ceph/src/boost/libs/tokenizer/tokenizerfunction.htm

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  10   <title>TokenizerFunction Concept</title>
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  15   <p><img src="../../boost.png" alt="C++ Boost" width="277" height="86"></p>
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  17   <h1 align="center">TokenizerFunction Concept</h1>
  18
  19   <p>A TokenizerFunction is a functor whose purpose is to parse a given
  20   sequence until exactly 1 token has been found or the end is reached. It
  21   then updates the token, and informs the caller of the location in the
  22   sequence of the next element immediately after the last element of the
  23   sequence that was parsed for the current token.</p>
  24
  25   <h2>Refinement of</h2>
  26
  27   <p>Assignable, CopyConstructable</p>
  28
  29   <h2>Notation</h2>
  30
  31   <table border="1" summary="">
  32     <tr>
  33       <td valign="top"><tt>X</tt></td>
  34
  35       <td valign="top">A type that is a model of TokenizerFunction</td>
  36     </tr>
  37
  38     <tr>
  39       <td valign="top"><tt>func</tt></td>
  40
  41       <td valign="top">Object of type <tt>X</tt></td>
  42     </tr>
  43
  44     <tr>
  45       <td valign="top"><tt>tok</tt></td>
  46
  47       <td valign="top">Object of Token</td>
  48     </tr>
  49
  50     <tr>
  51       <td>next</td>
  52
  53       <td>iterator that points to the first unparsed element of the sequence
  54       being parsed</td>
  55     </tr>
  56
  57     <tr>
  58       <td>end</td>
  59
  60       <td>iterator that points to the past the end of the sequence being
  61       parsed</td>
  62     </tr>
  63   </table>
  64
  65   <h2>Definitions</h2>
  66
  67   <p>A token is the result of parsing a sequence.</p>
  68
  69   <h2>Valid expressions</h2>
  70
  71   <p>In addition to the expression in Assignable and CopyConstructable the
  72   following expressions are valid</p>
  73
  74   <table border="1" summary="">
  75     <tr>
  76       <th>Name</th>
  77
  78       <th>Expression</th>
  79
  80       <th>Return type</th>
  81     </tr>
  82
  83     <tr>
  84       <td valign="top">Functor</td>
  85
  86       <td valign="top"><tt>func(next, end, tok)</tt></td>
  87
  88       <td valign="top"><tt>bool</tt></td>
  89     </tr>
  90
  91     <tr>
  92       <td valign="top">reset</td>
  93
  94       <td valign="top"><tt>reset()</tt></td>
  95
  96       <td valign="top"><tt>void</tt></td>
  97     </tr>
  98   </table>
  99
 100   <h2>Expression semantics</h2>
 101
 102   <p>In addition to the expression semantics in Assignable and
 103   CopyConstructable, TokenizerFunction has the following expression
 104   semantcs</p>
 105
 106   <table border="1" summary="">
 107     <tr>
 108       <th>Name</th>
 109
 110       <th>Expression</th>
 111
 112       <th>Precondition</th>
 113
 114       <th>Semantics</th>
 115
 116       <th>Postcondition</th>
 117     </tr>
 118
 119     <tr>
 120       <td>operator()</td>
 121
 122       <td><tt>func(next, end, tok)</tt></td>
 123
 124       <td><tt>next</tt> and <tt>end</tt> are valid iterators to the same
 125       sequence. next is a reference the function is free to modify. tok is
 126       constructed.</td>
 127
 128       <td>The return value indicates whether a new token was found in the
 129       sequence [next,end)</td>
 130
 131       <td>If the return value is true, the new token is assigned to tok. next
 132       is always updated to the position where parsing should start on the
 133       subsequent call.</td>
 134     </tr>
 135
 136     <tr>
 137       <td>reset</td>
 138
 139       <td><tt>reset()</tt></td>
 140
 141       <td><tt>None</tt></td>
 142
 143       <td>Clears out all state variables that are used by the object in
 144       parsing the current sequence.</td>
 145
 146       <td>A new sequence to parse can be given.</td>
 147     </tr>
 148   </table>
 149
 150   <h2>Complexity guarantees</h2>
 151
 152   <p>No guarantees. Models of TokenizerFunction are free to define their own
 153   complexity</p>
 154
 155   <h2>Models</h2>
 156
 157   <p><a href="escaped_list_separator.htm">escaped_list_separator</a></p>
 158
 159   <p><a href="offset_separator.htm">offset_separator</a></p>
 160
 161   <p><a href=
 162   "char_delimiters_separator.htm">char_delimiters_separator</a></p>
 163
 164   <p>&nbsp;</p>
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 171   <p>Revised
 172   <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->25
 173   December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38518" --></p>
 174
 175   <p><i>Copyright &copy; 2001 John R. Bandela</i></p>
 176
 177   <p><i>Distributed under the Boost Software License, Version 1.0. (See
 178   accompanying file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
 179   copy at <a href=
 180   "http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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