+++ /dev/null
-This is Info file ../../info/lispref.info, produced by Makeinfo version
-1.68 from the input file lispref.texi.
-
-INFO-DIR-SECTION XEmacs Editor
-START-INFO-DIR-ENTRY
-* Lispref: (lispref). XEmacs Lisp Reference Manual.
-END-INFO-DIR-ENTRY
-
- Edition History:
-
- GNU Emacs Lisp Reference Manual Second Edition (v2.01), May 1993 GNU
-Emacs Lisp Reference Manual Further Revised (v2.02), August 1993 Lucid
-Emacs Lisp Reference Manual (for 19.10) First Edition, March 1994
-XEmacs Lisp Programmer's Manual (for 19.12) Second Edition, April 1995
-GNU Emacs Lisp Reference Manual v2.4, June 1995 XEmacs Lisp
-Programmer's Manual (for 19.13) Third Edition, July 1995 XEmacs Lisp
-Reference Manual (for 19.14 and 20.0) v3.1, March 1996 XEmacs Lisp
-Reference Manual (for 19.15 and 20.1, 20.2, 20.3) v3.2, April, May,
-November 1997 XEmacs Lisp Reference Manual (for 21.0) v3.3, April 1998
-
- Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995 Free Software
-Foundation, Inc. Copyright (C) 1994, 1995 Sun Microsystems, Inc.
-Copyright (C) 1995, 1996 Ben Wing.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided that the
-entire resulting derived work is distributed under the terms of a
-permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that this permission notice may be stated in a
-translation approved by the Foundation.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the section entitled "GNU General Public License" is included
-exactly as in the original, and provided that the entire resulting
-derived work is distributed under the terms of a permission notice
-identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions, except that the section entitled "GNU General Public License"
-may be included in a translation approved by the Free Software
-Foundation instead of in the original English.
-
-\1f
-File: lispref.info, Node: Change Hooks, Next: Transformations, Prev: Transposition, Up: Text
-
-Change Hooks
-============
-
- These hook variables let you arrange to take notice of all changes in
-all buffers (or in a particular buffer, if you make them buffer-local).
-
- The functions you use in these hooks should save and restore the
-match data if they do anything that uses regular expressions;
-otherwise, they will interfere in bizarre ways with the editing
-operations that call them.
-
- Buffer changes made while executing the following hooks don't
-themselves cause any change hooks to be invoked.
-
- - Variable: before-change-functions
- This variable holds a list of a functions to call before any buffer
- modification. Each function gets two arguments, the beginning and
- end of the region that is about to change, represented as
- integers. The buffer that is about to change is always the
- current buffer.
-
- - Variable: after-change-functions
- This variable holds a list of a functions to call after any buffer
- modification. Each function receives three arguments: the
- beginning and end of the region just changed, and the length of
- the text that existed before the change. (To get the current
- length, subtract the region beginning from the region end.) All
- three arguments are integers. The buffer that's about to change
- is always the current buffer.
-
- - Variable: before-change-function
- This obsolete variable holds one function to call before any buffer
- modification (or `nil' for no function). It is called just like
- the functions in `before-change-functions'.
-
- - Variable: after-change-function
- This obsolete variable holds one function to call after any buffer
- modification (or `nil' for no function). It is called just like
- the functions in `after-change-functions'.
-
- - Variable: first-change-hook
- This variable is a normal hook that is run whenever a buffer is
- changed that was previously in the unmodified state.
-
-\1f
-File: lispref.info, Node: Transformations, Prev: Change Hooks, Up: Text
-
-Textual transformations--MD5 and base64 support
-===============================================
-
- Some textual operations inherently require examining each character
-in turn, and performing arithmetic operations on them. Such operations
-can, of course, be implemented in Emacs Lisp, but tend to be very slow
-for large portions of text or data. This is why some of them are
-implemented in C, with an appropriate interface for Lisp programmers.
-Examples of algorithms thus provided are MD5 and base64 support.
-
- MD5 is an algorithm for calculating message digests, as described in
-rfc1321. Given a message of arbitrary length, MD5 produces an 128-bit
-"fingerprint" ("message digest") corresponding to that message. It is
-considered computationally infeasible to produce two messages having
-the same MD5 digest, or to produce a message having a prespecified
-target digest. MD5 is used heavily by various authentication schemes.
-
- Emacs Lisp interface to MD5 consists of a single function `md5':
-
- - Function: md5 OBJECT &optional START END
- This function returns the MD5 message digest of OBJECT, a buffer
- or string.
-
- Optional arguments START and END denote positions for computing
- the digest of a portion of OBJECT.
