/[pcre]/code/trunk/doc/pcreapi.3
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revision 225 by ph10, Mon Aug 20 14:38:34 2007 UTC revision 227 by ph10, Tue Aug 21 15:00:15 2007 UTC
# Line 218  points during a matching operation. Deta Line 218  points during a matching operation. Deta
218  documentation.  documentation.
219  .  .
220  .  .
221    .\" HTML <a name="newlines"></a>
222  .SH NEWLINES  .SH NEWLINES
223  .rs  .rs
224  .sp  .sp
# Line 235  The default default is LF, which is the Line 236  The default default is LF, which is the
236  default can be overridden, either when a pattern is compiled, or when it is  default can be overridden, either when a pattern is compiled, or when it is
237  matched.  matched.
238  .P  .P
239    At compile time, the newline convention can be specified by the \fIoptions\fP
240    argument of \fBpcre_compile()\fP, or it can be specified by special text at the
241    start of the pattern itself; this overrides any other settings. See the
242    .\" HREF
243    \fBpcrepattern\fP
244    .\"
245    page for details of the special character sequences.
246    .P
247  In the PCRE documentation the word "newline" is used to mean "the character or  In the PCRE documentation the word "newline" is used to mean "the character or
248  pair of characters that indicate a line break". The choice of newline  pair of characters that indicate a line break". The choice of newline
249  convention affects the handling of the dot, circumflex, and dollar  convention affects the handling of the dot, circumflex, and dollar
250  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a  metacharacters, the handling of #-comments in /x mode, and, when CRLF is a
251  recognized line ending sequence, the match position advancement for a  recognized line ending sequence, the match position advancement for a
252  non-anchored pattern. The choice of newline convention does not affect the  non-anchored pattern. There is more detail about this in the
253  interpretation of the \en or \er escape sequences.  .\" HTML <a href="#execoptions">
254    .\" </a>
255    section on \fBpcre_exec()\fP options
256    .\"
257    below. The choice of newline convention does not affect the interpretation of
258    the \en or \er escape sequences.
259  .  .
260  .  .
261  .SH MULTITHREADING  .SH MULTITHREADING
# Line 882  table indicating a fixed set of bytes fo Line 896  table indicating a fixed set of bytes fo
896  string, a pointer to the table is returned. Otherwise NULL is returned. The  string, a pointer to the table is returned. Otherwise NULL is returned. The
897  fourth argument should point to an \fBunsigned char *\fP variable.  fourth argument should point to an \fBunsigned char *\fP variable.
898  .sp  .sp
899      PCRE_INFO_HASCRORLF
900    .sp
901    Return 1 if the pattern contains any explicit matches for CR or LF characters,
902    otherwise 0. The fourth argument should point to an \fBint\fP variable.
903    .sp
904    PCRE_INFO_JCHANGED    PCRE_INFO_JCHANGED
905  .sp  .sp
906  Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The  Return 1 if the (?J) option setting is used in the pattern, otherwise 0. The
# Line 1169  called. See the Line 1188  called. See the
1188  .\"  .\"
1189  documentation for a discussion of saving compiled patterns for later use.  documentation for a discussion of saving compiled patterns for later use.
1190  .  .
1191    .\" HTML <a name="execoptions"></a>
1192  .SS "Option bits for \fBpcre_exec()\fP"  .SS "Option bits for \fBpcre_exec()\fP"
1193  .rs  .rs
1194  .sp  .sp
# Line 1194  the pattern was compiled. For details, s Line 1214  the pattern was compiled. For details, s
1214  \fBpcre_compile()\fP above. During matching, the newline choice affects the  \fBpcre_compile()\fP above. During matching, the newline choice affects the
1215  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter  behaviour of the dot, circumflex, and dollar metacharacters. It may also alter
1216  the way the match position is advanced after a match failure for an unanchored  the way the match position is advanced after a match failure for an unanchored
1217  pattern. When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is  pattern.
1218  set, and a match attempt fails when the current position is at a CRLF sequence,  .P
1219  the match position is advanced by two characters instead of one, in other  When PCRE_NEWLINE_CRLF, PCRE_NEWLINE_ANYCRLF, or PCRE_NEWLINE_ANY is set, and a
1220  words, to after the CRLF.  match attempt for an unanchored pattern fails when the current position is at a
1221  .P  CRLF sequence, and the pattern contains no explicit matches for CR or NL
1222  Anomalous effects can occur when CRLF is a valid newline sequence and explicit  characters, the match position is advanced by two characters instead of one, in
1223  \er or \en escapes appear in the pattern. For example, the string "\er\enA"  other words, to after the CRLF.
1224  matches the unanchored pattern \enA but not [X\en]A. This happens because, in  .P
1225  the first case, PCRE knows that the match must start with \en, and so it skips  The above rule is a compromise that makes the most common cases work as
1226  there before trying to match. In the second case, it has no knowledge about the  expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1227  starting character, so it starts matching at the beginning of the string, and  set), it does not match the string "\er\enA" because, after failing at the
1228  on failing, skips over the CRLF as described above. However, if the pattern is  start, it skips both the CR and the LF before retrying. However, the pattern
1229  studied, the match succeeds, because then PCRE once again knows where to start.  [\er\en]A does match that string, because it contains an explicit CR or LF
1230    reference, and so advances only by one character after the first failure.
1231    Note than an explicit CR or LF reference occurs for negated character classes
1232    such as [^X] because they can match CR or LF characters.
1233    .P
1234    Notwithstanding the above, anomalous effects may still occur when CRLF is a
1235    valid newline sequence and explicit \er or \en escapes appear in the pattern.
1236  .sp  .sp
1237    PCRE_NOTBOL    PCRE_NOTBOL
1238  .sp  .sp
# Line 1895  Cambridge CB2 3QH, England. Line 1921  Cambridge CB2 3QH, England.
1921  .rs  .rs
1922  .sp  .sp
1923  .nf  .nf
1924  Last updated: 20 August 2007  Last updated: 21 August 2007
1925  Copyright (c) 1997-2007 University of Cambridge.  Copyright (c) 1997-2007 University of Cambridge.
1926  .fi  .fi
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