ardour/libs/glibmm2/gio/src/inputstream.hg

// -*- Mode: C++; indent-tabs-mode: nil; c-basic-offset: 2 -*-

/* Copyright (C) 2007 The giomm Development Team
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <glibmm/object.h>

#include <giomm/asyncresult.h>
#include <giomm/cancellable.h>

_DEFS(giomm,gio)
_PINCLUDE(glibmm/private/object_p.h)

namespace Gio
{

//TODO: Implement operator << and >> for streams?

/** Base class for implementing streaming input.
 *
 * @ingroup Streams
 *
 * @newin2p16
 */
class InputStream : public Glib::Object
{
  _CLASS_GOBJECT(InputStream, GInputStream, G_INPUT_STREAM, Glib::Object, GObject)

public:
  _WRAP_METHOD(gssize read(void* buffer, gsize count, const Glib::RefPtr<Cancellable>& cancellable),
               g_input_stream_read,
               errthrow)

  /** Tries to read @a count bytes from the stream into the buffer starting at
   *  @a buffer. Will block during this read.
   * 
   * If count is zero returns zero and does nothing. A value of @a count 
   * larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.
   * 
   * On success, the number of bytes read into the buffer is returned.
   * It is not an error if this is not the same as the requested size, as it
   * can happen e.g. near the end of a file. Zero is returned on end of file
   * (or if @a count is zero), but never otherwise.
   * 
   * On error -1 is returned.
   * @param buffer A buffer to read data into (which should be at least count bytes long).
   * @param count The number of bytes that will be read from the stream.
   * @return Number of bytes read, or -1 on error.
   */
  #ifdef GLIBMM_EXCEPTIONS_ENABLED
  gssize read(void* buffer, gsize count);
  #else
  gssize read(void* buffer, gsize count, std::auto_ptr<Glib::Error>& error);
  #endif //GLIBMM_EXCEPTIONS_ENABLED

  //TODO: for glibmm 2.17/18, we should decide whether to provide a read()
  // function as below, which would presumably read until EOL, or one with
  // an additional size parameter, at the same time taking into account
  // what operators >> and << (for OutputStream) will do.
  //TODO: gssize read(std::string& buffer, const Glib::RefPtr<Cancellable>& cancellable);
  //TODO: gssize read(std::string& buffer);

  _WRAP_METHOD(bool read_all(void* buffer, gsize count, gsize& bytes_read, const Glib::RefPtr<Cancellable>& cancellable),
               g_input_stream_read_all,
               errthrow)

  /** Tries to read @a count bytes from the stream into the buffer starting at
   *  @a buffer. Will block during this read.
   * 
   * This function is similar to read(), except it tries to
   * read as many bytes as requested, only stopping on an error or end of stream.
   * 
   * On a successful read of @a count bytes, or if we reached the end of the
   * stream, <tt>true</tt> is returned, and @a bytes_read is set to the number of bytes
   * read into @a buffer .
   * 
   * If there is an error during the operation <tt>false</tt> is returned and a Gio::Error 
   * is thrown to indicate the error status, @a bytes_read is updated to contain
   * the number of bytes read into @a buffer before the error occured.
   * @param buffer A buffer to read data into (which should be at least count bytes long).
   * @param count The number of bytes that will be read from the stream.
   * @param bytes_read Location to store the number of bytes that was read from the stream.
   * @return <tt>true</tt> on success, <tt>false</tt> if there was an error.
   */  
  #ifdef GLIBMM_EXCEPTIONS_ENABLED
  bool read_all(void* buffer, gsize count, gsize& bytes_read);
  #else
  bool read_all(void* buffer, gsize count, gsize& bytes_read, std::auto_ptr<Glib::Error>& error);
  #endif //GLIBMM_EXCEPTIONS_ENABLED

  //TODO: bool read_all(std::string& buffer, gsize count, gsize& bytes_read, const Glib::RefPtr<Cancellable>& cancellable);
  //TODO: bool read_all(std::string& buffer, gsize count, gsize& bytes_read)

  _WRAP_METHOD(gssize skip(gsize count, const Glib::RefPtr<Cancellable>& cancellable),
               g_input_stream_skip,
               errthrow)