-
- Some examples of usage:
-
- ;; Calculate the digest of the entire buffer
- (md5 (current-buffer))
- => "8842b04362899b1cda8d2d126dc11712"
-
- ;; Calculate the digest of the current line
- (md5 (current-buffer) (point-at-bol) (point-at-eol))
- => "60614d21e9dee27dfdb01fa4e30d6d00"
-
- ;; Calculate the digest of your name and email address
- (md5 (concat (format "%s <%s>" (user-full-name) user-mail-address)))
- => "0a2188c40fd38922d941fe6032fce516"
-
- Base64 is a portable encoding for arbitrary sequences of octets, in a
-form that need not be readable by humans. It uses a 65-character subset
-of US-ASCII, as described in rfc2045. Base64 is used by MIME to encode
-binary bodies, and to encode binary characters in message headers.
-
- The Lisp interface to base64 consists of four functions:
-
- - Function: base64-encode-region BEG END &optional NO-LINE-BREAK
- This function encodes the region between BEG and END of the
- current buffer to base64 format. This means that the original
- region is deleted, and replaced with its base64 equivalent.
-
- Normally, encoded base64 output is multi-line, with 76-character
- lines. If NO-LINE-BREAK is non-`nil', newlines will not be
- inserted, resulting in single-line output.
-
- Mule note: you should make sure that you convert the multibyte
- characters (those that do not fit into 0-255 range) to something
- else, because they cannot be meaningfully converted to base64. If
- the `base64-encode-region' encounters such characters, it will
- signal an error.
-
- `base64-encode-region' returns the length of the encoded text.
-
- ;; Encode the whole buffer in base64
- (base64-encode-region (point-min) (point-max))
-
- The function can also be used interactively, in which case it
- works on the currently active region.
-
- - Function: base64-encode-string STRING
- This function encodes STRING to base64, and returns the encoded
- string.
-
- For Mule, the same considerations apply as for
- `base64-encode-region'.
-
- (base64-encode-string "fubar")
- => "ZnViYXI="
-
- - Function: base64-decode-region BEG END
- This function decodes the region between BEG and END of the
- current buffer. The region should be in base64 encoding.
-
- If the region was decoded correctly, `base64-decode-region' returns
- the length of the decoded region. If the decoding failed, `nil' is
- returned.
-
- ;; Decode a base64 buffer, and replace it with the decoded version
- (base64-decode-region (point-min) (point-max))
-
- - Function: base64-decode-string STRING
- This function decodes STRING to base64, and returns the decoded
- string. STRING should be valid base64-encoded text.
-
- If encoding was not possible, `nil' is returned.
-
- (base64-decode-string "ZnViYXI=")
- => "fubar"
-
- (base64-decode-string "totally bogus")
- => nil
-
-\1f
-File: lispref.info, Node: Searching and Matching, Next: Syntax Tables, Prev: Text, Up: Top
-
-Searching and Matching
-**********************
-
- XEmacs 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 "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.
-* POSIX Regexps:: Searching POSIX-style for the longest match.
-* Search and Replace:: Internals of `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,...
-
- The `skip-chars...' functions also perform a kind of searching.
-*Note Skipping Characters::.
-
-\1f
-File: lispref.info, Node: String Search, Next: Regular Expressions, Up: Searching and Matching
-
-Searching for Strings
-=====================
-
- 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; LIMIT
-and NOERROR are set to `nil', and REPEAT is set to 1.
-
- - Command: search-forward STRING &optional LIMIT NOERROR REPEAT
- This function searches forward from point for an exact match for
- 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 NOERROR (see below).
-
- In the following example, point is initially at the beginning of
- the line. Then `(search-forward "fox")' moves point after the last
- letter of `fox':
-
- ---------- Buffer: foo ----------
- -!-The quick brown fox jumped over the lazy dog.
- ---------- Buffer: foo ----------
-
- (search-forward "fox")
- => 20
-
- ---------- Buffer: foo ----------
- The quick brown fox-!- jumped over the lazy dog.
- ---------- Buffer: foo ----------
-
- The argument 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 LIMIT is omitted or `nil', it
- defaults to the end of the accessible portion of the buffer.
-
- What happens when the search fails depends on the value of
- NOERROR. If NOERROR is `nil', a `search-failed' error is
- signaled. If NOERROR is `t', `search-forward' returns `nil' and
- does nothing. If NOERROR is neither `nil' nor `t', then
- `search-forward' moves point to the upper bound and returns `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
- `nil'.)
-
- If 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.
-
- - Command: search-backward STRING &optional LIMIT NOERROR REPEAT
- This function searches backward from point for STRING. It is just
- like `search-forward' except that it searches backwards and leaves
- point at the beginning of the match.
-
- - Command: word-search-forward STRING &optional LIMIT NOERROR REPEAT
- This function searches forward from point for a "word" match for
- STRING. If it finds a match, it sets point to the end of the
- match found, and returns the new value of point.
-
- Word matching regards 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 `ball' does not match the word `balls'),
- but the details of punctuation and spacing are ignored (searching
- for `ball boy' does match `ball. Boy!').
