libs/iostreams/doc/classes/file.html

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   4     <TITLE>File Wrappers</TITLE>
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  12     <H1 CLASS="title">File Wrappers</H1>
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  16
  17 <DL class="page-index">
  18   <DT><A href="#overview">Overview</A></DT>
  19   <DT><A href="#headers">Headers</A></DT>
  20   <DT><A href="#reference">Reference</A>
  21     <UL>
  22       <LI CLASS="square"><A href="#file_source">Class template <CODE>basic_file_source</CODE></A></LI>
  23       <LI CLASS="square"><A href="#file_sink">Class template <CODE>basic_file_sink</CODE></A></LI>
  24       <LI CLASS="square"><A href="#file">Class template <CODE>basic_file</CODE></A></LI>
  25     </UL>
  26   </DT>
  27 </DL>
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  30
  31 <A NAME="overview"></A>
  32 <H2>Overview</H2>
  33
  34 <P>
  35     The class templates <CODE>basic_file_source</CODE>, <CODE>basic_file_sink</CODE> and <CODE>basic_file</CODE> are wrappers for <CODE>std::basic_filebuf</CODE> which are <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html"  TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A>. They are useful whenever one wants to access a file without managing the lifetime of a standard file stream or stream buffer. This is because when a stream or stream buffer is added to a <A HREF="filtering_streambuf.html"><CODE>filtering_streambuf</CODE></A> or <A HREF="filtering_stream.html"><CODE>filtering_stream</CODE></A> it is stored as a reference which must remain valid until that stream or stream buffer is removed from the chain.
  36 </P>
  37 <P>
  38     The most common specializations are accessible via the typedefs <CODE>file_source</CODE>, <CODE>file_sink</CODE>, <CODE>file</CODE>, <CODE>wfile_source</CODE>, <CODE>wfile_sink</CODE> and <CODE>wfile</CODE>.
  39 </P>
  40
  41 <A NAME="headers"></A>
  42 <H2>Headers</H2>
  43
  44 <DL class="page-index">
  45   <DT><A CLASS="header" HREF="../../../../boost/iostreams/device/file.hpp"><CODE>&lt;boost/iostreams/device/file.hpp&gt;</CODE></A></DT>
  46 </DL>
  47
  48 <A NAME="reference"></A>
  49 <H2>Reference</H2>
  50
  51 <A NAME="file_source"></A>
  52 <H3>Class template <CODE>basic_file_source</CODE></H3>
  53
  54 <H4>Description</H4>
  55
  56 <P>
  57     <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-only mode.
  58 <P>
  59
  60 <A NAME="file_source_synopsis"></A>
  61 <H4>Synopsis</H4>
  62
  63 <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
  64
  65 <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">Ch</A>&gt;
  66 <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">basic_file_source</A> {
  67 <SPAN CLASS="keyword">public</SPAN>:
  68     <SPAN CLASS="keyword">typedef</SPAN> Ch                      char_type;
  69     <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN>  category;
  70     <A CLASS="documented" HREF="#basic_file_source_constructor">basic_file_source</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  71                        std::ios_base::openmode mode =
  72                            std::ios_base::in );
  73     <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_source_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
  74     <SPAN CLASS="omitted">...</SPAN>
  75 };
  76
  77 <SPAN CLASS="keyword">typedef</SPAN> basic_file_source&lt;<SPAN CLASS="keyword">char</SPAN>&gt;     <SPAN CLASS="defined">file_source</SPAN>;
  78 <SPAN CLASS="keyword">typedef</SPAN> basic_file_source&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt;  <SPAN CLASS="defined">wfile_source</SPAN>;
  79
  80 } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
  81
  82 <A NAME="basic_file_source_params"></A>
  83 <H4>Template parameters</H4>
  84
  85 <TABLE STYLE="margin-left:2em">
  86 <TR>
  87     <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
  88     <TD>The character type.</TD></TR>
  89 <TR>
  90 </TABLE>
  91
  92 <A NAME="basic_file_source_constructor"></A>
  93 <H4><CODE>basic_file_source::basic_file_source</CODE></H4>
  94
  95 <PRE CLASS="broken_ie">    basic_file_source( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  96                        std::ios_base::openmode mode );</PRE>
  97
  98 <P>
  99     Constructs a <CODE>basic_file_source</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
 100     <PRE CLASS="broken_ie">    mode |= std::ios_base::in;
 101     mode &amp;= ~std::ios_base::out;
 102     buf.open(path.c_str(), mode);</PRE>
 103 </P>
 104
 105 <A NAME="basic_file_source_is_open"></A>
 106 <H4><CODE>basic_file_source::is_open</CODE></H4>
 107
 108 <PRE CLASS="broken_ie">    <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
 109
 110 <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
 111
 112 <A NAME="file_sink"></A>
 113 <H3>Class template <CODE>basic_file_sink</CODE></H3>
 114
 115 <H4>Description</H4>
 116
 117 <P>
 118     <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in write-only mode.