  /** Tries to skip @a count bytes from the stream. Will block during the operation.
   * 
   * This is identical to read(), from a behaviour standpoint,
   * but the bytes that are skipped are not returned to the user. Some
   * streams have an implementation that is more efficient than reading the data.
   * 
   * This function is optional for inherited classes, as the default implementation
   * emulates it using read.
   * 
   * @param count The number of bytes that will be skipped from the stream.
   * @return Number of bytes skipped, or -1 on error.
   */
  #ifdef GLIBMM_EXCEPTIONS_ENABLED
  gssize skip(gsize count);
  #else
  gssize skip(gsize count, std::auto_ptr<Glib::Error>& error);
  #endif //GLIBMM_EXCEPTIONS_ENABLED

  _WRAP_METHOD(bool close(const Glib::RefPtr<Cancellable>& cancellable),
               g_input_stream_close,
               errthrow)

  /** Closes the stream, releasing resources related to it.
   * 
   * Once the stream is closed, all other operations will throw a Gio::Error with CLOSED.
   * Closing a stream multiple times will not return an error.
   * 
   * Streams will be automatically closed when the last reference
   * is dropped, but you might want to call this make sure resources
   * are released as early as possible.
   * 
   * Some streams might keep the backing store of the stream (e.g. a file descriptor)
   * open after the stream is closed. See the documentation for the individual
   * stream for details.
   * 
   * On failure the first error that happened will be reported, but the close
   * operation will finish as much as possible. A stream that failed to
   * close will still throw a Gio::Error with CLOSED for all operations. Still, it
   * is important to check and report the error to the user.
   * 
   * @return <tt>true</tt> on success, <tt>false</tt> on failure.
   */
  #ifdef GLIBMM_EXCEPTIONS_ENABLED
  bool close();
  #else
  bool close(std::auto_ptr<Glib::Error>& error);
  #endif //GLIBMM_EXCEPTIONS_ENABLED

  /** Request an asynchronous read of @a count bytes from the stream into the buffer
   * starting at @a buffer. When the operation is finished @a slot will be called. 
   * You can then call read_finish() to get the result of the 
   * operation.
   *
   * During an async request no other sync and async calls are allowed, and will
   * result in Gio::Error with PENDING being thrown. 
   *
   * A value of @a count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.
   *
   * On success, the number of bytes read into the buffer will be passed to the
   * @a slot callback. It is not an error if this is not the same as the requested size, as it
   * can happen e.g. near the end of a file, but generally we try to read
   * as many bytes as requested. Zero is returned on end of file
   * (or if @a count is zero), but never otherwise.
   *
   * Any outstanding i/o request with higher priority (lower numerical value) will
   * be executed before an outstanding request with lower priority. Default
   * priority is PRIORITY_DEFAULT.
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param buffer A buffer to read data into (which should be at least count bytes long).
   * @param count The number of bytes that will be read from the stream.
   * @param slot Callback to call when the request is satisfied.
   * @param cancellable A Cancellable object.
   * @param io_priority The I/O priority of the request. 
   */
  void read_async(void* buffer, gsize count, const SlotAsyncReady& slot, const Glib::RefPtr<Cancellable>& cancellable, int io_priority = Glib::PRIORITY_DEFAULT);

  /** Request an asynchronous read of @a count bytes from the stream into the buffer
   * starting at @a buffer. When the operation is finished @a slot will be called. 
   * You can then call read_finish() to get the result of the 
   * operation.
   *
   * During an async request no other sync and async calls are allowed, and will
   * result in a Gio::Error with PENDING being thrown. 
   *
   * A value of @a count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.
   *
   * On success, the number of bytes read into the buffer will be passed to the
   * @a slot callback. It is not an error if this is not the same as the requested size, as it
   * can happen e.g. near the end of a file, but generally we try to read
   * as many bytes as requested. Zero is returned on end of file
   * (or if @a count is zero), but never otherwise.
   *
   * Any outstanding i/o request with higher priority (lower numerical value) will
   * be executed before an outstanding request with lower priority. Default
   * priority is PRIORITY_DEFAULT.
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param buffer A buffer to read data into (which should be at least count bytes long).
   * @param count The number of bytes that will be read from the stream.
   * @param slot Callback to call when the request is satisfied.
   * @param io_priority The I/O priority of the request. 
   */
  void read_async(void* buffer, gsize count, const SlotAsyncReady& slot, int io_priority = Glib::PRIORITY_DEFAULT);
  _IGNORE(g_input_stream_read_async)

  _WRAP_METHOD(gssize read_finish(const Glib::RefPtr<AsyncResult>& result),
               g_input_stream_read_finish,
               errthrow)

  //TODO: Use std::size_type instead of gsize?