-
- In this example, point is initially at the beginning of the
- buffer; the search leaves it between the `y' and the `!'.
-
- ---------- Buffer: foo ----------
- -!-He said "Please! Find
- the ball boy!"
- ---------- Buffer: foo ----------
-
- (word-search-forward "Please find the ball, boy.")
- => 35
-
- ---------- Buffer: foo ----------
- He said "Please! Find
- the ball boy-!-!"
- ---------- Buffer: foo ----------
-
- If LIMIT is non-`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 NOERROR is `nil', then `word-search-forward' signals an error
- if the search fails. If NOERROR is `t', then it returns `nil'
- instead of signaling an error. If NOERROR is neither `nil' nor
- `t', it moves point to LIMIT (or the end of the buffer) and
- returns `nil'.
-
- If REPEAT is non-`nil', then the search is repeated that many
- times. Point is positioned at the end of the last match.
-
- - Command: word-search-backward STRING &optional LIMIT NOERROR REPEAT
- This function searches backward from point for a word match to
- STRING. This function is just like `word-search-forward' except
- that it searches backward and normally leaves point at the
- beginning of the match.
-
-\1f
-File: lispref.info, Node: Regular Expressions, Next: Regexp Search, Prev: String Search, Up: Searching and Matching
-
-Regular Expressions
-===================
-
- A "regular expression" ("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.
-
- To gain a thorough understanding of regular expressions and how to
-use them to best advantage, we recommend that you study `Mastering
-Regular Expressions, by Jeffrey E.F. Friedl, O'Reilly and Associates,
-1997'. (It's known as the "Hip Owls" book, because of the picture on its
-cover.) You might also read the manuals to *Note (gawk)Top::, *Note
-(ed)Top::, `sed', `grep', *Note (perl)Top::, *Note (regex)Top::, *Note
-(rx)Top::, `pcre', and *Note (flex)Top::, which also make good use of
-regular expressions.
-
- The XEmacs regular expression syntax most closely resembles that of
-`ed', or `grep', the GNU versions of which all utilize the GNU `regex'
-library. XEmacs' version of `regex' has recently been extended with
-some Perl-like capabilities, described in the next section.
-
-* Menu:
-
-* Syntax of Regexps:: Rules for writing regular expressions.
-* Regexp Example:: Illustrates regular expression syntax.
-
-\1f
-File: lispref.info, Node: Syntax of Regexps, Next: Regexp Example, Up: Regular Expressions
-
-Syntax of Regular Expressions
------------------------------
-
- Regular expressions have a syntax in which a few characters are
-special constructs and the rest are "ordinary". An ordinary character
-is a simple regular expression that matches that character and nothing
-else. The special characters are `.', `*', `+', `?', `[', `]', `^',
-`$', and `\'; no new special characters will be defined in the future.
-Any other character appearing in a regular expression is ordinary,
-unless a `\' precedes it.
-
- For example, `f' is not a special character, so it is ordinary, and
-therefore `f' is a regular expression that matches the string `f' and
-no other string. (It does *not* match the string `ff'.) Likewise, `o'
-is a regular expression that matches only `o'.
-
- Any two regular expressions A and B can be concatenated. The result
-is a regular expression that matches a string if A matches some amount
-of the beginning of that string and B matches the rest of the string.
-
- As a simple example, we can concatenate the regular expressions `f'
-and `o' to get the regular expression `fo', which matches only the
-string `fo'. Still trivial. To do something more powerful, you need
-to use one of the special characters. Here is a list of them:
-
-`. (Period)'
- is a special character that matches any single character except a
- newline. Using concatenation, we can make regular expressions
- like `a.b', which matches any three-character string that begins
- with `a' and ends with `b'.
-
-`*'
- is not a construct by itself; it is a quantifying suffix operator
- that means to repeat the preceding regular expression as many
- times as possible. In `fo*', the `*' applies to the `o', so `fo*'
- matches one `f' followed by any number of `o's. The case of zero
- `o's is allowed: `fo*' does match `f'.
-
- `*' always applies to the *smallest* possible preceding
- expression. Thus, `fo*' has a repeating `o', not a repeating `fo'.
-
- The matcher processes a `*' construct by matching, immediately, as
- many repetitions as can be found; it is "greedy". Then it
- continues with the rest of the pattern. If that fails,
- backtracking occurs, discarding some of the matches of the
- `*'-modified construct in case that makes it possible to match the
- rest of the pattern. For example, in matching `ca*ar' against the
- string `caaar', the `a*' first tries to match all three `a's; but
- the rest of the pattern is `ar' and there is only `r' left to
- match, so this try fails. The next alternative is for `a*' to
- match only two `a's. With this choice, the rest of the regexp
- matches successfully.
