PositionableStream.cc

Go to the documentation of this file.

/*
 * PositionableStream.cc
 *
 * Smalltalk like class library for C++
 * Abstract stream with positioning feature.
 *
 * 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/PositionableStream.h>
#include <stlib/Character.h>
#include <stlib/SequenceableCollection.h>
#include <stlib/String.h>
#include <stlib/WriteStream.h>

#include <stlib/IncompleteNextCountError.h>

/* Initialize/release protocol */
void PositionableStream::initialize(SequenceableCollection *coll)
{
    collection = coll;
    read_limit = write_limit = coll->size();
    _position = 0;
}

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

/* Accessing protocol */
SequenceableCollection *PositionableStream::contents(void)
{
    return dynamic_cast<SequenceableCollection *>(collection->copy(0, read_limit - 1));
}

SequenceableCollection *PositionableStream::next(long items,
                                                 SequenceableCollection *newColl,
                                                 long startIndex)
{
    if (items < 1) return newColl;
    if (atEnd())
        (new IncompleteNextCountError(__PRETTY_FUNCTION__, 0))->raiseFrom(this);

    /* Use next for the first read to make sure that the receiver is readable. */
    newColl->put(startIndex, next());

    long howManyRead = 1;
    while (howManyRead < items) {
        long increment, newHowManyRead;
        if (atEnd())
            (new IncompleteNextCountError(__PRETTY_FUNCTION__, howManyRead))->raiseFrom(this);
        long m1 = read_limit - _position;
        long m2 = items - howManyRead;
        increment = (m1 < m2) ? m1 : m2;
        newHowManyRead = howManyRead + increment;
        newColl->replace(startIndex + howManyRead, startIndex + newHowManyRead,
                         collection, _position);
        _position += increment;
        howManyRead = newHowManyRead;
    }
    return newColl;
}

bool PositionableStream::peekFor(Object *object)
{
    if (atEnd()) return false;
    Object *element = next();
    if (element->isEqual(object)) return true;
    skip(-1);
    return false;
}

/* Positioning protocol */
long PositionableStream::position(void)
{
    return _position;
}

void PositionableStream::position(long pos)
{
    read_limit = (read_limit < _position) ? _position : read_limit;
    // PositionableStream::position(pos);
    if (pos >= 0 && pos <= read_limit)
        _position = pos;
    else
        positionOutOfBoundsError(new String(__PRETTY_FUNCTION__), pos);
}

void PositionableStream::reset(void)
{
    read_limit = (read_limit < _position) ? _position : read_limit;
    _position = 0;
}

void PositionableStream::skip(long length)
{
    position(_position + length);
}

/* Testing protocol */
bool PositionableStream::atEnd(void)
{
    return basicAtEnd();
}

bool PositionableStream::isEmpty(void)
{
    return _position == 0;
}

bool PositionableStream::notEmpty(void)
{
    return _position > 0;
}

bool PositionableStream::isBinary(void)
{
    return collection->isByteArray();
}

/* Private protocol */
bool PositionableStream::basicAtEnd(void)
{
    return _position >= read_limit;
}

SequenceableCollection *PositionableStream::contentSpeciesFor(long items)
{
    return (SequenceableCollection *) collection->copyEmpty(items);
}

---