reader.h

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// Tencent is pleased to support the open source community by making RapidJSON available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.

#ifndef RAPIDJSON_READER_H_
#define RAPIDJSON_READER_H_

#include "allocators.h"
#include "stream.h"
#include "encodedstream.h"
#include "internal/meta.h"
#include "internal/stack.h"
#include "internal/strtod.h"
#include <limits>

#if defined(RAPIDJSON_SIMD) && defined(_MSC_VER)
#include <intrin.h>
#pragma intrinsic(_BitScanForward)
#endif
#ifdef RAPIDJSON_SSE42
#include <nmmintrin.h>
#elif defined(RAPIDJSON_SSE2)
#include <emmintrin.h>
#endif

#ifdef _MSC_VER
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(4127)  // conditional expression is constant
RAPIDJSON_DIAG_OFF(4702)  // unreachable code
#endif

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(old-style-cast)
RAPIDJSON_DIAG_OFF(padded)
RAPIDJSON_DIAG_OFF(switch-enum)
#endif

#ifdef __GNUC__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(effc++)
#endif

#define RAPIDJSON_NOTHING /* deliberately empty */
#ifndef RAPIDJSON_PARSE_ERROR_EARLY_RETURN
#define RAPIDJSON_PARSE_ERROR_EARLY_RETURN(value) \
    RAPIDJSON_MULTILINEMACRO_BEGIN \
    if (RAPIDJSON_UNLIKELY(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 */ \
    SetParseError(parseErrorCode, offset); \
    RAPIDJSON_MULTILINEMACRO_END
#endif

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

#include "error/error.h" // ParseErrorCode, ParseResult

RAPIDJSON_NAMESPACE_BEGIN

// ParseFlag

#ifndef RAPIDJSON_PARSE_DEFAULT_FLAGS
#define RAPIDJSON_PARSE_DEFAULT_FLAGS kParseNoFlags
#endif


enum ParseFlag {
    kParseNoFlags = 0,              
    kParseInsituFlag = 1,           
    kParseValidateEncodingFlag = 2, 
    kParseIterativeFlag = 4,        
    kParseStopWhenDoneFlag = 8,     
    kParseFullPrecisionFlag = 16,   
    kParseCommentsFlag = 32,        
    kParseNumbersAsStringsFlag = 64,    
    kParseTrailingCommasFlag = 128, 
    kParseNanAndInfFlag = 256,      
    kParseDefaultFlags = RAPIDJSON_PARSE_DEFAULT_FLAGS  
};

// Handler


// BaseReaderHandler


template<typename Encoding = UTF8<>, typename Derived = void>
struct BaseReaderHandler {
    typedef typename Encoding::Ch Ch;

    typedef typename internal::SelectIf<internal::IsSame<Derived, void>, BaseReaderHandler, Derived>::Type Override;

    bool Default() { return true; }
    bool Null() { return static_cast<Override&>(*this).Default(); }
    bool Bool(bool) { return static_cast<Override&>(*this).Default(); }
    bool Int(int) { return static_cast<Override&>(*this).Default(); }
    bool Uint(unsigned) { return static_cast<Override&>(*this).Default(); }
    bool Int64(int64_t) { return static_cast<Override&>(*this).Default(); }
    bool Uint64(uint64_t) { return static_cast<Override&>(*this).Default(); }
    bool Double(double) { return static_cast<Override&>(*this).Default(); }
    bool RawNumber(const Ch* str, SizeType len, bool copy) { return static_cast<Override&>(*this).String(str, len, copy); }
    bool String(const Ch*, SizeType, bool) { return static_cast<Override&>(*this).Default(); }
    bool StartObject() { return static_cast<Override&>(*this).Default(); }
    bool Key(const Ch* str, SizeType len, bool copy) { return static_cast<Override&>(*this).String(str, len, copy); }
    bool EndObject(SizeType) { return static_cast<Override&>(*this).Default(); }
    bool StartArray() { return static_cast<Override&>(*this).Default(); }
    bool EndArray(SizeType) { return static_cast<Override&>(*this).Default(); }
};

// StreamLocalCopy

namespace internal {

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

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_;
};

template<typename Stream>
class StreamLocalCopy<Stream, 0> {
public:
    StreamLocalCopy(Stream& original) : s(original) {}

    Stream& s;

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

} // namespace internal

// SkipWhitespace


template<typename InputStream>
void SkipWhitespace(InputStream& is) {
    internal::StreamLocalCopy<InputStream> copy(is);
    InputStream& s(copy.s);

    typename InputStream::Ch c;
    while ((c = s.Peek()) == ' ' || c == '\n' || c == '\r' || c == '\t')
        s.Take();
}

inline const char* SkipWhitespace(const char* p, const char* end) {
    while (p != end && (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t'))
        ++p;
    return p;
}

#ifdef RAPIDJSON_SSE42
inline const char *SkipWhitespace_SIMD(const char* p) {
    // Fast return for single non-whitespace
    if (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t')
        ++p;
    else
        return p;

    // 16-byte align to the next boundary
    const char* nextAligned = reinterpret_cast<const char*>((reinterpret_cast<size_t>(p) + 15) & static_cast<size_t>(~15));
    while (p != nextAligned)
        if (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t')
            ++p;
        else
            return p;

    // The rest of string using SIMD
    static const char whitespace[16] = " \n\r\t";
    const __m128i w = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&whitespace[0]));

    for (;; p += 16) {
        const __m128i s = _mm_load_si128(reinterpret_cast<const __m128i *>(p));
        const int r = _mm_cmpistri(w, s, _SIDD_UBYTE_OPS | _SIDD_CMP_EQUAL_ANY | _SIDD_LEAST_SIGNIFICANT | _SIDD_NEGATIVE_POLARITY);
        if (r != 16)    // some of characters is non-whitespace
            return p + r;
    }
}

inline const char *SkipWhitespace_SIMD(const char* p, const char* end) {
    // Fast return for single non-whitespace
    if (p != end && (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t'))
        ++p;
    else
        return p;

