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Diffstat (limited to 'doc/html/pcre2pattern.html')
| -rw-r--r-- | doc/html/pcre2pattern.html | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/doc/html/pcre2pattern.html b/doc/html/pcre2pattern.html index c88e931..797690a 100644 --- a/doc/html/pcre2pattern.html +++ b/doc/html/pcre2pattern.html @@ -1256,17 +1256,22 @@ build PCRE2 with the use of \C permanently disabled. <P> PCRE2 does not allow \C to appear in lookbehind assertions <a href="#lookbehind">(described below)</a> -in a UTF mode, because this would make it impossible to calculate the length of -the lookbehind. Neither the alternative matching function -<b>pcre2_dfa_match()</b> not the JIT optimizer support \C in a UTF mode. The -former gives a match-time error; the latter fails to optimize and so the match -is always run using the interpreter. +in UTF-8 or UTF-16 modes, because this would make it impossible to calculate +the length of the lookbehind. Neither the alternative matching function +<b>pcre2_dfa_match()</b> nor the JIT optimizer support \C in these UTF modes. +The former gives a match-time error; the latter fails to optimize and so the +match is always run using the interpreter. +</P> +<P> +In the 32-bit library, however, \C is always supported (when not explicitly +locked out) because it always matches a single code unit, whether or not UTF-32 +is specified. </P> <P> In general, the \C escape sequence is best avoided. However, one way of using -it that avoids the problem of malformed UTF characters is to use a lookahead to -check the length of the next character, as in this pattern, which could be used -with a UTF-8 string (ignore white space and line breaks): +it that avoids the problem of malformed UTF-8 or UTF-16 characters is to use a +lookahead to check the length of the next character, as in this pattern, which +could be used with a UTF-8 string (ignore white space and line breaks): <pre> (?| (?=[\x00-\x7f])(\C) | (?=[\x80-\x{7ff}])(\C)(\C) | @@ -3388,9 +3393,9 @@ Cambridge, England. </P> <br><a name="SEC30" href="#TOC1">REVISION</a><br> <P> -Last updated: 13 November 2015 +Last updated: 20 June 2016 <br> -Copyright © 1997-2015 University of Cambridge. +Copyright © 1997-2016 University of Cambridge. <br> <p> Return to the <a href="index.html">PCRE2 index page</a>. |