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Added better documentation on POSIX-conformance.

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[SVN r28278]
This commit is contained in:
John Maddock
2005-04-16 16:06:45 +00:00
parent 5d1f265345
commit 91b21e78ff
8 changed files with 98 additions and 28 deletions
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18
doc/syntax_extended.html
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@ -130,10 +130,11 @@ aaaa</PRE>
<P>For example [a-c] will match any single character in the range 'a' to
'c'.&nbsp; By default, for POSIX-Extended regular expressions, a character <EM>x</EM>
is within the range <EM>y</EM> to <EM>z</EM>, if it collates within that
range;&nbsp;this results in locale specific behavior.&nbsp; This behavior can
be turned off by unsetting the <EM><A href="syntax_option_type.html#extended">collate</A></EM>
option flag - in which case whether a character appears within a range is
determined by comparing the code points of the characters only</P>
range;&nbsp;<EM><STRONG>this results in locale specific behavior</STRONG></EM> .&nbsp;
This behavior can be turned off by unsetting the <EM><A href="syntax_option_type.html#extended">
collate</A></EM> option flag - in which case whether a character appears
within a range is determined by comparing the code points of the characters
only.</P>
<H5>Negation:</H5>
<P>If the bracket-expression begins with the ^ character, then it matches the
complement of the characters it contains, for example [^a-c] matches any
@ -149,13 +150,16 @@ aaaa</PRE>
point of a range, for example: [[.ae.]-c] matches the character sequence "ae",
plus any single character in the range "ae"-c, assuming that "ae" is treated as
a single collating element in the current locale.</P>
<P>Collating elements may be used in place of escapes (which are not normally
allowed inside character sets), for example [[.^.]abc] would match either one
of the characters 'abc^'.</P>
<P>As an extension, a collating element may also be specified via its <A href="collating_names.html">
symbolic name</A>, for example:</P>
<P>[[.NUL.]]</P>
<P>matches a NUL character.</P>
<H5>Equivalence classes:</H5>
<P>
An expression of theform[[=col=]], matches any character or collating element
An expression oftheform[[=col=]], matches any character or collating element
whose primary sort key is the same as that for collating element <EM>col</EM>,
as with colating elements the name <EM>col</EM> may be a <A href="collating_names.html">
symbolic name</A>.&nbsp; A primary sort key is one that ignores case,
@ -177,9 +181,9 @@ aaaa</PRE>
<LI>
The effect of any ordinary character being preceded by an escape is undefined.
<LI>
An escape inside a character class declaration shall match itself (in other
An escape inside a character class declaration shall match itself: in other
words the escape character is not "special" inside a character class
declaration).</LI></UL>
declaration; so [\^] will match either a literal '\' or a '^'.</LI></UL>
<P>However, that's rather restrictive, so the following standard-compatible
extensions are also supported by Boost.Regex:</P>
<BLOCKQUOTE dir="ltr" style="MARGIN-RIGHT: 0px">