  /** Request an asynchronous skip of @a count bytes from the stream into the buffer
   * starting at @a buffer. When the operation is finished @a slot will be called. 
   * You can then call skip_finish() to get the result of the operation.
   *
   * During an async request no other sync and async calls are allowed, and will
   * result in Gio::Error with PENDING being thrown. 
   *
   * A value of @a count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.
   *
   * On success, the number of bytes skipped will be passed to the
   * callback. It is not an error if this is not the same as the requested size, as it
   * can happen e.g. near the end of a file, but generally we try to skip
   * as many bytes as requested. Zero is returned on end of file
   * (or if @a count is zero), but never otherwise.
   *
   * Any outstanding i/o request with higher priority (lower numerical value) will
   * be executed before an outstanding request with lower priority. Default
   * priority is PRIORITY_DEFAULT.
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param count The number of bytes that will be skipped from the stream.
   * @param slot Callback to call when the request is satisfied.
   * @param cancellable A Cancellable object.
   * @param io_priority The I/O priority of the request. 
   */
  void skip_async(gsize count, const SlotAsyncReady& slot, const Glib::RefPtr<Cancellable>& cancellable, int io_priority = Glib::PRIORITY_DEFAULT);

  /** Request an asynchronous skip of @a count bytes from the stream into the buffer
   * starting at @a buffer. When the operation is finished @a slot will be called. 
   * You can then call skip_finish() to get the result of the operation.
   *
   * During an async request no other sync and async calls are allowed, and will
   * result in Gio::Error with PENDING being thrown. 
   *
   * A value of @a count larger than MAXSSIZE will cause a Gio::Error with INVALID_ARGUMENT to be thrown.
   *
   * On success, the number of bytes skipped will be passed to the
   * callback. It is not an error if this is not the same as the requested size, as it
   * can happen e.g. near the end of a file, but generally we try to skip
   * as many bytes as requested. Zero is returned on end of file
   * (or if @a count is zero), but never otherwise.
   *
   * Any outstanding i/o request with higher priority (lower numerical value) will
   * be executed before an outstanding request with lower priority. Default
   * priority is PRIORITY_DEFAULT.
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param count The number of bytes that will be skipped from the stream.
   * @param slot Callback to call when the request is satisfied.
   * @param io_priority The I/O priority of the request. 
   */
  void skip_async(gsize count, const SlotAsyncReady& slot, int io_priority = Glib::PRIORITY_DEFAULT);
  _IGNORE(g_input_stream_skip_async)

  _WRAP_METHOD(gssize skip_finish(const Glib::RefPtr<AsyncResult>& result),
               g_input_stream_skip_finish,
               errthrow)

  /** Requests an asynchronous closes of the stream, releasing resources related to it.
   * When the operation is finished @a slot will be called. 
   * You can then call close_finish() to get the result of the 
   * operation.
   *
   * For behaviour details see close().
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param slot Callback to call when the request is satisfied.
   * @param cancellable A Cancellable object.
   * @param io_priority The I/O priority of the request. 
   */
  void close_async(const SlotAsyncReady& slot, const Glib::RefPtr<Cancellable>& cancellable, int io_priority = Glib::PRIORITY_DEFAULT);

  /** Requests an asynchronous closes of the stream, releasing resources related to it.
   * When the operation is finished @a slot will be called. 
   * You can then call close_finish() to get the result of the 
   * operation.
   *
   * For behaviour details see close().
   *
   * The asyncronous methods have a default fallback that uses threads to implement
   * asynchronicity, so they are optional for inheriting classes. However, if you
   * override one you must override all.
   *
   * @param slot Callback to call when the request is satisfied.
   * @param io_priority The I/O priority of the request. 
   */
  void close_async(const SlotAsyncReady& slot, int io_priority = Glib::PRIORITY_DEFAULT);
  _IGNORE(g_input_stream_close_async)

  _WRAP_METHOD(gboolean close_finish(const Glib::RefPtr<AsyncResult>& result),
               g_input_stream_close_finish,
               errthrow)

  // These are private inside the module (for implementations)
  _IGNORE(g_input_stream_has_pending, g_input_stream_is_closed, g_input_stream_set_pending, g_input_stream_clear_pending)
};

} // namespace Gio