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diff --git a/lispref/searching.texi b/lispref/searching.texi deleted file mode 100644 index 28625c25bdb..00000000000 --- a/lispref/searching.texi +++ /dev/null @@ -1,1254 +0,0 @@ -@c -*-texinfo-*- -@c This is part of the GNU Emacs Lisp Reference Manual. -@c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc. -@c See the file elisp.texi for copying conditions. -@setfilename ../info/searching -@node Searching and Matching, Syntax Tables, Text, Top -@chapter Searching and Matching -@cindex 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. - -@menu -* String Search:: Search for an exact match. -* Regular Expressions:: Describing classes of strings. -* Regexp Search:: Searching for a match for a regexp. -* Search and Replace:: Internals of @code{query-replace}. -* Match Data:: Finding out which part of the text matched - various parts of a regexp, after regexp search. -* Searching and Case:: Case-independent or case-significant searching. -* Standard Regexps:: Useful regexps for finding sentences, pages,... -@end menu - - The @samp{skip-chars@dots{}} functions also perform a kind of searching. -@xref{Skipping Characters}. - -@node String Search -@section Searching for Strings -@cindex 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; -@var{limit} and @var{noerror} are set to @code{nil}, and @var{repeat} -is set to 1. - -@deffn Command search-forward string &optional limit noerror repeat - This function searches forward from point for an exact match for -@var{string}. 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). -@c 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}: - -@example -@group ----------- Buffer: foo ---------- -@point{}The quick brown fox jumped over the lazy dog. ----------- Buffer: foo ---------- -@end group - -@group -(search-forward "fox") - @result{} 20 - ----------- Buffer: foo ---------- -The quick brown fox@point{} jumped over the lazy dog. ----------- Buffer: foo ---------- -@end group -@end 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. - -@kindex search-failed - What happens when the search fails depends on the value of -@var{noerror}. 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 -@code{nil} 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 programs -may depend on a value of @code{nil}.) - - If @var{repeat} is non-@code{nil}, then the search is repeated that -many times. Point is positioned at the end of the last match. -@end deffn - -@deffn 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. -@end deffn - -@deffn Command word-search-forward string &optional limit noerror repeat -@cindex word search -This function searches forward from point for a ``word'' match for -@var{string}. If it finds a match, it sets point to the end of the -match found, and returns the new value of point. -@c Emacs 19 feature - -Word matching regards @var{string} as a sequence of words, disregarding -punctuation that separates them. It searches the buffer for the same -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{!}. - -@example -@group ----------- Buffer: foo ---------- -@point{}He said "Please! Find -the ball boy!" ----------- Buffer: foo ---------- -@end group - -@group -(word-search-forward "Please find the ball, boy.") - @result{} 35 - ----------- Buffer: foo ---------- -He said "Please! Find -the ball boy@point{}!" ----------- Buffer: foo ---------- -@end group -@end example - -If @var{limit} is non-@code{nil} (it must be a position in the current -buffer), then it is 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 buffer) and returns @code{nil}. - -If @var{repeat} is non-@code{nil}, then the search is repeated that many -times. Point is positioned at the end of the last match. -@end deffn - -@deffn Command word-search-backward string &optional limit noerror repeat -This function searches backward from point for a word match to -@var{string}. This function is just like @code{word-search-forward} -except that it searches backward and normally leaves point at the -beginning of the match. -@end deffn - -@node Regular Expressions -@section Regular Expressions -@cindex regular expression -@cindex 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. - -@menu -* Syntax of Regexps:: Rules for writing regular expressions. -* Regexp Example:: Illustrates regular expression syntax. -@end menu - -@node Syntax of Regexps -@subsection 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 which matches that character and nothing else. -The special characters are @samp{$}, @samp{^}, @samp{.}, @samp{*}, -@samp{+}, @samp{?}, @samp{[}, @samp{]} and @samp{\}; no new special -characters will be defined in the future. 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 -@samp{f} and no other string. (It does @emph{not} match the string -@samp{ff}.) Likewise, @samp{o} is a regular expression that matches -only @samp{o}.@refill - -Any two regular expressions @var{a} and @var{b} can be concatenated. The -result is a regular expression which matches a string if @var{a} matches -some amount of the beginning of that string and @var{b} matches the rest of -the string.