[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Emacs-diffs] Changes to searching.texi
|
From: |
Glenn Morris |
|
Subject: |
[Emacs-diffs] Changes to searching.texi |
|
Date: |
Thu, 06 Sep 2007 04:14:02 +0000 |
CVSROOT: /sources/emacs
Module name: emacs
Changes by: Glenn Morris <gm> 07/09/06 04:14:02
Index: searching.texi
===================================================================
RCS file: searching.texi
diff -N searching.texi
--- searching.texi 13 Jun 2007 17:49:14 -0000 1.83
+++ /dev/null 1 Jan 1970 00:00:00 -0000
@@ -1,1766 +0,0 @@
address@hidden -*-texinfo-*-
address@hidden This is part of the GNU Emacs Lisp Reference Manual.
address@hidden Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999,
2001,
address@hidden 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation,
Inc.
address@hidden See the file elisp.texi for copying conditions.
address@hidden ../info/searching
address@hidden Searching and Matching, Syntax Tables, Non-ASCII Characters, Top
address@hidden Searching and Matching
address@hidden searching
-
- GNU Emacs provides two ways to search through a buffer for specified
-text: exact string searches and regular expression searches. After a
-regular expression search, you can examine the @dfn{match data} to
-determine which text matched the whole regular expression or various
-portions of it.
-
address@hidden
-* String Search:: Search for an exact match.
-* Searching and Case:: Case-independent or case-significant searching.
-* Regular Expressions:: Describing classes of strings.
-* Regexp Search:: Searching for a match for a regexp.
-* POSIX Regexps:: Searching POSIX-style for the longest match.
-* Match Data:: Finding out which part of the text matched,
- after a string or regexp search.
-* Search and Replace:: Commands that loop, searching and replacing.
-* Standard Regexps:: Useful regexps for finding sentences, pages,...
address@hidden menu
-
- The @address@hidden functions also perform a kind of searching.
address@hidden Characters}. To search for changes in character
-properties, see @ref{Property Search}.
-
address@hidden String Search
address@hidden Searching for Strings
address@hidden string search
-
- These are the primitive functions for searching through the text in a
-buffer. They are meant for use in programs, but you may call them
-interactively. If you do so, they prompt for the search string; the
-arguments @var{limit} and @var{noerror} are @code{nil}, and @var{repeat}
-is 1.
-
- These search functions convert the search string to multibyte if the
-buffer is multibyte; they convert the search string to unibyte if the
-buffer is unibyte. @xref{Text Representations}.
-
address@hidden Command search-forward string &optional limit noerror repeat
-This function searches forward from point for an exact match for
address@hidden If successful, it sets point to the end of the occurrence
-found, and returns the new value of point. If no match is found, the
-value and side effects depend on @var{noerror} (see below).
address@hidden Emacs 19 feature
-
-In the following example, point is initially at the beginning of the
-line. Then @code{(search-forward "fox")} moves point after the last
-letter of @samp{fox}:
-
address@hidden
address@hidden
----------- Buffer: foo ----------
address@hidden quick brown fox jumped over the lazy dog.
----------- Buffer: foo ----------
address@hidden group
-
address@hidden
-(search-forward "fox")
- @result{} 20
-
----------- Buffer: foo ----------
-The quick brown address@hidden jumped over the lazy dog.
----------- Buffer: foo ----------
address@hidden group
address@hidden example
-
-The argument @var{limit} specifies the upper bound to the search. (It
-must be a position in the current buffer.) No match extending after
-that position is accepted. If @var{limit} is omitted or @code{nil}, it
-defaults to the end of the accessible portion of the buffer.
-
address@hidden search-failed
-What happens when the search fails depends on the value of
address@hidden If @var{noerror} is @code{nil}, a @code{search-failed}
-error is signaled. If @var{noerror} is @code{t}, @code{search-forward}
-returns @code{nil} and does nothing. If @var{noerror} is neither
address@hidden nor @code{t}, then @code{search-forward} moves point to the
-upper bound and returns @code{nil}. (It would be more consistent now to
-return the new position of point in that case, but some existing
-programs may depend on a value of @code{nil}.)
-
-The argument @var{noerror} only affects valid searches which fail to
-find a match. Invalid arguments cause errors regardless of
address@hidden
-
-If @var{repeat} is supplied (it must be a positive number), then the
-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, with results depending on the value of
address@hidden, as described above.
address@hidden deffn
-
address@hidden Command search-backward string &optional limit noerror repeat
-This function searches backward from point for @var{string}. It is
-just like @code{search-forward} except that it searches backwards and
-leaves point at the beginning of the match.
address@hidden deffn
-
address@hidden Command word-search-forward string &optional limit noerror repeat
address@hidden @cindex word search Redundant
-This function searches forward from point for a ``word'' match for
address@hidden If it finds a match, it sets point to the end of the
-match found, and returns the new value of point.
address@hidden 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
-sequence of words. Each word must be distinct in the buffer (searching
-for the word @samp{ball} does not match the word @samp{balls}), but the
-details of punctuation and spacing are ignored (searching for @samp{ball
-boy} does match @samp{ball. Boy!}).
-
-In this example, point is initially at the beginning of the buffer; the
-search leaves it between the @samp{y} and the @samp{!}.
-
address@hidden
address@hidden
----------- Buffer: foo ----------
address@hidden said "Please! Find
-the ball boy!"
----------- Buffer: foo ----------
address@hidden group
-
address@hidden
-(word-search-forward "Please find the ball, boy.")
- @result{} 35
-
----------- Buffer: foo ----------
-He said "Please! Find
-the ball address@hidden"
----------- Buffer: foo ----------
address@hidden group
address@hidden example
-
-If @var{limit} is address@hidden, it must be a position in the current
-buffer; it specifies the upper bound to the search. The match found
-must not extend after that position.
-
-If @var{noerror} is @code{nil}, then @code{word-search-forward} signals
-an error if the search fails. If @var{noerror} is @code{t}, then it
-returns @code{nil} instead of signaling an error. If @var{noerror} is
-neither @code{nil} nor @code{t}, it moves point to @var{limit} (or the
-end of the accessible portion of the buffer) and returns @code{nil}.
-
-If @var{repeat} is address@hidden, then the search is repeated that many
-times. Point is positioned at the end of the last match.
address@hidden deffn
-
address@hidden Command word-search-backward string &optional limit noerror
repeat
-This function searches backward from point for a word match to
address@hidden This function is just like @code{word-search-forward}
-except that it searches backward and normally leaves point at the
-beginning of the match.
address@hidden deffn
-
address@hidden Searching and Case
address@hidden Searching and Case
address@hidden searching and case
-
- By default, searches in Emacs ignore the case of the text they are
-searching through; if you specify searching for @samp{FOO}, then
address@hidden or @samp{foo} is also considered a match. This applies to
-regular expressions, too; thus, @samp{[aB]} would match @samp{a} or
address@hidden or @samp{b} or @samp{B}.
-
- If you do not want this feature, set the variable
address@hidden 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
address@hidden, which is the default value of
address@hidden for buffers that do not override it.
-
- 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.
-
address@hidden case-replace
-This variable determines whether the higher level replacement
-functions should preserve case. If the variable is @code{nil}, that
-means to use the replacement text verbatim. A address@hidden value
-means to convert the case of the replacement text according to the
-text being replaced.
