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142 lines
6.7 KiB
HTML
Executable File
142 lines
6.7 KiB
HTML
Executable File
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML>
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<HEAD>
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<TITLE>Class Template filter</TITLE>
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<LINK REL='stylesheet' HREF='../../../../boost.css'>
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<LINK REL='stylesheet' HREF='../theme/iostreams.css'>
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</HEAD>
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<BODY>
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<!-- Begin Banner -->
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<H1 CLASS='title'>Class Template <CODE>filter</CODE></H1>
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<HR CLASS='banner'>
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<!-- End Banner -->
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<DL class='page-index'>
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<DT><A href='#description'>Description</A></DT>
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<DT><A href='#headers'>Headers</A></DT>
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<DT><A href='#reference'>Reference</A></DT>
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</DL>
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<HR>
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<A NAME='description'>
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<H2>Description</H2>
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<P>
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The class template <CODE>filter</CODE>, its subcass <CODE>wfilter</CODE> and their specializations <CODE>input_filter</CODE>, <CODE>output_filter</CODE>, <CODE>input_wfilter</CODE> and <CODE>output_wfilter</CODE> are provided by the Iostreams Library to ease the definitions of new models of the various <A HREF='../concepts.html#filter_concepts'>Filter concepts</A>. These templates and <CODE>typedef</CODE>s supply the member types <CODE>io_char</CODE> and <CODE>io_category</CODE> required by the Iostreams Library; they are inteded to be used as base classes for user-defined Filters.
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</P>
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<P>
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The supplied <CODE>io_category</CODE> member is convertible to <A HREF='../traits.html#category_tags'><CODE>closable_tag</CODE></A> and to <A HREF='../traits.html#category_tags'><CODE>localizable_tag</CODE></A>. This allows users to define models of the concepts <A HREF='../concepts/closable.html'>Closable</A> and <A HREF='../concepts/closable.html'>Localizable</A> simply by providing definitions of member functions <CODE>close</CODE> and <CODE>imbue</CODE>.
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</P>
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<A NAME='headers'>
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<H2>Headers</H2>
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<DL class='page-index'>
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<DT><A CLASS='header' HREF='../../../../boost/iostreams/concepts.hpp'><CODE><boost/iostreams/concepts.hpp></CODE></A></DT>
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</DL>
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<A NAME='reference'>
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<H2>Reference</H2>
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<A NAME='synopsis'></A>
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<H3>Synopsis</H3>
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<PRE CLASS='broken_ie'><SPAN CLASS="keyword">namespace</SPAN> boost{ <SPAN CLASS="keyword">namespace</SPAN> iostreams {
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Mode, <SPAN CLASS="keyword">typename</SPAN> Ch = <SPAN CLASS="keyword">char</SPAN>>
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<SPAN CLASS="keyword">struct</SPAN> <A CLASS="documented" HREF="#description">filter</A>;
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Mode, <SPAN CLASS="keyword">typename</SPAN> Ch = <SPAN CLASS="keyword">wchar_t</SPAN>>
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<SPAN CLASS="keyword">struct</SPAN> <SPAN CLASS='defined'>wfilter</SPAN> : filter<Mode, Ch> { };
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<SPAN CLASS="keyword">typedef</SPAN> filter<input> <SPAN CLASS='defined'>input_filter</SPAN></A>;
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<SPAN CLASS="keyword">typedef</SPAN> filter<output> <SPAN CLASS='defined'>output_filter</SPAN>;
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<SPAN CLASS="keyword">typedef</SPAN> wfilter<input> <SPAN CLASS='defined'>input_wfilter</SPAN>;
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<SPAN CLASS="keyword">typedef</SPAN> wfilter<output> <SPAN CLASS='defined'>output_wfilter</SPAN>;
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#template_params">Mode</A>, <SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#template_params">Ch</A> = <SPAN CLASS="keyword">char</SPAN>>
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<SPAN CLASS="keyword">struct</SPAN> <A CLASS="documented" HREF="#description">filter</A> {
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<SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
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<SPAN CLASS="keyword">typedef</SPAN> <A STYLE='text-decoration:none' HREF='#io_category'><SPAN CLASS='omitted'>see below</SPAN></A> io_category;
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Device>
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<SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#close">close</A>(Device&);
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Device>
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<SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#close">close</A>(std::ios_base::openmode, Device&);
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<SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#imbue">imbue</A>(<SPAN CLASS="keyword">const</SPAN> std::locale&);
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};
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} } <SPAN CLASS='comment'>// End namespace boost::io</SPAN></PRE>
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<A NAME='template_params'></A>
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<H4>Template parameters</H4>
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<TABLE STYLE='margin-left:2em' BORDER=0 CELLPADDING=2>
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<TR>
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<TR>
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<TD VALIGN='top'><I>Mode</I></TD><TD WIDTH='2em' VALIGN='top'>-</TD>
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<TD>A <A HREF="../modes.html#mode_tags">mode tag</A>.</TD>
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</TR>
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<TR>
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<TD VALIGN='top'><I>Ch</I></TD><TD WIDTH='2em' VALIGN='top'>-</TD>
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<TD>The character type</TD>
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</TR>
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</TABLE>
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<A NAME='io_category'></A>
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<H4><CODE>filter::io_category</CODE></H4>
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<PRE CLASS='broken_ie'> <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS='omitted'>see below</SPAN> category;</PRE>
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<P>
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A category tag convertible to <A HREF='#template_params'><CODE>Mode</CODE></A>, <A HREF='../traits.html#category_tags'><CODE>filter_tag</CODE></A>, <A HREF='../traits.html#category_tags'><CODE>closable_tag</CODE></A> and <A HREF='../traits.html#category_tags'><CODE>localizable_tag</CODE></A>.
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</P>
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<A NAME='close'></A>
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<H4><CODE>filter::close</CODE></H4>
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<PRE CLASS='broken_ie'> <SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Device>
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<SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#close">close</A>(Device&);
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> Device>
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<SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#close">close</A>(std::ios_base::openmode, Device&);</PRE>
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<P>
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Both overloads are implemented as no-ops. The second is available only if <A HREF='#template_params'>Mode</A> is convertible to <A HREF='../modes.html#mode_tags'><CODE>bidirectional</CODE></A>. The first is available only if Mode is <I>not</I> convertible to <A HREF='../modes.html#mode_tags'><CODE>bidirectional</CODE></A>.
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</P>
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<P>
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Required by <A HREF='../concepts/closable.html'>Closable</A>.
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</P>
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<A NAME='imbue'></A>
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<H4><CODE>filter::imbue</CODE></H4>
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<PRE CLASS='broken_ie'> <SPAN CLASS="keyword">void</SPAN> <A CLASS="documented" HREF="#imbue">imbue</A>(<SPAN CLASS="keyword">const</SPAN> std::locale&);</PRE>
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<P>
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Implemented as a no-op. Required by <A HREF='../concepts/localizable.html'>Localizable</A>.
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</P>
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<!-- Begin Footer -->
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<HR>
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<P CLASS='copyright'>Revised
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<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B, %Y" startspan -->
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20 May, 2004
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<!--webbot bot="Timestamp" endspan i-checksum="38504" -->
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</P>
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<P CLASS='copyright'>© Copyright Jonathan Turkanis, 2004</P>
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<P CLASS='copyright'>
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Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF='http://www.boost.org/LICENSE_1_0.txt'>http://www.boost.org/LICENSE_1_0.txt</A>)
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</P>
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<!-- End Footer -->
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</BODY>
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