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(Entire Match Data): Clarify when match-data

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returns markers and when integers.
This commit is contained in:
Richard M. Stallman 2005-06-08 15:34:13 +00:00
parent b74f585b6b
commit 8135a25a77
1 changed files with 16 additions and 17 deletions
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33
lispref/searching.texi
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@ -1486,12 +1486,13 @@ character of the buffer counts as 1.)
write the entire match data, all at once.
@defun match-data &optional integers reuse
This function returns a newly constructed list containing all the
information on what text the last search matched. Element zero is the
position of the beginning of the match for the whole expression; element
one is the position of the end of the match for the expression. The
next two elements are the positions of the beginning and end of the
match for the first subexpression, and so on. In general, element
This function returns a list of positions (markers or integers) that
record all the information on what text the last search matched.
Element zero is the position of the beginning of the match for the
whole expression; element one is the position of the end of the match
for the expression. The next two elements are the positions of the
beginning and end of the match for the first subexpression, and so on.
In general, element
@ifnottex
number 2@var{n}
@end ifnottex
@ -1508,15 +1509,13 @@ number {\mathsurround=0pt $2n+1$}
@end tex
corresponds to @code{(match-end @var{n})}.
All the elements are markers or @code{nil} if matching was done on a
buffer and all are integers or @code{nil} if matching was done on a
string with @code{string-match}. If @var{integers} is
non-@code{nil}, then the elements are integers or @code{nil}, even if
matching was done on a buffer. In that case, the buffer itself is
appended as an additional element at the end of the list
to facilitate complete restoration of the match data. Also,
@code{match-beginning} and
@code{match-end} always return integers or @code{nil}.
Normally all the elements are markers or @code{nil}, but if
@var{integers} is non-@code{nil}, that means to use integers instead
of markers. (In that case, the buffer itself is appended as an
additional element at the end of the list, to facilitate complete
restoration of the match data.) If the last match was done on a
string with @code{string-match}, then integers are always used,
since markers can't point into a string.
If @var{reuse} is non-@code{nil}, it should be a list. In that case,
@code{match-data} stores the match data in @var{reuse}. That is,
@ -1524,8 +1523,8 @@ If @var{reuse} is non-@code{nil}, it should be a list. In that case,
have the right length. If it is not long enough to contain the match
data, it is extended. If it is too long, the length of @var{reuse}
stays the same, but the elements that were not used are set to
@code{nil}. The purpose of this feature is to avoid producing too
much garbage, that would later have to be collected.
@code{nil}. The purpose of this feature is to reduce the need for
garbage collection.
As always, there must be no possibility of intervening searches between
the call to a search function and the call to @code{match-data} that is