writer.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_WRITER_H_
#define RAPIDJSON_WRITER_H_

#include "rapidjson.h"
#include "internal/stack.h"
#include "internal/strfunc.h"
#include "internal/dtoa.h"
#include "internal/itoa.h"
#include "stringbuffer.h"
#include <new>      // placement new

#if RAPIDJSON_HAS_STDSTRING
#include <string>
#endif

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

RAPIDJSON_NAMESPACE_BEGIN


template<typename OutputStream, typename SourceEncoding = UTF8<>, typename TargetEncoding = UTF8<>, typename StackAllocator = CrtAllocator>
class Writer {
public:
    typedef typename SourceEncoding::Ch Ch;


    explicit
    Writer(OutputStream& os, StackAllocator* stackAllocator = 0, size_t levelDepth = kDefaultLevelDepth) : 
        os_(&os), level_stack_(stackAllocator, levelDepth * sizeof(Level)), hasRoot_(false) {}

    explicit
    Writer(StackAllocator* allocator = 0, size_t levelDepth = kDefaultLevelDepth) :
        os_(0), level_stack_(allocator, levelDepth * sizeof(Level)), hasRoot_(false) {}


    void Reset(OutputStream& os) {
        os_ = &os;
        hasRoot_ = false;
        level_stack_.Clear();
    }


    bool IsComplete() const {
        return hasRoot_ && level_stack_.Empty();
    }


    bool Null()                 { Prefix(kNullType);   return WriteNull(); }
    bool Bool(bool b)           { Prefix(b ? kTrueType : kFalseType); return WriteBool(b); }
    bool Int(int i)             { Prefix(kNumberType); return WriteInt(i); }
    bool Uint(unsigned u)       { Prefix(kNumberType); return WriteUint(u); }
    bool Int64(int64_t i64)     { Prefix(kNumberType); return WriteInt64(i64); }
    bool Uint64(uint64_t u64)   { Prefix(kNumberType); return WriteUint64(u64); }


    bool Double(double d)       { Prefix(kNumberType); return WriteDouble(d); }

    bool String(const Ch* str, SizeType length, bool copy = false) {
        (void)copy;
        Prefix(kStringType);
        return WriteString(str, length);
    }

#if RAPIDJSON_HAS_STDSTRING
    bool String(const std::basic_string<Ch>& str) {
        return String(str.data(), SizeType(str.size()));
    }
#endif

    bool StartObject() {
        Prefix(kObjectType);
        new (level_stack_.template Push<Level>()) Level(false);
        return WriteStartObject();
    }

    bool Key(const Ch* str, SizeType length, bool copy = false) { return String(str, length, copy); }
  
    bool EndObject(SizeType memberCount = 0) {
        (void)memberCount;
        RAPIDJSON_ASSERT(level_stack_.GetSize() >= sizeof(Level));
        RAPIDJSON_ASSERT(!level_stack_.template Top<Level>()->inArray);
        level_stack_.template Pop<Level>(1);
        bool ret = WriteEndObject();
        if (level_stack_.Empty())   // end of json text
            os_->Flush();
        return ret;
    }

    bool StartArray() {
        Prefix(kArrayType);
        new (level_stack_.template Push<Level>()) Level(true);
        return WriteStartArray();
    }

    bool EndArray(SizeType elementCount = 0) {
        (void)elementCount;
        RAPIDJSON_ASSERT(level_stack_.GetSize() >= sizeof(Level));
        RAPIDJSON_ASSERT(level_stack_.template Top<Level>()->inArray);
        level_stack_.template Pop<Level>(1);
        bool ret = WriteEndArray();
        if (level_stack_.Empty())   // end of json text
            os_->Flush();
        return ret;
    }


    bool String(const Ch* str) { return String(str, internal::StrLen(str)); }
    bool Key(const Ch* str) { return Key(str, internal::StrLen(str)); }


protected:
    struct Level {
        Level(bool inArray_) : valueCount(0), inArray(inArray_) {}
        size_t valueCount;  
        bool inArray;       
    };

    static const size_t kDefaultLevelDepth = 32;

    bool WriteNull()  {
        os_->Put('n'); os_->Put('u'); os_->Put('l'); os_->Put('l'); return true;
    }

    bool WriteBool(bool b)  {
        if (b) {
            os_->Put('t'); os_->Put('r'); os_->Put('u'); os_->Put('e');
        }
        else {
            os_->Put('f'); os_->Put('a'); os_->Put('l'); os_->Put('s'); os_->Put('e');
        }
        return true;
    }

    bool WriteInt(int i) {
        char buffer[11];
        const char* end = internal::i32toa(i, buffer);
        for (const char* p = buffer; p != end; ++p)
            os_->Put(*p);
        return true;
    }

    bool WriteUint(unsigned u) {
        char buffer[10];
        const char* end = internal::u32toa(u, buffer);
        for (const char* p = buffer; p != end; ++p)
            os_->Put(*p);
        return true;
    }

    bool WriteInt64(int64_t i64) {
        char buffer[21];
        const char* end = internal::i64toa(i64, buffer);
        for (const char* p = buffer; p != end; ++p)
            os_->Put(*p);
        return true;
    }

    bool WriteUint64(uint64_t u64) {
        char buffer[20];
        char* end = internal::u64toa(u64, buffer);
        for (char* p = buffer; p != end; ++p)
            os_->Put(*p);
        return true;
    }

    bool WriteDouble(double d) {
        char buffer[25];
        char* end = internal::dtoa(d, buffer);
        for (char* p = buffer; p != end; ++p)
            os_->Put(*p);
        return true;
    }

