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revision 191 by ph10, Mon Jul 30 11:13:54 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 601  page. Line 615  page.
615    PCRE_NO_UTF8_CHECK    PCRE_NO_UTF8_CHECK
616  .sp  .sp
617  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is  When PCRE_UTF8 is set, the validity of the pattern as a UTF-8 string is
618  automatically checked. If an invalid UTF-8 sequence of bytes is found,  automatically checked. There is a discussion about the
619  \fBpcre_compile()\fP returns an error. If you already know that your pattern is  .\" HTML <a href="pcre.html#utf8strings">
620  valid, and you want to skip this check for performance reasons, you can set the  .\" </a>
621  PCRE_NO_UTF8_CHECK option. When it is set, the effect of passing an invalid  validity of UTF-8 strings
622  UTF-8 string as a pattern is undefined. It may cause your program to crash.  .\"
623  Note that this option can also be passed to \fBpcre_exec()\fP and  in the main
624  \fBpcre_dfa_exec()\fP, to suppress the UTF-8 validity checking of subject  .\" HREF
625  strings.  \fBpcre\fP
626    .\"
627    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_compile()\fP
628    returns an error. If you already know that your pattern is valid, and you want
629    to skip this check for performance reasons, you can set the PCRE_NO_UTF8_CHECK
630    option. When it is set, the effect of passing an invalid UTF-8 string as a
631    pattern is undefined. It may cause your program to crash. Note that this option
632    can also be passed to \fBpcre_exec()\fP and \fBpcre_dfa_exec()\fP, to suppress
633    the UTF-8 validity checking of subject strings.
634  .  .
635  .  .
636  .SH "COMPILATION ERROR CODES"  .SH "COMPILATION ERROR CODES"
# Line 669  out of use. To avoid confusion, they hav Line 691  out of use. To avoid confusion, they hav
691    47  unknown property name after \eP or \ep    47  unknown property name after \eP or \ep
692    48  subpattern name is too long (maximum 32 characters)    48  subpattern name is too long (maximum 32 characters)
693    49  too many named subpatterns (maximum 10,000)    49  too many named subpatterns (maximum 10,000)
694    50  repeated subpattern is too long    50  [this code is not in use]
695    51  octal value is greater than \e377 (not in UTF-8 mode)    51  octal value is greater than \e377 (not in UTF-8 mode)
696    52  internal error: overran compiling workspace    52  internal error: overran compiling workspace
697    53  internal error: previously-checked referenced subpattern not found    53  internal error: previously-checked referenced subpattern not found
# Line 874  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 947  matching is used. Line 974  matching is used.
974  Return a copy of the options with which the pattern was compiled. The fourth  Return a copy of the options with which the pattern was compiled. The fourth
975  argument should point to an \fBunsigned long int\fP variable. These option bits  argument should point to an \fBunsigned long int\fP variable. These option bits
976  are those specified in the call to \fBpcre_compile()\fP, modified by any  are those specified in the call to \fBpcre_compile()\fP, modified by any
977  top-level option settings within the pattern itself.  top-level option settings at the start of the pattern itself. In other words,
978    they are the options that will be in force when matching starts. For example,
979    if the pattern /(?im)abc(?-i)d/ is compiled with the PCRE_EXTENDED option, the
980    result is PCRE_CASELESS, PCRE_MULTILINE, and PCRE_EXTENDED.
981  .P  .P
982  A pattern is automatically anchored by PCRE if all of its top-level  A pattern is automatically anchored by PCRE if all of its top-level
983  alternatives begin with one of the following:  alternatives begin with one of the following:
# Line 1158  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 1183  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    CRLF sequence, and the pattern contains no explicit matches for CR or NL
1222    characters, the match position is advanced by two characters instead of one, in
1223    other words, to after the CRLF.
1224    .P
1225    The above rule is a compromise that makes the most common cases work as
1226    expected. For example, if the pattern is .+A (and the PCRE_DOTALL option is not
1227    set), it does not match the string "\er\enA" because, after failing at the
1228    start, it skips both the CR and the LF before retrying. However, the pattern
1229    [\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 1229  code that demonstrates how to do this in Line 1275  code that demonstrates how to do this in
1275  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8  When PCRE_UTF8 is set at compile time, the validity of the subject as a UTF-8
1276  string is automatically checked when \fBpcre_exec()\fP is subsequently called.  string is automatically checked when \fBpcre_exec()\fP is subsequently called.