    // The middle of string using SIMD
    static const char whitespace[16] = " \n\r\t";
    const __m128i w = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&whitespace[0]));

    for (; p <= end - 16; p += 16) {
        const __m128i s = _mm_loadu_si128(reinterpret_cast<const __m128i *>(p));
        const int r = _mm_cmpistri(w, s, _SIDD_UBYTE_OPS | _SIDD_CMP_EQUAL_ANY | _SIDD_LEAST_SIGNIFICANT | _SIDD_NEGATIVE_POLARITY);
        if (r != 16)    // some of characters is non-whitespace
            return p + r;
    }

    return SkipWhitespace(p, end);
}

#elif defined(RAPIDJSON_SSE2)

inline const char *SkipWhitespace_SIMD(const char* p) {
    // Fast return for single non-whitespace
    if (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t')
        ++p;
    else
        return p;

    // 16-byte align to the next boundary
    const char* nextAligned = reinterpret_cast<const char*>((reinterpret_cast<size_t>(p) + 15) & static_cast<size_t>(~15));
    while (p != nextAligned)
        if (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t')
            ++p;
        else
            return p;

    // The rest of string
    #define C16(c) { c, c, c, c, c, c, c, c, c, c, c, c, c, c, c, c }
    static const char whitespaces[4][16] = { C16(' '), C16('\n'), C16('\r'), C16('\t') };
    #undef C16

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

    for (;; p += 16) {
        const __m128i s = _mm_load_si128(reinterpret_cast<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 = static_cast<unsigned short>(~_mm_movemask_epi8(x));
        if (r != 0) {   // some of characters may be non-whitespace
#ifdef _MSC_VER         // Find the index of first non-whitespace
            unsigned long offset;
            _BitScanForward(&offset, r);
            return p + offset;
#else
            return p + __builtin_ffs(r) - 1;
#endif
        }
    }
}

inline const char *SkipWhitespace_SIMD(const char* p, const char* end) {
    // Fast return for single non-whitespace
    if (p != end && (*p == ' ' || *p == '\n' || *p == '\r' || *p == '\t'))
        ++p;
    else
        return p;

    // The rest of string
    #define C16(c) { c, c, c, c, c, c, c, c, c, c, c, c, c, c, c, c }
    static const char whitespaces[4][16] = { C16(' '), C16('\n'), C16('\r'), C16('\t') };
    #undef C16

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

    for (; p <= end - 16; p += 16) {
        const __m128i s = _mm_loadu_si128(reinterpret_cast<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 = static_cast<unsigned short>(~_mm_movemask_epi8(x));
        if (r != 0) {   // some of characters may be non-whitespace
#ifdef _MSC_VER         // Find the index of first non-whitespace
            unsigned long offset;
            _BitScanForward(&offset, r);
            return p + offset;
#else
            return p + __builtin_ffs(r) - 1;
#endif
        }
    }

    return SkipWhitespace(p, end);
}

#endif // RAPIDJSON_SSE2

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

template<> inline void SkipWhitespace(StringStream& is) {
    is.src_ = SkipWhitespace_SIMD(is.src_);
}

template<> inline void SkipWhitespace(EncodedInputStream<UTF8<>, MemoryStream>& is) {
    is.is_.src_ = SkipWhitespace_SIMD(is.is_.src_, is.is_.end_);
}
#endif // RAPIDJSON_SIMD

// GenericReader


template <typename SourceEncoding, typename TargetEncoding, typename StackAllocator = CrtAllocator>
class GenericReader {
public:
    typedef typename SourceEncoding::Ch Ch; 


    GenericReader(StackAllocator* stackAllocator = 0, size_t stackCapacity = kDefaultStackCapacity) : stack_(stackAllocator, stackCapacity), parseResult_() {}


    template <unsigned parseFlags, typename InputStream, typename Handler>
    ParseResult Parse(InputStream& is, Handler& handler) {
        if (parseFlags & kParseIterativeFlag)
            return IterativeParse<parseFlags>(is, handler);

        parseResult_.Clear();

        ClearStackOnExit scope(*this);

        SkipWhitespaceAndComments<parseFlags>(is);
        RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);

        if (RAPIDJSON_UNLIKELY(is.Peek() == '\0')) {
            RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorDocumentEmpty, is.Tell());
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
        }
        else {
            ParseValue<parseFlags>(is, handler);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);

            if (!(parseFlags & kParseStopWhenDoneFlag)) {
                SkipWhitespaceAndComments<parseFlags>(is);
                RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);

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

        return parseResult_;
    }


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

    bool HasParseError() const { return parseResult_.IsError(); }

    ParseErrorCode GetParseErrorCode() const { return parseResult_.Code(); }

    size_t GetErrorOffset() const { return parseResult_.Offset(); }

protected:
    void SetParseError(ParseErrorCode code, size_t offset) { parseResult_.Set(code, 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_;
        ClearStackOnExit(const ClearStackOnExit&);
        ClearStackOnExit& operator=(const ClearStackOnExit&);
    };

    template<unsigned parseFlags, typename InputStream>
    void SkipWhitespaceAndComments(InputStream& is) {
        SkipWhitespace(is);

        if (parseFlags & kParseCommentsFlag) {
            while (RAPIDJSON_UNLIKELY(Consume(is, '/'))) {
                if (Consume(is, '*')) {
                    while (true) {
                        if (RAPIDJSON_UNLIKELY(is.Peek() == '\0'))
                            RAPIDJSON_PARSE_ERROR(kParseErrorUnspecificSyntaxError, is.Tell());
                        else if (Consume(is, '*')) {
                            if (Consume(is, '/'))
                                break;
                        }
                        else
                            is.Take();
                    }
                }
                else if (RAPIDJSON_LIKELY(Consume(is, '/')))
                    while (is.Peek() != '\0' && is.Take() != '\n') {}
                else
                    RAPIDJSON_PARSE_ERROR(kParseErrorUnspecificSyntaxError, is.Tell());

