8 
\fBmatch()\fP. This calls itself recursively at branch points in the pattern, 
\fBmatch()\fP. This calls itself recursively at branch points in the pattern, 
9 
in order to remember the state of the match so that it can back up and try a 
in order to remember the state of the match so that it can back up and try a 
10 
different alternative if the first one fails. As matching proceeds deeper and 
different alternative if the first one fails. As matching proceeds deeper and 
11 
deeper into the tree of possibilities, the recursion depth increases. 
deeper into the tree of possibilities, the recursion depth increases. The 
12 

\fBmatch()\P function is also called in other circumstances, for example, 
13 

whenever a parenthesized subpattern is entered, and in certain cases of 
14 

repetition. 
15 
.P 
.P 
16 
Not all calls of \fBmatch()\fP increase the recursion depth; for an item such 
Not all calls of \fBmatch()\fP increase the recursion depth; for an item such 
17 
as a* it may be called several times at the same level, after matching 
as a* it may be called several times at the same level, after matching 
173 
.rs 
.rs 
174 
.sp 
.sp 
175 
.nf 
.nf 
176 
Last updated: 03 January 2010 
Last updated: 22 July 2011 
177 
Copyright (c) 19972010 University of Cambridge. 
Copyright (c) 19972011 University of Cambridge. 
178 
.fi 
.fi 