/[pcre]/code/trunk/doc/pcrebuild.3
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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC
# Line 100  to the \fBconfigure\fP command. Line 100  to the \fBconfigure\fP command.
100  .rs  .rs
101  .sp  .sp
102  Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly  Internally, PCRE has a function called \fBmatch()\fP, which it calls repeatedly
103  (possibly recursively) when matching a pattern. By controlling the maximum  (possibly recursively) when matching a pattern with the \fBpcre_exec()\fP
104  number of times this function may be called during a single matching operation,  function. By controlling the maximum number of times this function may be
105  a limit can be placed on the resources used by a single call to  called during a single matching operation, a limit can be placed on the
106  \fBpcre_exec()\fP. The limit can be changed at run time, as described in the  resources used by a single call to \fBpcre_exec()\fP. The limit can be changed
107    at run time, as described in the
108  .\" HREF  .\" HREF
109  \fBpcreapi\fP  \fBpcreapi\fP
110  .\"  .\"
# Line 112  setting such as Line 113  setting such as
113  .sp  .sp
114    --with-match-limit=500000    --with-match-limit=500000
115  .sp  .sp
116  to the \fBconfigure\fP command.  to the \fBconfigure\fP command. This setting has no effect on the
117    \fBpcre_dfa_exec()\fP matching function.
118  .  .
119  .SH "HANDLING VERY LARGE PATTERNS"  .SH "HANDLING VERY LARGE PATTERNS"
120  .rs  .rs
# Line 138  of the compiled pattern, and this change Line 140  of the compiled pattern, and this change
140  .SH "AVOIDING EXCESSIVE STACK USAGE"  .SH "AVOIDING EXCESSIVE STACK USAGE"
141  .rs  .rs
142  .sp  .sp
143  PCRE implements backtracking while matching by making recursive calls to an  When matching with the \fBpcre_exec()\fP function, PCRE implements backtracking
144  internal function called \fBmatch()\fP. In environments where the size of the  by making recursive calls to an internal function called \fBmatch()\fP. In
145  stack is limited, this can severely limit PCRE's operation. (The Unix  environments where the size of the stack is limited, this can severely limit
146  environment does not usually suffer from this problem.) An alternative approach  PCRE's operation. (The Unix environment does not usually suffer from this
147  that uses memory from the heap to remember data, instead of using recursive  problem.) An alternative approach that uses memory from the heap to remember
148  function calls, has been implemented to work round this problem. If you want to  data, instead of using recursive function calls, has been implemented to work
149  build a version of PCRE that works this way, add  round this problem. If you want to build a version of PCRE that works this way,
150    add
151  .sp  .sp
152    --disable-stack-for-recursion    --disable-stack-for-recursion
153  .sp  .sp
# Line 155  predictable: the block sizes requested a Line 158  predictable: the block sizes requested a
158  always freed in reverse order. A calling program might be able to implement  always freed in reverse order. A calling program might be able to implement
159  optimized functions that perform better than the standard \fBmalloc()\fP and  optimized functions that perform better than the standard \fBmalloc()\fP and
160  \fBfree()\fP functions. PCRE runs noticeably more slowly when built in this  \fBfree()\fP functions. PCRE runs noticeably more slowly when built in this
161  way.  way. This option affects only the \fBpcre_exec()\fP function; it is not
162    relevant for the the \fBpcre_dfa_exec()\fP function.
163  .  .
164  .SH "USING EBCDIC CODE"  .SH "USING EBCDIC CODE"
165  .rs  .rs
# Line 169  compiled to run in an EBCDIC environment Line 173  compiled to run in an EBCDIC environment
173  to the \fBconfigure\fP command.  to the \fBconfigure\fP command.
174  .P  .P
175  .in 0  .in 0
176  Last updated: 09 September 2004  Last updated: 28 February 2005
177  .br  .br
178  Copyright (c) 1997-2004 University of Cambridge.  Copyright (c) 1997-2005 University of Cambridge.
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