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version 1.1.1.1, 2012/02/21 23:05:52
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version 1.1.1.2, 2012/02/21 23:50:25
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Line 25 man page, in case the conversion went wrong.
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Line 25 man page, in case the conversion went wrong.
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| <b>int (*pcre_callout)(pcre_callout_block *);</b> |
<b>int (*pcre_callout)(pcre_callout_block *);</b> |
| </P> |
</P> |
| <P> |
<P> |
| |
<b>int (*pcre16_callout)(pcre16_callout_block *);</b> |
| |
</P> |
| |
<P> |
| PCRE provides a feature called "callout", which is a means of temporarily |
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 |
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 |
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, | global variable <i>pcre_callout</i> (<i>pcre16_callout</i> for the 16-bit |
| which disables all calling out. | library). By default, this variable contains NULL, which disables all calling |
| | out. |
| </P> |
</P> |
| <P> |
<P> |
| Within a regular expression, (?C) indicates the points at which the external |
Within a regular expression, (?C) indicates the points at which the external |
|
Line 39 For example, this pattern has two callout points:
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Line 43 For example, this pattern has two callout points:
|
| <pre> |
<pre> |
| (?C1)abc(?C2)def |
(?C1)abc(?C2)def |
| </pre> |
</pre> |
| If the PCRE_AUTO_CALLOUT option bit is set when <b>pcre_compile()</b> or | If the PCRE_AUTO_CALLOUT option bit is set when a pattern is compiled, PCRE |
| <b>pcre_compile2()</b> is called, PCRE automatically inserts callouts, all with | automatically inserts callouts, all with number 255, before each item in the |
| number 255, before each item in the pattern. For example, if PCRE_AUTO_CALLOUT | pattern. For example, if PCRE_AUTO_CALLOUT is used with the pattern |
| is used with the pattern | |
| <pre> |
<pre> |
| A(\d{2}|--) |
A(\d{2}|--) |
| </pre> |
</pre> |
|
Line 86 been scanned far enough.
|
Line 89 been scanned far enough.
|
| </P> |
</P> |
| <P> |
<P> |
| You can disable these optimizations by passing the PCRE_NO_START_OPTIMIZE |
You can disable these optimizations by passing the PCRE_NO_START_OPTIMIZE |
| option to <b>pcre_compile()</b>, <b>pcre_exec()</b>, or <b>pcre_dfa_exec()</b>, | option to the matching function, or by starting the pattern with |
| or by starting the pattern with (*NO_START_OPT). This slows down the matching | (*NO_START_OPT). This slows down the matching process, but does ensure that |
| process, but does ensure that callouts such as the example above are obeyed. | callouts such as the example above are obeyed. |
| </P> |
</P> |
| <br><a name="SEC3" href="#TOC1">THE CALLOUT INTERFACE</a><br> |
<br><a name="SEC3" href="#TOC1">THE CALLOUT INTERFACE</a><br> |
| <P> |
<P> |
| During matching, when PCRE reaches a callout point, the external function |
During matching, when PCRE reaches a callout point, the external function |
| defined by <i>pcre_callout</i> is called (if it is set). This applies to both | defined by <i>pcre_callout</i> or <i>pcre16_callout</i> is called (if it is set). |
| the <b>pcre_exec()</b> and the <b>pcre_dfa_exec()</b> matching functions. The | This applies to both normal and DFA matching. The only argument to the callout |
| only argument to the callout function is a pointer to a <b>pcre_callout</b> | function is a pointer to a <b>pcre_callout</b> or <b>pcre16_callout</b> block. |
| block. This structure contains the following fields: | These structures contains the following fields: |
| <pre> |
<pre> |
| int <i>version</i>; | int <i>version</i>; |
| int <i>callout_number</i>; | int <i>callout_number</i>; |
| int *<i>offset_vector</i>; | int *<i>offset_vector</i>; |
| const char *<i>subject</i>; | const char *<i>subject</i>; (8-bit version) |
| int <i>subject_length</i>; | PCRE_SPTR16 <i>subject</i>; (16-bit version) |
| int <i>start_match</i>; | int <i>subject_length</i>; |
| int <i>current_position</i>; | int <i>start_match</i>; |
| int <i>capture_top</i>; | int <i>current_position</i>; |
| int <i>capture_last</i>; | int <i>capture_top</i>; |
| void *<i>callout_data</i>; | int <i>capture_last</i>; |
| int <i>pattern_position</i>; | void *<i>callout_data</i>; |
| int <i>next_item_length</i>; | </pre> |
| const unsigned char *<i>mark</i>; | int <i>next_item_length</i>; |
| | const unsigned char *<i>mark</i>; (8-bit version) |
| | const PCRE_UCHAR16 *<i>mark</i>; (16-bit version) |
| </pre> |
</pre> |
| The <i>version</i> field is an integer containing the version number of the |
The <i>version</i> field is an integer containing the version number of the |
| block format. The initial version was 0; the current version is 2. The version |
block format. The initial version was 0; the current version is 2. The version |
|
Line 124 automatically generated callouts).