                SkipWhitespace(is);
            }
        }
    }

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

        if (RAPIDJSON_UNLIKELY(!handler.StartObject()))
            RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());

        SkipWhitespaceAndComments<parseFlags>(is);
        RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

        if (Consume(is, '}')) {
            if (RAPIDJSON_UNLIKELY(!handler.EndObject(0)))  // empty object
                RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
            return;
        }

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

            ParseString<parseFlags>(is, handler, true);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            SkipWhitespaceAndComments<parseFlags>(is);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            if (RAPIDJSON_UNLIKELY(!Consume(is, ':')))
                RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissColon, is.Tell());

            SkipWhitespaceAndComments<parseFlags>(is);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            ParseValue<parseFlags>(is, handler);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            SkipWhitespaceAndComments<parseFlags>(is);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            ++memberCount;

            switch (is.Peek()) {
                case ',':
                    is.Take();
                    SkipWhitespaceAndComments<parseFlags>(is);
                    RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
                    break;
                case '}':
                    is.Take();
                    if (RAPIDJSON_UNLIKELY(!handler.EndObject(memberCount)))
                        RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
                    return;
                default:
                    RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissCommaOrCurlyBracket, is.Tell()); break; // This useless break is only for making warning and coverage happy
            }

            if (parseFlags & kParseTrailingCommasFlag) {
                if (is.Peek() == '}') {
                    if (RAPIDJSON_UNLIKELY(!handler.EndObject(memberCount)))
                        RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
                    is.Take();
                    return;
                }
            }
        }
    }

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

        if (RAPIDJSON_UNLIKELY(!handler.StartArray()))
            RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());

        SkipWhitespaceAndComments<parseFlags>(is);
        RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

        if (Consume(is, ']')) {
            if (RAPIDJSON_UNLIKELY(!handler.EndArray(0))) // empty array
                RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
            return;
        }

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

            ++elementCount;
            SkipWhitespaceAndComments<parseFlags>(is);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;

            if (Consume(is, ',')) {
                SkipWhitespaceAndComments<parseFlags>(is);
                RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
            }
            else if (Consume(is, ']')) {
                if (RAPIDJSON_UNLIKELY(!handler.EndArray(elementCount)))
                    RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
                return;
            }
            else
                RAPIDJSON_PARSE_ERROR(kParseErrorArrayMissCommaOrSquareBracket, is.Tell());

            if (parseFlags & kParseTrailingCommasFlag) {
                if (is.Peek() == ']') {
                    if (RAPIDJSON_UNLIKELY(!handler.EndArray(elementCount)))
                        RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
                    is.Take();
                    return;
                }
            }
        }
    }

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

        if (RAPIDJSON_LIKELY(Consume(is, 'u') && Consume(is, 'l') && Consume(is, 'l'))) {
            if (RAPIDJSON_UNLIKELY(!handler.Null()))
                RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
        }
        else
            RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell());
    }

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

        if (RAPIDJSON_LIKELY(Consume(is, 'r') && Consume(is, 'u') && Consume(is, 'e'))) {
            if (RAPIDJSON_UNLIKELY(!handler.Bool(true)))
                RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
        }
        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 (RAPIDJSON_LIKELY(Consume(is, 'a') && Consume(is, 'l') && Consume(is, 's') && Consume(is, 'e'))) {
            if (RAPIDJSON_UNLIKELY(!handler.Bool(false)))
                RAPIDJSON_PARSE_ERROR(kParseErrorTermination, is.Tell());
        }
        else
            RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell());
    }

    template<typename InputStream>
    RAPIDJSON_FORCEINLINE static bool Consume(InputStream& is, typename InputStream::Ch expect) {
        if (RAPIDJSON_LIKELY(is.Peek() == expect)) {
            is.Take();
            return true;
        }
        else
            return false;
    }

    // Helper function to parse four hexidecimal digits in \uXXXX in ParseString().
    template<typename InputStream>
    unsigned ParseHex4(InputStream& is, size_t escapeOffset) {
        unsigned codepoint = 0;
        for (int i = 0; i < 4; i++) {
            Ch c = is.Peek();
            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, escapeOffset);
                RAPIDJSON_PARSE_ERROR_EARLY_RETURN(0);
            }
            is.Take();
        }
        return codepoint;
    }

    template <typename CharType>
    class StackStream {
    public:
        typedef CharType Ch;

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

        RAPIDJSON_FORCEINLINE void* Push(SizeType count) {
            length_ += count;
            return stack_.template Push<Ch>(count);
        }

        size_t Length() const { return length_; }

        Ch* Pop() {
            return stack_.template Pop<Ch>(length_);
        }

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

        internal::Stack<StackAllocator>& stack_;
        SizeType length_;
    };

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

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

        bool success = false;
        if (parseFlags & kParseInsituFlag) {
            typename InputStream::Ch *head = s.PutBegin();
            ParseStringToStream<parseFlags, SourceEncoding, SourceEncoding>(s, s);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
            size_t length = s.PutEnd(head) - 1;
            RAPIDJSON_ASSERT(length <= 0xFFFFFFFF);
            const typename TargetEncoding::Ch* const str = reinterpret_cast<typename TargetEncoding::Ch*>(head);
            success = (isKey ? handler.Key(str, SizeType(length), false) : handler.String(str, SizeType(length), false));
        }
        else {
            StackStream<typename TargetEncoding::Ch> stackStream(stack_);
            ParseStringToStream<parseFlags, SourceEncoding, TargetEncoding>(s, stackStream);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN_VOID;
            SizeType length = static_cast<SizeType>(stackStream.Length()) - 1;
            const typename TargetEncoding::Ch* const str = stackStream.Pop();
            success = (isKey ? handler.Key(str, length, true) : handler.String(str, length, true));
        }
        if (RAPIDJSON_UNLIKELY(!success))
            RAPIDJSON_PARSE_ERROR(kParseErrorTermination, s.Tell());
    }

