assimp.assimp/include/assimp/IOStreamBuffer.h

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

Copyright (c) 2006-2021, 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,
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

----------------------------------------------------------------------
*/

#pragma once
#ifndef AI_IOSTREAMBUFFER_H_INC
#define AI_IOSTREAMBUFFER_H_INC

#ifdef __GNUC__
#   pragma GCC system_header
#endif

#include <assimp/types.h>
#include <assimp/IOStream.hpp>
#include <assimp/ParsingUtils.h>

#include <vector>

namespace Assimp {

// ---------------------------------------------------------------------------
/**
 *  Implementation of a cached stream buffer.
 */
template<class T>
class IOStreamBuffer {
public:
    /// @brief  The class constructor.
    IOStreamBuffer( size_t cache = 4096 * 4096 );

    /// @brief  The class destructor.
    ~IOStreamBuffer();

    /// @brief  Will open the cached access for a given stream.
    /// @param  stream      The stream to cache.
    /// @return true if successful.
    bool open( IOStream *stream );

    /// @brief  Will close the cached access.
    /// @return true if successful.
    bool close();

    /// @brief  Returns the file-size.
    /// @return The file-size.
    size_t size() const;
    
    /// @brief  Returns the cache size.
    /// @return The cache size.
    size_t cacheSize() const;

    /// @brief  Will read the next block.
    /// @return true if successful.
    bool readNextBlock();

    /// @brief  Returns the number of blocks to read.
    /// @return The number of blocks.
    size_t getNumBlocks() const;

    /// @brief  Returns the current block index.
    /// @return The current block index.
    size_t getCurrentBlockIndex() const;

    /// @brief  Returns the current file pos.
    /// @return The current file pos.
    size_t getFilePos() const;

    /// @brief  Will read the next line.
    /// @param  buffer      The buffer for the next line.
    /// @return true if successful.
    bool getNextDataLine( std::vector<T> &buffer, T continuationToken );

    /// @brief  Will read the next line ascii or binary end line char.
    /// @param  buffer      The buffer for the next line.
    /// @return true if successful.
    bool getNextLine(std::vector<T> &buffer);

    /// @brief  Will read the next block.
    /// @param  buffer      The buffer for the next block.
    /// @return true if successful.
    bool getNextBlock( std::vector<T> &buffer );

private:
    IOStream *m_stream;
    size_t m_filesize;
    size_t m_cacheSize;
    size_t m_numBlocks;
    size_t m_blockIdx;
    std::vector<T> m_cache;
    size_t m_cachePos;
    size_t m_filePos;
};

template<class T>
AI_FORCE_INLINE
IOStreamBuffer<T>::IOStreamBuffer( size_t cache )
: m_stream( nullptr )
, m_filesize( 0 )
, m_cacheSize( cache )
, m_numBlocks( 0 )
, m_blockIdx( 0 )
, m_cachePos( 0 )
, m_filePos( 0 ) {
    m_cache.resize( cache );
    std::fill( m_cache.begin(), m_cache.end(), '\n' );
}

template<class T>
AI_FORCE_INLINE
IOStreamBuffer<T>::~IOStreamBuffer() {
    // empty
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::open( IOStream *stream ) {
    //  file still opened!
    if ( nullptr != m_stream ) {
        return false;
    }

    //  Invalid stream pointer
    if ( nullptr == stream ) {
        return false;
    }

    m_stream = stream;
    m_filesize = m_stream->FileSize();
    if ( m_filesize == 0 ) {
        return false;
    }
    if ( m_filesize < m_cacheSize ) {
        m_cacheSize = m_filesize;
    }

    m_numBlocks = m_filesize / m_cacheSize;
    if ( ( m_filesize % m_cacheSize ) > 0 ) {
        m_numBlocks++;
    }

    return true;
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::close() {
    if ( nullptr == m_stream ) {
        return false;
    }