-
-This variable is used by passing it as an argument to the function
address@hidden @xref{Replacing Match}.
address@hidden defopt
-
address@hidden 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.
address@hidden defopt
-
address@hidden default-case-fold-search
-The value of this variable is the default value for
address@hidden in buffers that do not override it. This is the
-same as @code{(default-value 'case-fold-search)}.
address@hidden defvar
-
address@hidden Regular Expressions
address@hidden Regular Expressions
address@hidden regular expression
address@hidden regexp
-
- A @dfn{regular expression} (@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.
-
address@hidden re-builder
address@hidden regular expressions, developing
- For convenient interactive development of regular expressions, you
-can use the @kbd{M-x re-builder} command. It provides a convenient
-interface for creating regular expressions, by giving immediate visual
-feedback in a separate buffer. As you edit the regexp, all its
-matches in the target buffer are highlighted. Each parenthesized
-sub-expression of the regexp is shown in a distinct face, which makes
-it easier to verify even very complex regexps.
-
address@hidden
-* Syntax of Regexps:: Rules for writing regular expressions.
-* Regexp Example:: Illustrates regular expression syntax.
-* Regexp Functions:: Functions for operating on regular expressions.
address@hidden menu
-
address@hidden Syntax of Regexps
address@hidden Syntax of Regular Expressions
-
- Regular expressions have a syntax in which a few characters are
-special constructs and the rest are @dfn{ordinary}. An ordinary
-character is a simple regular expression that matches that character
-and nothing else. The special characters are @samp{.}, @samp{*},
address@hidden, @samp{?}, @samp{[}, @samp{^}, @samp{$}, and @samp{\}; no new
-special characters will be defined in the future. The character
address@hidden is special if it ends a character alternative (see later).
-The character @samp{-} is special inside a character alternative. A
address@hidden:} and balancing @samp{:]} enclose a character class inside a
-character alternative. Any other character appearing in a regular
-expression is ordinary, unless a @samp{\} precedes it.
-
- For example, @samp{f} is not a special character, so it is ordinary, and
-therefore @samp{f} is a regular expression that matches the string
address@hidden and no other string. (It does @emph{not} match the string
address@hidden, but it does match a @emph{part} of that string.) Likewise,
address@hidden is a regular expression that matches only @address@hidden
-
- Any two regular expressions @var{a} and @var{b} can be concatenated. The
-result is a regular expression that matches a string if @var{a} matches
-some amount of the beginning of that string and @var{b} matches the rest of
-the address@hidden
-
- As a simple example, we can concatenate the regular expressions @samp{f}
-and @samp{o} to get the regular expression @samp{fo}, which matches only
-the string @samp{fo}. Still trivial. To do something more powerful, you
-need to use one of the special regular expression constructs.
-
address@hidden
-* Regexp Special:: Special characters in regular expressions.
-* Char Classes:: Character classes used in regular expressions.
-* Regexp Backslash:: Backslash-sequences in regular expressions.
address@hidden menu
-
address@hidden Regexp Special
address@hidden Special Characters in Regular Expressions
-
- Here is a list of the characters that are special in a regular
-expression.
-
address@hidden 800
address@hidden @asis
address@hidden @samp{.}@: @r{(Period)}
address@hidden @samp{.} in regexp
-is a special character that matches any single character except a newline.
-Using concatenation, we can make regular expressions like @samp{a.b}, which
-matches any three-character string that begins with @samp{a} and ends with
address@hidden@refill
-
address@hidden @samp{*}
address@hidden @samp{*} in regexp
-is not a construct by itself; it is a postfix operator that means to
-match the preceding regular expression repetitively as many times as
-possible. Thus, @samp{o*} matches any number of @samp{o}s (including no
address@hidden).
-
address@hidden always applies to the @emph{smallest} possible preceding
-expression. Thus, @samp{fo*} has a repeating @samp{o}, not a repeating
address@hidden It matches @samp{f}, @samp{fo}, @samp{foo}, and so on.
-
-The matcher processes a @samp{*} construct by matching, immediately, as
-many repetitions as can be found. Then it continues with the rest of
-the pattern. If that fails, backtracking occurs, discarding some of the
-matches of the @samp{*}-modified construct in the hope that that will
-make it possible to match the rest of the pattern. For example, in
-matching @samp{ca*ar} against the string @samp{caaar}, the @samp{a*}
-first tries to match all three @samp{a}s; but the rest of the pattern is
address@hidden and there is only @samp{r} left to match, so this try fails.
-The next alternative is for @samp{a*} to match only two @samp{a}s. With
-this choice, the rest of the regexp matches successfully.
-
address@hidden:} Nested repetition operators can run for an
-indefinitely long time, if they lead to ambiguous matching. For
-example, trying to match the regular expression @samp{\(x+y*\)*a}
-against the string @samp{xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz} could
-take hours before it ultimately fails. Emacs must try each way of
-grouping the @samp{x}s before concluding that none of them can work.
-Even worse, @samp{\(x*\)*} can match the null string in infinitely
-many ways, so it causes an infinite loop. To avoid these problems,
-check nested repetitions carefully, to make sure that they do not
-cause combinatorial explosions in backtracking.
-
address@hidden @samp{+}
address@hidden @samp{+} in regexp
-is a postfix operator, similar to @samp{*} except that it must match
-the preceding expression at least once. So, for example, @samp{ca+r}
-matches the strings @samp{car} and @samp{caaaar} but not the string
address@hidden, whereas @samp{ca*r} matches all three strings.
-
address@hidden @samp{?}
address@hidden @samp{?} in regexp
-is a postfix operator, similar to @samp{*} except that it must match the
-preceding expression either once or not at all. For example,
address@hidden matches @samp{car} or @samp{cr}; nothing else.
-
address@hidden @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
address@hidden (The smallest possible match here for @samp{[ad]*?} that
-permits the whole expression to match is @samp{d}.)
-
address@hidden @samp{[ @dots{} ]}
address@hidden character alternative (in regexp)
address@hidden @samp{[} in regexp
address@hidden @samp{]} in regexp
-is a @dfn{character alternative}, which begins with @samp{[} and is
-terminated by @samp{]}. In the simplest case, the characters between
-the two brackets are what this character alternative can match.
-
-Thus, @samp{[ad]} matches either one @samp{a} or one @samp{d}, and
address@hidden matches any string composed of just @samp{a}s and @samp{d}s
-(including the empty string), from which it follows that @samp{c[ad]*r}
-matches @samp{cr}, @samp{car}, @samp{cdr}, @samp{caddaar}, etc.
-
-You can also include character ranges in a character alternative, by
-writing the starting and ending characters with a @samp{-} between them.
-Thus, @samp{[a-z]} matches any lower-case @acronym{ASCII} letter.
-Ranges may be intermixed freely with individual characters, as in
address@hidden, which matches any lower case @acronym{ASCII} letter
-or @samp{$}, @samp{%} or period.
-
-Note that the usual regexp special characters are not special inside a
-character alternative. A completely different set of characters is
-special inside character alternatives: @samp{]}, @samp{-} and @samp{^}.