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Line 129 automatically generated callouts).
|
| </P> |
</P> |
| <P> |
<P> |
| The <i>offset_vector</i> field is a pointer to the vector of offsets that was |
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> or <b>pcre_dfa_exec()</b>. When | passed by the caller to the matching function. When <b>pcre_exec()</b> or |
| <b>pcre_exec()</b> is used, the contents can be inspected in order to extract | <b>pcre16_exec()</b> is used, the contents can be inspected, in order to extract |
| substrings that have been matched so far, in the same way as for extracting |
substrings that have been matched so far, in the same way as for extracting |
| substrings after a match has completed. For <b>pcre_dfa_exec()</b> this field is | substrings after a match has completed. For the DFA matching functions, this |
| not useful. | field is not useful. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>subject</i> and <i>subject_length</i> fields contain copies of the values |
The <i>subject</i> and <i>subject_length</i> fields contain copies of the values |
| that were passed to <b>pcre_exec()</b>. | that were passed to the matching function. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>start_match</i> field normally contains the offset within the subject at |
The <i>start_match</i> field normally contains the offset within the subject at |
|
Line 147 The <i>current_position</i> field contains the offset
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Line 152 The <i>current_position</i> field contains the offset
|
| current match pointer. |
current match pointer. |
| </P> |
</P> |
| <P> |
<P> |
| When the <b>pcre_exec()</b> function is used, the <i>capture_top</i> field | When the <b>pcre_exec()</b> or <b>pcre16_exec()</b> is used, the |
| contains one more than the number of the highest numbered captured substring so | <i>capture_top</i> field contains one more than the number of the highest |
| far. If no substrings have been captured, the value of <i>capture_top</i> is | numbered captured substring so far. If no substrings have been captured, the |
| one. This is always the case when <b>pcre_dfa_exec()</b> is used, because it | value of <i>capture_top</i> is one. This is always the case when the DFA |
| does not support captured substrings. | functions are used, because they do not support captured substrings. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>capture_last</i> field contains the number of the most recently captured |
The <i>capture_last</i> field contains the number of the most recently captured |
| substring. If no substrings have been captured, its value is -1. This is always |
substring. If no substrings have been captured, its value is -1. This is always |
| the case when <b>pcre_dfa_exec()</b> is used. | the case for the DFA matching functions. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>callout_data</i> field contains a value that is passed to | The <i>callout_data</i> field contains a value that is passed to a matching |
| <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> specifically so that it can be | function specifically so that it can be passed back in callouts. It is passed |
| passed back in callouts. It is passed in the <i>pcre_callout</i> field of the | in the <i>callout_data</i> field of a <b>pcre_extra</b> or <b>pcre16_extra</b> |
| <b>pcre_extra</b> data structure. If no such data was passed, the value of | data structure. If no such data was passed, the value of <i>callout_data</i> in |
| <i>callout_data</i> in a <b>pcre_callout</b> block is NULL. There is a | a callout block is NULL. There is a description of the <b>pcre_extra</b> |
| description of the <b>pcre_extra</b> structure in the | structure in the |
| <a href="pcreapi.html"><b>pcreapi</b></a> |
<a href="pcreapi.html"><b>pcreapi</b></a> |
| documentation. |
documentation. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>pattern_position</i> field is present from version 1 of the | The <i>pattern_position</i> field is present from version 1 of the callout |
| <i>pcre_callout</i> structure. It contains the offset to the next item to be | structure. It contains the offset to the next item to be matched in the pattern |
