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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_regex.ref.concepts.traits_concept"></a><a class="link" href="traits_concept.html" title="Traits Class Requirements"> Traits Class
Requirements</a>
</h4></div></div></div>
<p>
There are two sets of requirements for the <code class="computeroutput"><span class="identifier">traits</span></code>
template argument to <a class="link" href="../basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a>: a mininal interface
(which is part of the regex standardization proposal), and an optional
Boost-specific enhanced interface.
</p>
<a name="boost_regex.ref.concepts.traits_concept.minimal_requirements_"></a><h5>
<a name="id1152061"></a>
<a class="link" href="traits_concept.html#boost_regex.ref.concepts.traits_concept.minimal_requirements_">Minimal
requirements.</a>
</h5>
<p>
In the following table <code class="computeroutput"><span class="identifier">X</span></code>
denotes a traits class defining types and functions for the character container
type <code class="computeroutput"><span class="identifier">charT</span></code>; <span class="emphasis"><em>u</em></span>
is an object of type <code class="computeroutput"><span class="identifier">X</span></code>;
<span class="emphasis"><em>v</em></span> is an object of type <code class="computeroutput"><span class="keyword">const</span>
<span class="identifier">X</span></code>; <span class="emphasis"><em>p</em></span> is
a value of type <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">charT</span><span class="special">*</span></code>; <span class="emphasis"><em>I1</em></span> and <span class="emphasis"><em>I2</em></span>
are Input Iterators; <span class="emphasis"><em>c</em></span> is a value of type <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">charT</span></code>;
<span class="emphasis"><em>s</em></span> is an object of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">string_type</span></code>;
<span class="emphasis"><em>cs</em></span> is an object of type <code class="computeroutput"><span class="keyword">const</span>
<span class="identifier">X</span><span class="special">::</span><span class="identifier">string_type</span></code>; <span class="emphasis"><em>b</em></span> is
a value of type <code class="computeroutput"><span class="keyword">bool</span></code>; <span class="emphasis"><em>I</em></span>
is a value of type <code class="computeroutput"><span class="keyword">int</span></code>; <span class="emphasis"><em>F1</em></span>
and <span class="emphasis"><em>F2</em></span> are values of type <code class="computeroutput"><span class="keyword">const</span>
<span class="identifier">charT</span><span class="special">*</span></code>;
and <span class="emphasis"><em>loc</em></span> is an object of type <code class="computeroutput"><span class="identifier">X</span><span class="special">::</span><span class="identifier">locale_type</span></code>.
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Return type
</p>
</th>
<th>
<p>
Assertion / Note Pre / Post condition
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
charT
</p>
</td>
<td>
<p>
The character container type used in the implementation of class
template basic_regex.
</p>
</td>
</tr>
<tr>
<td>
<p>
X::size_type
</p>
</td>
<td>
<p>
</p>
</td>
<td>
<p>
An unsigned integer type, capable of holding the length of a
null-terminated string of charT's.
</p>
</td>
</tr>
<tr>
<td>
<p>
X::string_type
</p>
</td>
<td>
<p>
std::basic_string<charT> or std::vector<charT>
</p>
</td>
<td>
<p>
</p>
</td>
</tr>
<tr>
<td>
<p>
X::locale_type
</p>
</td>
<td>
<p>
Implementation defined
</p>
</td>
<td>
<p>
A copy constructible type that represents the locale used by
the traits class.
</p>
</td>
</tr>
<tr>
<td>
<p>
X::char_class_type
</p>
</td>
<td>
<p>
Implementation defined
</p>
</td>
<td>
<p>
A bitmask type representing a particular character classification.
Multiple values of this type can be bitwise-or'ed together to
obtain a new valid value.
</p>
</td>
</tr>
<tr>
<td>
<p>
X::length(p)
</p>
</td>
<td>
<p>
X::size_type
</p>
</td>
<td>
<p>
Yields the smallest i such that p[i] == 0. Complexity is linear
in i.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.translate(c)
</p>
</td>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
Returns a character such that for any character d that is to
be considered equivalent to c then v.translate(c) == v.translate(d).
</p>
</td>
</tr>
<tr>
<td>
<p>
v.translate_nocase(c)
</p>
</td>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
For all characters C that are to be considered equivalent to
c when comparisons are to be performed without regard to case,
then v.translate_nocase(c) == v.translate_nocase(C).
</p>
</td>
</tr>
<tr>
<td>
<p>
v.transform(F1, F2)
</p>
</td>
<td>
<p>
X::string_type
</p>
</td>
<td>
<p>
Returns a sort key for the character sequence designated by the
iterator range [F1, F2) such that if the character sequence [G1,
G2) sorts before the character sequence [H1, H2) then v.transform(G1,
G2) < v.transform(H1, H2).
</p>
</td>
</tr>
<tr>
<td>
<p>
v.transform_primary(F1, F2)
</p>
</td>
<td>
<p>
X::string_type
</p>
</td>
<td>
<p>
Returns a sort key for the character sequence designated by the
iterator range [F1, F2) such that if the character sequence [G1,
G2) sorts before the character sequence [H1, H2) when character
case is not considered then v.transform_primary(G1, G2) <
v.transform_primary(H1, H2).
