673453e26a
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57408 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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// Name: stream.h
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// Purpose: topic overview
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// Author: wxWidgets team
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// RCS-ID: $Id$
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// Licence: wxWindows license
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/////////////////////////////////////////////////////////////////////////////
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/**
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@page overview_stream Stream classes overview
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Classes:
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@li wxStreamBase
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@li wxStreamBuffer
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@li wxInputStream
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@li wxOutputStream
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@li wxFilterInputStream
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@li wxFilterOutputStream
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@li wxFileInputStream
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@li wxFileOutputStream
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@li wxTextInputStream
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@li wxTextOutputStream
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@li wxDataInputStream
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@li wxDataOutputStream
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@li @ref overview_stream_intro
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@li @ref overview_stream_example
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<hr>
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@section overview_stream_intro Introduction
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wxWidgets provides its own set of stream classes in order to be
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independent of the standard C++ stream class and their different
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implementations.
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Besides, using @c std::iostream on Linux makes impossible to write programs that are
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binary compatible across different Linux distributions.
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Therefore, wxStreams have been added to wxWidgets so that an applications can
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reliably compile and run on all supported platforms without dependence on a
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particular release of libg++.
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wxStream classes are divided in two main groups:
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@li The core: wxStreamBase, wxStreamBuffer, wxInputStream, wxOutputStream,
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wxFilterInputStream, wxFilterOutputStream
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@li The "IO" classes: wxSocketInputStream, wxSocketOutputStream,
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wxFileInputStream, wxFileOutputStream, ...
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@li Classes for reading text or binary data from a particular stream
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such as wxTextInputStream, wxTextOutputStream, wxDataInputStream
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and wxDataOutputStream
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wxStreamBase is the base definition of a stream. It defines, for example, the
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API of OnSysRead(), OnSysWrite(), OnSysSeek() and OnSysTell(). These functions are
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really implemented by the "IO" classes.
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wxInputStream and wxOutputStream classes inherit from wxStreamBase and provide
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specialized methods for input and output.
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wxStreamBuffer is a cache manager for wxStreamBase: it manages a stream buffer
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linked to a stream. One stream can have multiple stream buffers but one stream
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has always one autoinitialized stream buffer.
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wxInputStream is the base class for read-only streams. It implements Read(),
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SeekI() (I for Input), and all read or IO generic related functions.
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wxOutputStream does the same thing for write-only streams.
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wxFilterInputStream and wxFileterOutputStream are the base class definitions for
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stream filtering.
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Stream filtering means a stream which does no syscall but filters data which
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are passed to it and then pass them to another stream.
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For example, wxZLibInputStream is an inline stream decompressor.
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The "IO" classes implements the specific parts of the stream. This could be
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nothing in the case of wxMemoryInputStream and wxMemoryOutputStream which base
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themselves on wxStreamBuffer.
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This could also be a simple link to the true syscall (for example read(...), write(...)).
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@section overview_stream_example Example
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Usage is simple. We can take the example of wxFileInputStream and here is some
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sample code:
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@code
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...
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// The constructor initializes the stream buffer and open the file descriptor
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// associated to the name of the file.
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wxFileInputStream in_stream("the_file_to_be_read");
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// Ok, read some bytes ... nb_datas is expressed in bytes.
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in_stream.Read(data, nb_datas);
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if (in_stream.LastError() != wxSTREAM_NOERROR) {
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// Oh oh, something bad happens.
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// For a complete list, look into the documentation at wxStreamBase.
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}
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// You can also inline all like this.
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if (in_stream.Read(data, nb_datas).LastError() != wxSTREAM_NOERROR) {
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// Do something.
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}
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// You can also get the last number of bytes REALLY put into the buffer.
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size_t really_read = in_stream.LastRead();
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// Ok, moves to the beginning of the stream. SeekI returns the last position
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// in the stream counted from the beginning.
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off_t old_position = in_stream.SeekI(0, wxFromBeginning);
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// What is my current position ?
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off_t position = in_stream.TellI();
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// wxFileInputStream will close the file descriptor on destruction.
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@endcode
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*/
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