path: root/camel/camel-seekable-stream.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/* 
 *
 * Author : 
 *  Bertrand Guiheneuf <bertrand@helixcode.com>
 *
 * Copyright 1999, 2000 Helix Code, Inc. (http://www.helixcode.com)
 *
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */



#include <config.h>
#include "camel-seekable-stream.h"

static CamelStreamClass *parent_class=NULL;


/* Returns the class for a CamelSeekableStream */
#define CSS_CLASS(so) CAMEL_SEEKABLE_STREAM_CLASS (GTK_OBJECT(so)->klass)

static off_t seek      (CamelSeekableStream *stream, 
                  off_t offset, 
                  CamelStreamSeekPolicy policy);
static  off_t  stream_tell (CamelSeekableStream *stream);
static void reset     (CamelStream *stream);
static void set_bounds (CamelSeekableStream *stream, off_t start, off_t end);


static void
camel_seekable_stream_class_init (CamelSeekableStreamClass *camel_seekable_stream_class)
{
    CamelStreamClass *camel_stream_class = CAMEL_STREAM_CLASS (camel_seekable_stream_class);

    parent_class = gtk_type_class (camel_stream_get_type ());
    
    /* seekable stream methods */
    camel_seekable_stream_class->seek = seek;
    camel_seekable_stream_class->tell = stream_tell;
    camel_seekable_stream_class->set_bounds = set_bounds;

    /* camel stream methods overload */
    camel_stream_class->reset = reset;
}

static void
camel_seekable_stream_init (void *o)
{
    CamelSeekableStream *stream = (CamelSeekableStream *)o;

    stream->bound_start = 0;
    stream->bound_end = CAMEL_STREAM_UNBOUND;
}

GtkType
camel_seekable_stream_get_type (void)
{
    static GtkType camel_seekable_stream_type = 0;
    
    if (!camel_seekable_stream_type)    {
        GtkTypeInfo camel_seekable_stream_info =    
        {
            "CamelSeekableStream",
            sizeof (CamelSeekableStream),
            sizeof (CamelSeekableStreamClass),
            (GtkClassInitFunc) camel_seekable_stream_class_init,
            (GtkObjectInitFunc) camel_seekable_stream_init,
                /* reserved_1 */ NULL,
                /* reserved_2 */ NULL,
            (GtkClassInitFunc) NULL,
        };
        
        camel_seekable_stream_type = gtk_type_unique (camel_stream_get_type (), &camel_seekable_stream_info);
    }
    
    return camel_seekable_stream_type;
}

static off_t
seek (CamelSeekableStream *stream, 
       off_t offset, 
       CamelStreamSeekPolicy policy)
{
    g_warning ("CamelSeekableStream::seek called on default implementation \n");
    return -1;
}

/**
 * camel_stream_seek:
 * @stream: a CamelStream object.
 * @offset: offset value
 * @policy: what to do with the offset
 * 
 * Seek to the specified position in @stream.
 *
 * If @policy is CAMEL_STREAM_SET, seeks to @offset.
 *
 * If @policy is CAMEL_STREAM_CUR, seeks to the current position plus
 * @offset.
 *
 * If @policy is CAMEL_STREAM_END, seeks to the end of the stream plus
 * @offset.
 *
 * Regardless of @policy, the stream's final position will be clamped
 * to the range specified by its lower and upper bounds.
 * 
 * Return value: new position, -1 if operation failed.
 **/
off_t
camel_seekable_stream_seek (CamelSeekableStream *stream, 
                off_t offset, 
                CamelStreamSeekPolicy policy)
{
    return CSS_CLASS (stream)->seek (stream, offset, policy);
}

static off_t
stream_tell(CamelSeekableStream *stream)
{
    return stream->position;
}

/**
 * camel_seekable_stream_tell: get the position of a stream
 * @stream: seekable stream object 
 * 
 * Get the current position of a seekable stream.
 * 
 * Return value: the position.
 **/
off_t
camel_seekable_stream_tell (CamelSeekableStream *stream)
{
    return CSS_CLASS (stream)->tell (stream);
}

static void
set_bounds (CamelSeekableStream *stream, off_t start, off_t end)
{
    /* store the bounds */
    stream->bound_start = start;
    stream->bound_end = end;

    /* FIXME: this is probably to be reset by seek ... */
    ((CamelStream *)stream)->eos = FALSE;

    if (start > stream->position)
        camel_seekable_stream_seek(stream, start, CAMEL_STREAM_SET);
}

/**
 * camel_seekable_stream_set_bounds:
 * @stream: 
 * @start: 
 * @end: 
 * 
 * Set the range of valid data this stream is allowed to cover.  If
 * there is to be no @end value, then @end should be set to
 * #CAMEL_STREAM_UNBOUND.
 **/
void
camel_seekable_stream_set_bounds(CamelSeekableStream *stream, off_t start, off_t end)
{
    CSS_CLASS (stream)->set_bounds (stream, start, end);
}

/* a default implementation of reset for seekable streams */
static void 
reset (CamelStream *stream)
{
    CamelSeekableStream *seekable_stream;

    g_assert (stream);
    seekable_stream = CAMEL_SEEKABLE_STREAM (stream);

    camel_seekable_stream_seek (seekable_stream, seekable_stream->bound_start, CAMEL_STREAM_SET);
}