filereadstream.h

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// 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_FILEREADSTREAM_H_
#define RAPIDJSON_FILEREADSTREAM_H_

#include "rapidjson.h"
#include <cstdio>

RAPIDJSON_NAMESPACE_BEGIN


class FileReadStream {
public:
    typedef char Ch;    


    FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false) { 
        RAPIDJSON_ASSERT(fp_ != 0);
        RAPIDJSON_ASSERT(bufferSize >= 4);
        Read();
    }

    Ch Peek() const { return *current_; }
    Ch Take() { Ch c = *current_; Read(); return c; }
    size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }

    // Not implemented
    void Put(Ch) { RAPIDJSON_ASSERT(false); }
    void Flush() { RAPIDJSON_ASSERT(false); } 
    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }

    // For encoding detection only.
    const Ch* Peek4() const {
        return (current_ + 4 <= bufferLast_) ? current_ : 0;
    }

private:
    void Read() {
        if (current_ < bufferLast_)
            ++current_;
        else if (!eof_) {
            count_ += readCount_;
            readCount_ = fread(buffer_, 1, bufferSize_, fp_);
            bufferLast_ = buffer_ + readCount_ - 1;
            current_ = buffer_;

            if (readCount_ < bufferSize_) {
                buffer_[readCount_] = '\0';
                ++bufferLast_;
                eof_ = true;
            }
        }
    }

    std::FILE* fp_;
    Ch *buffer_;
    size_t bufferSize_;
    Ch *bufferLast_;
    Ch *current_;
    size_t readCount_;
    size_t count_;  
    bool eof_;
};

RAPIDJSON_NAMESPACE_END

#endif // RAPIDJSON_FILESTREAM_H_