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Diffstat (limited to 'doc/html/pcre2unicode.html')
| -rw-r--r-- | doc/html/pcre2unicode.html | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/doc/html/pcre2unicode.html b/doc/html/pcre2unicode.html index 6ca367f..448a221 100644 --- a/doc/html/pcre2unicode.html +++ b/doc/html/pcre2unicode.html @@ -47,7 +47,7 @@ and documentation. Only the short names for properties are supported. For example, \p{L} matches a letter. Its Perl synonym, \p{Letter}, is not supported. Furthermore, in Perl, many properties may optionally be prefixed by "Is", for -compatibility with Perl 5.6. PCRE does not support this. +compatibility with Perl 5.6. PCRE2 does not support this. </P> <br><b> WIDE CHARACTERS AND UTF MODES @@ -109,10 +109,15 @@ However, the special horizontal and vertical white space matching escapes (\h, \H, \v, and \V) do match all the appropriate Unicode characters, whether or not PCRE2_UCP is set. </P> +<br><b> +CASE-EQUIVALENCE IN UTF MODES +</b><br> <P> -Case-insensitive matching in UTF mode makes use of Unicode properties. A few -Unicode characters such as Greek sigma have more than two codepoints that are -case-equivalent, and these are treated as such. +Case-insensitive matching in a UTF mode makes use of Unicode properties except +for characters whose code points are less than 128 and that have at most two +case-equivalent values. For these, a direct table lookup is used for speed. A +few Unicode characters such as Greek sigma have more than two codepoints that +are case-equivalent, and these are treated as such. </P> <br><b> VALIDITY OF UTF STRINGS @@ -173,6 +178,15 @@ or <b>pcre2_dfa_match()</b>. <P> If you pass an invalid UTF string when PCRE2_NO_UTF_CHECK is set, the result is undefined and your program may crash or loop indefinitely. +</P> +<P> +Note that setting PCRE2_NO_UTF_CHECK at compile time does not disable the error +that is given if an escape sequence for an invalid Unicode code point is +encountered in the pattern. If you want to allow escape sequences such as +\x{d800} (a surrogate code point) you can set the +PCRE2_EXTRA_ALLOW_SURROGATE_ESCAPES extra option. However, this is possible +only in UTF-8 and UTF-32 modes, because these values are not representable in +UTF-16. <a name="utf8strings"></a></P> <br><b> Errors in UTF-8 strings @@ -280,9 +294,9 @@ Cambridge, England. REVISION </b><br> <P> -Last updated: 03 July 2016 +Last updated: 17 May 2017 <br> -Copyright © 1997-2016 University of Cambridge. +Copyright © 1997-2017 University of Cambridge. <br> <p> Return to the <a href="index.html">PCRE2 index page</a>. |