-
-To include a @samp{]} in a character alternative, you must make it the
-first character. For example, @samp{[]a]} matches @samp{]} or @samp{a}.
-To include a @samp{-}, write @samp{-} as the first or last character of
-the character alternative, or put it after a range. Thus, @samp{[]-]}
-matches both @samp{]} and @samp{-}.
-
-To include @samp{^} in a character alternative, put it anywhere but at
-the beginning.
-
-The beginning and end of a range of multibyte characters must be in
-the same character set (@pxref{Character Sets}). Thus,
address@hidden"[\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 @address@hidden, the other is @address@hidden@var{c2}}, where
address@hidden is the first character of the charset to which @var{c2}
-belongs.
-
-You cannot always match all address@hidden characters with the regular
-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 address@hidden characters have codes
-above octal 0377. However, the regular expression @code{"[^\000-\177]"}
-does match all address@hidden characters (see below regarding @samp{^}),
-in both multibyte and unibyte representations, because only the
address@hidden characters are excluded.
-
-A character alternative can also specify named
-character classes (@pxref{Char Classes}). This is a POSIX feature whose
-syntax is @samp{[:@var{class}:]}. Using a character class is equivalent
-to mentioning each of the characters in that class; but the latter is
-not feasible in practice, since some classes include thousands of
-different characters.
-
address@hidden @samp{[^ @dots{} ]}
address@hidden @samp{^} in regexp
address@hidden begins a @dfn{complemented character alternative}. This
-matches any character except the ones specified. Thus,
address@hidden matches all characters @emph{except} letters and
-digits.
-
address@hidden is not special in a character alternative unless it is the first
-character. The character following the @samp{^} is treated as if it
-were first (in other words, @samp{-} and @samp{]} are not special there).
-
-A complemented character alternative can match a newline, unless newline is
-mentioned as one of the characters not to match. This is in contrast to
-the handling of regexps in programs such as @code{grep}.
-
address@hidden @samp{^}
address@hidden beginning of line in regexp
-When matching a buffer, @samp{^} matches the empty string, but only at the
-beginning of a line in the text being matched (or the beginning of the
-accessible portion of the buffer). Otherwise it fails to match
-anything. Thus, @samp{^foo} matches a @samp{foo} that occurs at 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.
-
-For historical compatibility reasons, @samp{^} can be used only at the
-beginning of the regular expression, or after @samp{\(}, @samp{\(?:}
-or @samp{\|}.
-
address@hidden @samp{$}
address@hidden @samp{$} in regexp
address@hidden end of line in regexp
-is similar to @samp{^} but matches only at the end of a line (or the
-end of the accessible portion of the buffer). Thus, @samp{x+$}
-matches a string of one @samp{x} or more at the end of a line.
-
-When matching a string instead of a buffer, @samp{$} matches at the end
-of the string or before a newline character.
-
-For historical compatibility reasons, @samp{$} can be used only at the
-end of the regular expression, or before @samp{\)} or @samp{\|}.
-
address@hidden @samp{\}
address@hidden @samp{\} in regexp
-has two functions: it quotes the special characters (including
address@hidden), and it introduces additional special constructs.
-
-Because @samp{\} quotes special characters, @samp{\$} is a regular
-expression that matches only @samp{$}, and @samp{\[} is a regular
-expression that matches only @samp{[}, and so on.
-
-Note that @samp{\} also has special meaning in the read syntax of Lisp
-strings (@pxref{String Type}), and must be quoted with @samp{\}. For
-example, the regular expression that matches the @samp{\} character is
address@hidden To write a Lisp string that contains the characters
address@hidden, Lisp syntax requires you to quote each @samp{\} with another
address@hidden Therefore, the read syntax for a regular expression matching
address@hidden is @code{"\\\\"address@hidden
address@hidden table
-
address@hidden note:} For historical compatibility, special characters
-are treated as ordinary ones if they are in contexts where their special
-meanings make no sense. For example, @samp{*foo} treats @samp{*} as
-ordinary since there is no preceding expression on which the @samp{*}
-can act. It is poor practice to depend on this behavior; quote the
-special character anyway, regardless of where it address@hidden
-
-As a @samp{\} is not special inside a character alternative, it can
-never remove the special meaning of @samp{-} or @samp{]}. So you
-should not quote these characters when they have no special meaning
-either. This would not clarify anything, since backslashes can
-legitimately precede these characters where they @emph{have} special
-meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string syntax),
-which matches any single character except a backslash.
-
-In practice, most @samp{]} that occur in regular expressions close a
-character alternative and hence are special. However, occasionally a
-regular expression may try to match a complex pattern of literal
address@hidden and @samp{]}. In such situations, it sometimes may be
-necessary to carefully parse the regexp from the start to determine
-which square brackets enclose a character alternative. For example,
address@hidden consists of the complemented character alternative
address@hidden (which matches any single character that is not a square
-bracket), followed by a literal @samp{]}.
-
-The exact rules are that at the beginning of a regexp, @samp{[} is
-special and @samp{]} not. This lasts until the first unquoted
address@hidden, after which we are in a character alternative; @samp{[} is
-no longer special (except when it starts a character class) but @samp{]}
-is special, unless it immediately follows the special @samp{[} or that
address@hidden followed by a @samp{^}. This lasts until the next special
address@hidden that does not end a character class. This ends the character
-alternative and restores the ordinary syntax of regular expressions;
-an unquoted @samp{[} is special again and a @samp{]} not.
-
address@hidden Char Classes
address@hidden Character Classes
address@hidden character classes in regexp
-
- Here is a table of the classes you can use in a character alternative,
-and what they mean:
-
address@hidden @samp
address@hidden [:ascii:]
-This matches any @acronym{ASCII} character (codes 0--127).
address@hidden [:alnum:]
-This matches any letter or digit. (At present, for multibyte
-characters, it matches anything that has word syntax.)
address@hidden [:alpha:]
-This matches any letter. (At present, for multibyte characters, it
-matches anything that has word syntax.)
address@hidden [:blank:]
-This matches space and tab only.
address@hidden [:cntrl:]
-This matches any @acronym{ASCII} control character.
address@hidden [:digit:]
-This matches @samp{0} through @samp{9}. Thus, @samp{[-+[:digit:]]}
-matches any digit, as well as @samp{+} and @samp{-}.
address@hidden [:graph:]
-This matches graphic characters---everything except @acronym{ASCII} control
-characters, space, and the delete character.
address@hidden [:lower:]
-This matches any lower-case letter, as determined by
-the current case table (@pxref{Case Tables}).
address@hidden [:multibyte:]
-This matches any multibyte character (@pxref{Text Representations}).
address@hidden [:nonascii:]
-This matches any address@hidden character.
address@hidden [:print:]
-This matches printing characters---everything except @acronym{ASCII} control
-characters and the delete character.
address@hidden [:punct:]
-This matches any punctuation character. (At present, for multibyte
-characters, it matches anything that has non-word syntax.)
address@hidden [:space:]
-This matches any character that has whitespace syntax
-(@pxref{Syntax Class Table}).
address@hidden [:unibyte:]
-This matches any unibyte character (@pxref{Text Representations}).
address@hidden [:upper:]
-This matches any upper-case letter, as determined by
-the current case table (@pxref{Case Tables}).
address@hidden [:word:]
-This matches any character that has word syntax (@pxref{Syntax Class
-Table}).
address@hidden [:xdigit:]
-This matches the hexadecimal digits: @samp{0} through @samp{9}, @samp{a}
-through @samp{f} and @samp{A} through @samp{F}.
address@hidden table
-
address@hidden Regexp Backslash
address@hidden Backslash Constructs in Regular Expressions
-
- For the most part, @samp{\} followed by any character matches only
-that character. However, there are several exceptions: certain
-two-character sequences starting with @samp{\} that have special
-meanings. (The character after the @samp{\} in such a sequence is
-always ordinary when used on its own.) Here is a table of the special
address@hidden constructs.