1277  The value of \fIstartoffset\fP is also checked to ensure that it points to the  The value of \fIstartoffset\fP is also checked to ensure that it points to the
1278  start of a UTF-8 character. If an invalid UTF-8 sequence of bytes is found,  start of a UTF-8 character. There is a discussion about the validity of UTF-8
1279  \fBpcre_exec()\fP returns the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP  strings in the
1280  contains an invalid value, PCRE_ERROR_BADUTF8_OFFSET is returned.  .\" HTML <a href="pcre.html#utf8strings">
1281    .\" </a>
1282    section on UTF-8 support
1283    .\"
1284    in the main
1285    .\" HREF
1286    \fBpcre\fP
1287    .\"
1288    page. If an invalid UTF-8 sequence of bytes is found, \fBpcre_exec()\fP returns
1289    the error PCRE_ERROR_BADUTF8. If \fIstartoffset\fP contains an invalid value,
1290    PCRE_ERROR_BADUTF8_OFFSET is returned.
1291  .P  .P
1292  If you already know that your subject is valid, and you want to skip these  If you already know that your subject is valid, and you want to skip these
1293  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when  checks for performance reasons, you can set the PCRE_NO_UTF8_CHECK option when
# Line 1463  The internal recursion limit, as specifi Line 1519  The internal recursion limit, as specifi
1519  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the  field in a \fBpcre_extra\fP structure (or defaulted) was reached. See the
1520  description above.  description above.
1521  .sp  .sp
   PCRE_ERROR_NULLWSLIMIT    (-22)  
 .sp  
 When a parenthesized subpattern that can match an empty substring is repeated  
 with an unbounded upper limit, the subject position at the start of the group  
 must be remembered, so that a test for an empty string can be made when the end  
 of the group is reached. The repetition loop is automatically terminated when  
 an empty string is matched.  
 .P  
 Some workspace is required for remembering the starting position. For most  
 capturing subpatterns, an internal recursive call of the match() function is  
 used, and in this case, the workspace is taken from the runtime stack. However,  
 for non-capturing subpatterns, this is not available. Instead, some fixed  
 workspace (taken from the top-level stack) is used. If it runs out, the  
 PCRE_ERROR_NULLWSLIMIT error is given. The size of the fixed workspace allows  
 for up to 1000 repetitions of a non-capturing subpattern that might match an  
 empty string. If this limit is a problem for you, you can sometimes get round  
 it by changing a non-capturing subpattern into a capturing one, but that will  
 increase the amount of runtime stack that is used.  
 .sp  
1522    PCRE_ERROR_BADNEWLINE     (-23)    PCRE_ERROR_BADNEWLINE     (-23)
1523  .sp  .sp
1524  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.  An invalid combination of PCRE_NEWLINE_\fIxxx\fP options was given.
1525  .P  .P
1526  Error numbers -16 to -20 are not used by \fBpcre_exec()\fP.  Error numbers -16 to -20 and -22 are not used by \fBpcre_exec()\fP.
1527  .  .
1528  .  .
1529  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"  .SH "EXTRACTING CAPTURED SUBSTRINGS BY NUMBER"
# Line 1651  example is shown in the Line 1688  example is shown in the
1688  .\" HREF  .\" HREF
1689  \fBpcrepattern\fP  \fBpcrepattern\fP
1690  .\"  .\"
1691  documentation. When duplicates are present, \fBpcre_copy_named_substring()\fP  documentation.
1692  and \fBpcre_get_named_substring()\fP return the first substring corresponding  .P
1693  to the given name that is set. If none are set, an empty string is returned.  When duplicates are present, \fBpcre_copy_named_substring()\fP and
1694  The \fBpcre_get_stringnumber()\fP function returns one of the numbers that are  \fBpcre_get_named_substring()\fP return the first substring corresponding to
1695  associated with the name, but it is not defined which it is.  the given name that is set. If none are set, PCRE_ERROR_NOSUBSTRING (-7) is
1696  .sp  returned; no data is returned. The \fBpcre_get_stringnumber()\fP function
1697    returns one of the numbers that are associated with the name, but it is not
1698    defined which it is.
1699    .P
1700  If you want to get full details of all captured substrings for a given name,  If you want to get full details of all captured substrings for a given name,
1701  you must use the \fBpcre_get_stringtable_entries()\fP function. The first  you must use the \fBpcre_get_stringtable_entries()\fP function. The first
1702  argument is the compiled pattern, and the second is the name. The third and  argument is the compiled pattern, and the second is the name. The third and
# Line 1881  Cambridge CB2 3QH, England. Line 1921  Cambridge CB2 3QH, England.
1921  .rs  .rs
1922  .sp  .sp
1923  .nf  .nf
1924  Last updated: 30 July 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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