    // 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

        for (;;) {
            // Scan and copy string before "\\\"" or < 0x20. This is an optional optimzation.
            if (!(parseFlags & kParseValidateEncodingFlag))
                ScanCopyUnescapedString(is, os);

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

    template<typename InputStream, typename OutputStream>
    static RAPIDJSON_FORCEINLINE void ScanCopyUnescapedString(InputStream&, OutputStream&) {
            // Do nothing for generic version
    }

#if defined(RAPIDJSON_SSE2) || defined(RAPIDJSON_SSE42)
    // StringStream -> StackStream<char>
    static RAPIDJSON_FORCEINLINE void ScanCopyUnescapedString(StringStream& is, StackStream<char>& os) {
        const char* p = is.src_;

        // Scan one by one until alignment (unaligned load may cross page boundary and cause crash)
        const char* nextAligned = reinterpret_cast<const char*>((reinterpret_cast<size_t>(p) + 15) & static_cast<size_t>(~15));
        while (p != nextAligned)
            if (RAPIDJSON_UNLIKELY(*p == '\"') || RAPIDJSON_UNLIKELY(*p == '\\') || RAPIDJSON_UNLIKELY(static_cast<unsigned>(*p) < 0x20)) {
                is.src_ = p;
                return;
            }
            else
                os.Put(*p++);

        // The rest of string using SIMD
        static const char dquote[16] = { '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"' };
        static const char bslash[16] = { '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\' };
        static const char space[16]  = { 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19 };
        const __m128i dq = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&dquote[0]));
        const __m128i bs = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&bslash[0]));
        const __m128i sp = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&space[0]));

        for (;; p += 16) {
            const __m128i s = _mm_load_si128(reinterpret_cast<const __m128i *>(p));
            const __m128i t1 = _mm_cmpeq_epi8(s, dq);
            const __m128i t2 = _mm_cmpeq_epi8(s, bs);
            const __m128i t3 = _mm_cmpeq_epi8(_mm_max_epu8(s, sp), sp); // s < 0x20 <=> max(s, 0x19) == 0x19
            const __m128i x = _mm_or_si128(_mm_or_si128(t1, t2), t3);
            unsigned short r = static_cast<unsigned short>(_mm_movemask_epi8(x));
            if (RAPIDJSON_UNLIKELY(r != 0)) {   // some of characters is escaped
                SizeType length;
    #ifdef _MSC_VER         // Find the index of first escaped
                unsigned long offset;
                _BitScanForward(&offset, r);
                length = offset;
    #else
                length = static_cast<SizeType>(__builtin_ffs(r) - 1);
    #endif
                char* q = reinterpret_cast<char*>(os.Push(length));
                for (size_t i = 0; i < length; i++)
                    q[i] = p[i];

                p += length;
                break;
            }
            _mm_storeu_si128(reinterpret_cast<__m128i *>(os.Push(16)), s);
        }

        is.src_ = p;
    }

    // InsituStringStream -> InsituStringStream
    static RAPIDJSON_FORCEINLINE void ScanCopyUnescapedString(InsituStringStream& is, InsituStringStream& os) {
        RAPIDJSON_ASSERT(&is == &os);
        (void)os;

        if (is.src_ == is.dst_) {
            SkipUnescapedString(is);
            return;
        }

        char* p = is.src_;
        char *q = is.dst_;

        // Scan one by one until alignment (unaligned load may cross page boundary and cause crash)
        const char* nextAligned = reinterpret_cast<const char*>((reinterpret_cast<size_t>(p) + 15) & static_cast<size_t>(~15));
        while (p != nextAligned)
            if (RAPIDJSON_UNLIKELY(*p == '\"') || RAPIDJSON_UNLIKELY(*p == '\\') || RAPIDJSON_UNLIKELY(static_cast<unsigned>(*p) < 0x20)) {
                is.src_ = p;
                is.dst_ = q;
                return;
            }
            else
                *q++ = *p++;

        // The rest of string using SIMD
        static const char dquote[16] = { '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"' };
        static const char bslash[16] = { '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\' };
        static const char space[16] = { 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19 };
        const __m128i dq = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&dquote[0]));
        const __m128i bs = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&bslash[0]));
        const __m128i sp = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&space[0]));

        for (;; p += 16, q += 16) {
            const __m128i s = _mm_load_si128(reinterpret_cast<const __m128i *>(p));
            const __m128i t1 = _mm_cmpeq_epi8(s, dq);
            const __m128i t2 = _mm_cmpeq_epi8(s, bs);
            const __m128i t3 = _mm_cmpeq_epi8(_mm_max_epu8(s, sp), sp); // s < 0x20 <=> max(s, 0x19) == 0x19
            const __m128i x = _mm_or_si128(_mm_or_si128(t1, t2), t3);
            unsigned short r = static_cast<unsigned short>(_mm_movemask_epi8(x));
            if (RAPIDJSON_UNLIKELY(r != 0)) {   // some of characters is escaped
                size_t length;
#ifdef _MSC_VER         // Find the index of first escaped
                unsigned long offset;
                _BitScanForward(&offset, r);
                length = offset;
#else
                length = static_cast<size_t>(__builtin_ffs(r) - 1);
#endif
                for (const char* pend = p + length; p != pend; )
                    *q++ = *p++;
                break;
            }
            _mm_storeu_si128(reinterpret_cast<__m128i *>(q), s);
        }

        is.src_ = p;
        is.dst_ = q;
    }

    // When read/write pointers are the same for insitu stream, just skip unescaped characters
    static RAPIDJSON_FORCEINLINE void SkipUnescapedString(InsituStringStream& is) {
        RAPIDJSON_ASSERT(is.src_ == is.dst_);
        char* p = is.src_;