-
address@hidden @samp
address@hidden \|
address@hidden @samp{|} in regexp
address@hidden regexp alternative
-specifies an alternative.
-Two regular expressions @var{a} and @var{b} with @samp{\|} in
-between form an expression that matches anything that either @var{a} or
address@hidden address@hidden
-
-Thus, @samp{foo\|bar} matches either @samp{foo} or @samp{bar}
-but no other address@hidden
-
address@hidden|} applies to the largest possible surrounding expressions. Only
a
-surrounding @samp{\( @dots{} \)} grouping can limit the grouping power of
address@hidden|address@hidden
-
-If you need full backtracking capability to handle multiple uses of
address@hidden|}, use the POSIX regular expression functions (@pxref{POSIX
-Regexps}).
-
address@hidden address@hidden@address@hidden
-is a postfix operator that repeats the previous pattern exactly @var{m}
-times. Thus, @address@hidden@}} matches the string @samp{xxxxx}
-and nothing else. @address@hidden@}r} matches string such as
address@hidden, @samp{cdddr}, @samp{cadar}, and so on.
-
address@hidden address@hidden@var{m},@address@hidden
-is a 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, @address@hidden,address@hidden matches the strings @samp{car},
address@hidden, @samp{caar}, @samp{cadr}, @samp{cdar}, and @samp{cddr}, and
-nothing address@hidden
address@hidden@{0,address@hidden or @address@hidden,address@hidden is
equivalent to @samp{?}. @*
address@hidden@{0,address@hidden or @address@hidden,address@hidden is
equivalent to @samp{*}. @*
address@hidden@{1,address@hidden is equivalent to @samp{+}.
-
address@hidden \( @dots{} \)
address@hidden @samp{(} in regexp
address@hidden @samp{)} in regexp
address@hidden regexp grouping
-is a grouping construct that serves three purposes:
-
address@hidden
address@hidden
-To enclose a set of @samp{\|} alternatives for other operations. Thus,
-the regular expression @samp{\(foo\|bar\)x} matches either @samp{foox}
-or @samp{barx}.
-
address@hidden
-To enclose a complicated expression for the postfix operators @samp{*},
address@hidden and @samp{?} to operate on. Thus, @samp{ba\(na\)*} matches
address@hidden, @samp{bana}, @samp{banana}, @samp{bananana}, etc., with any
-number (zero or more) of @samp{na} strings.
-
address@hidden
-To record a matched substring for future reference with
address@hidden@var{digit}} (see below).
address@hidden enumerate
-
-This last application is not a consequence of the idea of a
-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.
-
address@hidden \(?: @dots{} \)
-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 @address@hidden
-
-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.
-
address@hidden \(address@hidden: @dots{} \)
-is the @dfn{explicitly numbered group} construct. Normal groups get
-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.
-Implicitly numbered groups always get the smallest integer larger than
-the one of any previous group.
-
address@hidden address@hidden
-matches the same text that matched the @var{digit}th occurrence of a
-grouping (@samp{\( @dots{} \)}) construct.
-
-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 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
address@hidden 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 @samp{\( @dots{} \)} construct matches more than once (which can
-happen, for instance, if it is followed by @samp{*}), only the last
-match is recorded.
-
-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 @address@hidden 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}.
-
address@hidden \w
address@hidden @samp{\w} in regexp
-matches any word-constituent character. The editor syntax table
-determines which characters these are. @xref{Syntax Tables}.
-
address@hidden \W
address@hidden @samp{\W} in regexp
-matches any character that is not a word constituent.
-
address@hidden address@hidden
address@hidden @samp{\s} in regexp
-matches any character whose syntax is @var{code}. Here @var{code} is a
-character that represents a syntax code: thus, @samp{w} for word
-constituent, @samp{-} for whitespace, @samp{(} for open parenthesis,
-etc. To represent whitespace syntax, use either @samp{-} or a space
-character. @xref{Syntax Class Table}, for a list of syntax codes and
-the characters that stand for them.
-
address@hidden address@hidden
address@hidden @samp{\S} in regexp
-matches any character whose syntax is not @var{code}.
-
address@hidden address@hidden
-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.
-
address@hidden address@hidden
-matches any character whose category is not @var{c}.
address@hidden table
-
- The following regular expression constructs match the empty string---that is,
-they don't use up any characters---but whether they match depends on the
-context. For all, the beginning and end of the accessible portion of
-the buffer are treated as if they were the actual beginning and end of
-the buffer.
-
address@hidden @samp
address@hidden \`
address@hidden @samp{\`} in regexp
-matches the empty string, but only at the beginning
-of the buffer or string being matched against.
-
address@hidden \'
address@hidden @samp{\'} in regexp
-matches the empty string, but only at the end of
-the buffer or string being matched against.
-
address@hidden \=
address@hidden @samp{\=} in regexp
-matches the empty string, but only at point.
-(This construct is not defined when matching against a string.)
-
address@hidden \b
address@hidden @samp{\b} in regexp
-matches the empty string, but only at the beginning or
-end of a word. Thus, @samp{\bfoo\b} matches any occurrence of
address@hidden as a separate word. @samp{\bballs?\b} matches
address@hidden or @samp{balls} as a separate address@hidden
-
address@hidden matches at the beginning or end of the buffer (or string)
-regardless of what text appears next to it.
-
address@hidden \B
address@hidden @samp{\B} in regexp
-matches the empty string, but @emph{not} at the beginning or
-end of a word, nor at the beginning or end of the buffer (or string).
-
address@hidden \<
address@hidden @samp{\<} in regexp
-matches the empty string, but only at the beginning of a word.
address@hidden<} matches at the beginning of the buffer (or string) only if a
-word-constituent character follows.
-
address@hidden \>
address@hidden @samp{\>} in regexp
-matches the empty string, but only at the end of a word. @samp{\>}
-matches at the end of the buffer (or string) only if the contents end
-with a word-constituent character.
-
address@hidden \_<
address@hidden @samp{\_<} in regexp
-matches the empty string, but only at the beginning of a symbol. A
-symbol is a sequence of one or more word or symbol constituent
-characters. @samp{\_<} matches at the beginning of the buffer (or
-string) only if a symbol-constituent character follows.
-
address@hidden \_>
address@hidden @samp{\_>} in regexp
-matches the empty string, but only at the end of a symbol. @samp{\_>}
-matches at the end of the buffer (or string) only if the contents end
-with a symbol-constituent character.
address@hidden table
-
address@hidden invalid-regexp
- Not every string is a valid regular expression. For example, a string
-that ends inside a character alternative without terminating @samp{]}
-is invalid, and so is a string that ends with a single @samp{\}. If
-an invalid regular expression is passed to any of the search functions,
-an @code{invalid-regexp} error is signaled.
