@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
+@c 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
search is repeated that many times (each time starting at the end of the
previous time's match). If these successive searches succeed, the
function succeeds, moving point and returning its new value. Otherwise
-the search fails.
+the search fails, leaving point where it started.
@end deffn
@deffn Command search-backward string &optional limit noerror repeat
preceding expression either once or not at all. For example,
@samp{ca?r} matches @samp{car} or @samp{cr}; nothing else.
+@item @samp{*?}, @samp{+?}, @samp{??}
+These are ``non-greedy'' variants of the operators @samp{*}, @samp{+}
+and @samp{?}. Where those operators match the largest possible
+substring (consistent with matching the entire containing expression),
+the non-greedy variants match the smallest possible substring
+(consistent with matching the entire containing expression).
+
+For example, the regular expression @samp{c[ad]*a} when applied to the
+string @samp{cdaaada} matches the whole string; but the regular
+expression @samp{c[ad]*?a}, applied to that same string, matches just
+@samp{cda}. (The smallest possible match here for @samp{[ad]*?} that
+permits the whole expression to match is @samp{d}.)
+
@item @samp{[ @dots{} ]}
@cindex character alternative (in regexp)
@cindex @samp{[} in regexp
To include @samp{^} in a character alternative, put it anywhere but at
the beginning.
-The beginning and end of a range must be in the same character set
-(@pxref{Character Sets}). Thus, @samp{[a-\x8e0]} is invalid because
-@samp{a} is in the @sc{ascii} character set but the character 0x8e0
-(@samp{a} with grave accent) is in the Emacs character set for Latin-1.
-
+The beginning and end of a range of multibyte characters must be in
+the same character set (@pxref{Character Sets}). Thus,
+@code{"[\x8e0-\x97c]"} is invalid because character 0x8e0 (@samp{a}
+with grave accent) is in the Emacs character set for Latin-1 but the
+character 0x97c (@samp{u} with diaeresis) is in the Emacs character
+set for Latin-2. (We use Lisp string syntax to write that example,
+and a few others in the next few paragraphs, in order to include hex
+escape sequences in them.)
+
+If a range starts with a unibyte character @var{c} and ends with a
+multibyte character @var{c2}, the range is divided into two parts: one
+is @samp{@var{c}..?\377}, the other is @samp{@var{c1}..@var{c2}}, where
+@var{c1} is the first character of the charset to which @var{c2}
+belongs.
+
You cannot always match all non-@sc{ascii} characters with the regular
-expression @samp{[\200-\377]}. This works when searching a unibyte
+expression @code{"[\200-\377]"}. This works when searching a unibyte
buffer or string (@pxref{Text Representations}), but not in a multibyte
buffer or string, because many non-@sc{ascii} characters have codes
-above octal 0377. However, the regular expression @samp{[^\000-\177]}
+above octal 0377. However, the regular expression @code{"[^\000-\177]"}
does match all non-@sc{ascii} characters (see below regarding @samp{^}),
in both multibyte and unibyte representations, because only the
@sc{ascii} characters are excluded.
the beginning of a line.
When matching a string instead of a buffer, @samp{^} matches at the
-beginning of the string or after a newline character @samp{\n}.
+beginning of the string or after a newline character.
For historical compatibility reasons, @samp{^} can be used only at the
beginning of the regular expression, or after @samp{\(} or @samp{\|}.
@samp{x+$} matches a string of one @samp{x} or more at the end of a line.
When matching a string instead of a buffer, @samp{$} matches at the end
-of the string or before a newline character @samp{\n}.
+of the string or before a newline character.
For historical compatibility reasons, @samp{$} can be used only at the
end of the regular expression, or before @samp{\)} or @samp{\|}.
@table @samp
@item [:ascii:]
-This matches any ASCII (unibyte) character.
+This matches any @sc{ascii} (unibyte) character.
@item [:alnum:]
This matches any letter or digit. (At present, for multibyte
characters, it matches anything that has word syntax.)
@item [:blank:]
This matches space and tab only.
@item [:cntrl:]
-This matches any ASCII control character.