-
- Nested repetition operators can be extremely slow if they specify
- backtracking loops. For example, it could take hours for the
- regular expression `\(x+y*\)*a' to match the sequence
- `xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxz'. The slowness is because
- Emacs must try each imaginable way of grouping the 35 `x''s before
- concluding that none of them can work. To make sure your regular
- expressions run fast, check nested repetitions carefully.
-
-`+'
- is a quantifying suffix operator similar to `*' except that the
- preceding expression must match at least once. It is also
- "greedy". So, for example, `ca+r' matches the strings `car' and
- `caaaar' but not the string `cr', whereas `ca*r' matches all three
- strings.
-
-`?'
- is a quantifying suffix operator similar to `*', except that the
- preceding expression can match either once or not at all. For
- example, `ca?r' matches `car' or `cr', but does not match anything
- else.
-
-`*?'
- works just like `*', except that rather than matching the longest
- match, it matches the shortest match. `*?' is known as a
- "non-greedy" quantifier, a regexp construct borrowed from Perl.
-
- This construct very useful for when you want to match the text
- inside a pair of delimiters. For instance, `/\*.*?\*/' will match
- C comments in a string. This could not be achieved without the
- use of greedy quantifier.
-
- This construct has not been available prior to XEmacs 20.4. It is
- not available in FSF Emacs.
-
-`+?'
- is the `+' analog to `*?'.
-
-`\{n,m\}'
- serves as an interval quantifier, analogous to `*' or `+', but
- specifies that the expression must match at least N times, but no
- more than M times. This syntax is supported by most Unix regexp
- utilities, and has been introduced to XEmacs for the version 20.3.
-
-`[ ... ]'
- `[' begins a "character set", which is terminated by a `]'. In
- the simplest case, the characters between the two brackets form
- the set. Thus, `[ad]' matches either one `a' or one `d', and
- `[ad]*' matches any string composed of just `a's and `d's
- (including the empty string), from which it follows that `c[ad]*r'
- matches `cr', `car', `cdr', `caddaar', etc.
-
- The usual regular expression special characters are not special
- inside a character set. A completely different set of special
- characters exists inside character sets: `]', `-' and `^'.
-
- `-' is used for ranges of characters. To write a range, write two
- characters with a `-' between them. Thus, `[a-z]' matches any
- lower case letter. Ranges may be intermixed freely with individual
- characters, as in `[a-z$%.]', which matches any lower case letter
- or `$', `%', or a period.
-
- To include a `]' in a character set, make it the first character.
- For example, `[]a]' matches `]' or `a'. To include a `-', write
- `-' as the first character in the set, or put it immediately after
- a range. (You can replace one individual character C with the
- range `C-C' to make a place to put the `-'.) There is no way to
- write a set containing just `-' and `]'.
-
- To include `^' in a set, put it anywhere but at the beginning of
- the set.
-
-`[^ ... ]'
- `[^' begins a "complement character set", which matches any
- character except the ones specified. Thus, `[^a-z0-9A-Z]' matches
- all characters *except* letters and digits.
-
- `^' is not special in a character set unless it is the first
- character. The character following the `^' is treated as if it
- were first (thus, `-' and `]' 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.
-
-`^'
- 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, `^foo' matches a `foo' that occurs
- at the beginning of a line.
-
- When matching a string instead of a buffer, `^' matches at the
- beginning of the string or after a newline character `\n'.
-
-`$'
- is similar to `^' but matches only at the end of a line. Thus,
- `x+$' matches a string of one `x' or more at the end of a line.
-
- When matching a string instead of a buffer, `$' matches at the end
- of the string or before a newline character `\n'.
-
-`\'
- has two functions: it quotes the special characters (including
- `\'), and it introduces additional special constructs.
-
- Because `\' quotes special characters, `\$' is a regular
- expression that matches only `$', and `\[' is a regular expression
- that matches only `[', and so on.
-
- Note that `\' also has special meaning in the read syntax of Lisp
- strings (*note String Type::.), and must be quoted with `\'. For
- example, the regular expression that matches the `\' character is
- `\\'. To write a Lisp string that contains the characters `\\',
- Lisp syntax requires you to quote each `\' with another `\'.
- Therefore, the read syntax for a regular expression matching `\'
- is `"\\\\"'.
-
- *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, `*foo' treats `*' as ordinary
-since there is no preceding expression on which the `*' can act. It is
-poor practice to depend on this behavior; quote the special character
-anyway, regardless of where it appears.
-
- For the most part, `\' followed by any character matches only that
-character. However, there are several exceptions: characters that,
-when preceded by `\', are special constructs. Such characters are
-always ordinary when encountered on their own. Here is a table of `\'
-constructs:
-
-`\|'
- specifies an alternative. Two regular expressions A and B with
- `\|' in between form an expression that matches anything that
- either A or B matches.