| matched in the pattern string. | string. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>next_item_length</i> field is present from version 1 of the | The <i>next_item_length</i> field is present from version 1 of the callout |
| <i>pcre_callout</i> structure. It contains the length of the next item to be | structure. It contains the length of the next item to be matched in the pattern |
| matched in the pattern string. When the callout immediately precedes an | string. When the callout immediately precedes an alternation bar, a closing |
| alternation bar, a closing parenthesis, or the end of the pattern, the length | parenthesis, or the end of the pattern, the length is zero. When the callout |
| is zero. When the callout precedes an opening parenthesis, the length is that | precedes an opening parenthesis, the length is that of the entire subpattern. |
| of the entire subpattern. | |
| </P> |
</P> |
| <P> |
<P> |
| The <i>pattern_position</i> and <i>next_item_length</i> fields are intended to |
The <i>pattern_position</i> and <i>next_item_length</i> fields are intended to |
|
Line 187 help in distinguishing between different automatic cal
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Line 191 help in distinguishing between different automatic cal
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| same callout number. However, they are set for all callouts. |
same callout number. However, they are set for all callouts. |
| </P> |
</P> |
| <P> |
<P> |
| The <i>mark</i> field is present from version 2 of the <i>pcre_callout</i> | The <i>mark</i> field is present from version 2 of the callout structure. In |
| structure. In callouts from <b>pcre_exec()</b> it contains a pointer to the | callouts from <b>pcre_exec()</b> or <b>pcre16_exec()</b> it contains a pointer to |
| zero-terminated name of the most recently passed (*MARK), (*PRUNE), or (*THEN) | the zero-terminated name of the most recently passed (*MARK), (*PRUNE), or |
| item in the match, or NULL if no such items have been passed. Instances of | (*THEN) item in the match, or NULL if no such items have been passed. Instances |
| (*PRUNE) or (*THEN) without a name do not obliterate a previous (*MARK). In | of (*PRUNE) or (*THEN) without a name do not obliterate a previous (*MARK). In |
| callouts from <b>pcre_dfa_exec()</b> this field always contains NULL. | callouts from the DFA matching functions this field always contains NULL. |
| </P> |
</P> |
| <br><a name="SEC4" href="#TOC1">RETURN VALUES</a><br> |
<br><a name="SEC4" href="#TOC1">RETURN VALUES</a><br> |
| <P> |
<P> |
|
Line 200 The external callout function returns an integer to PC
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Line 204 The external callout function returns an integer to PC
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| matching proceeds as normal. If the value is greater than zero, matching fails |
matching proceeds as normal. If the value is greater than zero, matching fails |
| at the current point, but the testing of other matching possibilities goes |
at the current point, but the testing of other matching possibilities goes |
| ahead, just as if a lookahead assertion had failed. If the value is less than |
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> or <b>pcre_dfa_exec()</b> | zero, the match is abandoned, the matching function returns the negative value. |
| returns the negative value. | |
| </P> |
</P> |
| <P> |
<P> |
| Negative values should normally be chosen from the set of PCRE_ERROR_xxx |
Negative values should normally be chosen from the set of PCRE_ERROR_xxx |
|
Line 220 Cambridge CB2 3QH, England.
|
Line 223 Cambridge CB2 3QH, England.
|
| </P> |
</P> |
| <br><a name="SEC6" href="#TOC1">REVISION</a><br> |
<br><a name="SEC6" href="#TOC1">REVISION</a><br> |
| <P> |
<P> |
| Last updated: 30 November 2011 | Last updated: 08 Janurary 2012 |
| <br> |
<br> |
| Copyright © 1997-2011 University of Cambridge. | Copyright © 1997-2012 University of Cambridge. |
| <br> |
<br> |
| <p> |
<p> |
| Return to the <a href="index.html">PCRE index page</a>. |
Return to the <a href="index.html">PCRE index page</a>. |
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