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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 172 by ph10, Tue Jun 5 10:40:13 2007 UTC
# Line 17  man page, in case the conversion went wr Line 17  man page, in case the conversion went wr
17  <li><a name="TOC2" href="#SEC2">MISSING CALLOUTS</a>  <li><a name="TOC2" href="#SEC2">MISSING CALLOUTS</a>
18  <li><a name="TOC3" href="#SEC3">THE CALLOUT INTERFACE</a>  <li><a name="TOC3" href="#SEC3">THE CALLOUT INTERFACE</a>
19  <li><a name="TOC4" href="#SEC4">RETURN VALUES</a>  <li><a name="TOC4" href="#SEC4">RETURN VALUES</a>
20    <li><a name="TOC5" href="#SEC5">AUTHOR</a>
21    <li><a name="TOC6" href="#SEC6">REVISION</a>
22  </ul>  </ul>
23  <br><a name="SEC1" href="#TOC1">PCRE CALLOUTS</a><br>  <br><a name="SEC1" href="#TOC1">PCRE CALLOUTS</a><br>
24  <P>  <P>
# Line 35  function is to be called. Different call Line 37  function is to be called. Different call
37  a number less than 256 after the letter C. The default value is zero.  a number less than 256 after the letter C. The default value is zero.
38  For example, this pattern has two callout points:  For example, this pattern has two callout points:
39  <pre>  <pre>
40    (?C1)\deabc(?C2)def    (?C1)abc(?C2)def
41  </pre>  </pre>
42  If the PCRE_AUTO_CALLOUT option bit is set when <b>pcre_compile()</b> is called,  If the PCRE_AUTO_CALLOUT option bit is set when <b>pcre_compile()</b> is called,
43  PCRE automatically inserts callouts, all with number 255, before each item in  PCRE automatically inserts callouts, all with number 255, before each item in
# Line 72  no match, the callout is obeyed. Line 74  no match, the callout is obeyed.
74  <br><a name="SEC3" href="#TOC1">THE CALLOUT INTERFACE</a><br>  <br><a name="SEC3" href="#TOC1">THE CALLOUT INTERFACE</a><br>
75  <P>  <P>
76  During matching, when PCRE reaches a callout point, the external function  During matching, when PCRE reaches a callout point, the external function
77  defined by <i>pcre_callout</i> is called (if it is set). The only argument is a  defined by <i>pcre_callout</i> is called (if it is set). This applies to both
78  pointer to a <b>pcre_callout</b> block. This structure contains the following  the <b>pcre_exec()</b> and the <b>pcre_dfa_exec()</b> matching functions. The
79  fields:  only argument to the callout function is a pointer to a <b>pcre_callout</b>
80    block. This structure contains the following fields:
81  <pre>  <pre>
82    int          <i>version</i>;    int          <i>version</i>;
83    int          <i>callout_number</i>;    int          <i>callout_number</i>;
# Line 101  automatically generated callouts). Line 104  automatically generated callouts).
104  </P>  </P>
105  <P>  <P>
106  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
107  passed by the caller to <b>pcre_exec()</b>. The contents can be inspected in  passed by the caller to <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b>. When
108  order to extract substrings that have been matched so far, in the same way as  <b>pcre_exec()</b> is used, the contents can be inspected in order to extract
109  for extracting substrings after a match has completed.  substrings that have been matched so far, in the same way as for extracting
110    substrings after a match has completed. For <b>pcre_dfa_exec()</b> this field is
111    not useful.
112  </P>  </P>
113  <P>  <P>
114  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
115  that were passed to <b>pcre_exec()</b>.  that were passed to <b>pcre_exec()</b>.
116  </P>  </P>
117  <P>  <P>
118  The <i>start_match</i> field contains the offset within the subject at which the  The <i>start_match</i> field normally contains the offset within the subject at
119  current match attempt started. If the pattern is not anchored, the callout  which the current match attempt started. However, if the escape sequence \K
120  function may be called several times from the same point in the pattern for  has been encountered, this value is changed to reflect the modified starting
121  different starting points in the subject.  point. If the pattern is not anchored, the callout function may be called
122    several times from the same point in the pattern for different starting points
123    in the subject.