-
- Thus, `foo\|bar' matches either `foo' or `bar' but no other string.
-
- `\|' applies to the largest possible surrounding expressions.
- Only a surrounding `\( ... \)' grouping can limit the grouping
- power of `\|'.
-
- Full backtracking capability exists to handle multiple uses of
- `\|'.
-
-`\( ... \)'
- is a grouping construct that serves three purposes:
-
- 1. To enclose a set of `\|' alternatives for other operations.
- Thus, `\(foo\|bar\)x' matches either `foox' or `barx'.
-
- 2. To enclose an expression for a suffix operator such as `*' to
- act on. Thus, `ba\(na\)*' matches `bananana', etc., with any
- (zero or more) number of `na' strings.
-
- 3. To record a matched substring for future reference.
-
- This last application is not a consequence of the idea of a
- parenthetical grouping; it is a separate feature that happens to be
- assigned as a second meaning to the same `\( ... \)' construct
- because there is no conflict in practice between the two meanings.
- Here is an explanation of this feature:
-
-`\DIGIT'
- matches the same text that matched the DIGITth occurrence of a `\(
- ... \)' construct.
-
- In other words, after the end of a `\( ... \)' 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
- `\' followed by DIGIT to match that same text, whatever it may
- have been.
-
- The strings matching the first nine `\( ... \)' 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 `\1' through `\9' to refer to the text
- matched by the corresponding `\( ... \)' constructs.
-
- For example, `\(.*\)\1' matches any newline-free string that is
- composed of two identical halves. The `\(.*\)' matches the first
- half, which may be anything, but the `\1' that follows must match
- the same exact text.
-
-`\(?: ... \)'
- is called a "shy" grouping operator, and it is used just like `\(
- ... \)', except that it does not cause the matched substring to be
- recorded for future reference.
-
- This is useful when you need a lot of grouping `\( ... \)'
- constructs, but only want to remember one or two. Then you can use
- not want to remember them for later use with `match-string'.
-
- Using `\(?: ... \)' rather than `\( ... \)' when you don't need
- the captured substrings ought to speed up your programs some,
- since it shortens the code path followed by the regular expression
- engine, as well as the amount of memory allocation and string
- copying it must do. The actual performance gain to be observed
- has not been measured or quantified as of this writing.
-
- The shy grouping operator has been borrowed from Perl, and has not
- been available prior to XEmacs 20.3, nor is it available in FSF
- Emacs.
-
-`\w'
- matches any word-constituent character. The editor syntax table
- determines which characters these are. *Note Syntax Tables::.
-
-`\W'
- matches any character that is not a word constituent.
-
-`\sCODE'
- matches any character whose syntax is CODE. Here CODE is a
- character that represents a syntax code: thus, `w' for word
- constituent, `-' for whitespace, `(' for open parenthesis, etc.
- *Note Syntax Tables::, for a list of syntax codes and the
- characters that stand for them.
-
-`\SCODE'
- matches any character whose syntax is not CODE.
-
- 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.
-
-`\`'
- matches the empty string, but only at the beginning of the buffer
- or string being matched against.
-
-`\''
- matches the empty string, but only at the end of the buffer or
- string being matched against.
-
-`\='
- matches the empty string, but only at point. (This construct is
- not defined when matching against a string.)
-
-`\b'
- matches the empty string, but only at the beginning or end of a
- word. Thus, `\bfoo\b' matches any occurrence of `foo' as a
- separate word. `\bballs?\b' matches `ball' or `balls' as a
- separate word.
-
-`\B'
- matches the empty string, but *not* at the beginning or end of a
- word.
-
-`\<'
- matches the empty string, but only at the beginning of a word.
-
-`\>'
- matches the empty string, but only at the end of a word.
-
- Not every string is a valid regular expression. For example, a
-string with unbalanced square brackets is invalid (with a few
-exceptions, such as `[]]'), and so is a string that ends with a single
-`\'. If an invalid regular expression is passed to any of the search
-functions, an `invalid-regexp' error is signaled.
-
- - Function: regexp-quote STRING
- This function returns a regular expression string that matches
- exactly STRING and nothing else. This allows you to request an
- exact string match when calling a function that wants a regular
- expression.
-
- (regexp-quote "^The cat$")
- => "\\^The cat\\$"
-
- One use of `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 `string', surrounded
- by whitespace:
-
- (re-search-forward
- (concat "\\s-" (regexp-quote string) "\\s-"))
-
-\1f
-File: lispref.info, Node: Regexp Example, Prev: Syntax of Regexps, Up: Regular Expressions
-
-Complex Regexp Example
-----------------------
-
- Here is a complicated regexp, used by XEmacs to recognize the end of
-a sentence together with any whitespace that follows. It is the value
-of the variable `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. `\"' stands for a double-quote as part of the string,
-`\\' for a backslash as part of the string, `\t' for a tab and `\n' for
-a newline.