        // Scan one by one until alignment (unaligned load may cross page boundary and cause crash)
        const char* nextAligned = reinterpret_cast<const char*>((reinterpret_cast<size_t>(p) + 15) & static_cast<size_t>(~15));
        for (; p != nextAligned; p++)
            if (RAPIDJSON_UNLIKELY(*p == '\"') || RAPIDJSON_UNLIKELY(*p == '\\') || RAPIDJSON_UNLIKELY(static_cast<unsigned>(*p) < 0x20)) {
                is.src_ = is.dst_ = p;
                return;
            }

        // The rest of string using SIMD
        static const char dquote[16] = { '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"', '\"' };
        static const char bslash[16] = { '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\', '\\' };
        static const char space[16] = { 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19, 0x19 };
        const __m128i dq = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&dquote[0]));
        const __m128i bs = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&bslash[0]));
        const __m128i sp = _mm_loadu_si128(reinterpret_cast<const __m128i *>(&space[0]));

        for (;; p += 16) {
            const __m128i s = _mm_load_si128(reinterpret_cast<const __m128i *>(p));
            const __m128i t1 = _mm_cmpeq_epi8(s, dq);
            const __m128i t2 = _mm_cmpeq_epi8(s, bs);
            const __m128i t3 = _mm_cmpeq_epi8(_mm_max_epu8(s, sp), sp); // s < 0x20 <=> max(s, 0x19) == 0x19
            const __m128i x = _mm_or_si128(_mm_or_si128(t1, t2), t3);
            unsigned short r = static_cast<unsigned short>(_mm_movemask_epi8(x));
            if (RAPIDJSON_UNLIKELY(r != 0)) {   // some of characters is escaped
                size_t length;
#ifdef _MSC_VER         // Find the index of first escaped
                unsigned long offset;
                _BitScanForward(&offset, r);
                length = offset;
#else
                length = static_cast<size_t>(__builtin_ffs(r) - 1);
#endif
                p += length;
                break;
            }
        }

        is.src_ = is.dst_ = p;
    }
#endif

    template<typename InputStream, bool backup, bool pushOnTake>
    class NumberStream;

    template<typename InputStream>
    class NumberStream<InputStream, false, false> {
    public:
        typedef typename InputStream::Ch Ch;

        NumberStream(GenericReader& reader, InputStream& s) : is(s) { (void)reader;  }

        RAPIDJSON_FORCEINLINE Ch Peek() const { return is.Peek(); }
        RAPIDJSON_FORCEINLINE Ch TakePush() { return is.Take(); }
        RAPIDJSON_FORCEINLINE Ch Take() { return is.Take(); }
          RAPIDJSON_FORCEINLINE void Push(char) {}

        size_t Tell() { return is.Tell(); }
        size_t Length() { return 0; }
        const char* Pop() { return 0; }

    protected:
        NumberStream& operator=(const NumberStream&);

        InputStream& is;
    };

    template<typename InputStream>
    class NumberStream<InputStream, true, false> : public NumberStream<InputStream, false, false> {
        typedef NumberStream<InputStream, false, false> Base;
    public:
        NumberStream(GenericReader& reader, InputStream& is) : Base(reader, is), stackStream(reader.stack_) {}

        RAPIDJSON_FORCEINLINE Ch TakePush() {
            stackStream.Put(static_cast<char>(Base::is.Peek()));
            return Base::is.Take();
        }

        RAPIDJSON_FORCEINLINE void Push(char c) {
            stackStream.Put(c);
        }

        size_t Length() { return stackStream.Length(); }

        const char* Pop() {
            stackStream.Put('\0');
            return stackStream.Pop();
        }

    private:
        StackStream<char> stackStream;
    };

    template<typename InputStream>
    class NumberStream<InputStream, true, true> : public NumberStream<InputStream, true, false> {
        typedef NumberStream<InputStream, true, false> Base;
    public:
        NumberStream(GenericReader& reader, InputStream& is) : Base(reader, is) {}

        RAPIDJSON_FORCEINLINE Ch Take() { return Base::TakePush(); }
    };

    template<unsigned parseFlags, typename InputStream, typename Handler>
    void ParseNumber(InputStream& is, Handler& handler) {
        internal::StreamLocalCopy<InputStream> copy(is);
        NumberStream<InputStream,
            ((parseFlags & kParseNumbersAsStringsFlag) != 0) ?
                ((parseFlags & kParseInsituFlag) == 0) :
                ((parseFlags & kParseFullPrecisionFlag) != 0),
            (parseFlags & kParseNumbersAsStringsFlag) != 0 &&
                (parseFlags & kParseInsituFlag) == 0> s(*this, copy.s);

        size_t startOffset = s.Tell();
        double d = 0.0;
        bool useNanOrInf = false;

        // Parse minus
        bool minus = Consume(s, '-');