124  </P>  </P>
125  <P>  <P>
126  The <i>current_position</i> field contains the offset within the subject of the  The <i>current_position</i> field contains the offset within the subject of the
127  current match pointer.  current match pointer.
128  </P>  </P>
129  <P>  <P>
130  The <i>capture_top</i> field contains one more than the number of the highest  When the <b>pcre_exec()</b> function is used, the <i>capture_top</i> field
131  numbered captured substring so far. If no substrings have been captured,  contains one more than the number of the highest numbered captured substring so
132  the value of <i>capture_top</i> is one.  far. If no substrings have been captured, the value of <i>capture_top</i> is
133    one. This is always the case when <b>pcre_dfa_exec()</b> is used, because it
134    does not support captured substrings.
135  </P>  </P>
136  <P>  <P>
137  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
138  substring. If no substrings have been captured, its value is -1.  substring. If no substrings have been captured, its value is -1. This is always
139    the case when <b>pcre_dfa_exec()</b> is used.
140  </P>  </P>
141  <P>  <P>
142  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
143  <b>pcre_exec()</b> by the caller specifically so that it can be passed back in  <b>pcre_exec()</b> or <b>pcre_dfa_exec()</b> specifically so that it can be
144  callouts. It is passed in the <i>pcre_callout</i> field of the <b>pcre_extra</b>  passed back in callouts. It is passed in the <i>pcre_callout</i> field of the
145  data structure. If no such data was passed, the value of <i>callout_data</i> in  <b>pcre_extra</b> data structure. If no such data was passed, the value of
146  a <b>pcre_callout</b> block is NULL. There is a description of the  <i>callout_data</i> in a <b>pcre_callout</b> block is NULL. There is a
147  <b>pcre_extra</b> structure in the  description of the <b>pcre_extra</b> structure in the
148  <a href="pcreapi.html"><b>pcreapi</b></a>  <a href="pcreapi.html"><b>pcreapi</b></a>
149  documentation.  documentation.
150  </P>  </P>
# Line 160  same callout number. However, they are s Line 170  same callout number. However, they are s
170  <P>  <P>
171  The external callout function returns an integer to PCRE. If the value is zero,  The external callout function returns an integer to PCRE. If the value is zero,
172  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
173  at the current point, but backtracking to test other matching possibilities  at the current point, but the testing of other matching possibilities goes
174  goes ahead, just as if a lookahead assertion had failed. If the value is less  ahead, just as if a lookahead assertion had failed. If the value is less than
175  than zero, the match is abandoned, and <b>pcre_exec()</b> returns the negative  zero, the match is abandoned, and <b>pcre_exec()</b> (or <b>pcre_dfa_exec()</b>)
176  value.  returns the negative value.
177  </P>  </P>
178  <P>  <P>
179  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 171  values. In particular, PCRE_ERROR_NOMATC Line 181  values. In particular, PCRE_ERROR_NOMATC
181  The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions;  The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions;
182  it will never be used by PCRE itself.  it will never be used by PCRE itself.
183  </P>  </P>
184    <br><a name="SEC5" href="#TOC1">AUTHOR</a><br>
185  <P>  <P>
186  Last updated: 09 September 2004  Philip Hazel
187    <br>
188    University Computing Service
189    <br>
190    Cambridge CB2 3QH, England.
191    <br>
192    </P>
193    <br><a name="SEC6" href="#TOC1">REVISION</a><br>
194    <P>
195    Last updated: 29 May 2007
196    <br>
197    Copyright &copy; 1997-2007 University of Cambridge.
198  <br>  <br>
 Copyright &copy; 1997-2004 University of Cambridge.  
199  <p>  <p>
200  Return to the <a href="index.html">PCRE index page</a>.  Return to the <a href="index.html">PCRE index page</a>.
201  </p>  </p>

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