+This matches any @sc{ascii} control character.
@item [:digit:]
This matches @samp{0} through @samp{9}. Thus, @samp{[-+[:digit:]]}
matches any digit, as well as @samp{+} and @samp{-}.
@item [:graph:]
-This matches graphic characters---everything except ASCII control characters,
-space, and DEL.
+This matches graphic characters---everything except @sc{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}).
@item [:nonascii:]
-This matches any non-ASCII (multibyte) character.
+This matches any non-@sc{ascii} (multibyte) character.
@item [:print:]
-This matches printing characters---everything except ASCII control
-characters and DEL.
+This matches printing characters---everything except @sc{ascii} control
+characters and the delete character.
@item [:punct:]
This matches any punctuation character. (At present, for multibyte
characters, it matches anything that has non-word syntax.)
surrounding @samp{\( @dots{} \)} grouping can limit the grouping power of
@samp{\|}.@refill
-Full backtracking capability exists to handle multiple uses of
-@samp{\|}, if you use the POSIX regular expression functions
-(@pxref{POSIX Regexps}).
+If you need full backtracking capability to handle multiple uses of
+@samp{\|}, use the POSIX regular expression functions (@pxref{POSIX
+Regexps}).
+
+@item \@{@var{m}\@}
+is a postfix operator that repeats the previous pattern exactly @var{m}
+times. Thus, @samp{x\@{5\@}} matches the string @samp{xxxxx}
+and nothing else. @samp{c[ad]\@{3\@}r} matches string such as
+@samp{caaar}, @samp{cdddr}, @samp{cadar}, and so on.
+
+@item \@{@var{m},@var{n}\@}
+is more general postfix operator that specifies repetition with a
+minimum of @var{m} repeats and a maximum of @var{n} repeats. If @var{m}
+is omitted, the minimum is 0; if @var{n} is omitted, there is no
+maximum.
+
+For example, @samp{c[ad]\@{1,2\@}r} matches the strings @samp{car},
+@samp{cdr}, @samp{caar}, @samp{cadr}, @samp{cdar}, and @samp{cddr}, and
+nothing else.@*
+@samp{\@{0,1\@}} or @samp{\@{,1\@}} is equivalent to @samp{?}. @*
+@samp{\@{0,\@}} or @samp{\@{,\@}} is equivalent to @samp{*}. @*
+@samp{\@{1,\@}} is equivalent to @samp{+}.
@item \( @dots{} \)
@cindex @samp{(} in regexp
number (zero or more) of @samp{na} strings.
@item
-To record a matched substring for future reference.
+To record a matched substring for future reference with
+@samp{\@var{digit}} (see below).
@end enumerate
This last application is not a consequence of the idea of a
-parenthetical grouping; it is a separate feature that happens to be
-assigned as a second meaning to the same @samp{\( @dots{} \)} construct
-because there is no conflict in practice between the two meanings.
-Here is an explanation of this feature:
+parenthetical grouping; it is a separate feature that was assigned as a
+second meaning to the same @samp{\( @dots{} \)} construct because, in
+practice, there was usually no conflict between the two meanings. But
+occasionally there is a conflict, and that led to the introduction of
+shy groups.
+
+@item \(?: @dots{} \)
+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}}.
+
+Shy groups are particulary useful for mechanically-constructed regular
+expressions because they can be added automatically without altering the
+numbering of any ordinary, non-shy groups.
@item \@var{digit}
matches the same text that matched the @var{digit}th occurrence of a
-@samp{\( @dots{} \)} construct.
+grouping (@samp{\( @dots{} \)}) construct.
-In other words, after the end of a @samp{\( @dots{} \)} construct, the
-matcher remembers the beginning and end of the text matched by that
-construct. Then, later on in the regular expression, you can use
-@samp{\} followed by @var{digit} to match that same text, whatever it
-may have been.
+In other words, after the end of a group, the matcher remembers the
+beginning and end of the text matched by that group. Later on in the
+regular expression you can use @samp{\} followed by @var{digit} to
+match that same text, whatever it may have been.