-
- "[.?!][]\"')}]*\\($\\| $\\|\t\\| \\)[ \t\n]*"
-
- In contrast, if you evaluate the variable `sentence-end', you will
-see the following:
-
- sentence-end
- =>
- "[.?!][]\"')}]*\\($\\| $\\| \\| \\)[
- ]*"
-
-In this output, tab and newline appear as themselves.
-
- This regular expression contains four parts in succession and can be
-deciphered as follows:
-
-`[.?!]'
- The first part of the pattern is a character set that matches any
- one of three characters: period, question mark, and exclamation
- mark. The match must begin with one of these three characters.
-
-`[]\"')}]*'
- The second part of the pattern matches any closing braces and
- quotation marks, zero or more of them, that may follow the period,
- question mark or exclamation mark. The `\"' is Lisp syntax for a
- double-quote in a string. The `*' at the end indicates that the
- immediately preceding regular expression (a character set, in this
- case) may be repeated zero or more times.
-
-`\\($\\| $\\|\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 delimit a group and the
- vertical bars separate alternatives. The dollar sign is used to
- match the end of a line.
-
-`[ \t\n]*'
- Finally, the last part of the pattern matches any additional
- whitespace beyond the minimum needed to end a sentence.
-
-\1f
-File: lispref.info, Node: Regexp Search, Next: POSIX Regexps, Prev: Regular Expressions, Up: Searching and Matching
-
-Regular Expression Searching
-============================
-
- In XEmacs, you can search for the next match for a regexp either
-incrementally or not. Incremental search commands are described in the
-`The XEmacs Reference Manual'. *Note Regular Expression Search:
-(emacs)Regexp Search. Here we describe only the search functions
-useful in programs. The principal one is `re-search-forward'.
-
- - 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 REGEXP. The
- function skips over any amount of text that is not matched by
- REGEXP, and leaves point at the end of the first match found. It
- returns the new value of point.
-
- If LIMIT is non-`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
- NOERROR. If NOERROR is `nil', a `search-failed' error is
- signaled. If NOERROR is `t', `re-search-forward' does nothing and
- returns `nil'. If NOERROR is neither `nil' nor `t', then
- `re-search-forward' moves point to LIMIT (or the end of the
- buffer) and returns `nil'.
-
- If 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 `T'.
- Evaluating the search call moves point to the end of that line
- (between the `t' of `hat' and the newline).
-
- ---------- Buffer: foo ----------
- I read "-!-The cat in the hat
- comes back" twice.
- ---------- Buffer: foo ----------
-
- (re-search-forward "[a-z]+" nil t 5)
- => 27
-
- ---------- Buffer: foo ----------
- I read "The cat in the hat-!-
- comes back" twice.
- ---------- Buffer: foo ----------
-
- - 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 REGEXP, leaving
- point at the beginning of the first text found.
-
- This function is analogous to `re-search-forward', but they are not
- simple mirror images. `re-search-forward' finds the match whose
- beginning is as close as possible to the starting point. If
- `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 starts at a specified
- beginning position.
-
- A true mirror-image of `re-search-forward' would require a special
- feature for matching regexps from end to beginning. It's not
- worth the trouble of implementing that.
-
- - Function: string-match REGEXP STRING &optional START
- This function returns the index of the start of the first match for
- the regular expression REGEXP in STRING, or `nil' if there is no
- match. If START is non-`nil', the search starts at that index in
- STRING.
-
- For example,
-
- (string-match
- "quick" "The quick brown fox jumped quickly.")
- => 4
- (string-match
- "quick" "The quick brown fox jumped quickly." 8)
- => 27
-
- 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 `(match-end 0)'. *Note Match
- Data::.
-
- (string-match
- "quick" "The quick brown fox jumped quickly." 8)
- => 27
-
- (match-end 0)
- => 32
-
- - Function: split-string STRING &optional PATTERN
- This function splits STRING to substrings delimited by PATTERN,
- and returns a list of substrings. If PATTERN is omitted, it
- defaults to `[ \f\t\n\r\v]+', which means that it splits STRING by
- white-space.
-
- (split-string "foo bar")
- => ("foo" "bar")
-
- (split-string "something")
- => ("something")
-
- (split-string "a:b:c" ":")
- => ("a" "b" "c")
-
- (split-string ":a::b:c" ":")
- => ("" "a" "" "b" "c")
-
- - Function: split-path PATH
- This function splits a search path into a list of strings. The
- path components are separated with the characters specified with
- `path-separator'. Under Unix, `path-separator' will normally be
- `:', while under Windows, it will be `;'.
-
- - Function: looking-at REGEXP
- This function determines whether the text in the current buffer
- directly following point matches the regular expression 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 `t' if so, `nil'
- otherwise.
