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<h1 align="center">TokenizerFunction Concept</h1>
<p>A TokenizerFunction is a functor whose purpose is to parse a given
sequence until exactly 1 token has been found or the end is reached. It
then updates the token, and informs the caller of the location in the
sequence of the next element immediately after the last element of the
sequence that was parsed for the current token.</p>
<h2>Refinement of</h2>
<p>Assignable, CopyConstructable</p>
<h2>Notation</h2>
<table border="1" summary="">
<tr>
<td valign="top"><tt>X</tt></td>
<td valign="top">A type that is a model of TokenizerFunction</td>
</tr>
<tr>
<td valign="top"><tt>func</tt></td>
<td valign="top">Object of type <tt>X</tt></td>
</tr>
<tr>
<td valign="top"><tt>tok</tt></td>
<td valign="top">Object of Token</td>
</tr>
<tr>
<td>next</td>
<td>iterator that points to the first unparsed element of the sequence
being parsed</td>
</tr>
<tr>
<td>end</td>
<td>iterator that points to the past the end of the sequence being
parsed</td>
</tr>
</table>
<h2>Definitions</h2>
<p>A token is the result of parsing a sequence.</p>
<h2>Valid expressions</h2>
<p>In addition to the expression in Assignable and CopyConstructable the
following expressions are valid</p>
<table border="1" summary="">
<tr>
<th>Name</th>
<th>Expression</th>
<th>Return type</th>
</tr>
<tr>
<td valign="top">Functor</td>
<td valign="top"><tt>func(next, end, tok)</tt></td>
<td valign="top"><tt>bool</tt></td>
</tr>
<tr>
<td valign="top">reset</td>
<td valign="top"><tt>reset()</tt></td>
<td valign="top"><tt>void</tt></td>
</tr>
</table>
<h2>Expression semantics</h2>
<p>In addition to the expression semantics in Assignable and
CopyConstructable, TokenizerFunction has the following expression
semantcs</p>
<table border="1" summary="">
<tr>
<th>Name</th>
<th>Expression</th>
<th>Precondition</th>
<th>Semantics</th>
<th>Postcondition</th>
</tr>
<tr>
<td>operator()</td>
<td><tt>func(next, end, tok)</tt></td>
<td><tt>next</tt> and <tt>end</tt> are valid iterators to the same
sequence. next is a reference the function is free to modify. tok is
constructed.</td>
<td>The return value indicates whether a new token was found in the
sequence [next,end)</td>
<td>If the return value is true, the new token is assigned to tok. next
is always updated to the position where parsing should start on the
subsequent call.</td>
</tr>
<tr>
<td>reset</td>
<td><tt>reset()</tt></td>
<td><tt>None</tt></td>
<td>Clears out all state variables that are used by the object in
parsing the current sequence.</td>
<td>A new sequence to parse can be given.</td>
</tr>
</table>
<h2>Complexity guarantees</h2>
<p>No guarantees. Models of TokenizerFunction are free to define their own
complexity</p>
<h2>Models</h2>
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<p>Revised
<!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %B, %Y" startspan -->25
December, 2006<!--webbot bot="Timestamp" endspan i-checksum="38518" --></p>
<p><i>Copyright © 2001 John R. Bandela</i></p>
<p><i>Distributed under the Boost Software License, Version 1.0. (See
accompanying file <a href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
copy at <a href=
"http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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