-The strings matching the first nine @samp{\( @dots{} \)} constructs
-appearing in a regular expression are assigned numbers 1 through 9 in
-the order that the open parentheses appear in the regular expression.
-So you can use @samp{\1} through @samp{\9} to refer to the text matched
-by the corresponding @samp{\( @dots{} \)} constructs.
+The strings matching the first nine grouping constructs appearing in
+the entire regular expression passed to a search or matching function
+are assigned numbers 1 through 9 in the order that the open
+parentheses appear in the regular expression. So you can use
+@samp{\1} through @samp{\9} to refer to the text matched by the
+corresponding grouping constructs.
For example, @samp{\(.*\)\1} matches any newline-free string that is
composed of two identical halves. The @samp{\(.*\)} matches the first
half, which may be anything, but the @samp{\1} that follows must match
the same exact text.
+If a particular grouping construct in the regular expression was never
+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}
+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
+alternative matches @samp{foob} and @samp{\2} matches @samp{b}.
+
@item \w
@cindex @samp{\w} in regexp
matches any word-constituent character. The editor syntax table
@item \S@var{code}
@cindex @samp{\S} in regexp
matches any character whose syntax is not @var{code}.
+
+@item \c@var{c}
+matches any character whose category is @var{c}. Here @var{c} is a
+character that represents a category: thus, @samp{c} for Chinese
+characters or @samp{g} for Greek characters in the standard category
+table.
+
+@item \C@var{c}
+matches any character whose category is not @var{c}.
@end table
The following regular expression constructs match the empty string---that is,
Here is a complicated regexp, used by Emacs to recognize the end of a
sentence together with any whitespace that follows. It is the value of
-the variable @code{sentence-end}.
+the variable @code{sentence-end}.
First, we show the regexp as a string in Lisp syntax to distinguish
spaces from tab characters. The string constant begins and ends with a
@example
@group
sentence-end
- @result{} "[.?!][]\"')@}]*\\($\\| $\\| \\| \\)[
+ @result{} "[.?!][]\"')@}]*\\($\\| $\\| \\| \\)[
]*"
@end group
@end example
@end defun
@defun regexp-opt strings &optional paren
-@tindex regexp-opt
This function returns an efficient regular expression that will match
any of the strings @var{strings}. This is useful when you need to make
matching or searching as fast as possible---for example, for Font Lock
@end defun
@defun regexp-opt-depth regexp
-@tindex regexp-opt-depth
This function returns the total number of grouping constructs
(parenthesized expressions) in @var{regexp}.
@end defun
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
+non-greedy repetition operators. This is because POSIX backtracking
+conflicts with the semantics of non-greedy repetition.
+
@defun 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
This function is a synonym of @code{how-many}.
@end deffn
-@deffn Command list-matching-lines regexp nlines
+@deffn Command list-matching-lines regexp &optional nlines
This function is a synonym of @code{occur}.
Show all lines following point containing a match for @var{regexp}.
Display each line with @var{nlines} lines before and after,
@section Search and Replace
@cindex replacement
-@defun perform-replace from-string replacements query-flag regexp-flag delimited-flag &optional repeat-count map
-This function is the guts of @code{query-replace} and related commands.
-It searches for occurrences of @var{from-string} and replaces some or
-all of them. If @var{query-flag} is @code{nil}, it replaces all
+@defun perform-replace from-string replacements query-flag regexp-flag delimited-flag &optional repeat-count map start end
+This function is the guts of @code{query-replace} and related
+commands. It searches for occurrences of @var{from-string} in the
+text between positions @var{start} and @var{end} and replaces some or
+all of them. If @var{start} is @code{nil} (or omitted), point is used
+instead, and the buffer's end is used for @var{end}.
+
+If @var{query-flag} is @code{nil}, it replaces all
occurrences; otherwise, it asks the user what to do about each one.
If @var{regexp-flag} is non-@code{nil}, then @var{from-string} is
with. If it is a string, that string is used. It can also be a list of
strings, to be used in cyclic order.
