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diff --git a/external-libs/pcre/doc/html/pcrecallout.html b/external-libs/pcre/doc/html/pcrecallout.html new file mode 100644 index 00000000..f4b7104e --- /dev/null +++ b/external-libs/pcre/doc/html/pcrecallout.html @@ -0,0 +1,117 @@ +<html> +<head> +<title>pcrecallout specification</title> +</head> +<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"> +This HTML document has been generated automatically from the original man page. +If there is any nonsense in it, please consult the man page, in case the +conversion went wrong.<br> +<ul> +<li><a name="TOC1" href="#SEC1">PCRE CALLOUTS</a> +<li><a name="TOC2" href="#SEC2">RETURN VALUES</a> +</ul> +<br><a name="SEC1" href="#TOC1">PCRE CALLOUTS</a><br> +<P> +<b>int (*pcre_callout)(pcre_callout_block *);</b> +</P> +<P> +PCRE provides a feature called "callout", which is a means of temporarily +passing control to the caller of PCRE in the middle of pattern matching. The +caller of PCRE provides an external function by putting its entry point in the +global variable <i>pcre_callout</i>. By default, this variable contains NULL, +which disables all calling out. +</P> +<P> +Within a regular expression, (?C) indicates the points at which the external +function is to be called. Different callout points can be identified by putting +a number less than 256 after the letter C. The default value is zero. +For example, this pattern has two callout points: +</P> +<P> +<pre> + (?C1)\dabc(?C2)def +</PRE> +</P> +<P> +During matching, when PCRE reaches a callout point (and <i>pcre_callout</i> is +set), the external function is called. Its only argument is a pointer to a +<b>pcre_callout</b> block. This contains the following variables: +</P> +<P> +<pre> + int <i>version</i>; + int <i>callout_number</i>; + int *<i>offset_vector</i>; + const char *<i>subject</i>; + int <i>subject_length</i>; + int <i>start_match</i>; + int <i>current_position</i>; + int <i>capture_top</i>; + int <i>capture_last</i>; + void *<i>callout_data</i>; +</PRE> +</P> +<P> +The <i>version</i> field is an integer containing the version number of the +block format. The current version is zero. The version number may change in +future if additional fields are added, but the intention is never to remove any +of the existing fields. +</P> +<P> +The <i>callout_number</i> field contains the number of the callout, as compiled +into the pattern (that is, the number after ?C). +</P> +<P> +The <i>offset_vector</i> field is a pointer to the vector of offsets that was +passed by the caller to <b>pcre_exec()</b>. The contents can be inspected in +order to extract substrings that have been matched so far, in the same way as +for extracting substrings after a match has completed. +</P> +<P> +The <i>subject</i> and <i>subject_length</i> fields contain copies the values +that were passed to <b>pcre_exec()</b>. +</P> +<P> +The <i>start_match</i> field contains the offset within the subject at which the +current match attempt started. If the pattern is not anchored, the callout +function may be called several times for different starting points. +</P> +<P> +The <i>current_position</i> field contains the offset within the subject of the +current match pointer. +</P> +<P> +The <i>capture_top</i> field contains one more than the number of the highest +numbered captured substring so far. If no substrings have been captured, +the value of <i>capture_top</i> is one. +</P> +<P> +The <i>capture_last</i> field contains the number of the most recently captured +substring. +</P> +<P> +The <i>callout_data</i> field contains a value that is passed to +<b>pcre_exec()</b> by the caller specifically so that it can be passed back in +callouts. It is passed in the <i>pcre_callout</i> field of the <b>pcre_extra</b> +data structure. If no such data was passed, the value of <i>callout_data</i> in +a <b>pcre_callout</b> block is NULL. There is a description of the +<b>pcre_extra</b> structure in the <b>pcreapi</b> documentation. +</P> +<br><a name="SEC2" href="#TOC1">RETURN VALUES</a><br> +<P> +The callout function returns an integer. If the value is zero, matching +proceeds as normal. If the value is greater than zero, matching fails at the +current point, but backtracking to test other possibilities goes ahead, just as +if a lookahead assertion had failed. If the value is less than zero, the match +is abandoned, and <b>pcre_exec()</b> returns the value. +</P> +<P> +Negative values should normally be chosen from the set of PCRE_ERROR_xxx +values. In particular, PCRE_ERROR_NOMATCH forces a standard "no match" failure. +The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions; +it will never be used by PCRE itself. +</P> +<P> +Last updated: 21 January 2003 +<br> +Copyright © 1997-2003 University of Cambridge. |