ExternalReadStream.cc

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/*
 * ExternalReadStream.cc
 *
 * Smalltalk like class library for C++
 * External read stream.
 *
 * 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/ExternalReadStream.h>
#include <stlib/Character.h>
#include <stlib/IOBuffer.h>
#include <stlib/LineEndConvention.h>
#include <stlib/SequenceableCollection.h>
#include <stlib/String.h>

ExternalReadStream::ExternalReadStream(IOAccessor *accessor)
  : ExternalStream(accessor)
{
    /* Does nothing */
}

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

/* Accessing protocol */
void ExternalReadStream::flush(void)
{
    /* Does nothing */
}

Object *ExternalReadStream::next(void)
{
    Object *ch;

    if (_position >= read_limit) {
        ch = pastEnd();
        if (ch == nil) return nil;
    } else {
        ch = collection->at(_position++);
    }
    return ch;
}

void ExternalReadStream::nextPut(Object *object)
{
    shouldNotImplement(new String(__PRETTY_FUNCTION__));
}

/* Positioning protocol */
void ExternalReadStream::skip(long n)
{
    long pos;

    pos = _position + n;
    if (pos >= 0 && pos <= read_limit)
        _position = pos;
    else {
        if (io_buffer->isSeekable())
            setPosition(readPosition() + n);
        else {
            if (n > 0) next(n);
            else {
                /* Cannot move back on unseekable stream.
                   May raise an exception here.
                 */
            }
        }
    }
}

/* Testing protocol */
bool ExternalReadStream::isReadable(void)
{
    return true;
}

bool ExternalReadStream::isWritable(void)
{
    return false;
}

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