@refill - -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 characters. Here is a list of them: - -@need 1200 -@table @kbd -@item .@: @r{(Period)} -@cindex @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 -@samp{b}.@refill - -@item * -@cindex @samp{*} in regexp -is not a construct by itself; it is a suffix operator that means to -repeat the preceding regular expression as many times as possible. In -@samp{fo*}, the @samp{*} applies to the @samp{o}, so @samp{fo*} matches -one @samp{f} followed by any number of @samp{o}s. The case of zero -@samp{o}s is allowed: @samp{fo*} does match @samp{f}.@refill - -@samp{*} always applies to the @emph{smallest} possible preceding -expression. Thus, @samp{fo*} has a repeating @samp{o}, not a -repeating @samp{fo}.@refill - -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 case that makes -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 -@samp{ar} 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.@refill - -@item + -@cindex @samp{+} in regexp -is a suffix operator similar to @samp{*} except that the preceding -expression must match at least once. So, for example, @samp{ca+r} -matches the strings @samp{car} and @samp{caaaar} but not the string -@samp{cr}, whereas @samp{ca*r} matches all three strings. - -@item ? -@cindex @samp{?} in regexp -is a suffix operator similar to @samp{*} except that the preceding -expression can match either once or not at all. For example, -@samp{ca?r} matches @samp{car} or @samp{cr}, but does not match anyhing -else. - -@item [ @dots{} ] -@cindex character set (in regexp) -@cindex @samp{[} in regexp -@cindex @samp{]} in regexp -@samp{[} begins a @dfn{character set}, which is terminated by a -@samp{]}. In the simplest case, the characters between the two brackets -form the set. Thus, @samp{[ad]} matches either one @samp{a} or one -@samp{d}, and @samp{[ad]*} 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.@refill - -The usual regular expression special characters are not special inside a -character set. A completely different set of special characters exists -inside character sets: @samp{]}, @samp{-} and @samp{^}.@refill - -@samp{-} is used for ranges of characters. To write a range, write two -characters with a @samp{-} between them. Thus, @samp{[a-z]} matches any -lower case letter. Ranges may be intermixed freely with individual -characters, as in @samp{[a-z$%.]}, which matches any lower case letter -or @samp{$}, @samp{%} or a period.@refill - -To include a @samp{]} in a character set, make it the first character. -For example, @samp{[]a]} matches @samp{]} or @samp{a}. To include a -@samp{-}, write @samp{-} as the first character in the set, or put -immediately after a range. (You can replace one individual character -@var{c} with the range @samp{@var{c}-@var{c}} to make a place to put the -@samp{-}). There is no way to write a set containing just @samp{-} and -@samp{]}. - -To include @samp{^} in a set, put it anywhere but at the beginning of -the set. - -@item [^ @dots{} ] -@cindex @samp{^} in regexp -@samp{[^} begins a @dfn{complement character set}, which matches any -character except the ones specified. Thus, @samp{[^a-z0-9A-Z]} -matches all characters @emph{except} letters and digits.@refill - -@samp{^} is not special in a character set unless it is the first -character. The character following the @samp{^} is treated as if it -were first (thus, @samp{-} and @samp{]} are not special there). - -Note that a complement character set can match a newline, unless -newline is mentioned as one of the characters not to match. - -@item ^ -@cindex @samp{^} in regexp -@cindex beginning of line in regexp -is a special character that matches the empty string, but only at -the beginning of a line in the text being matched. Otherwise it fails -to match anything. Thus, @samp{^foo} matches a @samp{foo} which occurs -at the beginning of a line. - -When matching a string, @samp{^} matches at the beginning of the string -or after a newline character @samp{\n}. - -@item $ -@cindex @samp{$} in regexp -is similar to @samp{^} but matches only at the end of a line. Thus, -@samp{x+$} matches a string of one @samp{x} or more at the end of a line. - -When matching a string, @samp{$} matches at the end of the string -or before a newline character @samp{\n}. - -@item \ -@cindex @samp{\} in regexp -has two functions: it quotes the special characters (including -@samp{\}), and it introduces additional special constructs. - -Because @samp{\} quotes special characters, @samp{\$} is a regular -expression which matches only @samp{$}, and @samp{\[} is a regular -expression which 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 -@samp{\\}. To write a Lisp string that contains the characters -@samp{\\}, Lisp syntax requires you to quote each @samp{\} with another -@samp{\}. Therefore, the read syntax for a regular expression matching -@samp{\} is @code{"\\\\"}.@refill -@end table - -@strong{Please 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; better to -quote the special character anyway, regardless of where it -appears.