-
address@hidden Regexp Example
address@hidden node-name, next, previous, up
address@hidden Complex Regexp Example
-
- Here is a complicated regexp which was formerly used by Emacs to
-recognize the end of a sentence together with any whitespace that
-follows. (Nowadays Emacs uses a similar but more complex default
-regexp constructed by the function @code{sentence-end}.
address@hidden Regexps}.)
-
- 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
-double-quote. @samp{\"} stands for a double-quote as part of the
-string, @samp{\\} for a backslash as part of the string, @samp{\t} for a
-tab and @samp{\n} for a newline.
-
address@hidden
-"[.?!][]\"')@}]*\\($\\| $\\|\t\\|@ @ \\)[ \t\n]*"
address@hidden example
-
address@hidden
-In contrast, if you evaluate this string, you will see the following:
-
address@hidden
address@hidden
-"[.?!][]\"')@}]*\\($\\| $\\|\t\\|@ @ \\)[ \t\n]*"
- @result{} "[.?!][]\"')@}]*\\($\\| $\\| \\|@ @ \\)[
-]*"
address@hidden group
address@hidden example
-
address@hidden
-In this output, tab and newline appear as themselves.
-
- This regular expression contains four parts in succession and can be
-deciphered as follows:
-
address@hidden @code
address@hidden [.?!]
-The first part of the pattern is a character alternative that matches
-any one of three characters: period, question mark, and exclamation
-mark. The match must begin with one of these three characters. (This
-is one point where the new default regexp used by Emacs differs from
-the old. The new value also allows some address@hidden
-characters that end a sentence without any following whitespace.)
-
address@hidden []\"')@}]*
-The second part of the pattern matches any closing braces and quotation
-marks, zero or more of them, that may follow the period, question mark
-or exclamation mark. The @code{\"} is Lisp syntax for a double-quote in
-a string. The @samp{*} at the end indicates that the immediately
-preceding regular expression (a character alternative, in this case) may be
-repeated zero or more times.
-
address@hidden \\($\\|@ $\\|\t\\|@ @ \\)
-The third part of the pattern matches the whitespace that follows the
-end of a sentence: the end of a line (optionally with a space), or a
-tab, or two spaces. The double backslashes mark the parentheses and
-vertical bars as regular expression syntax; the parentheses delimit a
-group and the vertical bars separate alternatives. The dollar sign is
-used to match the end of a line.
-
address@hidden [ \t\n]*
-Finally, the last part of the pattern matches any additional whitespace
-beyond the minimum needed to end a sentence.
address@hidden table
-
address@hidden Regexp Functions
address@hidden Regular Expression Functions
-
- These functions operate on regular expressions.
-
address@hidden regexp-quote string
-This function returns a regular expression whose only exact match is
address@hidden Using this regular expression in @code{looking-at} will
-succeed only if the next characters in the buffer are @var{string};
-using it in a search function will succeed if the text being searched
-contains @var{string}.
-
-This allows you to request an exact string match or search when calling
-a function that wants a regular expression.
-
address@hidden
address@hidden
-(regexp-quote "^The cat$")
- @result{} "\\^The cat\\$"
address@hidden group
address@hidden example
-
-One use of @code{regexp-quote} is to combine an exact string match with
-context described as a regular expression. For example, this searches
-for the string that is the value of @var{string}, surrounded by
-whitespace:
-
address@hidden
address@hidden
-(re-search-forward
- (concat "\\s-" (regexp-quote string) "\\s-"))
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden regexp-opt strings &optional paren
-This function returns an efficient regular expression that will match
-any of the strings in the list @var{strings}. This is useful when you
-need to make matching or searching as fast as possible---for example,
-for Font Lock mode.
-
-If the optional argument @var{paren} is address@hidden, then the
-returned regular expression is always enclosed by at least one
-parentheses-grouping construct. If @var{paren} is @code{words}, then
-that construct is additionally surrounded by @samp{\<} and @samp{\>}.
-
-This simplified definition of @code{regexp-opt} produces a
-regular expression which is equivalent to the actual value
-(but not as efficient):
-
address@hidden
-(defun regexp-opt (strings paren)
- (let ((open-paren (if paren "\\(" ""))
- (close-paren (if paren "\\)" "")))
- (concat open-paren
- (mapconcat 'regexp-quote strings "\\|")
- close-paren)))
address@hidden example
address@hidden defun
-
address@hidden regexp-opt-depth regexp
-This function returns the total number of grouping constructs
-(parenthesized expressions) in @var{regexp}. (This does not include
-shy groups.)
address@hidden defun
-
address@hidden Regexp Search
address@hidden Regular Expression Searching
address@hidden regular expression searching
address@hidden regexp searching
address@hidden searching for regexp
-
- In GNU Emacs, you can search for the next match for a regular
-expression either incrementally or not. For incremental search
-commands, see @ref{Regexp Search, , Regular Expression Search, emacs,
-The GNU Emacs Manual}. Here we describe only the search functions
-useful in programs. The principal one is @code{re-search-forward}.
-
- These search functions convert the regular expression to multibyte if
-the buffer is multibyte; they convert the regular expression to unibyte
-if the buffer is unibyte. @xref{Text Representations}.
-
address@hidden Command re-search-forward regexp &optional limit noerror repeat
-This function searches forward in the current buffer for a string of
-text that is matched by the regular expression @var{regexp}. The
-function skips over any amount of text that is not matched by
address@hidden, and leaves point at the end of the first match found.
-It returns the new value of point.
-
-If @var{limit} is address@hidden, it must be a position in the current
-buffer. It specifies the upper bound to the search. No match
-extending after that position is accepted.
-
-If @var{repeat} is supplied, it must be a positive number; the search
-is repeated that many times; each repetition starts at the end of the
-previous match. If all these successive searches succeed, the search
-succeeds, moving point and returning its new value. Otherwise the
-search fails. What @code{re-search-forward} does when the search
-fails depends on the value of @var{noerror}:
-
address@hidden @asis
address@hidden @code{nil}
-Signal a @code{search-failed} error.
address@hidden @code{t}
-Do nothing and return @code{nil}.
address@hidden anything else
-Move point to @var{limit} (or the end of the accessible portion of the
-buffer) and return @code{nil}.
address@hidden table
-
-In the following example, point is initially before the @samp{T}.
-Evaluating the search call moves point to the end of that line (between
-the @samp{t} of @samp{hat} and the newline).
-
address@hidden
address@hidden
----------- Buffer: foo ----------
-I read "@point{}The cat in the hat
-comes back" twice.
----------- Buffer: foo ----------
address@hidden group
-
address@hidden
-(re-search-forward "[a-z]+" nil t 5)
- @result{} 27
-
----------- Buffer: foo ----------
-I read "The cat in the address@hidden
-comes back" twice.
----------- Buffer: foo ----------
address@hidden group
address@hidden example
address@hidden deffn
-
address@hidden Command re-search-backward regexp &optional limit noerror repeat
-This function searches backward in the current buffer for a string of
-text that is matched by the regular expression @var{regexp}, leaving
-point at the beginning of the first text found.
