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thingatpt.el
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Lisp/Scheme
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2000-07-31
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13KB
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393 lines
;;; thingatpt.el --- Get the `thing' at point
;; Copyright (C) 1991,92,93,94,95,96,97,1998 Free Software Foundation, Inc.
;; Author: Mike Williams <mikew@gopher.dosli.govt.nz>
;; Keywords: extensions, matching, mouse
;; Created: Thu Mar 28 13:48:23 1991
;; This file is part of GNU Emacs.
;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;;; Commentary:
;; This file provides routines for getting the "thing" at the location of
;; point, whatever that "thing" happens to be. The "thing" is defined by
;; its beginning and end positions in the buffer.
;;
;; The function bounds-of-thing-at-point finds the beginning and end
;; positions by moving first forward to the end of the "thing", and then
;; backwards to the beginning. By default, it uses the corresponding
;; forward-"thing" operator (eg. forward-word, forward-line).
;;
;; Special cases are allowed for using properties associated with the named
;; "thing":
;;
;; forward-op Function to call to skip forward over a "thing" (or
;; with a negative argument, backward).
;;
;; beginning-op Function to call to skip to the beginning of a "thing".
;; end-op Function to call to skip to the end of a "thing".
;;
;; Reliance on existing operators means that many `things' can be accessed
;; without further code: eg.
;; (thing-at-point 'line)
;; (thing-at-point 'page)
;;; Code:
(provide 'thingatpt)
;; Basic movement
;;;###autoload
(defun forward-thing (thing &optional n)
"Move forward to the end of the next THING."
(let ((forward-op (or (get thing 'forward-op)
(intern-soft (format "forward-%s" thing)))))
(if (fboundp forward-op)
(funcall forward-op (or n 1))
(error "Can't determine how to move over a %s" thing))))
;; General routines
;;;###autoload
(defun bounds-of-thing-at-point (thing)
"Determine the start and end buffer locations for the THING at point.
THING is a symbol which specifies the kind of syntactic entity you want.
Possibilities include `symbol', `list', `sexp', `defun', `filename', `url',
`word', `sentence', `whitespace', `line', `page' and others.
See the file `thingatpt.el' for documentation on how to define
a symbol as a valid THING.
The value is a cons cell (START . END) giving the start and end positions
of the textual entity that was found."
(if (get thing 'bounds-of-thing-at-point)
(funcall (get thing 'bounds-of-thing-at-point))
(let ((orig (point)))
(condition-case nil
(save-excursion
;; Try moving forward, then back.
(let ((end (progn
(funcall
(or (get thing 'end-op)
(function (lambda () (forward-thing thing 1)))))
(point)))
(beg (progn
(funcall
(or (get thing 'beginning-op)
(function (lambda () (forward-thing thing -1)))))
(point))))
(if (not (and beg (> beg orig)))
;; If that brings us all the way back to ORIG,
;; it worked. But END may not be the real end.
;; So find the real end that corresponds to BEG.
(let ((real-end
(progn
(funcall
(or (get thing 'end-op)
(function (lambda () (forward-thing thing 1)))))
(point))))
(if (and beg real-end (<= beg orig) (<= orig real-end))
(cons beg real-end)))
(goto-char orig)
;; Try a second time, moving backward first and then forward,
;; so that we can find a thing that ends at ORIG.
(let ((beg (progn
(funcall
(or (get thing 'beginning-op)
(function (lambda () (forward-thing thing -1)))))
(point)))
(end (progn
(funcall
(or (get thing 'end-op)
(function (lambda () (forward-thing thing 1)))))
(point)))
(real-beg
(progn
(funcall
(or (get thing 'beginning-op)
(function (lambda () (forward-thing thing -1)))))
(point))))
(if (and real-beg end (<= real-beg orig) (<= orig end))
(cons real-beg end))))))
(error nil)))))
;;;###autoload
(defun thing-at-point (thing)
"Return the THING at point.
THING is a symbol which specifies the kind of syntactic entity you want.
Possibilities include `symbol', `list', `sexp', `defun', `filename', `url',
`word', `sentence', `whitespace', `line', `page' and others.
See the file `thingatpt.el' for documentation on how to define
a symbol as a valid THING."