@refill - -For the most part, @samp{\} followed by any character matches only -that character. However, there are several exceptions: characters -which, when preceded by @samp{\}, are special constructs. Such -characters are always ordinary when encountered on their own. Here -is a table of @samp{\} constructs: - -@table @kbd -@item \| -@cindex @samp{|} in regexp -@cindex 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 -@var{b} matches.@refill - -Thus, @samp{foo\|bar} matches either @samp{foo} or @samp{bar} -but no other string.@refill - -@samp{\|} applies to the largest possible surrounding expressions. Only a -surrounding @samp{\( @dots{} \)} grouping can limit the grouping power of -@samp{\|}.@refill - -Full backtracking capability exists to handle multiple uses of @samp{\|}. - -@item \( @dots{} \) -@cindex @samp{(} in regexp -@cindex @samp{)} in regexp -@cindex regexp grouping -is a grouping construct that serves three purposes: - -@enumerate -@item -To enclose a set of @samp{\|} alternatives for other operations. -Thus, @samp{\(foo\|bar\)x} matches either @samp{foox} or @samp{barx}. - -@item -To enclose an expression for a suffix operator such as @samp{*} to act -on. Thus, @samp{ba\(na\)*} matches @samp{bananana}, etc., with any -(zero or more) number of @samp{na} strings.@refill - -@item -To record a matched substring for future reference. -@end enumerate - -This last application is not a consequence of the idea of a -parenthetical grouping; it is a separate feature which 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: - -@item \@var{digit} -matches the same text which matched the @var{digit}th occurrence of a -@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. - -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. - -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. - -@item \w -@cindex @samp{\w} in regexp -matches any word-constituent character. The editor syntax table -determines which characters these are. @xref{Syntax Tables}. - -@item \W -@cindex @samp{\W} in regexp -matches any character that is not a word-constituent. - -@item \s@var{code} -@cindex @samp{\s} in regexp -matches any character whose syntax is @var{code}. Here @var{code} is a -character which represents a syntax code: thus, @samp{w} for word -constituent, @samp{-} for whitespace, @samp{(} for open parenthesis, -etc. @xref{Syntax Tables}, for a list of syntax codes and the -characters that stand for them. - -@item \S@var{code} -@cindex @samp{\S} in regexp -matches any character whose syntax is not @var{code}. -@end table - - These regular expression constructs match the empty string---that is, -they don't use up any characters---but whether they match depends on the -context. - -@table @kbd -@item \` -@cindex @samp{\`} in regexp -matches the empty string, but only at the beginning -of the buffer or string being matched against. - -@item \' -@cindex @samp{\'} in regexp -matches the empty string, but only at the end of -the buffer or string being matched against. - -@item \= -@cindex @samp{\=} in regexp -matches the empty string, but only at point. -(This construct is not defined when matching against a string.) - -@item \b -@cindex @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 -@samp{foo} as a separate word. @samp{\bballs?\b} matches -@samp{ball} or @samp{balls} as a separate word.@refill - -@item \B -@cindex @samp{\B} in regexp -matches the empty string, but @emph{not} at the beginning or -end of a word. - -@item \< -@cindex @samp{\<} in regexp -matches the empty string, but only at the beginning of a word. - -@item \> -@cindex @samp{\>} in regexp -matches the empty string, but only at the end of a word. -@end table - -@kindex invalid-regexp - Not every string is a valid regular expression. For example, a string -with unbalanced square brackets is invalid (with a few exceptions, such -as @samp{[]]}, 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. - -@defun regexp-quote string -This function returns a regular expression string that matches exactly -@var{string} and nothing else. This allows you to request an exact -string match when calling a function that wants a regular expression. - -@example -@group -(regexp-quote "^The cat$") - @result{} "\\^The cat\\$" -@end group -@end 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 which is the value of @code{string}, surrounded by -whitespace: - -@example -@group -(re-search-forward - (concat "\\s " (regexp-quote string) "\\s ")) -@end group -@end example -@end defun - -@node Regexp Example -@comment node-name, next, previous, up -@subsection Complex Regexp Example - - 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}. - - 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. - -@example -"[.?!][]\"')@}]*\\($\\| $\\|\t\\| \\)[ \t\n]*" -@end example - - In contrast, if you evaluate the variable @code{sentence-end}, you -will see the following: - -@example -@group -sentence-end -@result{} -"[.?!][]\"')@}]*\\($\\| $\\| \\| \\)[ -]*" -@end group -@end example - -@noindent -In this output, tab and newline appear as themselves. - - This regular expression contains four parts in succession and can be -deciphered as follows: - -@table @code -@item [.?!] -The first part of the pattern consists of three characters, a period, a -question mark and an exclamation mark, within square brackets. The -match must begin with one of these three characters. - -@item []\"')@}]* -The second part of the pattern matches any closing braces and quotation -marks, zero or more of them, that may follow the period, question mark -or exclamation mark. The @code{\"} is Lisp syntax for a double-quote in -a string. The @samp{*} at the end indicates that the immediately -preceding regular expression (a character set, in this case) may be -repeated zero or more times. - -@item \\($\\|@ \\|\t\\|@ @ \\) -The third part of the pattern matches the whitespace that follows the -end of a sentence: the end of a line, or a tab, or two spaces. The -double backslashes mark the parentheses and vertical bars as regular -expression syntax; the parentheses mark the group and the vertical bars -separate alternatives. The dollar sign is used to match the end of a -line. - -@item [ \t\n]* -Finally, the last part of the pattern matches any additional whitespace -beyond the minimum needed to end a sentence. -@end table - -@node Regexp Search -@section Regular Expression Searching -@cindex regular expression searching -@cindex regexp searching -@cindex searching for regexp - - In GNU Emacs, you can search for the next match for a regexp 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}. - -@deffn 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 -@var{regexp}, and leaves point at the end of the first match found. -It returns the new value of point. - -If @var{limit} is non-@code{nil} (it must be a position in the current -buffer), then it is the upper bound to the search. No match extending -after that position is accepted. - -What happens when the search fails depends on the value of -@var{noerror}. If @var{noerror} is @code{nil}, a @code{search-failed} -error is signaled. If @var{noerror} is @code{t}, -@code{re-search-forward} does nothing and returns @code{nil}. If -@var{noerror} is neither @code{nil} nor @code{t}, then -@code{re-search-forward} moves point to @var{limit} (or the end of the -buffer) and returns @code{nil}. - -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. - -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). - -@example -@group ----------- Buffer: foo ---------- -I read "@point{}The cat in the hat -comes back" twice. ----------- Buffer: foo ---------- -@end group - -@group -(re-search-forward "[a-z]+" nil t 5) - @result{} 27 - ----------- Buffer: foo ---------- -I read "The cat in the hat@point{} -comes back" twice. ----------- Buffer: foo ---------- -@end group -@end example -@end deffn - -@deffn 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. If @code{re-search-backward} -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. The reason is that matching a regular -expression at a given spot always works from beginning to end, and is -done at a specified beginning position. - -A true mirror-image of @code{re-search-forward} would require a special -feature for matching regexps from end to beginning. It's not worth the -trouble of implementing that. -@end deffn - -@defun 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 non-@code{nil}, the search starts -at that index in @var{string}. - -For example, - -@example -@group -(string-match - "quick" "The quick brown fox jumped quickly.") - @result{} 4 -@end group -@group -(string-match - "quick" "The quick brown fox jumped quickly." 8) - @result{} 27 -@end group -@end example - -@noindent -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}. - -@example -@group -(string-match - "quick" "The quick brown fox jumped quickly." 8) - @result{} 27 -@end group - -@group -(match-end 0) - @result{} 32 -@end group -@end example -@end defun - -@defun 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}. -@xref{Match Data}. - -In this example, point is located directly before the @samp{T}. If it -were anywhere else, the result would be @code{nil}. - -@example -@group ----------- Buffer: foo ---------- -I read "@point{}The cat in the hat -comes back" twice. ----------- Buffer: foo ---------- - -(looking-at "The cat in the hat$") - @result{} t -@end group -@end example -@end defun - -@ignore -@deffn Command delete-matching-lines regexp -This function is identical to @code{delete-non-matching-lines}, save -that it deletes what @code{delete-non-matching-lines} keeps. - -In the example below, point is located on the first line of text. - -@example -@group ----------- Buffer: foo ---------- -We hold these truths -to be self-evident, -that all men are created -equal, and that they are ----------- Buffer: foo ---------- -@end group - -@group -(delete-matching-lines "the") - @result{} nil - ----------- Buffer: foo ---------- -to be self-evident, -that all men are created ----------- Buffer: foo ---------- -@end group -@end example -@end deffn - -@deffn Command flush-lines regexp -This function is the same as @code{delete-matching-lines}. -@end deffn - -@defun delete-non-matching-lines regexp -This function deletes all lines following point which don't -contain a match for the regular expression @var{regexp}. -@end defun - -@deffn Command keep-lines regexp -This function is the same as @code{delete-non-matching-lines}. -@end deffn - -@deffn Command how-many regexp -This function counts the number of matches for @var{regexp} there are in -the current buffer following point. It prints this number in -the echo area, returning the string printed. -@end deffn - -@deffn Command count-matches regexp -This function is a synonym of @code{how-many}. -@end deffn - -@deffn Command list-matching-lines regexp 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, -or @code{-}@var{nlines} before if @var{nlines} is negative. -@var{nlines} defaults to @code{list-matching-lines-default-context-lines}. -Interactively it is the prefix arg. - -The lines are shown in a buffer named @samp{*Occur*}. -It serves as a menu to find any of the occurrences in this buffer. -@kbd{C-h m} (@code{describe-mode} in that buffer gives help. -@end deffn - -@defopt list-matching-lines-default-context-lines -Default value is 0. -Default number of context lines to include around a @code{list-matching-lines} -match. A negative number means to include that many lines before the match. -A positive number means to include that many lines both before and after. -@end defopt -@end ignore - -@node Search and Replace -@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 -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 -considered a regular expression; otherwise, it must match literally. If -@var{delimited-flag} is non-@code{nil}, 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{repeat-count} is non-@code{nil}, it should be an integer, the -number of occurrences to consider. In this case, @code{perform-replace} -returns after considering that many occurrences. - -Normally, the keymap @code{query-replace-map} defines the possible user -responses. The argument @var{map}, if non-@code{nil}, is a keymap to -use instead of @code{query-replace-map}. -@end defun - -@defvar query-replace-map -This variable holds a special keymap that defines the valid user -responses for @code{query-replace} and related functions, as well as -@code{y-or-n-p} and @code{map-y-or-n-p}. It is unusual in two ways: - -@itemize @bullet -@item -The ``key bindings'' are not commands, just symbols that are meaningful -to the functions that use this map. - -@item -Prefix keys are not supported; each key binding must be for a single event -key sequence. This is because the functions don't use read key sequence to -get the input; instead, they read a single event and look it up ``by hand.'' -@end itemize -@end defvar - -Here are the meaningful ``bindings'' for @code{query-replace-map}. -Several of them are meaningful only for @code{query-replace} and -friends. - -@table @code -@item act -Do take the action being considered---in other words, ``yes.'' - -@item skip -Do not take action for this question---in other words, ``no.'' - -@item exit -Answer this question ``no,'' and don't ask any more. - -@item act-and-exit -Answer this question ``yes,'' and don't ask any more. - -@item act-and-show -Answer this question ``yes,'' but show the results---don't advance yet -to the next question. - -@item automatic -Answer this question and all subsequent questions in the series with -``yes,'' without further user interaction. - -@item backup -Move back to the previous place that a question was asked about. - -@item edit -Enter a recursive edit to deal with this question---instead of any -other action that would normally be taken. - -@item delete-and-edit -Delete the text being considered, then enter a recursive edit to replace -it. - -@item recenter -Redisplay and center the window, then ask the same question again. - -@item quit -Perform a quit right away. Only @code{y-or-n-p} and related functions -use this answer. - -@item help -Display some help, then ask again. -@end table - -@node Match Data -@section The Match Data -@cindex match data - - Emacs keeps track of the positions of the start and end of segments of -text found during a regular expression search. This means, for example, -that you can search for a complex pattern, such as a date in an Rmail -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. - -@menu -* Simple Match Data:: Accessing single items of match data, - such as where a particular subexpression started. -* Replacing Match:: Replacing a substring that was matched. -* Entire Match Data:: Accessing the entire match data at once, as a list. -* Saving Match Data:: Saving and restoring the match data. -@end menu - -@node Simple Match Data -@subsection Simple Match Data Access - - This section explains how to use the match data to find the starting -point or ending point of the text that was matched by a particular -search, or by a particular