IOStreamBuffer.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.
 
----------------------------------------------------------------------
*/
 
#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 {
 
// ---------------------------------------------------------------------------
template<class T>
class IOStreamBuffer {
public:
    IOStreamBuffer( size_t cache = 4096 * 4096 );
 
    ~IOStreamBuffer();
 
    bool open( IOStream *stream );
 
    bool close();
 
    size_t size() const;
    
    size_t cacheSize() const;
 
    bool readNextBlock();
 
    size_t getNumBlocks() const;
 
    size_t getCurrentBlockIndex() const;
 
    size_t getFilePos() const;
 
    bool getNextDataLine( std::vector<T> &buffer, T continuationToken );
 
    bool getNextLine(std::vector<T> &buffer);
 
    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;
        }
    }
 
    bool continuationFound( false );
    size_t i = 0;
    for( ;; ) {
        if ( continuationToken == m_cache[ m_cachePos ] ) {
            continuationFound = true;
            ++m_cachePos;
        }
        if ( IsLineEnd( m_cache[ m_cachePos ] ) ) {
            if ( !continuationFound ) {
                // the end of the data line
                break;
            } else {
                // skip line end
                while ( m_cache[m_cachePos] != '\n') {
                    ++m_cachePos;
                }
                ++m_cachePos;
                continuationFound = false;
            }
        }
 
        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