if (s.Peek() == 'e' || s.Peek() == 'E') {
			if (!useDouble) {
				d = try64bit ? (double)i64 : (double)i;
				useDouble = true;
			}
			s.Take();

			bool expMinus = false;
			if (s.Peek() == '+')
				s.Take();
			else if (s.Peek() == '-') {
				s.Take();
				expMinus = true;
			}

			if (s.Peek() >= '0' && s.Peek() <= '9') {
				exp = s.Take() - '0';
				while (s.Peek() >= '0' && s.Peek() <= '9') {
					exp = exp * 10 + (s.Take() - '0');
					if (exp > 308)
						RAPIDJSON_PARSE_ERROR(kParseErrorNumberTooBig, s.Tell());
				}
			}
			else
				RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissExponent, s.Tell());

			if (expMinus)
				exp = -exp;
		}

		// Finish parsing, call event according to the type of number.
		if (useDouble) {
			int expSum = exp + expFrac;
			if (expSum < -308) {
				// Prevent expSum < -308, making Pow10(expSum) = 0
				d *= internal::Pow10(exp);
				d *= internal::Pow10(expFrac);
			}
			else
				d *= internal::Pow10(expSum);

			handler.Double(minus ? -d : d);
		}
		else {
			if (try64bit) {
				if (minus)
					handler.Int64(-(int64_t)i64);
				else
					handler.Uint64(i64);
			}
			else {
				if (minus)
					handler.Int(-(int)i);
				else
					handler.Uint(i);
			}
		}
	}

	// Parse any JSON value
	template<unsigned parseFlags, typename InputStream, typename Handler>
	void ParseValue(InputStream& is, Handler& handler) {
		switch (is.Peek()) {
			case 'n': ParseNull  <parseFlags>(is, handler); break;
			case 't': ParseTrue  <parseFlags>(is, handler); break;
			case 'f': ParseFalse <parseFlags>(is, handler); break;
			case '"': ParseString<parseFlags>(is, handler); break;
			case '{': ParseObject<parseFlags>(is, handler); break;
			case '[': ParseArray <parseFlags>(is, handler); break;
			default : ParseNumber<parseFlags>(is, handler);
		}
	}

	// Iterative Parsing

	// States
	enum IterativeParsingState {
		IterativeParsingStartState = 0,
		IterativeParsingFinishState,
		IterativeParsingErrorState,

		// Object states
		IterativeParsingObjectInitialState,
		IterativeParsingMemberKeyState,
		IterativeParsingKeyValueDelimiterState,
		IterativeParsingMemberValueState,
		IterativeParsingMemberDelimiterState,
		IterativeParsingObjectFinishState,

		// Array states
		IterativeParsingArrayInitialState,
		IterativeParsingElementState,
		IterativeParsingElementDelimiterState,
		IterativeParsingArrayFinishState,

		cIterativeParsingStateCount
	};

	// Tokens
	enum IterativeParsingToken {
		IterativeParsingLeftBracketToken = 0,
		IterativeParsingRightBracketToken,

		IterativeParsingLeftCurlyBracketToken,
		IterativeParsingRightCurlyBracketToken,

		IterativeParsingCommaToken,
		IterativeParsingColonToken,

		IterativeParsingStringToken,
		IterativeParsingFalseToken,
		IterativeParsingTrueToken,
		IterativeParsingNullToken,
		IterativeParsingNumberToken,

		cIterativeParsingTokenCount
	};

	IterativeParsingToken GuessToken(Ch c) {
		switch (c) {
		case '[': return IterativeParsingLeftBracketToken;
		case ']': return IterativeParsingRightBracketToken;
		case '{': return IterativeParsingLeftCurlyBracketToken;
		case '}': return IterativeParsingRightCurlyBracketToken;
		case ',': return IterativeParsingCommaToken;
		case ':': return IterativeParsingColonToken;
		case '"': return IterativeParsingStringToken;
		case 'f': return IterativeParsingFalseToken;
		case 't': return IterativeParsingTrueToken;
		case 'n': return IterativeParsingNullToken;
		default: return IterativeParsingNumberToken;
		}
	}