parenthetical subexpression of a regular -expression. - -@defun 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. - -The argument @var{count}, a number, specifies a subexpression whose -start position is the value. If @var{count} is zero, then the value is -the position of the text matched by the whole regexp. If @var{count} is -greater than zero, then the value is the position of the beginning of -the text matched by the @var{count}th subexpression. - -Subexpressions of a regular expression are those expressions grouped -inside of parentheses, @samp{\(@dots{}\)}. The @var{count}th -subexpression is found by counting occurrences of @samp{\(} from the -beginning of the whole regular expression. The first subexpression is -numbered 1, the second 2, and so on. - -The value is @code{nil} for a parenthetical grouping inside of a -@samp{\|} alternative that wasn't used in the match. -@end defun - -@defun match-end count -This function returns the position of the end of the text that matched -the last regular expression searched for, or a subexpression of it. -This function is otherwise similar to @code{match-beginning}. -@end defun - - Here is an example of using the match data, with a comment showing the -positions within the text: - -@example -@group -(string-match "\\(qu\\)\\(ick\\)" - "The quick fox jumped quickly.") - ;0123456789 - @result{} 4 -@end group - -@group -(match-beginning 1) ; @r{The beginning of the match} - @result{} 4 ; @r{with @samp{qu} is at index 4.} -@end group - -@group -(match-beginning 2) ; @r{The beginning of the match} - @result{} 6 ; @r{with @samp{ick} is at index 6.} -@end group - -@group -(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.} -@end group -@end 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 -@samp{in}. 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}). - -@example -@group -(list - (re-search-forward "The \\(cat \\)") - (match-beginning 0) - (match-beginning 1)) - @result{} (t 9 13) -@end group - -@group ----------- Buffer: foo ---------- -I read "The cat @point{}in the hat comes back" twice. - ^ ^ - 9 13 ----------- Buffer: foo ---------- -@end group -@end example - -@noindent -(In this case, the index returned is a buffer position; the first -character of the buffer counts as 1.) - -@node Replacing Match -@subsection Replacing the Text That Matched - - This function replaces the text matched by the last search with -@var{replacement}. - -@cindex case in replacements -@defun replace-match replacement &optional fixedcase literal -This function replaces the buffer text matched by the last search, with -@var{replacement}. It applies only to buffers; you can't use -@code{replace-match} to replace a substring found with -@code{string-match}. - -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, except when all of the words in the original -text are only one character long. In that event, the replacement text -is capitalized. If @emph{any} of the words in the original text is -capitalized, then all of the words in the replacement text are -capitalized. - -If @var{literal} is non-@code{nil}, 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: - -@table @asis -@item @samp{\&} -@cindex @samp{&} in replacement -@samp{\&} stands for the entire text being replaced. - -@item @samp{\@var{n}} -@cindex @samp{\@var{n}} in replacement -@samp{\@var{n}} stands for the text that matched the @var{n}th -subexpression in the original regexp. Subexpressions are those -expressions grouped inside of @samp{\(@dots{}\)}. @var{n} is a digit. - -@item @samp{\\} -@cindex @samp{\} in replacement -@samp{\\} stands for a single @samp{\} in the replacement text. -@end table - -@code{replace-match} leaves point at the end of the replacement text, -and returns @code{t}. -@end defun - -@node Entire Match Data -@subsection 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. - -@defun match-data -This function returns a newly constructed list containing all the -information on what text the last search matched. Element zero is the -position of the beginning of the match for the whole expression; element -one is the position of the end of the match for the expression. The -next two elements are the positions of the beginning and end of the -match for the first subexpression, and so on. In general, element -@ifinfo -number 2@var{n} -@end ifinfo -@tex -number {\mathsurround=0pt $2n$} -@end tex -corresponds to @code{(match-beginning @var{n})}; and -element -@ifinfo -number 2@var{n} + 1 -@end ifinfo -@tex -number {\mathsurround=0pt $2n+1$} -@end tex -corresponds to @code{(match-end @var{n})}. - -All the elements are markers or @code{nil} if matching was done on a -buffer, and all are integers or @code{nil} if matching was done on a -string with @code{string-match}. (In Emacs 18 and earlier versions, -markers were used even for matching on a string, except in the case -of the integer 0.) - -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. - -@example -@group -(match-data) - @result{} (#<marker at 9 in foo> - #<marker at 17 in foo> - #<marker at 13 in foo> - #<marker