@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/searching
@node Searching and Matching, Syntax Tables, Non-ASCII Characters, Top
@end deffn
@deffn Command word-search-forward string &optional limit noerror repeat
-@c @cindex word search Redundant
This function searches forward from point for a ``word'' match for
@var{string}. If it finds a match, it sets point to the end of the
match found, and returns the new value of point.
-@c Emacs 19 feature
Word matching regards @var{string} as a sequence of words, disregarding
punctuation that separates them. It searches the buffer for the same
times. Point is positioned at the end of the last match.
@end deffn
+@deffn Command word-search-forward-lax string &optional limit noerror repeat
+This command is identical to @code{word-search-forward}, except that
+the end of @code{string} need not match a word boundary unless it ends
+in whitespace. For instance, searching for @samp{ball boy} matches
+@samp{ball boyee}, but does not match @samp{aball boy}.
+@end deffn
+
@deffn Command word-search-backward string &optional limit noerror repeat
This function searches backward from point for a word match to
@var{string}. This function is just like @code{word-search-forward}
beginning of the match.
@end deffn
+@deffn Command word-search-backward-lax string &optional limit noerror repeat
+This command is identical to @code{word-search-backward}, except that
+the end of @code{string} need not match a word boundary unless it ends
+in whitespace.
+@end deffn
+
@node Searching and Case
@section Searching and Case
@cindex searching and case
@code{case-fold-search} to @code{nil}. Then all letters must match
exactly, including case. This is a buffer-local variable; altering the
variable affects only the current buffer. (@xref{Intro to
-Buffer-Local}.) Alternatively, you may change the value of
-@code{default-case-fold-search}, which is the default value of
-@code{case-fold-search} for buffers that do not override it.
+Buffer-Local}.) Alternatively, you may change the default value of
+@code{case-fold-search}.
Note that the user-level incremental search feature handles case
-distinctions differently. When given a lower case letter, it looks for
-a match of either case, but when given an upper case letter, it looks
-for an upper case letter only. But this has nothing to do with the
-searching functions used in Lisp code.
+distinctions differently. When the search string contains only lower
+case letters, the search ignores case, but when the search string
+contains one or more upper case letters, the search becomes
+case-sensitive. But this has nothing to do with the searching
+functions used in Lisp code.
+
+@defopt case-fold-search
+This buffer-local variable determines whether searches should ignore
+case. If the variable is @code{nil} they do not ignore case; otherwise
+they do ignore case.
+@end defopt
@defopt case-replace
This variable determines whether the higher level replacement
@code{replace-match}. @xref{Replacing Match}.
@end defopt
-@defopt case-fold-search
-This buffer-local variable determines whether searches should ignore
-case. If the variable is @code{nil} they do not ignore case; otherwise
-they do ignore case.
-@end defopt
-
-@defvar default-case-fold-search
-The value of this variable is the default value for
-@code{case-fold-search} in buffers that do not override it. This is the
-same as @code{(default-value 'case-fold-search)}.
-@end defvar
-
@node Regular Expressions
@section Regular Expressions
@cindex regular expression
@cindex regexp
- A @dfn{regular expression} (@dfn{regexp}, for short) is a pattern that
+ A @dfn{regular expression}, or @dfn{regexp} for short, is a pattern that
denotes a (possibly infinite) set of strings. Searching for matches for
a regexp is a very powerful operation. This section explains how to write
regexps; the following section says how to search for them.
This matches graphic characters---everything except @acronym{ASCII} control
characters, space, and the delete character.
@item [:lower:]
-This matches any lower-case letter, as determined by
-the current case table (@pxref{Case Tables}).
+This matches any lower-case letter, as determined by the current case
+table (@pxref{Case Tables}). If @code{case-fold-search} is
+non-@code{nil}, this also matches any upper-case letter.
@item [:multibyte:]
This matches any multibyte character (@pxref{Text Representations}).
@item [:nonascii:]
@item [:unibyte:]
This matches any unibyte character (@pxref{Text Representations}).
@item [:upper:]
-This matches any upper-case letter, as determined by
-the current case table (@pxref{Case Tables}).
+This matches any upper-case letter, as determined by the current case
+table (@pxref{Case Tables}). If @code{case-fold-search} is
+non-@code{nil}, this also matches any lower-case letter.
