ceph/src/boost/libs/iostreams/doc/concepts/symmetric_filter.html

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  12     <H1 CLASS="title">SymmetricFilter</H1>
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  16
  17 <H2>Description</H2>
  18
  19 <P>
  20     A SymmetricFilter processes a character sequence fed to it incrementally in a user-supplied buffer and outputs a filtered sequence incrementally to a second user-supplied buffer. It is useful for defining filters based on C language APIs.
  21 </P>
  22
  23 <P>
  24     SymmetricFilter does not refine <A HREF="filter.html">Filter</A>. Instead, the template <A HREF="../classes/symmetric_filter.html"><CODE>symmetric_filter</CODE></A> can used to generate a Filter from a SymmetricFilter. The Filters generated in this manner are <A HREF="dual_use_filter.html">DualUseFilters</A> and are <A HREF="../../../../doc/html/CopyConstructible.html" TARGET="_top">CopyConstructible</A> regardless of whether the SymmetricFilters on which they are based are  <A HREF="../../../../doc/html/CopyConstructible.html">CopyConstructible</A>.
  25 </P>
  26
  27 <P>
  28     The concept SymmetricFilter is notable in that its definition does not involve the concept of a <A HREF="source.html">Source</A> or <A HREF="sink.html">Sink</A>.
  29 </P>
  30
  31 <H2>Associated Types</H2>
  32
  33 <TABLE CELLPADDING="5" BORDER="1">
  34     <TR><TD>Character type</TD><TD>The type of the characters in the filtered sequences</TD></TR>
  35 </TABLE>
  36
  37 <H2>Notation</H2>
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  39 <TABLE CELLPADDING="2">
  40     <TR><TD><CODE>F</CODE></TD><TD>- A type which is a model of SymmetricFilter</TD></TR>
  41     <TR><TD><CODE>Ch</CODE></TD><TD>- The character type of <CODE>F</CODE></TD></TR>
  42     <TR><TD><CODE>f</CODE></TD><TD>- Object of type <CODE>F</CODE></TD></TR>
  43     <TR><TD><CODE>i1, i2</CODE></TD><TD>- Objects of type <CODE>const Ch*</CODE></TD></TR>
  44     <TR><TD><CODE>o1, o2</CODE></TD><TD>- Objects of type <CODE>Ch*</CODE></TD></TR>
  45     <TR><TD><CODE>flush</CODE></TD><TD>- Object of type <CODE>bool</CODE></TD></TR>
  46 </TABLE>
  47
  48 <H2>Valid Expressions / Semantics &#8212; Typenames</H2>
  49
  50 <TABLE CELLPADDING="5" BORDER="1">
  51     <TR><TH>Expression</TH><TH>Expression Type</TH></TR>
  52     <TR>
  53         <TD>
  54             <PRE CLASS="plain_code"><CODE>typename <A HREF="../guide/traits.html#char_type_of_ref">char_type_of</A>&lt;F&gt;::type</CODE></PRE>
  55         </TD>
  56         <TD><CODE>typename</CODE> of the character type</TD>
  57     </TR>
  58 </TABLE>
  59
  60 <H2>Valid Expressions / Semantics &#8212; Member Functions</H2>
  61
  62 <TABLE CELLPADDING="5" BORDER="1">
  63     <TR><TH>Expression</TH><TH>Expression Type</TH><TH>Semantics</TH><TH>Postcondition</TH></TR>
  64     <TR>
  65         <TD><PRE CLASS="plain_code"><CODE>f.filter(i1, i2, o1, o2, flush)</CODE></PRE></TD>
  66         <TD><CODE>bool</CODE></TD>
  67         <TD>
  68             Attempts to filter the sequence <CODE>[i1, i2)</CODE>, storing the result in the sequence <CODE>[o1, o2)</CODE>. If <CODE>flush</CODE> is true, writes as much output to <CODE>[o1, o2)</CODE> as possible. If <CODE>flush</CODE> is <CODE>false</CODE>, returns <CODE>false</CODE> to indicate that a &#8220;natural&#8221; end of stream has been detected. Otherwise, returns <CODE>true</CODE> to indicate that additional characters, not yet stored in <CODE>[o1, o2)</CODE>, are available for output.
  69         </TD>
  70         <TD>
  71                 <P><CODE>i1</CODE> points to the first unconsumed character in the orginal sequence <CODE>[i1, i2)</CODE>.
  72                 <P><CODE>o1</CODE> points to the first unconsumed character in the orginal sequence <CODE>[o1, o2)</CODE>.
  73                 <P>Either <CODE>i1 == i2</CODE> or <CODE>o1 == o2</CODE>.
  74         </TD>
  75     </TR>
  76     <TR>
  77         <TD><PRE CLASS="plain_code"><CODE>f.close()</CODE></PRE></TD>
  78         <TD><CODE>void</CODE></TD>
  79         <TD ALIGN="center">-</TD>
  80         <TD>
  81             <CODE></CODE><CODE>f</CODE> is ready to begin filtering a new sequence
  82         </TD>
  83     </TR>
  84 </TABLE>
  85
  86 <H2>Exceptions</H2>
  87
  88 <P>
  89     Errors which occur during the execution of <CODE>filter</CODE> or <CODE>close</CODE> are indicated by throwing exceptions.
  90 </P>
  91
  92 <H2>Models</H2>
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  98 <P CLASS="copyright">&copy; Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>&copy; Copyright 2004-2007 <a href="http://www.coderage.com/turkanis/" target="_top">Jonathan Turkanis</a></P>
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 100     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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