ceph/src/boost/libs/iostreams/doc/functions/compose.html

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  12     <H1 CLASS="title">Function Template <CODE>compose</CODE></H1>
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  17 <DL class="page-index">
  18   <DT><A href="#description">Description</A></DT>
  19   <DT><A href="#headers">Headers</A></DT>
  20   <DT><A href="#reference">Reference</A></DT>
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  25 <A NAME="description"></A>
  26 <H2>Description</H2>
  27
  28 <P>
  29     Given a Filter <CODE>f</CODE> and a Device <CODE>d</CODE>, we may construct a device <CODE>c</CODE> whose member functions are implemented by invoking the fundamental i/o operations <A HREF='../functions/read.html'><CODE>read</CODE></A>, <A HREF='../functions/write.html'><CODE>write</CODE></A>, <I>etc.</I> with <CODE>f</CODE> as the first argument and <CODE>d</CODE> as the second. Similarly, if we are given two filters <CODE>f1</CODE> and <CODE>f2</CODE>, we may construct a third filter <CODE>f3</CODE> whose member function templates are implemented by invoking the fundamental i/o operations <A HREF='../functions/read.html'><CODE>read</CODE></A>, <A HREF='../functions/write.html'><CODE>write</CODE></A>, <I>etc.</I>, with first argument equal to <CODE>f1</CODE> and second argument equal to the result of composing <CODE>f2</CODE> with the provided Device.
  30 </P>
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  32 <P>
  33     The function template <A HREF='#composite'><CODE>composite</CODE></A> represents a Filter or Device which has been constructed in the above manner. The function template <A HREF='#compose'><CODE>compose</CODE></A> is an <A HREF='http://www.boost.org/more/generic_programming.html#object_generator' TARGET='_top'>object generator</A> which given a pair of components returns an appropriate instance of <CODE>composite</CODE>.
  34 </P>
  35
  36 <P>
  37     The <A HREF='../guide/modes.html'>mode</A> of a <CODE>composite</CODE> is defined to provide a maximal subset of the common functionality of the two components. A <CODE>composite</CODE> is <A HREF='../concepts/closable.html'>Closable</A>, <A HREF='../concepts/flushable.html'>Flushable</A>, <A HREF='../concepts/localizable.html'>Localizable</A> and <A HREF='../concepts/optimally_buffered.html'>OptimallyBuffered</A>.
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  40 <A NAME="headers"></A>
  41 <H2>Headers</H2>
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  43 <DL class="page-index">
  44   <DT><A CLASS="header" HREF="../../../../boost/iostreams/compose.hpp"><CODE>&lt;boost/iostreams/compose.hpp&gt;</CODE></A></DT>
  45 </DL>
  46
  47 <A NAME="reference"></A>
  48 <H2>Reference</H2>
  49
  50 <A NAME="synopsis"></A>
  51 <H4>Synopsis</H4>
  52
  53 <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
  54
  55 <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#composite_template_params">Filter</A>, <SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#composite_template_params">FilterOrDevice</A>&gt;
  56 <SPAN CLASS='keyword'>class</SPAN> <A CLASS='documented' HREF='#composite'>composite</A> {
  57 <SPAN CLASS='keyword'>public:</SPAN>
  58     <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='keyword'>typename</SPAN> <A CLASS='documented' HREF='../guide/traits.html#char_type'>char_type_of</A>&lt;Filter&gt;::type  char_type;
  59     <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>implementation-defined</SPAN>               mode;
  60
  61     <A CLASS='documented' HREF='#composite_ctor'>composite</A>(<SPAN CLASS='keyword'>const</SPAN> Filter&amp; first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice&amp; second);
  62
  63     <SPAN CLASS='comment'>// Filter or Device member functions</SPAN>
  64 };
  65
  66 <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#compose_template_params">Filter</A>, <SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#compose_template_params">FilterOrDevice</A>&gt;
  67 <A CLASS='documented' HREF='#composite'>composite</A>&lt;Filter, FilterOrDevice&gt;
  68 <A CLASS='documented' HREF='#compose'>compose</A>(<SPAN CLASS='keyword'>const</SPAN> Filter&amp; first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice&amp; second);
  69
  70 } } // End namespace boost::io</PRE>
  71
  72 <A NAME="composite"></A>
  73 <H2>Class Template <CODE>composite</CODE></H2>
  74
  75 <A NAME="composite_template_params"></A>
  76 <H4>Template parameters</H4>
  77
  78 <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2>
  79 <TR>
  80     <TR>
  81         <TD VALIGN="top"><I>Filter</I></TD><TD WIDTH="2em" VALIGN="top">-</TD>
  82         <TD>A model of <A HREF='../concepts/filter.html'>Filter</A></TD>
  83     </TR>
  84     <TR>
  85         <TD VALIGN="top"><I>FilterOrDevice</I></TD><TD WIDTH="2em" VALIGN="top">-</TD>
  86         <TD>A model of <A HREF='../concepts/filter.html'>Filter</A> or <A HREF='../concepts/device.html'>Device</A></TD>
  87     </TR>
  88 </TABLE>
  89
  90 <A NAME="composite_ctor"></A>
  91 <H4><CODE>composite::composite</CODE></H4>
  92
  93 <PRE CLASS="broken_ie">    composite(<SPAN CLASS='keyword'>const</SPAN> Filter&amp; first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice&amp; second);</PRE>
  94
  95 <P>
  96     Constructs an instance of <CODE>composite</CODE> based on the given components. If <CODE>FilterOrDevice</CODE> is a stream or stream buffer type, the second parameter is a non-<CODE>const</CODE> reference; otherwise it is a <CODE>const</CODE> reference.
  97 </P>
  98
  99 <A NAME="compose"></A>
 100 <H2>Function Template <CODE>compose</CODE></H2>
 101
 102 <PRE CLASS="broken_ie">    composite(<SPAN CLASS='keyword'>const</SPAN> Filter&amp; first, [<SPAN CLASS='keyword'>const</SPAN>] FilterOrDevice&amp; second);</PRE>
 103
 104 <A NAME="compose_template_params"></A>
 105 <H4>Template parameters</H4>
 106
 107 <TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2>
 108 <TR>
 109     <TR>
 110         <TD VALIGN="top"><I>Filter</I></TD><TD WIDTH="2em" VALIGN="top">-</TD>
 111         <TD>A model of <A HREF='../concepts/filter.html'>Filter</A></TD>
 112     </TR>
 113     <TR>
 114         <TD VALIGN="top"><I>FilterOrDevice</I></TD><TD WIDTH="2em" VALIGN="top">-</TD>
 115         <TD>A model of <A HREF='../concepts/filter.html'>Filter</A> or <A HREF='../concepts/device.html'>Device</A></TD>
 116     </TR>
 117 </TABLE>
 118
 119 <P>
 120     Returns an instance of an appropriate specialization of <CODE>composite</CODE> constructed from the given components. If <CODE>FilterOrDevice</CODE> is a stream or stream buffer type, the second parameter is a non-<CODE>const</CODE> reference; otherwise it is a <CODE>const</CODE> reference.
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