-If @var{replacements} is a cons cell, @var{(@var{function}
+If @var{replacements} is a cons cell, @code{(@var{function}
. @var{data})}, this means to call @var{function} after each match to
get the replacement text. This function is called with two arguments:
@var{data}, and the number of replacements already made.
Then @code{replace-match} does the replacement by constructing and
returning a new string.
-If @var{fixedcase} is non-@code{nil}, then the case of the replacement
-text is not changed; otherwise, the replacement text is converted to a
-different case depending upon the capitalization of the text to be
-replaced. If the original text is all upper case, the replacement text
-is converted to upper case. If the first word of the original text is
-capitalized, then the first word of the replacement text is capitalized.
-If the original text contains just one word, and that word is a capital
-letter, @code{replace-match} considers this a capitalized first word
-rather than all upper case.
+If @var{fixedcase} is non-@code{nil}, then @code{replace-match} uses
+the replacement text without case conversion; otherwise, it converts
+the replacement text depending upon the capitalization of the text to
+be replaced. If the original text is all upper case, this converts
+the replacement text to upper case. If all words of the original text
+are capitalized, this capitalizes all the words of the replacement
+text. If all the words are one-letter and they are all upper case,
+they are treated as capitalized words rather than all-upper-case
+words.
If @var{literal} is non-@code{nil}, then @var{replacement} is inserted
exactly as it is, the only alterations being case changes as needed.
@samp{\\} stands for a single @samp{\} in the replacement text.
@end table
+These substitutions occur after case conversion, if any,
+so 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
the entire match. For example, after matching @samp{foo \(ba*r\)},
@subsection Simple Match Data Access
This section explains how to use the match data to find out what was
-matched by the last search or match operation.
+matched by the last search or match operation, if it succeeded.
You can ask about the entire matching text, or about a particular
parenthetical subexpression of a regular expression. The @var{count}
A search which fails may or may not alter the match data. In the
past, a failing search did not do this, but we may change it in the
-future.
+future. So don't try to rely on the value of the match data after
+a failing search.
@defun match-string count &optional in-string
This function returns, as a string, the text matched in the last search
or match operation. It returns the entire text if @var{count} is zero,
or just the portion corresponding to the @var{count}th parenthetical
-subexpression, if @var{count} is positive. If @var{count} is out of
-range, or if that subexpression didn't match anything, the value is
-@code{nil}.
+subexpression, if @var{count} is positive.
If the last such operation was done against a string with
@code{string-match}, then you should pass the same string as the
should make sure that the current buffer when you call
@code{match-string} is the one in which you did the searching or
matching.
+
+The value is @code{nil} if @var{count} is out of range, or for a
+subexpression inside a @samp{\|} alternative that wasn't used or a
+repetition that repeated zero times.
@end defun
-@defun match-string-no-properties count
+@defun match-string-no-properties count &optional in-string
This function is like @code{match-string} except that the result
has no text properties.
@end defun
position of the match for that subexpression.
The value is @code{nil} for a subexpression inside a @samp{\|}
-alternative that wasn't used in the match.
+alternative that wasn't used or a repetition that repeated zero times.
@end defun
@defun match-end count
@group
(string-match "\\(qu\\)\\(ick\\)"
"The quick fox jumped quickly.")
- ;0123456789
+ ;0123456789
@result{} 4
@end group
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
-@ifinfo
+@ifnottex
number 2@var{n}
-@end ifinfo
+@end ifnottex
@tex
number {\mathsurround=0pt $2n$}
@end tex
corresponds to @code{(match-beginning @var{n})}; and
element
-@ifinfo
+@ifnottex
number 2@var{n} + 1
-@end ifinfo
+@end ifnottex
@tex
number {\mathsurround=0pt $2n+1$}
@end tex
@defun set-match-data match-list
This function sets the match data from the elements of @var{match-list},
which should be a list that was the value of a previous call to
-@code{match-data}.
+@code{match-data}. (More precisely, anything that has the same format
+will work.)
If @var{match-list} refers to a buffer that doesn't exist, you don't get
an error; that sets the match data in a meaningless but harmless way.
HCoop / bpt / emacs.git / blobdiff