-
-This function is analogous to @code{re-search-forward}, but they are not
-simple mirror images. @code{re-search-forward} finds the match whose
-beginning is as close as possible to the starting point. If
address@hidden were a perfect mirror image, it would find the
-match whose end is as close as possible. However, in fact it finds the
-match whose beginning is as close as possible (and yet ends before the
-starting point). The reason for this is that matching a regular
-expression at a given spot always works from beginning to end, and
-starts at a specified beginning position.
-
-A true mirror-image of @code{re-search-forward} would require a special
-feature for matching regular expressions from end to beginning. It's
-not worth the trouble of implementing that.
address@hidden deffn
-
address@hidden string-match regexp string &optional start
-This function returns the index of the start of the first match for
-the regular expression @var{regexp} in @var{string}, or @code{nil} if
-there is no match. If @var{start} is address@hidden, the search starts
-at that index in @var{string}.
-
-For example,
-
address@hidden
address@hidden
-(string-match
- "quick" "The quick brown fox jumped quickly.")
- @result{} 4
address@hidden group
address@hidden
-(string-match
- "quick" "The quick brown fox jumped quickly." 8)
- @result{} 27
address@hidden group
address@hidden example
-
address@hidden
-The index of the first character of the
-string is 0, the index of the second character is 1, and so on.
-
-After this function returns, the index of the first character beyond
-the match is available as @code{(match-end 0)}. @xref{Match Data}.
-
address@hidden
address@hidden
-(string-match
- "quick" "The quick brown fox jumped quickly." 8)
- @result{} 27
address@hidden group
-
address@hidden
-(match-end 0)
- @result{} 32
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden looking-at regexp
-This function determines whether the text in the current buffer directly
-following point matches the regular expression @var{regexp}. ``Directly
-following'' means precisely that: the search is ``anchored'' and it can
-succeed only starting with the first character following point. The
-result is @code{t} if so, @code{nil} otherwise.
-
-This function does not move point, but it updates the match data, which
-you can access using @code{match-beginning} and @code{match-end}.
address@hidden Data}.
-
-In this example, point is located directly before the @samp{T}. If it
-were anywhere else, the result would be @code{nil}.
-
address@hidden
address@hidden
----------- Buffer: foo ----------
-I read "@point{}The cat in the hat
-comes back" twice.
----------- Buffer: foo ----------
-
-(looking-at "The cat in the hat$")
- @result{} t
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden looking-back regexp &optional limit
-This function returns @code{t} if @var{regexp} matches text before
-point, ending at point, and @code{nil} otherwise.
-
-Because regular expression matching works only going forward, this is
-implemented by searching backwards from point for a match that ends at
-point. That can be quite slow if it has to search a long distance.
-You can bound the time required by specifying @var{limit}, which says
-not to search before @var{limit}. In this case, the match that is
-found must begin at or after @var{limit}.
-
address@hidden
address@hidden
----------- Buffer: foo ----------
-I read "@point{}The cat in the hat
-comes back" twice.
----------- Buffer: foo ----------
-
-(looking-back "read \"" 3)
- @result{} t
-(looking-back "read \"" 4)
- @result{} nil
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden search-spaces-regexp
-If this variable is address@hidden, it should be a regular expression
-that says how to search for whitespace. In that case, any group of
-spaces in a regular expression being searched for stands for use of
-this regular expression. However, spaces inside of constructs such as
address@hidden@dots{}]} and @samp{*}, @samp{+}, @samp{?} are not affected by
address@hidden
-
-Since this variable affects all regular expression search and match
-constructs, you should bind it temporarily for as small as possible
-a part of the code.
address@hidden defvar
-
address@hidden POSIX Regexps
address@hidden POSIX Regular Expression Searching
-
- The usual regular expression functions do backtracking when necessary
-to handle the @samp{\|} and repetition constructs, but they continue
-this only until they find @emph{some} match. Then they succeed and
-report the first match found.
-
- This section describes alternative search functions which perform the
-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
-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.
-
address@hidden 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.
address@hidden defun
-
address@hidden 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.
address@hidden defun
-
address@hidden posix-looking-at regexp
-This is like @code{looking-at} except that it performs the full
-backtracking specified by the POSIX standard for regular expression
-matching.
address@hidden defun
-
address@hidden posix-string-match regexp string &optional start
-This is like @code{string-match} except that it performs the full
-backtracking specified by the POSIX standard for regular expression
-matching.
address@hidden defun
-
address@hidden Match Data
address@hidden The Match Data
address@hidden match data
-
- Emacs keeps track of the start and end positions of the segments of
-text found during a search; this is called the @dfn{match data}.
-Thanks to the match data, you can search for a complex pattern, such
-as a date in a mail message, and then extract parts of the match under
-control of the pattern.
-
- Because the match data normally describe the most recent search only,
-you must be careful not to do another search inadvertently between the
-search you wish to refer back to and the use of the match data. If you
-can't avoid another intervening search, you must save and restore the
-match data around it, to prevent it from being overwritten.
-
address@hidden
-* Replacing Match:: Replacing a substring that was matched.
-* Simple Match Data:: Accessing single items of match data,
- such as where a particular subexpression started.
-* Entire Match Data:: Accessing the entire match data at once, as a list.
-* Saving Match Data:: Saving and restoring the match data.
address@hidden menu
-
address@hidden Replacing Match
address@hidden Replacing the Text that Matched
address@hidden replace matched text
-
- This function replaces all or part of the text matched by the last
-search. It works by means of the match data.
-
address@hidden case in replacements
address@hidden replace-match replacement &optional fixedcase literal string
subexp
-This function replaces the text in the buffer (or in @var{string}) that
-was matched by the last search. It replaces that text with
address@hidden
-
-If you did the last search in a buffer, you should specify @code{nil}
-for @var{string} and make sure that the current buffer when you call
address@hidden is the one in which you did the searching or
-matching. Then @code{replace-match} does the replacement by editing
-the buffer; it leaves point at the end of the replacement text, and
-returns @code{t}.
-
-If you did the search in a string, pass the same string as @var{string}.
-Then @code{replace-match} does the replacement by constructing and
-returning a new string.
-
-If @var{fixedcase} is address@hidden, 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 address@hidden, then @var{replacement} is inserted
-exactly as it is, the only alterations being case changes as needed.
-If it is @code{nil} (the default), then the character @samp{\} is treated
-specially. If a @samp{\} appears in @var{replacement}, then it must be
-part of one of the following sequences:
-
address@hidden @asis
address@hidden @samp{\&}
address@hidden @samp{&} in replacement
address@hidden&} stands for the entire text being replaced.
-
address@hidden @address@hidden
address@hidden @address@hidden in replacement
address@hidden@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.
-
address@hidden @samp{\\}
address@hidden @samp{\} in replacement
address@hidden stands for a single @samp{\} in the replacement text.
address@hidden table
-
-These substitutions occur after case conversion, if any,
-so the strings they substitute are never case-converted.
-
-If @var{subexp} is address@hidden, 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 \(ba*r\)},
-calling @code{replace-match} with 1 as @var{subexp} means to replace
-just the text that matched @samp{\(ba*r\)}.
address@hidden defun
-
address@hidden Simple Match Data
address@hidden 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, if it succeeded.