at 17 in foo>) -@end group -@end example -@end defun - -@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}. - -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. - -@findex store-match-data -@code{store-match-data} is an alias for @code{set-match-data}. -@end defun - -@node Saving Match Data -@subsection Saving and Restoring the Match Data - - All asynchronous process functions (filters and sentinels) and -functions that use @code{recursive-edit} should save and restore the -match data if they do a search or if they let the user type arbitrary -commands. Saving the match data is useful in other cases as -well---whenever you want to access the match data resulting from an -earlier search, notwithstanding another intervening search. - - This example shows the problem that can arise if you fail to -attend to this requirement: - -@example -@group -(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!} -@end group -@end example - - In Emacs versions 19 and later, you can save and restore the match -data with @code{save-match-data}: - -@defspec save-match-data body@dots{} -This special form executes @var{body}, saving and restoring the match -data around it. This is useful if you wish to do a search without -altering the match data that resulted from an earlier search. -@end defspec - - You can use @code{set-match-data} together with @code{match-data} to -imitate the effect of the special form @code{save-match-data}. This is -useful for writing code that can run in Emacs 18. Here is how: - -@example -@group -(let ((data (match-data))) - (unwind-protect - @dots{} ; @r{May change the original match data.} - (set-match-data data))) -@end group -@end example - -@ignore - Here is a function which restores the match data provided the buffer -associated with it still exists. - -@smallexample -@group -(defun restore-match-data (data) -@c It is incorrect to split the first line of a doc string. -@c 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)) -@end group - (while d - (and (car d) - (null (marker-buffer (car d))) -@group - ;; @file{match-data} @r{buffer is deleted.} - (throw 'foo nil)) - (setq d (cdr d))) - (set-match-data data)))) -@end group -@end smallexample -@end ignore - -@node Searching and Case -@section Searching and Case -@cindex 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 -@samp{Foo} or @samp{foo} is also considered a match. Regexps, and in -particular character sets, are included: thus, @samp{[aB]} would match -@samp{a} or @samp{A} or @samp{b} or @samp{B}. - - If you do not want this feature, set the variable -@code{case-fold-search} to @code{nil}. Then all letters must match -exactly, including case. This is a per-buffer-local variable; altering -the variable affects only the current buffer. (@xref{Intro to -Buffer-Local}.) Alternatively, you may change the value of -@code{default-case-fold-search}, which is the default value of -@code{case-fold-search} for buffers that do not override it. - - 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 Lisp functions use. - -@defopt case-replace -This variable determines whether @code{query-replace} should preserve -case in replacements. If the variable is @code{nil}, then -@code{replace-match} should not try to convert case. -@end defopt - -@defopt case-fold-search -This buffer-local variable determines whether searches should ignore -case. If the variable is @code{nil} they do not ignore case; otherwise -they do ignore case. -@end defopt - -@defvar default-case-fold-search -The value of this variable is the default value for -@code{case-fold-search} in buffers that do not override it. This is the -same as @code{(default-value 'case-fold-search)}. -@end defvar - -@node Standard Regexps -@section Standard Regular Expressions Used in Editing -@cindex regexps used standardly in editing -@cindex standard regexps used in editing - - This section describes some variables that hold regular expressions -used for certain purposes in editing: - -@defvar page-delimiter -This is the regexp describing line-beginnings that separate pages. The -default value is @code{"^\014"} (i.e., @code{"^^L"} or @code{"^\C-l"}). -@end defvar - -@defvar 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 @code{"^[ -\t\f]*$"}, which is a line that consists entirely of spaces, tabs, and -form feeds. -@end defvar - -@defvar paragraph-start -This is the regular expression for recognizing the beginning of a line -that starts @emph{or} separates paragraphs. The default value is -@code{"^[ \t\n\f]"}, which matches a line starting with a space, tab, -newline, or form feed. -@end defvar - -@defvar sentence-end -This is the regular expression describing the end of a sentence. (All -paragraph boundaries also end sentences, regardless.) The default value -is: - -@example -"[.?!][]\"')@}]*\\($\\|\t\\| \\)[ \t\n]*" -@end example - -This means a period, question mark or exclamation mark, followed by a -closing brace, followed by tabs, spaces or new lines. - -For a detailed explanation of this regular expression, see @ref{Regexp -Example}. -@end defvar |