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revision 468 by ph10, Mon Oct 5 10:59:35 2009 UTC revision 469 by ph10, Mon Oct 19 14:38:48 2009 UTC
# Line 165  so returns that when PCRE_PARTIAL_HARD i Line 165  so returns that when PCRE_PARTIAL_HARD i
165  </P>  </P>
166  <br><a name="SEC4" href="#TOC1">PARTIAL MATCHING AND WORD BOUNDARIES</a><br>  <br><a name="SEC4" href="#TOC1">PARTIAL MATCHING AND WORD BOUNDARIES</a><br>
167  <P>  <P>
168  If a pattern ends with one of sequences \w or \W, which test for word  If a pattern ends with one of sequences \b or \B, which test for word
169  boundaries, partial matching with PCRE_PARTIAL_SOFT can give counter-intuitive  boundaries, partial matching with PCRE_PARTIAL_SOFT can give counter-intuitive
170  results. Consider this pattern:  results. Consider this pattern:
171  <pre>  <pre>
# Line 269  Consider an unanchored pattern that matc Line 269  Consider an unanchored pattern that matc
269    data&#62; The date is 23ja\P    data&#62; The date is 23ja\P
270    Partial match: 23ja    Partial match: 23ja
271  </pre>  </pre>
272  The this stage, an application could discard the text preceding "23ja", add on  At this stage, an application could discard the text preceding "23ja", add on
273  text from the next segment, and call <b>pcre_exec()</b> again. Unlike  text from the next segment, and call <b>pcre_exec()</b> again. Unlike
274  <b>pcre_dfa_exec()</b>, the entire matching string must always be available, and  <b>pcre_dfa_exec()</b>, the entire matching string must always be available, and
275  the complete matching process occurs for each call, so more memory and more  the complete matching process occurs for each call, so more memory and more
# Line 347  matching multi-segment data. The example Line 347  matching multi-segment data. The example
347  <P>  <P>
348  4. Patterns that contain alternatives at the top level which do not all  4. Patterns that contain alternatives at the top level which do not all
349  start with the same pattern item may not work as expected when  start with the same pattern item may not work as expected when
350  <b>pcre_dfa_exec()</b> is used. For example, consider this pattern:  PCRE_DFA_RESTART is used with <b>pcre_dfa_exec()</b>. For example, consider this
351    pattern:
352  <pre>  <pre>
353    1234|3789    1234|3789
354  </pre>  </pre>
# Line 363  patterns or patterns such as: Line 364  patterns or patterns such as:
364    1234|ABCD    1234|ABCD
365  </pre>  </pre>
366  where no string can be a partial match for both alternatives. This is not a  where no string can be a partial match for both alternatives. This is not a
367  problem if \fPpcre_exec()\fP is used, because the entire match has to be rerun  problem if <b>pcre_exec()</b> is used, because the entire match has to be rerun
368  each time:  each time:
369  <pre>  <pre>
370      re&#62; /1234|3789/      re&#62; /1234|3789/
# Line 371  each time: Line 372  each time:
372    Partial match: 123    Partial match: 123
373    data&#62; 1237890    data&#62; 1237890
374     0: 3789     0: 3789
375    </pre>
376  </PRE>  Of course, instead of using PCRE_DFA_PARTIAL, the same technique of re-running
377    the entire match can also be used with <b>pcre_dfa_exec()</b>. Another
378    possibility is to work with two buffers. If a partial match at offset <i>n</i>
379    in the first buffer is followed by "no match" when PCRE_DFA_RESTART is used on
380    the second buffer, you can then try a new match starting at offset <i>n+1</i> in
381    the first buffer.
382  </P>  </P>
383  <br><a name="SEC10" href="#TOC1">AUTHOR</a><br>  <br><a name="SEC10" href="#TOC1">AUTHOR</a><br>
384  <P>  <P>
# Line 385  Cambridge CB2 3QH, England. Line 391  Cambridge CB2 3QH, England.
391  </P>  </P>
392  <br><a name="SEC11" href="#TOC1">REVISION</a><br>  <br><a name="SEC11" href="#TOC1">REVISION</a><br>
393  <P>  <P>
394  Last updated: 29 September 2009  Last updated: 19 October 2009
395  <br>  <br>
396  Copyright &copy; 1997-2009 University of Cambridge.  Copyright &copy; 1997-2009 University of Cambridge.
397  <br>  <br>
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