Match Structures
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A "match structure" is the object returned by `string-match' and
`regexp-exec'. It describes which portion of a string, if any, matched
the given regular expression. Match structures include: a reference to
the string that was checked for matches; the starting and ending
positions of the regexp match; and, if the regexp included any
parenthesized subexpressions, the starting and ending positions of each
submatch.
In each of the regexp match functions described below, the `match'
argument must be a match structure returned by a previous call to
`string-match' or `regexp-exec'. Most of these functions return some
information about the original target string that was matched against a
regular expression; we will call that string TARGET for easy reference.
- procedure: regexp-match? obj
Return `#t' if OBJ is a match structure returned by a previous
call to `regexp-exec', or `#f' otherwise.
- procedure: match:substring match [n]
Return the portion of TARGET matched by subexpression number N.
Submatch 0 (the default) represents the entire regexp match. If
the regular expression as a whole matched, but the subexpression
number N did not match, return `#f'.
- procedure: match:start match [n]
Return the starting position of submatch number N.
- procedure: match:end match [n]
Return the ending position of submatch number N.
- procedure: match:prefix match
Return the unmatched portion of TARGET preceding the regexp match.
- procedure: match:suffix match
Return the unmatched portion of TARGET following the regexp match.
- procedure: match:count match
Return the number of parenthesized subexpressions from MATCH.
Note that the entire regular expression match itself counts as a
subexpression, and failed submatches are included in the count.
- procedure: match:string match
Return the original TARGET string.