    bool WriteString(const Ch* str, SizeType length)  {
        static const char hexDigits[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        static const char escape[256] = {
#define Z16 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
            //0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
            'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'b', 't', 'n', 'u', 'f', 'r', 'u', 'u', // 00
            'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', 'u', // 10
              0,   0, '"',   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0, // 20
            Z16, Z16,                                                                       // 30~4F
              0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,'\\',   0,   0,   0, // 50
            Z16, Z16, Z16, Z16, Z16, Z16, Z16, Z16, Z16, Z16                                // 60~FF
#undef Z16
        };

        os_->Put('\"');
        GenericStringStream<SourceEncoding> is(str);
        while (is.Tell() < length) {
            const Ch c = is.Peek();
            if (!TargetEncoding::supportUnicode && (unsigned)c >= 0x80) {
                // Unicode escaping
                unsigned codepoint;
                if (!SourceEncoding::Decode(is, &codepoint))
                    return false;
                os_->Put('\\');
                os_->Put('u');
                if (codepoint <= 0xD7FF || (codepoint >= 0xE000 && codepoint <= 0xFFFF)) {
                    os_->Put(hexDigits[(codepoint >> 12) & 15]);
                    os_->Put(hexDigits[(codepoint >>  8) & 15]);
                    os_->Put(hexDigits[(codepoint >>  4) & 15]);
                    os_->Put(hexDigits[(codepoint      ) & 15]);
                }
                else {
                    RAPIDJSON_ASSERT(codepoint >= 0x010000 && codepoint <= 0x10FFFF);
                    // Surrogate pair
                    unsigned s = codepoint - 0x010000;
                    unsigned lead = (s >> 10) + 0xD800;
                    unsigned trail = (s & 0x3FF) + 0xDC00;
                    os_->Put(hexDigits[(lead >> 12) & 15]);
                    os_->Put(hexDigits[(lead >>  8) & 15]);
                    os_->Put(hexDigits[(lead >>  4) & 15]);
                    os_->Put(hexDigits[(lead      ) & 15]);
                    os_->Put('\\');
                    os_->Put('u');
                    os_->Put(hexDigits[(trail >> 12) & 15]);
                    os_->Put(hexDigits[(trail >>  8) & 15]);
                    os_->Put(hexDigits[(trail >>  4) & 15]);
                    os_->Put(hexDigits[(trail      ) & 15]);                    
                }
            }
            else if ((sizeof(Ch) == 1 || (unsigned)c < 256) && escape[(unsigned char)c])  {
                is.Take();
                os_->Put('\\');
                os_->Put(escape[(unsigned char)c]);
                if (escape[(unsigned char)c] == 'u') {
                    os_->Put('0');
                    os_->Put('0');
                    os_->Put(hexDigits[(unsigned char)c >> 4]);
                    os_->Put(hexDigits[(unsigned char)c & 0xF]);
                }
            }
            else
                if (!Transcoder<SourceEncoding, TargetEncoding>::Transcode(is, *os_))
                    return false;
        }
        os_->Put('\"');
        return true;
    }

    bool WriteStartObject() { os_->Put('{'); return true; }
    bool WriteEndObject()   { os_->Put('}'); return true; }
    bool WriteStartArray()  { os_->Put('['); return true; }
    bool WriteEndArray()    { os_->Put(']'); return true; }

    void Prefix(Type type) {
        (void)type;
        if (level_stack_.GetSize() != 0) { // this value is not at root
            Level* level = level_stack_.template Top<Level>();
            if (level->valueCount > 0) {
                if (level->inArray) 
                    os_->Put(','); // add comma if it is not the first element in array
                else  // in object
                    os_->Put((level->valueCount % 2 == 0) ? ',' : ':');
            }
            if (!level->inArray && level->valueCount % 2 == 0)
                RAPIDJSON_ASSERT(type == kStringType);  // if it's in object, then even number should be a name
            level->valueCount++;
        }
        else {
            RAPIDJSON_ASSERT(!hasRoot_);    // Should only has one and only one root.
            hasRoot_ = true;
        }
    }

    OutputStream* os_;
    internal::Stack<StackAllocator> level_stack_;
    bool hasRoot_;

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

// Full specialization for StringStream to prevent memory copying

template<>
inline bool Writer<StringBuffer>::WriteInt(int i) {
    char *buffer = os_->Push(11);
    const char* end = internal::i32toa(i, buffer);
    os_->Pop(static_cast<size_t>(11 - (end - buffer)));
    return true;
}

template<>
inline bool Writer<StringBuffer>::WriteUint(unsigned u) {
    char *buffer = os_->Push(10);
    const char* end = internal::u32toa(u, buffer);
    os_->Pop(static_cast<size_t>(10 - (end - buffer)));
    return true;
}

template<>
inline bool Writer<StringBuffer>::WriteInt64(int64_t i64) {
    char *buffer = os_->Push(21);
    const char* end = internal::i64toa(i64, buffer);
    os_->Pop(static_cast<size_t>(21 - (end - buffer)));
    return true;
}

template<>
inline bool Writer<StringBuffer>::WriteUint64(uint64_t u) {
    char *buffer = os_->Push(20);
    const char* end = internal::u64toa(u, buffer);
    os_->Pop(static_cast<size_t>(20 - (end - buffer)));
    return true;
}

template<>
inline bool Writer<StringBuffer>::WriteDouble(double d) {
    char *buffer = os_->Push(25);
    char* end = internal::dtoa(d, buffer);
    os_->Pop(static_cast<size_t>(25 - (end - buffer)));
    return true;
}

RAPIDJSON_NAMESPACE_END

#ifdef _MSC_VER
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_RAPIDJSON_H_