writer.h

// Copyright (C) 2011 Milo Yip
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#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

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

namespace rapidjson {

//! JSON writer
/*! Writer implements the concept Handler.
    It generates JSON text by events to an output os.

    User may programmatically calls the functions of a writer to generate JSON text.

    On the other side, a writer can also be passed to objects that generates events, 

    for example Reader::Parse() and Document::Accept().

    \tparam OutputStream Type of output stream.
    \tparam SourceEncoding Encoding of source string.
    \tparam TargetEncoding Encoding of output stream.
    \tparam Allocator Type of allocator for allocating memory of stack.
    \note implements Handler concept
*/
template<typename OutputStream, typename SourceEncoding = UTF8<>, typename TargetEncoding = UTF8<>, typename Allocator = MemoryPoolAllocator<> >
class Writer {
public:
    typedef typename SourceEncoding::Ch Ch;

    //! Constructor
    /*! \param os Output stream.
        \param allocator User supplied allocator. If it is null, it will create a private one.
        \param levelDepth Initial capacity of stack.
    */
    Writer(OutputStream& os, Allocator* allocator = 0, size_t levelDepth = kDefaultLevelDepth) : 
        os_(&os), level_stack_(allocator, levelDepth * sizeof(Level)), hasRoot_(false) {}

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

    //! Reset the writer with a new stream.
    /*!
        This function reset the writer with a new stream and default settings,
        in order to make a Writer object reusable for output multiple JSONs.

        \param os New output stream.
        \code
        Writer<OutputStream> writer(os1);
        writer.StartObject();
        // ...
        writer.EndObject();

        writer.Reset(os2);
        writer.StartObject();
        // ...
        writer.EndObject();
        \endcode
    */
    void Reset(OutputStream& os) {
        os_ = &os;
        hasRoot_ = false;
        level_stack_.Clear();
    }

    //! Checks whether the output is a complete JSON.
    /*!
        A complete JSON has a complete root object or array.
    */
    bool IsComplete() const {
        return hasRoot_ && level_stack_.Empty();
    }

    /*!@name Implementation of Handler
        \see Handler
    */
    //@{

    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); }

    //! Writes the given \c double value to the stream
    /*!
        \param d The value to be written.
        \return Whether it is succeed.
    */
    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);
    }

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

    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;
    }
    //@}

    /*! @name Convenience extensions */
    //@{

    //! Simpler but slower overload.
    bool String(const Ch* str) { return String(str, internal::StrLen(str)); }

    //@}

protected:
    //! Information for each nested level
    struct Level {
        Level(bool inArray_) : valueCount(0), inArray(inArray_) {}
        size_t valueCount;  //!< number of values in this level
        bool inArray;       //!< true if in array, otherwise in object
    };

    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 if (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
                    return false;   // invalid code point
            }
            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
                Transcoder<SourceEncoding, TargetEncoding>::Transcode(is, *os_);
        }
        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<Allocator> 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(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(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(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(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(25 - (end - buffer));
    return true;
}

} // namespace rapidjson

#ifdef _MSC_VER
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_RAPIDJSON_H_