        // Parse int: zero / ( digit1-9 *DIGIT )
        unsigned i = 0;
        uint64_t i64 = 0;
        bool use64bit = false;
        int significandDigit = 0;
        if (RAPIDJSON_UNLIKELY(s.Peek() == '0')) {
            i = 0;
            s.TakePush();
        }
        else if (RAPIDJSON_LIKELY(s.Peek() >= '1' && s.Peek() <= '9')) {
            i = static_cast<unsigned>(s.TakePush() - '0');

            if (minus)
                while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                    if (RAPIDJSON_UNLIKELY(i >= 214748364)) { // 2^31 = 2147483648
                        if (RAPIDJSON_LIKELY(i != 214748364 || s.Peek() > '8')) {
                            i64 = i;
                            use64bit = true;
                            break;
                        }
                    }
                    i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
                    significandDigit++;
                }
            else
                while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                    if (RAPIDJSON_UNLIKELY(i >= 429496729)) { // 2^32 - 1 = 4294967295
                        if (RAPIDJSON_LIKELY(i != 429496729 || s.Peek() > '5')) {
                            i64 = i;
                            use64bit = true;
                            break;
                        }
                    }
                    i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
                    significandDigit++;
                }
        }
        // Parse NaN or Infinity here
        else if ((parseFlags & kParseNanAndInfFlag) && RAPIDJSON_LIKELY((s.Peek() == 'I' || s.Peek() == 'N'))) {
            useNanOrInf = true;
            if (RAPIDJSON_LIKELY(Consume(s, 'N') && Consume(s, 'a') && Consume(s, 'N'))) {
                d = std::numeric_limits<double>::quiet_NaN();
            }
            else if (RAPIDJSON_LIKELY(Consume(s, 'I') && Consume(s, 'n') && Consume(s, 'f'))) {
                d = (minus ? -std::numeric_limits<double>::infinity() : std::numeric_limits<double>::infinity());
                if (RAPIDJSON_UNLIKELY(s.Peek() == 'i' && !(Consume(s, 'i') && Consume(s, 'n')
                                                            && Consume(s, 'i') && Consume(s, 't') && Consume(s, 'y'))))
                    RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
            }
            else
                RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
        }
        else
            RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());

        // Parse 64bit int
        bool useDouble = false;
        if (use64bit) {
            if (minus)
                while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                     if (RAPIDJSON_UNLIKELY(i64 >= RAPIDJSON_UINT64_C2(0x0CCCCCCC, 0xCCCCCCCC))) // 2^63 = 9223372036854775808
                        if (RAPIDJSON_LIKELY(i64 != RAPIDJSON_UINT64_C2(0x0CCCCCCC, 0xCCCCCCCC) || s.Peek() > '8')) {
                            d = static_cast<double>(i64);
                            useDouble = true;
                            break;
                        }
                    i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
                    significandDigit++;
                }
            else
                while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                    if (RAPIDJSON_UNLIKELY(i64 >= RAPIDJSON_UINT64_C2(0x19999999, 0x99999999))) // 2^64 - 1 = 18446744073709551615
                        if (RAPIDJSON_LIKELY(i64 != RAPIDJSON_UINT64_C2(0x19999999, 0x99999999) || s.Peek() > '5')) {
                            d = static_cast<double>(i64);
                            useDouble = true;
                            break;
                        }
                    i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
                    significandDigit++;
                }
        }

        // Force double for big integer
        if (useDouble) {
            while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                if (RAPIDJSON_UNLIKELY(d >= 1.7976931348623157e307)) // DBL_MAX / 10.0
                    RAPIDJSON_PARSE_ERROR(kParseErrorNumberTooBig, startOffset);
                d = d * 10 + (s.TakePush() - '0');
            }
        }

        // Parse frac = decimal-point 1*DIGIT
        int expFrac = 0;
        size_t decimalPosition;
        if (Consume(s, '.')) {
            decimalPosition = s.Length();

            if (RAPIDJSON_UNLIKELY(!(s.Peek() >= '0' && s.Peek() <= '9')))
                RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());

            if (!useDouble) {
#if RAPIDJSON_64BIT
                // Use i64 to store significand in 64-bit architecture
                if (!use64bit)
                    i64 = i;

                while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                    if (i64 > RAPIDJSON_UINT64_C2(0x1FFFFF, 0xFFFFFFFF)) // 2^53 - 1 for fast path
                        break;
                    else {
                        i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
                        --expFrac;
                        if (i64 != 0)
                            significandDigit++;
                    }
                }

                d = static_cast<double>(i64);
#else
                // Use double to store significand in 32-bit architecture
                d = static_cast<double>(use64bit ? i64 : i);
#endif
                useDouble = true;
            }

            while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                if (significandDigit < 17) {
                    d = d * 10.0 + (s.TakePush() - '0');
                    --expFrac;
                    if (RAPIDJSON_LIKELY(d > 0.0))
                        significandDigit++;
                }
                else
                    s.TakePush();
            }
        }
        else
            decimalPosition = s.Length(); // decimal position at the end of integer.

        // Parse exp = e [ minus / plus ] 1*DIGIT
        int exp = 0;
        if (Consume(s, 'e') || Consume(s, 'E')) {
            if (!useDouble) {
                d = static_cast<double>(use64bit ? i64 : i);
                useDouble = true;
            }

            bool expMinus = false;
            if (Consume(s, '+'))
                ;
            else if (Consume(s, '-'))
                expMinus = true;

            if (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                exp = static_cast<int>(s.Take() - '0');
                if (expMinus) {
                    while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                        exp = exp * 10 + static_cast<int>(s.Take() - '0');
                        if (exp >= 214748364) {                         // Issue #313: prevent overflow exponent
                            while (RAPIDJSON_UNLIKELY(s.Peek() >= '0' && s.Peek() <= '9'))  // Consume the rest of exponent
                                s.Take();
                        }
                    }
                }
                else {  // positive exp
                    int maxExp = 308 - expFrac;
                    while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
                        exp = exp * 10 + static_cast<int>(s.Take() - '0');
                        if (RAPIDJSON_UNLIKELY(exp > maxExp))
                            RAPIDJSON_PARSE_ERROR(kParseErrorNumberTooBig, startOffset);
                    }
                }
            }
            else
                RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissExponent, s.Tell());

            if (expMinus)
                exp = -exp;
        }

        // Finish parsing, call event according to the type of number.
        bool cont = true;