	IterativeParsingState Transit(IterativeParsingState state, IterativeParsingToken token) {
		// current state x one lookahead token -> new state
		static const IterativeParsingState G[cIterativeParsingStateCount][cIterativeParsingTokenCount] = {
			// Start
			{
				IterativeParsingArrayInitialState,	// Left bracket
				IterativeParsingErrorState,			// Right bracket
				IterativeParsingObjectInitialState,	// Left curly bracket
				IterativeParsingErrorState,			// Right curly bracket
				IterativeParsingErrorState,			// Comma
				IterativeParsingErrorState,			// Colon
				IterativeParsingErrorState,			// String
				IterativeParsingErrorState,			// False
				IterativeParsingErrorState,			// True
				IterativeParsingErrorState,			// Null
				IterativeParsingErrorState			// Number
			},
			// Finish(sink state)
			{
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState
			},
			// Error(sink state)
			{
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState
			},
			// ObjectInitial
			{
				IterativeParsingErrorState,			// Left bracket
				IterativeParsingErrorState,			// Right bracket
				IterativeParsingErrorState,			// Left curly bracket
				IterativeParsingObjectFinishState,	// Right curly bracket
				IterativeParsingErrorState,			// Comma
				IterativeParsingErrorState,			// Colon
				IterativeParsingMemberKeyState,		// String
				IterativeParsingErrorState,			// False
				IterativeParsingErrorState,			// True
				IterativeParsingErrorState,			// Null
				IterativeParsingErrorState			// Number
			},
			// MemberKey
			{
				IterativeParsingErrorState,				// Left bracket
				IterativeParsingErrorState,				// Right bracket
				IterativeParsingErrorState,				// Left curly bracket
				IterativeParsingErrorState,				// Right curly bracket
				IterativeParsingErrorState,				// Comma
				IterativeParsingKeyValueDelimiterState,	// Colon
				IterativeParsingErrorState,				// String
				IterativeParsingErrorState,				// False
				IterativeParsingErrorState,				// True
				IterativeParsingErrorState,				// Null
				IterativeParsingErrorState				// Number
			},
			// KeyValueDelimiter
			{
				IterativeParsingArrayInitialState,		// Left bracket(push MemberValue state)
				IterativeParsingErrorState,				// Right bracket
				IterativeParsingObjectInitialState,		// Left curly bracket(push MemberValue state)
				IterativeParsingErrorState,				// Right curly bracket
				IterativeParsingErrorState,				// Comma
				IterativeParsingErrorState,				// Colon
				IterativeParsingMemberValueState,		// String
				IterativeParsingMemberValueState,		// False
				IterativeParsingMemberValueState,		// True
				IterativeParsingMemberValueState,		// Null
				IterativeParsingMemberValueState		// Number
			},
			// MemberValue
			{
				IterativeParsingErrorState,				// Left bracket
				IterativeParsingErrorState,				// Right bracket
				IterativeParsingErrorState,				// Left curly bracket
				IterativeParsingObjectFinishState,		// Right curly bracket
				IterativeParsingMemberDelimiterState,	// Comma
				IterativeParsingErrorState,				// Colon
				IterativeParsingErrorState,				// String
				IterativeParsingErrorState,				// False
				IterativeParsingErrorState,				// True
				IterativeParsingErrorState,				// Null
				IterativeParsingErrorState				// Number
			},
			// MemberDelimiter
			{
				IterativeParsingErrorState,			// Left bracket
				IterativeParsingErrorState,			// Right bracket
				IterativeParsingErrorState,			// Left curly bracket
				IterativeParsingErrorState,			// Right curly bracket
				IterativeParsingErrorState,			// Comma
				IterativeParsingErrorState,			// Colon
				IterativeParsingMemberKeyState,		// String
				IterativeParsingErrorState,			// False
				IterativeParsingErrorState,			// True
				IterativeParsingErrorState,			// Null
				IterativeParsingErrorState			// Number
			},
			// ObjectFinish(sink state)
			{
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState
			},
			// ArrayInitial
			{
				IterativeParsingArrayInitialState,		// Left bracket(push Element state)
				IterativeParsingArrayFinishState,		// Right bracket
				IterativeParsingObjectInitialState,		// Left curly bracket(push Element state)
				IterativeParsingErrorState,				// Right curly bracket
				IterativeParsingErrorState,				// Comma
				IterativeParsingErrorState,				// Colon
				IterativeParsingElementState,			// String
				IterativeParsingElementState,			// False
				IterativeParsingElementState,			// True
				IterativeParsingElementState,			// Null
				IterativeParsingElementState			// Number
			},
			// Element
			{
				IterativeParsingErrorState,				// Left bracket
				IterativeParsingArrayFinishState,		// Right bracket
				IterativeParsingErrorState,				// Left curly bracket
				IterativeParsingErrorState,				// Right curly bracket
				IterativeParsingElementDelimiterState,	// Comma
				IterativeParsingErrorState,				// Colon
				IterativeParsingErrorState,				// String
				IterativeParsingErrorState,				// False
				IterativeParsingErrorState,				// True
				IterativeParsingErrorState,				// Null
				IterativeParsingErrorState				// Number
			},
			// ElementDelimiter
			{
				IterativeParsingArrayInitialState,		// Left bracket(push Element state)
				IterativeParsingErrorState,				// Right bracket
				IterativeParsingObjectInitialState,		// Left curly bracket(push Element state)
				IterativeParsingErrorState,				// Right curly bracket
				IterativeParsingErrorState,				// Comma
				IterativeParsingErrorState,				// Colon
				IterativeParsingElementState,			// String
				IterativeParsingElementState,			// False
				IterativeParsingElementState,			// True
				IterativeParsingElementState,			// Null
				IterativeParsingElementState			// Number
			},
			// ArrayFinish(sink state)
			{
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
				IterativeParsingErrorState
			}
		}; // End of G