(if (get thing 'thing-at-point)
(funcall (get thing 'thing-at-point))
(let ((bounds (bounds-of-thing-at-point thing)))
(if bounds
(buffer-substring (car bounds) (cdr bounds))))))
;; Go to beginning/end
(defun beginning-of-thing (thing)
(let ((bounds (bounds-of-thing-at-point thing)))
(or bounds (error "No %s here" thing))
(goto-char (car bounds))))
(defun end-of-thing (thing)
(let ((bounds (bounds-of-thing-at-point thing)))
(or bounds (error "No %s here" thing))
(goto-char (cdr bounds))))
;; Special cases
;; Lines
;; bolp will be false when you click on the last line in the buffer
;; and it has no final newline.
(put 'line 'beginning-op
(function (lambda () (if (bolp) (forward-line -1) (beginning-of-line)))))
;; Sexps
(defun in-string-p ()
(let ((orig (point)))
(save-excursion
(beginning-of-defun)
(nth 3 (parse-partial-sexp (point) orig)))))
(defun end-of-sexp ()
(let ((char-syntax (char-syntax (char-after (point)))))
(if (or (eq char-syntax ?\))
(and (eq char-syntax ?\") (in-string-p)))
(forward-char 1)
(forward-sexp 1))))
(put 'sexp 'end-op 'end-of-sexp)
(defun beginning-of-sexp ()
(let ((char-syntax (char-syntax (char-before (point)))))
(if (or (eq char-syntax ?\()
(and (eq char-syntax ?\") (in-string-p)))
(forward-char -1)
(forward-sexp -1))))
(put 'sexp 'beginning-op 'beginning-of-sexp)
;; Lists
(put 'list 'end-op (function (lambda () (up-list 1))))
(put 'list 'beginning-op 'backward-sexp)
;; Filenames and URLs
(defvar thing-at-point-file-name-chars "~/A-Za-z0-9---_.${}#%,:"
"Characters allowable in filenames.")
(put 'filename 'end-op
'(lambda () (skip-chars-forward thing-at-point-file-name-chars)))
(put 'filename 'beginning-op
'(lambda () (skip-chars-backward thing-at-point-file-name-chars)))
(defvar thing-at-point-url-path-regexp
"[^]\t\n \"'()<>[^`{}]*[^]\t\n \"'()<>[^`{}.,;]+"
"A regular expression probably matching the host, path or e-mail part of a URL.")
(defvar thing-at-point-short-url-regexp
(concat "[-A-Za-z0-9.]+" thing-at-point-url-path-regexp)
"A regular expression probably matching a URL without an access scheme.
Hostname matching is stricter in this case than for
``thing-at-point-url-regexp''.")
(defvar thing-at-point-url-regexp
(concat
"\\(https?://\\|ftp://\\|gopher://\\|telnet://\\|wais://\\|file:/\\|s?news:\\|mailto:\\)"
thing-at-point-url-path-regexp)
"A regular expression probably matching a complete URL.")
(defvar thing-at-point-markedup-url-regexp
"<URL:[^>]+>"
"A regular expression matching a URL marked up per RFC1738.
This may contain whitespace (including newlines) .")
(put 'url 'bounds-of-thing-at-point 'thing-at-point-bounds-of-url-at-point)
(defun thing-at-point-bounds-of-url-at-point ()
(let ((url "") short strip)
(if (or (setq strip (thing-at-point-looking-at
thing-at-point-markedup-url-regexp))
(thing-at-point-looking-at thing-at-point-url-regexp)
;; Access scheme omitted?
(setq short (thing-at-point-looking-at
thing-at-point-short-url-regexp)))
(let ((beginning (match-beginning 0))
(end (match-end 0)))
(cond (strip
(setq beginning (+ beginning 5))
(setq end (- end 1))))
(cons beginning end)))))
(put 'url 'thing-at-point 'thing-at-point-url-at-point)
(defun thing-at-point-url-at-point ()
"Return the URL around or before point.
Search backwards for the start of a URL ending at or after point. If
no URL found, return nil. The access scheme will be prepended if
absent: \"mailto:\" if the string contains \"@\", \"ftp://\" if it
starts with \"ftp\" and not \"ftp:/\", or \"http://\" by default."
(let ((url "") short strip)
(if (or (setq strip (thing-at-point-looking-at
thing-at-point-markedup-url-regexp))
(thing-at-point-looking-at thing-at-point-url-regexp)
;; Access scheme omitted?
(setq short (thing-at-point-looking-at
thing-at-point-short-url-regexp)))
(progn
(setq url (buffer-substring-no-properties (match-beginning 0)
(match-end 0)))
(and strip (setq url (substring url 5 -1))) ; Drop "<URL:" & ">"
;; strip whitespace
(while (string-match "\\s +\\|\n+" url)
(setq url (replace-match "" t t url)))
(and short (setq url (concat (cond ((string-match "@" url)
"mailto:")
;; e.g. ftp.swiss... or ftp-swiss...