        if (parseFlags & kParseNumbersAsStringsFlag) {
            if (parseFlags & kParseInsituFlag) {
                s.Pop();  // Pop stack no matter if it will be used or not.
                typename InputStream::Ch* head = is.PutBegin();
                const size_t length = s.Tell() - startOffset;
                RAPIDJSON_ASSERT(length <= 0xFFFFFFFF);
                // unable to insert the \0 character here, it will erase the comma after this number
                const typename TargetEncoding::Ch* const str = reinterpret_cast<typename TargetEncoding::Ch*>(head);
                cont = handler.RawNumber(str, SizeType(length), false);
            }
            else {
                SizeType numCharsToCopy = static_cast<SizeType>(s.Length());
                StringStream srcStream(s.Pop());
                StackStream<typename TargetEncoding::Ch> dstStream(stack_);
                while (numCharsToCopy--) {
                    Transcoder<UTF8<>, TargetEncoding>::Transcode(srcStream, dstStream);
                }
                dstStream.Put('\0');
                const typename TargetEncoding::Ch* str = dstStream.Pop();
                const SizeType length = static_cast<SizeType>(dstStream.Length()) - 1;
                cont = handler.RawNumber(str, SizeType(length), true);
            }
        }
        else {
           size_t length = s.Length();
           const char* decimal = s.Pop();  // Pop stack no matter if it will be used or not.

           if (useDouble) {
               int p = exp + expFrac;
               if (parseFlags & kParseFullPrecisionFlag)
                   d = internal::StrtodFullPrecision(d, p, decimal, length, decimalPosition, exp);
               else
                   d = internal::StrtodNormalPrecision(d, p);

               cont = handler.Double(minus ? -d : d);
           }
           else if (useNanOrInf) {
               cont = handler.Double(d);
           }
           else {
               if (use64bit) {
                   if (minus)
                       cont = handler.Int64(static_cast<int64_t>(~i64 + 1));
                   else
                       cont = handler.Uint64(i64);
               }
               else {
                   if (minus)
                       cont = handler.Int(static_cast<int32_t>(~i + 1));
                   else
                       cont = handler.Uint(i);
               }
           }
        }
        if (RAPIDJSON_UNLIKELY(!cont))
            RAPIDJSON_PARSE_ERROR(kParseErrorTermination, startOffset);
    }

    // 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);
                      break;

        }
    }

    // Iterative Parsing

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

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

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

        // Single value state
        IterativeParsingValueState
    };

    enum { cIterativeParsingStateCount = IterativeParsingValueState + 1 };

    // Tokens
    enum Token {
        LeftBracketToken = 0,
        RightBracketToken,

        LeftCurlyBracketToken,
        RightCurlyBracketToken,

        CommaToken,
        ColonToken,

        StringToken,
        FalseToken,
        TrueToken,
        NullToken,
        NumberToken,

        kTokenCount
    };

    RAPIDJSON_FORCEINLINE Token Tokenize(Ch c) {

#define N NumberToken
#define N16 N,N,N,N,N,N,N,N,N,N,N,N,N,N,N,N
        // Maps from ASCII to Token
        static const unsigned char tokenMap[256] = {
            N16, // 00~0F
            N16, // 10~1F
            N, N, StringToken, N, N, N, N, N, N, N, N, N, CommaToken, N, N, N, // 20~2F
            N, N, N, N, N, N, N, N, N, N, ColonToken, N, N, N, N, N, // 30~3F
            N16, // 40~4F
            N, N, N, N, N, N, N, N, N, N, N, LeftBracketToken, N, RightBracketToken, N, N, // 50~5F
            N, N, N, N, N, N, FalseToken, N, N, N, N, N, N, N, NullToken, N, // 60~6F
            N, N, N, N, TrueToken, N, N, N, N, N, N, LeftCurlyBracketToken, N, RightCurlyBracketToken, N, N, // 70~7F
            N16, N16, N16, N16, N16, N16, N16, N16 // 80~FF
        };
#undef N
#undef N16

        if (sizeof(Ch) == 1 || static_cast<unsigned>(c) < 256)
            return static_cast<Token>(tokenMap[static_cast<unsigned char>(c)]);
        else
            return NumberToken;
    }

    RAPIDJSON_FORCEINLINE IterativeParsingState Predict(IterativeParsingState state, Token token) {
        // current state x one lookahead token -> new state
        static const char G[cIterativeParsingStateCount][kTokenCount] = {
            // Start
            {
                IterativeParsingArrayInitialState,  // Left bracket
                IterativeParsingErrorState,         // Right bracket
                IterativeParsingObjectInitialState, // Left curly bracket
                IterativeParsingErrorState,         // Right curly bracket
                IterativeParsingErrorState,         // Comma
                IterativeParsingErrorState,         // Colon
                IterativeParsingValueState,         // String
                IterativeParsingValueState,         // False
                IterativeParsingValueState,         // True
                IterativeParsingValueState,         // Null
                IterativeParsingValueState          // 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
                IterativeParsingObjectFinishState,  // 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)
                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
            },
            // ArrayFinish(sink state)
            {
                IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
                IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
                IterativeParsingErrorState
            },
            // Single Value (sink state)
            {
                IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
                IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState, IterativeParsingErrorState,
                IterativeParsingErrorState
            }
        }; // End of G

        return static_cast<IterativeParsingState>(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>
    RAPIDJSON_FORCEINLINE IterativeParsingState Transit(IterativeParsingState src, Token token, IterativeParsingState dst, InputStream& is, Handler& handler) {
        (void)token;

        switch (dst) {
        case IterativeParsingErrorState:
            return dst;

        case IterativeParsingObjectInitialState:
        case IterativeParsingArrayInitialState:
        {
            // 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.
            IterativeParsingState n = src;
            if (src == IterativeParsingArrayInitialState || src == IterativeParsingElementDelimiterState)
                n = IterativeParsingElementState;
            else if (src == IterativeParsingKeyValueDelimiterState)
                n = IterativeParsingMemberValueState;
            // Push current state.
            *stack_.template Push<SizeType>(1) = n;
            // Initialize and push the member/element count.
            *stack_.template Push<SizeType>(1) = 0;
            // Call handler
            bool hr = (dst == IterativeParsingObjectInitialState) ? handler.StartObject() : handler.StartArray();
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return dst;
            }
        }