</p>
</td>
</tr>
<tr>
<td>
<p>
v.lookup_classname(F1, F2)
</p>
</td>
<td>
<p>
X::char_class_type
</p>
</td>
<td>
<p>
Converts the character sequence designated by the iterator range
[F1,F2) into a bitmask type that can subsequently be passed to
isctype. Values returned from lookup_classname can be safely
bitwise or'ed together. Returns 0 if the character sequence is
not the name of a character class recognized by X. The value
returned shall be independent of the case of the characters in
the sequence.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.lookup_collatename(F1, F2)
</p>
</td>
<td>
<p>
X::string_type
</p>
</td>
<td>
<p>
Returns a sequence of characters that represents the collating
element consisting of the character sequence designated by the
iterator range [F1, F2). Returns an empty string if the character
sequence is not a valid collating element.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.isctype(c, v.lookup_classname (F1, F2))
</p>
</td>
<td>
<p>
bool
</p>
</td>
<td>
<p>
Returns true if character c is a member of the character class
designated by the iterator range [F1, F2), false otherwise.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.value(c, I)
</p>
</td>
<td>
<p>
int
</p>
</td>
<td>
<p>
Returns the value represented by the digit c in base I if the
character c is a valid digit in base I; otherwise returns -1.
[Note: the value of I will only be 8, 10, or 16. -end note]
</p>
</td>
</tr>
<tr>
<td>
<p>
u.imbue(loc)
</p>
</td>
<td>
<p>
X::locale_type
</p>
</td>
<td>
<p>
Imbues u with the locale loc, returns the previous locale used
by u if any.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.getloc()
</p>
</td>
<td>
<p>
X::locale_type
</p>
</td>
<td>
<p>
Returns the current locale used by v if any.
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="boost_regex.ref.concepts.traits_concept.additional_optional_requirements"></a><h5>
<a name="id1152718"></a>
<a class="link" href="traits_concept.html#boost_regex.ref.concepts.traits_concept.additional_optional_requirements">Additional
Optional Requirements</a>
</h5>
<p>
The following additional requirements are strictly optional, however in
order for <a class="link" href="../basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a>
to take advantage of these additional interfaces, all of the following
requirements must be met; <a class="link" href="../basic_regex.html" title="basic_regex"><code class="computeroutput"><span class="identifier">basic_regex</span></code></a> will detect the presence
or absense of the member <code class="computeroutput"><span class="identifier">boost_extensions_tag</span></code>
and configure itself appropriately.
</p>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Expression
</p>
</th>
<th>
<p>
Result
</p>
</th>
<th>
<p>
Assertion / Note Pre / Post condition
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
X::boost_extensions_tag
</p>
</td>
<td>
<p>
An unspecified type.
</p>
</td>
<td>
<p>
When present, all of the extensions listed in this table must
be present.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.syntax_type(c)
</p>
</td>
<td>
<p>
regex_constants::syntax_type
</p>
</td>
<td>
<p>
Returns a symbolic value of type regex_constants::syntax_type
that signifies the meaning of character c within the regular
expression grammar.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.escape_syntax_type(c)
</p>
</td>
<td>
<p>
regex_constants::escape_syntax_type
</p>
</td>
<td>
<p>
Returns a symbolic value of type regex_constants::escape_syntax_type,
that signifies the meaning of character c within the regular
expression grammar, when c has been preceded by an escape character.
Precondition: if b is the character preceding c in the expression
being parsed then: <code class="computeroutput"><span class="identifier">v</span><span class="special">.</span><span class="identifier">syntax_type</span><span class="special">(</span><span class="identifier">b</span><span class="special">)</span> <span class="special">==</span>
<span class="identifier">syntax_escape</span></code>
</p>
</td>
</tr>
<tr>
<td>
<p>
v.translate(c, b)
</p>
</td>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
Returns a character d such that: for any character d that is
to be considered equivalent to c then <code class="computeroutput"><span class="identifier">v</span><span class="special">.</span><span class="identifier">translate</span><span class="special">(</span><span class="identifier">c</span><span class="special">,</span><span class="keyword">false</span><span class="special">)==</span><span class="identifier">v</span><span class="special">.</span><span class="identifier">translate</span><span class="special">(</span><span class="identifier">d</span><span class="special">,</span><span class="keyword">false</span><span class="special">)</span></code>. Likewise for all characters
C that are to be considered equivalent to c when comparisons
are to be performed without regard to case, then <code class="computeroutput"><span class="identifier">v</span><span class="special">.</span><span class="identifier">translate</span><span class="special">(</span><span class="identifier">c</span><span class="special">,</span><span class="keyword">true</span><span class="special">)==</span><span class="identifier">v</span><span class="special">.</span><span class="identifier">translate</span><span class="special">(</span><span class="identifier">C</span><span class="special">,</span><span class="keyword">true</span><span class="special">)</span></code>.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.toi(I1, I2, i)
</p>
</td>
<td>
<p>
An integer type capable of holding either a charT or an int.
</p>
</td>
<td>
<p>
Behaves as follows: if <code class="computeroutput"><span class="identifier">p</span>
<span class="special">==</span> <span class="identifier">q</span></code>
or if <code class="computeroutput"><span class="special">*</span><span class="identifier">p</span></code>
is not a digit character then returns -1. Otherwise performs
formatted numeric input on the sequence [p,q) and returns the
result as an int. Postcondition: either p == q or *p is a non-digit
character.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.error_string(I)
</p>
</td>
<td>
<p>
std::string
</p>
</td>
<td>
<p>
Returns a human readable error string for the error condition
i, where i is one of the values enumerated by type regex_constants::error_type.
If the value <span class="emphasis"><em>I</em></span> is not recognized then returns
the string "Unknown error" or a localized equivalent.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.tolower(c)
</p>
</td>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
Converts c to lower case, used for Perl-style \l and \L formating
operations.
</p>
</td>
</tr>
<tr>
<td>
<p>
v.toupper(c)
</p>
</td>
<td>
<p>
X::char_type
</p>
</td>
<td>
<p>
Converts c to upper case, used for Perl-style \u and \U formating
operations.
</p>
</td>
</tr>
</tbody>
</table></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 1998 -2007 John Maddock<p>
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" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
</div></td>
</tr></table>
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