StreamReader.h

/*
---------------------------------------------------------------------------
Open Asset Import Library (assimp)
---------------------------------------------------------------------------
 
Copyright (c) 2006-2020, assimp team
 
All rights reserved.
 
Redistribution and use of this software in source and binary forms,
with or without modification, are permitted provided that the following
conditions are met:
 
* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.
 
* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
  materials provided with the distribution.
 
* Neither the name of the assimp team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the assimp team.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
 
#pragma once
#ifndef AI_STREAMREADER_H_INCLUDED
#define AI_STREAMREADER_H_INCLUDED
 
#ifdef __GNUC__
#pragma GCC system_header
#endif
 
#include <assimp/ByteSwapper.h>
#include <assimp/Defines.h>
#include <assimp/Exceptional.h>
#include <assimp/IOStream.hpp>
 
#include <memory>
 
namespace Assimp {
 
// --------------------------------------------------------------------------------------------
// --------------------------------------------------------------------------------------------
template <bool SwapEndianess = false, bool RuntimeSwitch = false>
class StreamReader {
public:
    using diff = size_t;
    using pos = size_t;
 
    // ---------------------------------------------------------------------
    StreamReader(std::shared_ptr<IOStream> stream, bool le = false) :
            mStream(stream),
            mBuffer(nullptr),
            mCurrent(nullptr),
            mEnd(nullptr),
            mLimit(nullptr),
            mLe(le) {
        ai_assert(stream);
        InternBegin();
    }
 
    // ---------------------------------------------------------------------
    StreamReader(IOStream *stream, bool le = false) :
            mStream(std::shared_ptr<IOStream>(stream)),
            mBuffer(nullptr),
            mCurrent(nullptr),
            mEnd(nullptr),
            mLimit(nullptr),
            mLe(le) {
        ai_assert(nullptr != stream);
        InternBegin();
    }
 
    // ---------------------------------------------------------------------
    ~StreamReader() {
        delete[] mBuffer;
    }
 
    // deprecated, use overloaded operator>> instead
 
    // ---------------------------------------------------------------------
    float GetF4() {
        return Get<float>();
    }
 
    // ---------------------------------------------------------------------
    double GetF8() {
        return Get<double>();
    }
 
    // ---------------------------------------------------------------------
    int16_t GetI2() {
        return Get<int16_t>();
    }
 
    // ---------------------------------------------------------------------
    int8_t GetI1() {
        return Get<int8_t>();
    }
 
    // ---------------------------------------------------------------------
    int32_t GetI4() {
        return Get<int32_t>();
    }
 
    // ---------------------------------------------------------------------
    int64_t GetI8() {
        return Get<int64_t>();
    }
 
    // ---------------------------------------------------------------------
    uint16_t GetU2() {
        return Get<uint16_t>();
    }
 
    // ---------------------------------------------------------------------
    uint8_t GetU1() {
        return Get<uint8_t>();
    }
 
    // ---------------------------------------------------------------------
    uint32_t GetU4() {
        return Get<uint32_t>();
    }
 
    // ---------------------------------------------------------------------
    uint64_t GetU8() {
        return Get<uint64_t>();
    }
 
    // ---------------------------------------------------------------------
    size_t GetRemainingSize() const {
        return (unsigned int)(mEnd - mCurrent);
    }
 
    // ---------------------------------------------------------------------
    size_t GetRemainingSizeToLimit() const {
        return (unsigned int)(mLimit - mCurrent);
    }
 
    // ---------------------------------------------------------------------
    void IncPtr(intptr_t plus) {
        mCurrent += plus;
        if (mCurrent > mLimit) {
            throw DeadlyImportError("End of file or read limit was reached");
        }
    }
 
    // ---------------------------------------------------------------------
    int8_t *GetPtr() const {
        return mCurrent;
    }
 
    // ---------------------------------------------------------------------
    void SetPtr(int8_t *p) {
        mCurrent = p;
        if (mCurrent > mLimit || mCurrent < mBuffer) {
            throw DeadlyImportError("End of file or read limit was reached");
        }
    }
 
    // ---------------------------------------------------------------------
    void CopyAndAdvance(void *out, size_t bytes) {
        int8_t *ur = GetPtr();
        SetPtr(ur + bytes); // fire exception if eof
 
        ::memcpy(out, ur, bytes);
    }
 
    int GetCurrentPos() const {
        return (unsigned int)(mCurrent - mBuffer);
    }
 
    void SetCurrentPos(size_t pos) {
        SetPtr(mBuffer + pos);
    }
 
    // ---------------------------------------------------------------------
    unsigned int SetReadLimit(unsigned int _limit) {
        unsigned int prev = GetReadLimit();
        if (UINT_MAX == _limit) {
            mLimit = mEnd;
            return prev;
        }
 
        mLimit = mBuffer + _limit;
        if (mLimit > mEnd) {
            throw DeadlyImportError("StreamReader: Invalid read limit");
        }
        return prev;
    }
 
    // ---------------------------------------------------------------------
    unsigned int GetReadLimit() const {
        return (unsigned int)(mLimit - mBuffer);
    }
 
    // ---------------------------------------------------------------------
    void SkipToReadLimit() {
        mCurrent = mLimit;
    }
 
    // ---------------------------------------------------------------------
    template <typename T>
    StreamReader &operator>>(T &f) {
        f = Get<T>();
        return *this;
    }
 
    // ---------------------------------------------------------------------
    template <typename T>
    T Get() {
        if (mCurrent + sizeof(T) > mLimit) {
            throw DeadlyImportError("End of file or stream limit was reached");
        }
 
        T f;
        ::memcpy(&f, mCurrent, sizeof(T));
        Intern::Getter<SwapEndianess, T, RuntimeSwitch>()(&f, mLe);
        mCurrent += sizeof(T);
 
        return f;
    }
 
private:
    // ---------------------------------------------------------------------
    void InternBegin() {
        if (nullptr == mStream) {
            throw DeadlyImportError("StreamReader: Unable to open file");
        }
 
        const size_t filesize = mStream->FileSize() - mStream->Tell();
        if (0 == filesize) {
            throw DeadlyImportError("StreamReader: File is empty or EOF is already reached");
        }
 
        mCurrent = mBuffer = new int8_t[filesize];
        const size_t read = mStream->Read(mCurrent, 1, filesize);
        // (read < s) can only happen if the stream was opened in text mode, in which case FileSize() is not reliable
        ai_assert(read <= filesize);
        mEnd = mLimit = &mBuffer[read - 1] + 1;
    }
 
private:
    std::shared_ptr<IOStream> mStream;
    int8_t *mBuffer;
    int8_t *mCurrent;
    int8_t *mEnd;
    int8_t *mLimit;
    bool mLe;
};
 
// --------------------------------------------------------------------------------------------
// `static` StreamReaders. Their byte order is fixed and they might be a little bit faster.
#ifdef AI_BUILD_BIG_ENDIAN
typedef StreamReader<true> StreamReaderLE;
typedef StreamReader<false> StreamReaderBE;
#else
typedef StreamReader<true> StreamReaderBE;
typedef StreamReader<false> StreamReaderLE;
#endif
 
// `dynamic` StreamReader. The byte order of the input data is specified in the
// c'tor. This involves runtime branching and might be a little bit slower.
typedef StreamReader<true, true> StreamReaderAny;
 
} // end namespace Assimp
 
#endif // !! AI_STREAMREADER_H_INCLUDED