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

        case IterativeParsingKeyValueDelimiterState:
            RAPIDJSON_ASSERT(token == ColonToken);
            is.Take();
            return dst;

        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<SizeType>() = *stack_.template Top<SizeType>() + 1;
            return dst;

        case IterativeParsingObjectFinishState:
        {
            // Transit from delimiter is only allowed when trailing commas are enabled
            if (!(parseFlags & kParseTrailingCommasFlag) && src == IterativeParsingMemberDelimiterState) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorObjectMissName, is.Tell());
                return IterativeParsingErrorState;
            }
            // Get member count.
            SizeType c = *stack_.template Pop<SizeType>(1);
            // If the object is not empty, count the last member.
            if (src == IterativeParsingMemberValueState)
                ++c;
            // Restore the state.
            IterativeParsingState n = static_cast<IterativeParsingState>(*stack_.template Pop<SizeType>(1));
            // Transit to Finish state if this is the topmost scope.
            if (n == IterativeParsingStartState)
                n = IterativeParsingFinishState;
            // Call handler
            bool hr = handler.EndObject(c);
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return n;
            }
        }

        case IterativeParsingArrayFinishState:
        {
            // Transit from delimiter is only allowed when trailing commas are enabled
            if (!(parseFlags & kParseTrailingCommasFlag) && src == IterativeParsingElementDelimiterState) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorValueInvalid, is.Tell());
                return IterativeParsingErrorState;
            }
            // Get element count.
            SizeType c = *stack_.template Pop<SizeType>(1);
            // If the array is not empty, count the last element.
            if (src == IterativeParsingElementState)
                ++c;
            // Restore the state.
            IterativeParsingState n = static_cast<IterativeParsingState>(*stack_.template Pop<SizeType>(1));
            // Transit to Finish state if this is the topmost scope.
            if (n == IterativeParsingStartState)
                n = IterativeParsingFinishState;
            // Call handler
            bool hr = handler.EndArray(c);
            // On handler short circuits the parsing.
            if (!hr) {
                RAPIDJSON_PARSE_ERROR_NORETURN(kParseErrorTermination, is.Tell());
                return IterativeParsingErrorState;
            }
            else {
                is.Take();
                return n;
            }
        }

        default:
            // This branch is for IterativeParsingValueState actually.
            // Use `default:` rather than
            // `case IterativeParsingValueState:` is for code coverage.

            // The IterativeParsingStartState is not enumerated in this switch-case.
            // It is impossible for that case. And it can be caught by following assertion.

            // The IterativeParsingFinishState is not enumerated in this switch-case either.
            // It is a "derivative" state which cannot triggered from Predict() directly.
            // Therefore it cannot happen here. And it can be caught by following assertion.
            RAPIDJSON_ASSERT(dst == IterativeParsingValueState);

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

    template <typename InputStream>
    void HandleError(IterativeParsingState src, InputStream& is) {
        if (HasParseError()) {
            // Error flag has been set.
            return;
        }

        switch (src) {
        case IterativeParsingStartState:            RAPIDJSON_PARSE_ERROR(kParseErrorDocumentEmpty, is.Tell()); return;
        case IterativeParsingFinishState:           RAPIDJSON_PARSE_ERROR(kParseErrorDocumentRootNotSingular, is.Tell()); return;
        case IterativeParsingObjectInitialState:
        case IterativeParsingMemberDelimiterState:  RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissName, is.Tell()); return;
        case IterativeParsingMemberKeyState:        RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissColon, is.Tell()); return;
        case IterativeParsingMemberValueState:      RAPIDJSON_PARSE_ERROR(kParseErrorObjectMissCommaOrCurlyBracket, is.Tell()); return;
        case IterativeParsingKeyValueDelimiterState:
        case IterativeParsingArrayInitialState:
        case IterativeParsingElementDelimiterState: RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, is.Tell()); return;
        default: RAPIDJSON_ASSERT(src == IterativeParsingElementState); RAPIDJSON_PARSE_ERROR(kParseErrorArrayMissCommaOrSquareBracket, is.Tell()); return;
        }
    }

    template <unsigned parseFlags, typename InputStream, typename Handler>
    ParseResult IterativeParse(InputStream& is, Handler& handler) {
        parseResult_.Clear();
        ClearStackOnExit scope(*this);
        IterativeParsingState state = IterativeParsingStartState;

        SkipWhitespaceAndComments<parseFlags>(is);
        RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
        while (is.Peek() != '\0') {
            Token t = Tokenize(is.Peek());
            IterativeParsingState n = Predict(state, t);
            IterativeParsingState d = Transit<parseFlags>(state, t, n, is, handler);

            if (d == IterativeParsingErrorState) {
                HandleError(state, is);
                break;
            }

            state = d;

            // Do not further consume streams if a root JSON has been parsed.
            if ((parseFlags & kParseStopWhenDoneFlag) && state == IterativeParsingFinishState)
                break;

            SkipWhitespaceAndComments<parseFlags>(is);
            RAPIDJSON_PARSE_ERROR_EARLY_RETURN(parseResult_);
        }

        // Handle the end of file.
        if (state != IterativeParsingFinishState)
            HandleError(state, is);

        return parseResult_;
    }

    static const size_t kDefaultStackCapacity = 256;    
    internal::Stack<StackAllocator> stack_;  
    ParseResult parseResult_;
}; // class GenericReader

typedef GenericReader<UTF8<>, UTF8<> > Reader;

RAPIDJSON_NAMESPACE_END

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif


#ifdef __GNUC__
RAPIDJSON_DIAG_POP
#endif

#ifdef _MSC_VER
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_READER_H_