-
- You can ask about the entire matching text, or about a particular
-parenthetical subexpression of a regular expression. The @var{count}
-argument in the functions below specifies which. If @var{count} is
-zero, you are asking about the entire match. If @var{count} is
-positive, it specifies which subexpression you want.
-
- Recall that the subexpressions of a regular expression are those
-expressions grouped with escaped parentheses, @samp{\(@dots{}\)}. The
address@hidden subexpression is found by counting occurrences of
address@hidden(} from the beginning of the whole regular expression. The first
-subexpression is numbered 1, the second 2, and so on. Only regular
-expressions can have subexpressions---after a simple string search, the
-only information available is about the entire match.
-
- Every successful search sets the match data. Therefore, you should
-query the match data immediately after searching, before calling any
-other function that might perform another search. Alternatively, you
-may save and restore the match data (@pxref{Saving Match Data}) around
-the call to functions that could perform another search.
-
- 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. So don't try to rely on the value of the match data after
-a failing search.
-
address@hidden 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 the last such operation was done against a string with
address@hidden, then you should pass the same string as the
-argument @var{in-string}. After a buffer search or match,
-you should omit @var{in-string} or pass @code{nil} for it; but you
-should make sure that the current buffer when you call
address@hidden 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.
address@hidden defun
-
address@hidden match-string-no-properties count &optional in-string
-This function is like @code{match-string} except that the result
-has no text properties.
address@hidden defun
-
address@hidden match-beginning count
-This function returns the position of the start of text matched by the
-last regular expression searched for, or a subexpression of it.
-
-If @var{count} is zero, then the value is the position of the start of
-the entire match. Otherwise, @var{count} specifies a subexpression in
-the regular expression, and the value of the function is the starting
-position of the match for that subexpression.
-
-The value is @code{nil} for a subexpression inside a @samp{\|}
-alternative that wasn't used or a repetition that repeated zero times.
address@hidden defun
-
address@hidden match-end count
-This function is like @code{match-beginning} except that it returns the
-position of the end of the match, rather than the position of the
-beginning.
address@hidden defun
-
- Here is an example of using the match data, with a comment showing the
-positions within the text:
-
address@hidden
address@hidden
-(string-match "\\(qu\\)\\(ick\\)"
- "The quick fox jumped quickly.")
- ;0123456789
- @result{} 4
address@hidden group
-
address@hidden
-(match-string 0 "The quick fox jumped quickly.")
- @result{} "quick"
-(match-string 1 "The quick fox jumped quickly.")
- @result{} "qu"
-(match-string 2 "The quick fox jumped quickly.")
- @result{} "ick"
address@hidden group
-
address@hidden
-(match-beginning 1) ; @r{The beginning of the match}
- @result{} 4 ; @r{with @samp{qu} is at index 4.}
address@hidden group
-
address@hidden
-(match-beginning 2) ; @r{The beginning of the match}
- @result{} 6 ; @r{with @samp{ick} is at index 6.}
address@hidden group
-
address@hidden
-(match-end 1) ; @r{The end of the match}
- @result{} 6 ; @r{with @samp{qu} is at index 6.}
-
-(match-end 2) ; @r{The end of the match}
- @result{} 9 ; @r{with @samp{ick} is at index 9.}
address@hidden group
address@hidden example
-
- Here is another example. Point is initially located at the beginning
-of the line. Searching moves point to between the space and the word
address@hidden The beginning of the entire match is at the 9th character of
-the buffer (@samp{T}), and the beginning of the match for the first
-subexpression is at the 13th character (@samp{c}).
-
address@hidden
address@hidden
-(list
- (re-search-forward "The \\(cat \\)")
- (match-beginning 0)
- (match-beginning 1))
- @result{} (9 9 13)
address@hidden group
-
address@hidden
----------- Buffer: foo ----------
-I read "The cat @point{}in the hat comes back" twice.
- ^ ^
- 9 13
----------- Buffer: foo ----------
address@hidden group
address@hidden example
-
address@hidden
-(In this case, the index returned is a buffer position; the first
-character of the buffer counts as 1.)
-
address@hidden Entire Match Data
address@hidden Accessing the Entire Match Data
-
- The functions @code{match-data} and @code{set-match-data} read or
-write the entire match data, all at once.
-
address@hidden match-data &optional integers reuse reseat
-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
address@hidden
-number address@hidden
address@hidden ifnottex
address@hidden
-number {\mathsurround=0pt $2n$}
address@hidden tex
-corresponds to @code{(match-beginning @var{n})}; and
-element
address@hidden
-number address@hidden + 1
address@hidden ifnottex
address@hidden
-number {\mathsurround=0pt $2n+1$}
address@hidden tex
-corresponds to @code{(match-end @var{n})}.
-
-Normally all the elements are markers or @code{nil}, but if
address@hidden is address@hidden, 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 address@hidden, it should be a list. In that case,
address@hidden stores the match data in @var{reuse}. That is,
address@hidden is destructively modified. @var{reuse} does not need to
-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
address@hidden The purpose of this feature is to reduce the need for
-garbage collection.
-
-If @var{reseat} is address@hidden, all markers on the @var{reuse} list
-are reseated to point to nowhere.
-
-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
-intended to access the match data for that search.
-
address@hidden
address@hidden
-(match-data)
- @result{} (#<marker at 9 in foo>
- #<marker at 17 in foo>
- #<marker at 13 in foo>
- #<marker at 17 in foo>)
address@hidden group
address@hidden example
address@hidden defun
-
address@hidden set-match-data match-list &optional reseat
-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
address@hidden (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.
-
-If @var{reseat} is address@hidden, all markers on the @var{match-list} list
-are reseated to point to nowhere.
-
address@hidden store-match-data
address@hidden is a semi-obsolete alias for @code{set-match-data}.
address@hidden defun
-
address@hidden Saving Match Data
address@hidden Saving and Restoring the Match Data
-
- When you call a function that may do a search, you may need to save
-and restore the match data around that call, if you want to preserve the
-match data from an earlier search for later use. Here is an example
-that shows the problem that arises if you fail to save the match data:
-
address@hidden
address@hidden
-(re-search-forward "The \\(cat \\)")
- @result{} 48
-(foo) ; @r{Perhaps @code{foo} does}
- ; @r{more searching.}
-(match-end 0)
- @result{} 61 ; @r{Unexpected result---not 48!}
address@hidden group
address@hidden example
-
- You can save and restore the match data with @code{save-match-data}:
-
address@hidden save-match-data address@hidden
-This macro executes @var{body}, saving and restoring the match
-data around it. The return value is the value of the last form in
address@hidden
address@hidden defmac
-
- You could use @code{set-match-data} together with @code{match-data} to
-imitate the effect of the special form @code{save-match-data}. Here is
-how:
-
address@hidden
address@hidden
-(let ((data (match-data)))
- (unwind-protect
- @dots{} ; @r{Ok to change the original match data.}
- (set-match-data data)))
address@hidden group
address@hidden example
-
- Emacs automatically saves and restores the match data when it runs
-process filter functions (@pxref{Filter Functions}) and process
-sentinels (@pxref{Sentinels}).
-
address@hidden
- Here is a function which restores the match data provided the buffer
-associated with it still exists.