-
- This function does not move point, but it updates the match data,
- which you can access using `match-beginning' and `match-end'.
- *Note Match Data::.
-
- In this example, point is located directly before the `T'. If it
- were anywhere else, the result would be `nil'.
-
- ---------- Buffer: foo ----------
- I read "-!-The cat in the hat
- comes back" twice.
- ---------- Buffer: foo ----------
-
- (looking-at "The cat in the hat$")
- => t
-
-\1f
-File: lispref.info, Node: POSIX Regexps, Next: Search and Replace, Prev: Regexp Search, Up: Searching and Matching
-
-POSIX Regular Expression Searching
-==================================
-
- The usual regular expression functions do backtracking when necessary
-to handle the `\|' and repetition constructs, but they continue this
-only until they find *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.
-
- In Emacs versions prior to 19.29, these functions did not exist, and
-the functions described above implemented full POSIX backtracking.
-
- - Function: posix-search-forward REGEXP &optional LIMIT NOERROR REPEAT
- This is like `re-search-forward' except that it performs the full
- backtracking specified by the POSIX standard for regular expression
- matching.
-
- - Function: posix-search-backward REGEXP &optional LIMIT NOERROR REPEAT
- This is like `re-search-backward' except that it performs the full
- backtracking specified by the POSIX standard for regular expression
- matching.
-
- - Function: posix-looking-at REGEXP
- This is like `looking-at' except that it performs the full
- backtracking specified by the POSIX standard for regular expression
- matching.
-
- - Function: posix-string-match REGEXP STRING &optional START
- This is like `string-match' except that it performs the full
- backtracking specified by the POSIX standard for regular expression
- matching.
-
-\1f
-File: lispref.info, Node: Search and Replace, Next: Match Data, Prev: POSIX Regexps, Up: Searching and Matching
-
-Search and Replace
-==================
-
- - Function: perform-replace FROM-STRING REPLACEMENTS QUERY-FLAG
- REGEXP-FLAG DELIMITED-FLAG &optional REPEAT-COUNT MAP
- This function is the guts of `query-replace' and related commands.
- It searches for occurrences of FROM-STRING and replaces some or
- all of them. If QUERY-FLAG is `nil', it replaces all occurrences;
- otherwise, it asks the user what to do about each one.
-
- If REGEXP-FLAG is non-`nil', then FROM-STRING is considered a
- regular expression; otherwise, it must match literally. If
- DELIMITED-FLAG is non-`nil', then only replacements surrounded by
- word boundaries are considered.
-
- The argument 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 REPEAT-COUNT is non-`nil', it should be an integer. Then it
- specifies how many times to use each of the strings in the
- REPLACEMENTS list before advancing cyclicly to the next one.
-
- Normally, the keymap `query-replace-map' defines the possible user
- responses for queries. The argument MAP, if non-`nil', is a
- keymap to use instead of `query-replace-map'.
-
- - Variable: query-replace-map
- This variable holds a special keymap that defines the valid user
- responses for `query-replace' and related functions, as well as
- `y-or-n-p' and `map-y-or-n-p'. It is unusual in two ways:
-
- * The "key bindings" are not commands, just symbols that are
- meaningful to the functions that use this map.
-
- * 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."
-
- Here are the meaningful "bindings" for `query-replace-map'. Several
-of them are meaningful only for `query-replace' and friends.
-
-`act'
- Do take the action being considered--in other words, "yes."
-
-`skip'
- Do not take action for this question--in other words, "no."
-
-`exit'
- Answer this question "no," and give up on the entire series of
- questions, assuming that the answers will be "no."
-
-`act-and-exit'
- Answer this question "yes," and give up on the entire series of
- questions, assuming that subsequent answers will be "no."
-
-`act-and-show'
- Answer this question "yes," but show the results--don't advance yet
- to the next question.
-
-`automatic'
- Answer this question and all subsequent questions in the series
- with "yes," without further user interaction.
-
-`backup'
- Move back to the previous place that a question was asked about.
-
-`edit'
- Enter a recursive edit to deal with this question--instead of any
- other action that would normally be taken.
-
-`delete-and-edit'
- Delete the text being considered, then enter a recursive edit to
- replace it.
-
-`recenter'
- Redisplay and center the window, then ask the same question again.
-
-`quit'
- Perform a quit right away. Only `y-or-n-p' and related functions
- use this answer.
-
-`help'
- Display some help, then ask again.
-
-\1f
-File: lispref.info, Node: Match Data, Next: Searching and Case, Prev: Search and Replace, Up: Searching and Matching
-
-The Match Data
-==============
-
- XEmacs 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.
-
-\1f
-File: lispref.info, Node: Simple Match Data, Next: Replacing Match, Up: Match Data
-
-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.