 119 <P>
 120
 121 <A NAME="file_sink_synopsis"></A>
 122 <H4>Synopsis</H4>
 123
 124 <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
 125
 126 <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">Ch</A>&gt;
 127 <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">basic_file_sink</A> {
 128 <SPAN CLASS="keyword">public</SPAN>:
 129     <SPAN CLASS="keyword">typedef</SPAN> Ch                      char_type;
 130     <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN>  category;
 131     <A CLASS="documented" HREF="#basic_file_sink_constructor">basic_file_sink</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
 132                      std::ios_base::openmode mode =
 133                          std::ios_base::out );
 134     <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_sink_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
 135     <SPAN CLASS="omitted">...</SPAN>
 136 };
 137
 138 <SPAN CLASS="keyword">typedef</SPAN> basic_file_sink&lt;<SPAN CLASS="keyword">char</SPAN>&gt;     <SPAN CLASS="defined">file_sink</SPAN>;
 139 <SPAN CLASS="keyword">typedef</SPAN> basic_file_sink&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt;  <SPAN CLASS="defined">wfile_sink</SPAN>;
 140
 141 } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
 142
 143 <A NAME="basic_file_sink_params"></A>
 144 <H4>Template parameters</H4>
 145
 146 <TABLE STYLE="margin-left:2em">
 147 <TR>
 148     <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
 149     <TD>The character type.</TD></TR>
 150 <TR>
 151 </TABLE>
 152
 153 <A NAME="basic_file_sink_constructor"></A>
 154 <H4><CODE>basic_file_sink::basic_file_sink</CODE></H4>
 155
 156 <PRE CLASS="broken_ie">    basic_file_sink( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
 157                      std::ios_base::openmode mode );</PRE>
 158
 159 <P>
 160     Constructs a <CODE>basic_file_sink</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
 161     <PRE CLASS="broken_ie">    mode |= std::ios_base::out;
 162     mode &amp;= ~std::ios_base::in;
 163     buf.open(path.c_str(), mode);</PRE>
 164 </P>
 165
 166 <A NAME="basic_file_sink_is_open"></A>
 167 <H4><CODE>basic_file_sink::is_open</CODE></H4>
 168
 169 <PRE CLASS="broken_ie">    <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
 170
 171 <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
 172
 173 <A NAME="file"></A>
 174 <H3>Class template <CODE>basic_file</CODE></H3>
 175
 176 <H4>Description</H4>
 177
 178 <P><A HREF="http://www.boost.org/libs/utility/CopyConstructible.html"  TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-write mode by default.
 179
 180 <A NAME="file_synopsis"></A>
 181 <H4>Synopsis</H4>
 182
 183 <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
 184
 185 <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_params">Ch</A>&gt;
 186 <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_params">basic_file</A> {
 187 <SPAN CLASS="keyword">public</SPAN>:
 188     <SPAN CLASS="keyword">typedef</SPAN> Ch                      char_type;
 189     <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN>  category;
 190     <A CLASS="documented" HREF="#basic_file_constructor">basic_file</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
 191                 std::ios_base::openmode mode =
 192                     std::ios_base::in | std::ios_base::out );
 193     <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
 194     <SPAN CLASS="omitted">...</SPAN>
 195 };
 196
 197 <SPAN CLASS="keyword">typedef</SPAN> basic_file&lt;<SPAN CLASS="keyword">char</SPAN>&gt;     <SPAN CLASS="defined">file</SPAN>;
 198 <SPAN CLASS="keyword">typedef</SPAN> basic_file&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt;  <SPAN CLASS="defined">wfile</SPAN>;
 199
 200 } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
 201
 202 <A NAME="basic_file_params"></A>
 203 <H4>Template parameters</H4>
 204
 205 <TABLE STYLE="margin-left:2em">
 206 <TR>
 207     <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
 208     <TD>The character type.</TD></TR>
 209 <TR>
 210 </TABLE>
 211
 212 <A NAME="basic_file_constructor"></A>
 213 <H4><CODE>basic_file_::basic_file</CODE></H4>
 214
 215 <PRE CLASS="broken_ie">    basic_file( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
 216                 std::ios_base::openmode mode );</PRE>
 217
 218 <P>
 219     Constructs a <CODE>basic_file</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
 220     <PRE CLASS="broken_ie">    mode |= std::ios_base::in | std::ios_base::out;
 221     buf.open(path.c_str(), mode);</PRE>
 222 </P>
 223
 224 <A NAME="basic_file_is_open"></A>
 225 <H4><CODE>basic_file::is_open</CODE></H4>
 226
 227 <PRE CLASS="broken_ie">    <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
 228
 229 <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
 230
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 235 <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>
 236 <P CLASS="copyright">
 237     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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