		return G[state][token];
	}

	// Make an advance in the token stream and state based on the candidate destination state which was returned by Transit().
	// May return a new state on state pop.
	template <unsigned parseFlags, typename InputStream, typename Handler>
	IterativeParsingState Advance(IterativeParsingState src, IterativeParsingToken token, IterativeParsingState dst, InputStream& is, Handler& handler) {
		int c = 0;
		IterativeParsingState n;

		switch (dst) {
		case IterativeParsingStartState:
			RAPIDJSON_ASSERT(false);
			return IterativeParsingErrorState;

		case IterativeParsingFinishState:
			is.Take();
			return dst;

		case IterativeParsingErrorState:
			return dst;

		case IterativeParsingObjectInitialState:
		case IterativeParsingArrayInitialState:
			is.Take();
			// Push the state(Element or MemeberValue) if we are nested in another array or value of member.
			// In this way we can get the correct state on ObjectFinish or ArrayFinish by frame pop.
			n = src;
			if (src == IterativeParsingArrayInitialState || src == IterativeParsingElementDelimiterState)
				n = IterativeParsingElementState;
			else if (src == IterativeParsingKeyValueDelimiterState)
				n = IterativeParsingMemberValueState;
			// Push current state.
			*stack_.template Push<IterativeParsingState>(1) = n;
			// Initialize and push the member/element count.
			*stack_.template Push<int>(1) = 0;
			// Call handler
			if (dst == IterativeParsingObjectInitialState)
				handler.StartObject();
			else
				handler.StartArray();
			return dst;

		case IterativeParsingMemberKeyState:
			ParseString<parseFlags>(is, handler);
			if (HasParseError())
				return IterativeParsingErrorState;
			else
				return dst;

		case IterativeParsingKeyValueDelimiterState:
			if (token == IterativeParsingColonToken) {
				is.Take();
				return dst;
			}
			else
				return IterativeParsingErrorState;

		case IterativeParsingMemberValueState:
			// Must be non-compound value. Or it would be ObjectInitial or ArrayInitial state.
			ParseValue<parseFlags>(is, handler);
			if (HasParseError()) {
				return IterativeParsingErrorState;
			}
			return dst;

		case IterativeParsingElementState:
			// Must be non-compound value. Or it would be ObjectInitial or ArrayInitial state.
			ParseValue<parseFlags>(is, handler);
			if (HasParseError()) {
				return IterativeParsingErrorState;
			}
			return dst;

		case IterativeParsingMemberDelimiterState:
		case IterativeParsingElementDelimiterState:
			is.Take();
			// Update member/element count.
			*stack_.template Top<int>() = *stack_.template Top<int>() + 1;
			return dst;

		case IterativeParsingObjectFinishState:
			is.Take();
			// Get member count.
			c = *stack_.template Pop<int>(1);
			// If the object is not empty, count the last member.
			if (src == IterativeParsingMemberValueState)
				++c;
			// Restore the state.
			n = *stack_.template Pop<IterativeParsingState>(1);
			// Transit to Finish state if this is the topmost scope.
			if (n == IterativeParsingStartState)
				n = IterativeParsingFinishState;
			// Call handler
			handler.EndObject(c);
			return n;

		case IterativeParsingArrayFinishState:
			is.Take();
			// Get element count.
			c = *stack_.template Pop<int>(1);
			// If the array is not empty, count the last element.
			if (src == IterativeParsingElementState)
				++c;
			// Restore the state.
			n = *stack_.template Pop<IterativeParsingState>(1);
			// Transit to Finish state if this is the topmost scope.
			if (n == IterativeParsingStartState)
				n = IterativeParsingFinishState;
			// Call handler
			handler.EndArray(c);
			return n;

		default:
			RAPIDJSON_ASSERT(false);
			return IterativeParsingErrorState;
		}
	}

	template <unsigned parseFlags, typename InputStream, typename Handler>
	bool IterativeParse(InputStream& is, Handler& handler) {
		IterativeParsingState state = IterativeParsingStartState;

		SkipWhitespace(is);
		while (is.Peek() != '\0') {
			IterativeParsingToken t = GuessToken(is.Peek());
			IterativeParsingState n = Transit(state, t);

			if ((n = Advance<parseFlags>(state, t, n, is, handler)) != IterativeParsingErrorState)
				state = n;
			else
				break;

			SkipWhitespace(is);
		}

		stack_.Clear();
		return state == IterativeParsingFinishState;
	}

	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_;
}; // class GenericReader

//! Reader with UTF8 encoding and default allocator.
typedef GenericReader<UTF8<>, UTF8<> > Reader;

} // namespace rapidjson

#ifdef _MSC_VER
#pragma warning(pop)
#endif

#endif // RAPIDJSON_READER_H_