@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990-1995, 1998-1999, 2001-2012
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2013 Free Software
+@c Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@node Searching and Matching
@chapter Searching and Matching
matches upper-case letters. Note that a range like @samp{[a-z]} is
not affected by the locale's collation sequence, it always represents
a sequence in @acronym{ASCII} order.
-@c This wasn't obvious to me, since eg the grep manual "Character
+@c This wasn't obvious to me, since, e.g., the grep manual "Character
@c Classes and Bracket Expressions" specifically notes the opposite
@c behavior. But by experiment Emacs seems unaffected by LC_COLLATE
@c in this regard.
their number implicitly, based on their position, which can be
inconvenient. This construct allows you to force a particular group
number. There is no particular restriction on the numbering,
-e.g.@: you can have several groups with the same number in which case
-the last one to match (i.e.@: the rightmost match) will win.
+e.g., you can have several groups with the same number in which case
+the last one to match (i.e., the rightmost match) will win.
Implicitly numbered groups always get the smallest integer larger than
the one of any previous group.
guarantee that its result is absolutely the most efficient form
possible. A hand-tuned regular expression can sometimes be slightly
more efficient, but is almost never worth the effort.}.
-@c See eg http://debbugs.gnu.org/2816
+@c E.g., see http://debbugs.gnu.org/2816
If the optional argument @var{paren} is non-@code{nil}, then the
returned regular expression is always enclosed by at least one
full backtracking specified by the POSIX standard for regular expression
matching. They continue backtracking until they have tried all
possibilities and found all matches, so they can report the longest
-match, as required by POSIX. This is much slower, so use these
+match, as required by POSIX@. This is much slower, so use these
functions only when you really need the longest match.
The POSIX search and match functions do not properly support the
@table @asis
@item @samp{\&}
@cindex @samp{&} in replacement
-@samp{\&} stands for the entire text being replaced.
+This stands for the entire text being replaced.
-@item @samp{\@var{n}}
+@item @samp{\@var{n}}, where @var{n} is a digit
@cindex @samp{\@var{n}} in replacement
-@samp{\@var{n}}, where @var{n} is a digit, stands for the text that
-matched the @var{n}th subexpression in the original regexp.
-Subexpressions are those expressions grouped inside @samp{\(@dots{}\)}.
-If the @var{n}th subexpression never matched, an empty string is substituted.
+This stands for the text that matched the @var{n}th subexpression in
+the original regexp. Subexpressions are those expressions grouped
+inside @samp{\(@dots{}\)}. If the @var{n}th subexpression never
+matched, an empty string is substituted.
@item @samp{\\}
@cindex @samp{\} in replacement
-@samp{\\} stands for a single @samp{\} in the replacement text.
+This stands for a single @samp{\} in the replacement text.
+
+@item @samp{\?}
+This stands for itself (for compatibility with @code{replace-regexp}
+and related commands; @pxref{Regexp Replacement,,, emacs, The GNU
+Emacs Manual}).
@end table
-These substitutions occur after case conversion, if any,
-so the strings they substitute are never case-converted.
+@noindent
+Any other character following @samp{\} signals an error.
+
+The substitutions performed by @samp{\&} and @samp{\@var{n}} occur
+after case conversion, if any. Therefore, the strings they substitute
+are never case-converted.
If @var{subexp} is non-@code{nil}, that says to replace just
subexpression number @var{subexp} of the regexp that was matched, not
may save and restore the match data (@pxref{Saving Match Data}) around
the call to functions that could perform another search. Or use the
functions that explicitly do not modify the match data;
-e.g. @code{string-match-p}.
+e.g., @code{string-match-p}.
@c This is an old comment and presumably there is no prospect of this
@c changing now. But still the advice stands.
HCoop / bpt / emacs.git / blobdiff