-
address@hidden
address@hidden
-(defun restore-match-data (data)
address@hidden It is incorrect to split the first line of a doc string.
address@hidden If there's a problem here, it should be solved in some other way.
- "Restore the match data DATA unless the buffer is missing."
- (catch 'foo
- (let ((d data))
address@hidden group
- (while d
- (and (car d)
- (null (marker-buffer (car d)))
address@hidden
- ;; @file{match-data} @r{buffer is deleted.}
- (throw 'foo nil))
- (setq d (cdr d)))
- (set-match-data data))))
address@hidden group
address@hidden smallexample
address@hidden ignore
-
address@hidden Search and Replace
address@hidden Search and Replace
address@hidden replacement after search
address@hidden searching and replacing
-
- If you want to find all matches for a regexp in part of the buffer,
-and replace them, the best way is to write an explicit loop using
address@hidden and @code{replace-match}, like this:
-
address@hidden
-(while (re-search-forward "foo[ \t]+bar" nil t)
- (replace-match "foobar"))
address@hidden example
-
address@hidden
address@hidden Match,, Replacing the Text that Matched}, for a
-description of @code{replace-match}.
-
- However, replacing matches in a string is more complex, especially
-if you want to do it efficiently. So Emacs provides a function to do
-this.
-
address@hidden replace-regexp-in-string regexp rep string &optional fixedcase
literal subexp start
-This function copies @var{string} and searches it for matches for
address@hidden, and replaces them with @var{rep}. It returns the
-modified copy. If @var{start} is address@hidden, the search for
-matches starts at that index in @var{string}, so matches starting
-before that index are not changed.
-
-This function uses @code{replace-match} to do the replacement, and it
-passes the optional arguments @var{fixedcase}, @var{literal} and
address@hidden along to @code{replace-match}.
-
-Instead of a string, @var{rep} can be a function. In that case,
address@hidden calls @var{rep} for each match,
-passing the text of the match as its sole argument. It collects the
-value @var{rep} returns and passes that to @code{replace-match} as the
-replacement string. The match-data at this point are the result
-of matching @var{regexp} against a substring of @var{string}.
address@hidden defun
-
- If you want to write a command along the lines of @code{query-replace},
-you can use @code{perform-replace} to do the work.
-
address@hidden 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 end of the buffer's accessible portion is used for
address@hidden
-
-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 address@hidden, then @var{from-string} is
-considered a regular expression; otherwise, it must match literally. If
address@hidden is address@hidden, then only replacements
-surrounded by word boundaries are considered.
-
-The argument @var{replacements} specifies what to replace occurrences
-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, @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:
address@hidden, and the number of replacements already made.
-
-If @var{repeat-count} is address@hidden, it should be an integer. Then
-it specifies how many times to use each of the strings in the
address@hidden list before advancing cyclically to the next one.
-
-If @var{from-string} contains upper-case letters, then
address@hidden binds @code{case-fold-search} to @code{nil}, and
-it uses the @code{replacements} without altering the case of them.
-
-Normally, the keymap @code{query-replace-map} defines the possible
-user responses for queries. The argument @var{map}, if
address@hidden, specifies a keymap to use instead of
address@hidden
address@hidden defun
-
address@hidden query-replace-map
-This variable holds a special keymap that defines the valid user
-responses for @code{perform-replace} and the commands that use it, as
-well as @code{y-or-n-p} and @code{map-y-or-n-p}. This map is unusual
-in two ways:
-
address@hidden @bullet
address@hidden
-The ``key bindings'' are not commands, just symbols that are meaningful
-to the functions that use this map.
-
address@hidden
-Prefix keys are not supported; each key binding must be for a
-single-event key sequence. This is because the functions don't use
address@hidden to get the input; instead, they read a single
-event and look it up ``by hand.''
address@hidden itemize
address@hidden defvar
-
-Here are the meaningful ``bindings'' for @code{query-replace-map}.
-Several of them are meaningful only for @code{query-replace} and
-friends.
-
address@hidden @code
address@hidden act
-Do take the action being considered---in other words, ``yes.''
-
address@hidden skip
-Do not take action for this question---in other words, ``no.''
-
address@hidden exit
-Answer this question ``no,'' and give up on the entire series of
-questions, assuming that the answers will be ``no.''
-
address@hidden act-and-exit
-Answer this question ``yes,'' and give up on the entire series of
-questions, assuming that subsequent answers will be ``no.''
-
address@hidden act-and-show
-Answer this question ``yes,'' but show the results---don't advance yet
-to the next question.
-
address@hidden automatic
-Answer this question and all subsequent questions in the series with
-``yes,'' without further user interaction.
-
address@hidden backup
-Move back to the previous place that a question was asked about.
-
address@hidden edit
-Enter a recursive edit to deal with this question---instead of any
-other action that would normally be taken.
-
address@hidden delete-and-edit
-Delete the text being considered, then enter a recursive edit to replace
-it.
-
address@hidden recenter
-Redisplay and center the window, then ask the same question again.
-
address@hidden quit
-Perform a quit right away. Only @code{y-or-n-p} and related functions
-use this answer.
-
address@hidden help
-Display some help, then ask again.
address@hidden table
-
address@hidden Standard Regexps
address@hidden Standard Regular Expressions Used in Editing
address@hidden regexps used standardly in editing
address@hidden standard regexps used in editing
-
- This section describes some variables that hold regular expressions
-used for certain purposes in editing:
-
address@hidden page-delimiter
-This is the regular expression describing line-beginnings that separate
-pages. The default value is @code{"^\014"} (i.e., @code{"^^L"} or
address@hidden"^\C-l"}); this matches a line that starts with a formfeed
-character.
address@hidden defvar
-
- The following two regular expressions should @emph{not} assume the
-match always starts at the beginning of a line; they should not use
address@hidden to anchor the match. Most often, the paragraph commands do
-check for a match only at the beginning of a line, which means that
address@hidden would be superfluous. When there is a nonzero left margin,
-they accept matches that start after the left margin. In that case, a
address@hidden would be incorrect. However, a @samp{^} is harmless in modes
-where a left margin is never used.
-
address@hidden 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
address@hidden@code{"[@ \t\f]*$"}}, which matches a line that consists entirely
of
-spaces, tabs, and form feeds (after its left margin).
address@hidden defvar
-
address@hidden paragraph-start
-This is the regular expression for recognizing the beginning of a line
-that starts @emph{or} separates paragraphs. The default value is
address@hidden@code{"\f\\|[ \t]*$"}}, which matches a line containing only
-whitespace or starting with a form feed (after its left margin).
address@hidden defvar
-
address@hidden sentence-end
-If address@hidden, 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.)
-
-If the value is @code{nil}, the default, then the function
address@hidden 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.
address@hidden defvar
-
address@hidden sentence-end
-This function returns the value of the variable @code{sentence-end},
-if address@hidden Otherwise it returns a default value based on the
-values of the variables @code{sentence-end-double-space}
-(@pxref{Definition of sentence-end-double-space}),
address@hidden and
address@hidden
address@hidden defun
-
address@hidden
- arch-tag: c2573ca2-18aa-4839-93b8-924043ef831f
address@hidden ignore
- [Emacs-diffs] Changes to searching.texi,
Glenn Morris <=