    // init counters and state vars
    m_stream    = nullptr;
    m_filesize  = 0;
    m_numBlocks = 0;
    m_blockIdx  = 0;
    m_cachePos  = 0;
    m_filePos   = 0;

    return true;
}

template<class T>
AI_FORCE_INLINE
size_t IOStreamBuffer<T>::size() const {
    return m_filesize;
}

template<class T>
AI_FORCE_INLINE
size_t IOStreamBuffer<T>::cacheSize() const {
    return m_cacheSize;
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::readNextBlock() {
    m_stream->Seek( m_filePos, aiOrigin_SET );
    size_t readLen = m_stream->Read( &m_cache[ 0 ], sizeof( T ), m_cacheSize );
    if ( readLen == 0 ) {
        return false;
    }
    if ( readLen < m_cacheSize ) {
        m_cacheSize = readLen;
    }
    m_filePos += m_cacheSize;
    m_cachePos = 0;
    m_blockIdx++;

    return true;
}

template<class T>
AI_FORCE_INLINE
size_t IOStreamBuffer<T>::getNumBlocks() const {
    return m_numBlocks;
}

template<class T>
AI_FORCE_INLINE
size_t IOStreamBuffer<T>::getCurrentBlockIndex() const {
    return m_blockIdx;
}

template<class T>
AI_FORCE_INLINE
size_t IOStreamBuffer<T>::getFilePos() const {
    return m_filePos;
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::getNextDataLine( std::vector<T> &buffer, T continuationToken ) {
    buffer.resize( m_cacheSize );
    if ( m_cachePos >= m_cacheSize || 0 == m_filePos ) {
        if ( !readNextBlock() ) {
            return false;
        }
    }

    size_t i = 0;
    for( ;; ) {
        if ( continuationToken == m_cache[ m_cachePos ] && IsLineEnd( m_cache[ m_cachePos + 1 ] ) ) {
            ++m_cachePos;
            while ( m_cache[ m_cachePos ] != '\n' ) {
                ++m_cachePos;
            }
            ++m_cachePos;
        } else if ( IsLineEnd ( m_cache[ m_cachePos ] ) ) {
            break;
        }

        buffer[ i ] = m_cache[ m_cachePos ];
        ++m_cachePos;
        ++i;
        if (m_cachePos >= size()) {
            break;
        }
        if ( m_cachePos >= m_cacheSize ) {
            if ( !readNextBlock() ) {
                return false;
            }
        }
    }
    
    buffer[ i ] = '\n';
    ++m_cachePos;

    return true;
}

static AI_FORCE_INLINE
bool isEndOfCache( size_t pos, size_t cacheSize ) {
    return ( pos == cacheSize );
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::getNextLine(std::vector<T> &buffer) {
    buffer.resize(m_cacheSize);
    if ( isEndOfCache( m_cachePos, m_cacheSize ) || 0 == m_filePos) {
       if (!readNextBlock()) {
          return false;
       }
      }

    if (IsLineEnd(m_cache[m_cachePos])) {
        // skip line end
        while (m_cache[m_cachePos] != '\n') {
            ++m_cachePos;
        }
        ++m_cachePos;
        if ( isEndOfCache( m_cachePos, m_cacheSize ) ) {
            if ( !readNextBlock() ) {
                return false;
            }
        }
    }

    size_t i( 0 );
    while (!IsLineEnd(m_cache[ m_cachePos ])) {
        buffer[i] = m_cache[ m_cachePos ];
        ++m_cachePos;
        ++i;
        if (m_cachePos >= m_cacheSize) {
            if (!readNextBlock()) {
                return false;
            }
        }
    }
    buffer[i] = '\n';
    ++m_cachePos;

    return true;
}

template<class T>
AI_FORCE_INLINE
bool IOStreamBuffer<T>::getNextBlock( std::vector<T> &buffer) {
    // Return the last block-value if getNextLine was used before
    if ( 0 != m_cachePos ) {      
        buffer = std::vector<T>( m_cache.begin() + m_cachePos, m_cache.end() );
        m_cachePos = 0;
    } else {
        if ( !readNextBlock() ) {
            return false;
        }

        buffer = std::vector<T>(m_cache.begin(), m_cache.end());
    }

    return true;
}

} // !ns Assimp

#endif // AI_IOSTREAMBUFFER_H_INC