IOBuffer.cc

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/*
 * IOBuffer.cc
 *
 * Smalltalk like class library for C++
 * Buffer for I/O accessors.
 *
 * Copyright (c) 2003 Milan Cermak
 */
/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include <stlib/IOBuffer.h>

#include <stlib/IOAccessor.h>
#include <stlib/SequenceableCollection.h>
#include <stlib/ByteArray.h>
#include <stlib/String.h>

IOBuffer::IOBuffer(IOAccessor *accessor)
{
    io_accessor = accessor;
    _buffer = new ByteArray(io_accessor->bufferSize());
    buffer_amount = 0;
}

/* Class-accessing protocol */
String *IOBuffer::className(void) const
{
    return new String("IOBuffer");
}

/* Buffer accessing protocol */
ByteArray *IOBuffer::buffer(void)
{
    return _buffer;
}

/* Buffer state protocol */
void IOBuffer::bufferChanged(void)
{
    /* Does nothing */
}

/* Position accessing protocol */
long IOBuffer::currentBufferPosition(void)
{
    return 0;
}

long IOBuffer::firstDataPosition(void)
{
    return 0;
}

long IOBuffer::lastDataPosition(void)
{
    return buffer_amount;
}

long IOBuffer::lastWriteablePosition(void)
{
    return _buffer->size() - 1;
}

/* Positioning protocol */
bool IOBuffer::isSeekable(void)
{
    return io_accessor->isSeekable();
}

ByteArray *IOBuffer::readPositionAndSetOffset(long position, long &offset)
{
    io_accessor->seekTo(position);
    buffer_amount = readBufferStartingAt(1);
    offset = 1;
    return _buffer;
}

/* Reading protocol */
ByteArray *IOBuffer::nextAndSetOffset(long &offset)
{
    long amt, start;

    stepToNextBuffer();
    start = buffer_amount % _buffer->size();
    amt = readBufferStartingAt(start);
    offset = start;
    buffer_amount = start + amt;
    return _buffer;
}

/* Status protocol */
void IOBuffer::commit(void)
{
    io_accessor->commit();
}

/* Writing protocol */
void IOBuffer::flushBufferUpTo(long position)
{
    if (position > 0)
        io_accessor->writeForSureFrom(_buffer, 0, position);
}

/* Private protocol */
long IOBuffer::readBufferStartingAt(long position)
{
    long amt;
    amt = _buffer->size() - position;
    amt = io_accessor->readInto(_buffer, position, amt);
    /* Tady by se mely osetrit chyby cteni. */
    return amt;
}

void IOBuffer::stepToNextBuffer(void)
{
    /* Does nothing */
}

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