-
- You can ask about the entire matching text, or about a particular
-parenthetical subexpression of a regular expression. The COUNT
-argument in the functions below specifies which. If COUNT is zero, you
-are asking about the entire match. If COUNT is positive, it specifies
-which subexpression you want.
-
- Recall that the subexpressions of a regular expression are those
-expressions grouped with escaped parentheses, `\(...\)'. The COUNTth
-subexpression is found by counting occurrences of `\(' 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.
-
- - Function: 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 COUNT is
- zero, or just the portion corresponding to the COUNTth
- parenthetical subexpression, if COUNT is positive. If COUNT is
- out of range, or if that subexpression didn't match anything, the
- value is `nil'.
-
- If the last such operation was done against a string with
- `string-match', then you should pass the same string as the
- argument IN-STRING. Otherwise, after a buffer search or match,
- you should omit IN-STRING or pass `nil' for it; but you should
- make sure that the current buffer when you call `match-string' is
- the one in which you did the searching or matching.
-
- - Function: 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 COUNT is zero, then the value is the position of the start of
- the entire match. Otherwise, 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 `nil' for a subexpression inside a `\|' alternative
- that wasn't used in the match.
-
- - Function: match-end COUNT
- This function is like `match-beginning' except that it returns the
- position of the end of the match, rather than the position of the
- beginning.
-
- Here is an example of using the match data, with a comment showing
-the positions within the text:
-
- (string-match "\\(qu\\)\\(ick\\)"
- "The quick fox jumped quickly.")
- ;0123456789
- => 4
-
- (match-string 0 "The quick fox jumped quickly.")
- => "quick"
- (match-string 1 "The quick fox jumped quickly.")
- => "qu"
- (match-string 2 "The quick fox jumped quickly.")
- => "ick"
-
- (match-beginning 1) ; The beginning of the match
- => 4 ; with `qu' is at index 4.
-
- (match-beginning 2) ; The beginning of the match
- => 6 ; with `ick' is at index 6.
-
- (match-end 1) ; The end of the match
- => 6 ; with `qu' is at index 6.
-
- (match-end 2) ; The end of the match
- => 9 ; with `ick' is at index 9.
-
- Here is another example. Point is initially located at the beginning
-of the line. Searching moves point to between the space and the word
-`in'. The beginning of the entire match is at the 9th character of the
-buffer (`T'), and the beginning of the match for the first
-subexpression is at the 13th character (`c').
-
- (list
- (re-search-forward "The \\(cat \\)")
- (match-beginning 0)
- (match-beginning 1))
- => (9 9 13)
-
- ---------- Buffer: foo ----------
- I read "The cat -!-in the hat comes back" twice.
- ^ ^
- 9 13
- ---------- Buffer: foo ----------
-
-(In this case, the index returned is a buffer position; the first
-character of the buffer counts as 1.)
-
-\1f
-File: lispref.info, Node: Replacing Match, Next: Entire Match Data, Prev: Simple Match Data, Up: Match Data
-
-Replacing the Text That Matched
--------------------------------
-
- This function replaces the text matched by the last search with
-REPLACEMENT.
-
- - Function: replace-match REPLACEMENT &optional FIXEDCASE LITERAL
- STRING
- This function replaces the text in the buffer (or in STRING) that
- was matched by the last search. It replaces that text with
- REPLACEMENT.
-
- If you did the last search in a buffer, you should specify `nil'
- for STRING. Then `replace-match' does the replacement by editing
- the buffer; it leaves point at the end of the replacement text,
- and returns `t'.
-
- If you did the search in a string, pass the same string as STRING.
- Then `replace-match' does the replacement by constructing and
- returning a new string.
-
- If FIXEDCASE is non-`nil', then the case of the replacement text
- is not changed; otherwise, the replacement text is converted to a
- different case depending upon the capitalization of the text to be
- replaced. If the original text is all upper case, the replacement
- text is converted to upper case. If the first word of the
- original text is capitalized, then the first word of the
- replacement text is capitalized. If the original text contains
- just one word, and that word is a capital letter, `replace-match'
- considers this a capitalized first word rather than all upper case.
-
- If `case-replace' is `nil', then case conversion is not done,
- regardless of the value of FIXED-CASE. *Note Searching and Case::.
-
- If LITERAL is non-`nil', then REPLACEMENT is inserted exactly as
- it is, the only alterations being case changes as needed. If it
- is `nil' (the default), then the character `\' is treated
- specially. If a `\' appears in REPLACEMENT, then it must be part
- of one of the following sequences:
-
- `\&'
- `\&' stands for the entire text being replaced.
-
- `\N'
- `\N', where N is a digit, stands for the text that matched
- the Nth subexpression in the original regexp. Subexpressions
- are those expressions grouped inside `\(...\)'.
-
- `\\'
- `\\' stands for a single `\' in the replacement text.
-
projects / chise / xemacs-chise.git.1 / blobdiff