((string-match "^ftp" url)
"ftp://")
(t "http://"))
url)))
(if (string-equal "" url)
nil
url)))))
;; The normal thingatpt mechanism doesn't work for complex regexps.
;; This should work for almost any regexp wherever we are in the
;; match. To do a perfect job for any arbitrary regexp would mean
;; testing every position before point. Regexp searches won't find
;; matches that straddle the start position so we search forwards once
;; and then back repeatedly and then back up a char at a time.
(defun thing-at-point-looking-at (regexp)
"Return non-nil if point is in or just after a match for REGEXP.
Set the match data from the earliest such match ending at or after
point."
(save-excursion
(let ((old-point (point)) match)
(and (looking-at regexp)
(>= (match-end 0) old-point)
(setq match (point)))
;; Search back repeatedly from end of next match.
;; This may fail if next match ends before this match does.
(re-search-forward regexp nil 'limit)
(while (and (re-search-backward regexp nil t)
(or (> (match-beginning 0) old-point)
(and (looking-at regexp) ; Extend match-end past search start
(>= (match-end 0) old-point)
(setq match (point))))))
(if (not match) nil
(goto-char match)
;; Back up a char at a time in case search skipped
;; intermediate match straddling search start pos.
(while (and (not (bobp))
(progn (backward-char 1) (looking-at regexp))
(>= (match-end 0) old-point)
(setq match (point))))
(goto-char match)
(looking-at regexp)))))
(put 'url 'end-op
(function (lambda ()
(let ((bounds (thing-at-point-bounds-of-url-at-point)))
(if bounds
(goto-char (cdr bounds))
(error "No URL here"))))))
(put 'url 'beginning-op
(function (lambda ()
(let ((bounds (thing-at-point-bounds-of-url-at-point)))
(if bounds
(goto-char (car bounds))
(error "No URL here"))))))
;; Whitespace
(defun forward-whitespace (arg)
(interactive "p")
(if (natnump arg)
(re-search-forward "[ \t]+\\|\n" nil 'move arg)
(while (< arg 0)
(if (re-search-backward "[ \t]+\\|\n" nil 'move)
(or (eq (char-after (match-beginning 0)) 10)
(skip-chars-backward " \t")))
(setq arg (1+ arg)))))
;; Buffer
(put 'buffer 'end-op '(lambda () (goto-char (point-max))))
(put 'buffer 'beginning-op '(lambda () (goto-char (point-min))))
;; Symbols
(defun forward-symbol (arg)
(interactive "p")
(if (natnump arg)
(re-search-forward "\\(\\sw\\|\\s_\\)+" nil 'move arg)
(while (< arg 0)
(if (re-search-backward "\\(\\sw\\|\\s_\\)+" nil 'move)
(skip-syntax-backward "w_"))
(setq arg (1+ arg)))))
;; Syntax blocks
(defun forward-same-syntax (&optional arg)
(interactive "p")
(while (< arg 0)
(skip-syntax-backward
(char-to-string (char-syntax (char-after (1- (point))))))
(setq arg (1+ arg)))
(while (> arg 0)
(skip-syntax-forward (char-to-string (char-syntax (char-after (point)))))
(setq arg (1- arg))))
;; Aliases
(defun word-at-point () (thing-at-point 'word))
(defun sentence-at-point () (thing-at-point 'sentence))
(defun read-from-whole-string (str)
"Read a lisp expression from STR.
Signal an error if the entire string was not used."
(let* ((read-data (read-from-string str))
(more-left
(condition-case nil
(progn (read-from-string (substring str (cdr read-data)))
t)
(end-of-file nil))))
(if more-left
(error "Can't read whole string")
(car read-data))))
(defun form-at-point (&optional thing pred)
(let ((sexp (condition-case nil
(read-from-whole-string (thing-at-point (or thing 'sexp)))
(error nil))))
(if (or (not pred) (funcall pred sexp)) sexp)))
(defun sexp-at-point () (form-at-point 'sexp))
(defun symbol-at-point () (form-at-point 'sexp 'symbolp))
(defun number-at-point () (form-at-point 'sexp 'numberp))
(defun list-at-point () (form-at-point 'list 'listp))
;; thingatpt.el ends here.