@item [:word:]
This matches any character that has word syntax (@pxref{Syntax Class
Table}).
shy groups.
@item \(?: @dots{} \)
+@cindex shy groups
+@cindex non-capturing group
+@cindex unnumbered group
+@cindex @samp{(?:} in regexp
is the @dfn{shy group} construct. A shy group serves the first two
purposes of an ordinary group (controlling the nesting of other
operators), but it does not get a number, so you cannot refer back to
-its value with @samp{\@var{digit}}.
+its value with @samp{\@var{digit}}. Shy groups are particularly
+useful for mechanically-constructed regular expressions, because they
+can be added automatically without altering the numbering of ordinary,
+non-shy groups.
-Shy groups are particularly useful for mechanically-constructed regular
-expressions because they can be added automatically without altering the
-numbering of any ordinary, non-shy groups.
+Shy groups are also called @dfn{non-capturing} or @dfn{unnumbered
+groups}.
@item \(?@var{num}: @dots{} \)
is the @dfn{explicitly numbered group} construct. Normal groups get
matched---for instance, if it appears inside of an alternative that
wasn't used, or inside of a repetition that repeated zero times---then
the corresponding @samp{\@var{digit}} construct never matches
-anything. To use an artificial example,, @samp{\(foo\(b*\)\|lose\)\2}
+anything. To use an artificial example, @samp{\(foo\(b*\)\|lose\)\2}
cannot match @samp{lose}: the second alternative inside the larger
group matches it, but then @samp{\2} is undefined and can't match
anything. But it can match @samp{foobb}, because the first
@defun regexp-opt-depth regexp
This function returns the total number of grouping constructs
-(parenthesized expressions) in @var{regexp}. (This does not include
-shy groups.)
+(parenthesized expressions) in @var{regexp}. This does not include
+shy groups (@pxref{Regexp Backslash}).
@end defun
@node Regexp Search
This is because POSIX backtracking conflicts with the semantics of
non-greedy repetition.
-@defun posix-search-forward regexp &optional limit noerror repeat
+@deffn Command posix-search-forward regexp &optional limit noerror repeat
This is like @code{re-search-forward} except that it performs the full
backtracking specified by the POSIX standard for regular expression
matching.
-@end defun
+@end deffn
-@defun posix-search-backward regexp &optional limit noerror repeat
+@deffn Command posix-search-backward regexp &optional limit noerror repeat
This is like @code{re-search-backward} except that it performs the full
backtracking specified by the POSIX standard for regular expression
matching.
-@end defun
+@end deffn
@defun posix-looking-at regexp
This is like @code{looking-at} except that it performs the full
This section describes some variables that hold regular expressions
used for certain purposes in editing:
-@defvar page-delimiter
+@defopt page-delimiter
This is the regular expression describing line-beginnings that separate
pages. The default value is @code{"^\014"} (i.e., @code{"^^L"} or
@code{"^\C-l"}); this matches a line that starts with a formfeed
character.
-@end defvar
+@end defopt
The following two regular expressions should @emph{not} assume the
match always starts at the beginning of a line; they should not use
@samp{^} would be incorrect. However, a @samp{^} is harmless in modes
where a left margin is never used.
-@defvar paragraph-separate
+@defopt paragraph-separate
This is the regular expression for recognizing the beginning of a line
that separates paragraphs. (If you change this, you may have to
change @code{paragraph-start} also.) The default value is
@w{@code{"[@ \t\f]*$"}}, which matches a line that consists entirely of
spaces, tabs, and form feeds (after its left margin).
-@end defvar
+@end defopt
-@defvar paragraph-start
+@defopt paragraph-start
This is the regular expression for recognizing the beginning of a line
that starts @emph{or} separates paragraphs. The default value is
@w{@code{"\f\\|[ \t]*$"}}, which matches a line containing only
whitespace or starting with a form feed (after its left margin).
-@end defvar
+@end defopt
-@defvar sentence-end
+@defopt sentence-end
If non-@code{nil}, the value should be a regular expression describing
the end of a sentence, including the whitespace following the
sentence. (All paragraph boundaries also end sentences, regardless.)
@code{sentence-end} has to construct the regexp. That is why you
should always call the function @code{sentence-end} to obtain the
regexp to be used to recognize the end of a sentence.
-@end defvar
+@end defopt
@defun sentence-end
This function returns the value of the variable @code{sentence-end},