lisp/thingatpt.el

   1 ;;; thingatpt.el --- get the `thing' at point
   2
   3 ;; Copyright (C) 1991-1998, 2000-2014 Free Software Foundation, Inc.
   4
   5 ;; Author: Mike Williams <mikew@gopher.dosli.govt.nz>
   6 ;; Maintainer: FSF
   7 ;; Keywords: extensions, matching, mouse
   8 ;; Created: Thu Mar 28 13:48:23 1991
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This file provides routines for getting the "thing" at the location of
  28 ;; point, whatever that "thing" happens to be.  The "thing" is defined by
  29 ;; its beginning and end positions in the buffer.
  30 ;;
  31 ;; The function bounds-of-thing-at-point finds the beginning and end
  32 ;; positions by moving first forward to the end of the "thing", and then
  33 ;; backwards to the beginning.  By default, it uses the corresponding
  34 ;; forward-"thing" operator (eg. forward-word, forward-line).
  35 ;;
  36 ;; Special cases are allowed for using properties associated with the named
  37 ;; "thing":
  38 ;;
  39 ;;   forward-op         Function to call to skip forward over a "thing" (or
  40 ;;                      with a negative argument, backward).
  41 ;;
  42 ;;   beginning-op       Function to call to skip to the beginning of a "thing".
  43 ;;   end-op             Function to call to skip to the end of a "thing".
  44 ;;
  45 ;; Reliance on existing operators means that many `things' can be accessed
  46 ;; without further code:  eg.
  47 ;;     (thing-at-point 'line)
  48 ;;     (thing-at-point 'page)
  49
  50 ;;; Code:
  51
  52 (provide 'thingatpt)
  53
  54 ;; Basic movement
  55
  56 ;;;###autoload
  57 (defun forward-thing (thing &optional n)
  58   "Move forward to the end of the Nth next THING.
  59 THING should be a symbol specifying a type of syntactic entity.
  60 Possibilities include `symbol', `list', `sexp', `defun',
  61 `filename', `url', `email', `word', `sentence', `whitespace',
  62 `line', and `page'."
  63   (let ((forward-op (or (get thing 'forward-op)
  64                         (intern-soft (format "forward-%s" thing)))))
  65     (if (functionp forward-op)
  66         (funcall forward-op (or n 1))
  67       (error "Can't determine how to move over a %s" thing))))
  68
  69 ;; General routines
  70
  71 ;;;###autoload
  72 (defun bounds-of-thing-at-point (thing)
  73   "Determine the start and end buffer locations for the THING at point.
  74 THING should be a symbol specifying a type of syntactic entity.
  75 Possibilities include `symbol', `list', `sexp', `defun',
  76 `filename', `url', `email', `word', `sentence', `whitespace',
  77 `line', and `page'.
  78
  79 See the file `thingatpt.el' for documentation on how to define a
  80 valid THING.
  81
  82 Return a cons cell (START . END) giving the start and end
  83 positions of the thing found."
  84   (if (get thing 'bounds-of-thing-at-point)
  85       (funcall (get thing 'bounds-of-thing-at-point))
  86     (let ((orig (point)))
  87       (ignore-errors
  88         (save-excursion
  89           ;; Try moving forward, then back.
  90           (funcall ;; First move to end.
  91            (or (get thing 'end-op)
  92                (lambda () (forward-thing thing 1))))
  93           (funcall ;; Then move to beg.
  94            (or (get thing 'beginning-op)
  95                (lambda () (forward-thing thing -1))))
  96           (let ((beg (point)))
  97             (if (<= beg orig)
  98                 ;; If that brings us all the way back to ORIG,
  99                 ;; it worked.  But END may not be the real end.
 100                 ;; So find the real end that corresponds to BEG.
 101                 ;; FIXME: in which cases can `real-end' differ from `end'?
 102                 (let ((real-end
 103                        (progn
 104                          (funcall
 105                           (or (get thing 'end-op)
 106                               (lambda () (forward-thing thing 1))))
 107                          (point))))
 108                   (when (and (<= orig real-end) (< beg real-end))
 109                     (cons beg real-end)))
 110               (goto-char orig)
 111               ;; Try a second time, moving backward first and then forward,
 112               ;; so that we can find a thing that ends at ORIG.
 113               (funcall ;; First, move to beg.
 114                (or (get thing 'beginning-op)
 115                    (lambda () (forward-thing thing -1))))
 116               (funcall ;; Then move to end.
 117                (or (get thing 'end-op)
 118                    (lambda () (forward-thing thing 1))))
 119               (let ((end (point))
 120                     (real-beg
 121                      (progn
 122                        (funcall
 123                         (or (get thing 'beginning-op)
 124                             (lambda () (forward-thing thing -1))))
 125                        (point))))
 126                 (if (and (<= real-beg orig) (<= orig end) (< real-beg end))
 127                     (cons real-beg end))))))))))
 128
 129 ;;;###autoload
 130 (defun thing-at-point (thing &optional no-properties)
 131   "Return the THING at point.
 132 THING should be a symbol specifying a type of syntactic entity.
 133 Possibilities include `symbol', `list', `sexp', `defun',
 134 `filename', `url', `email', `word', `sentence', `whitespace',
 135 `line', `number', and `page'.
 136
 137 When the optional argument NO-PROPERTIES is non-nil,
 138 strip text properties from the return value.
 139
 140 See the file `thingatpt.el' for documentation on how to define
 141 a symbol as a valid THING."
 142   (let ((text
 143          (if (get thing 'thing-at-point)
 144              (funcall (get thing 'thing-at-point))
 145            (let ((bounds (bounds-of-thing-at-point thing)))
 146              (when bounds
 147                (buffer-substring (car bounds) (cdr bounds)))))))
 148     (when (and text no-properties)
 149       (set-text-properties 0 (length text) nil text))
 150     text))
 151
 152 ;; Go to beginning/end
 153
 154 (defun beginning-of-thing (thing)
 155   "Move point to the beginning of THING.
 156 The bounds of THING are determined by `bounds-of-thing-at-point'."
 157   (let ((bounds (bounds-of-thing-at-point thing)))
 158     (or bounds (error "No %s here" thing))
 159     (goto-char (car bounds))))
 160
 161 (defun end-of-thing (thing)
 162   "Move point to the end of THING.
 163 The bounds of THING are determined by `bounds-of-thing-at-point'."
 164   (let ((bounds (bounds-of-thing-at-point thing)))
 165     (or bounds (error "No %s here" thing))
 166     (goto-char (cdr bounds))))
 167
 168 ;;  Special cases
 169
 170 ;;  Lines
 171
 172 ;; bolp will be false when you click on the last line in the buffer
 173 ;; and it has no final newline.
 174
 175 (put 'line 'beginning-op
 176      (lambda () (if (bolp) (forward-line -1) (beginning-of-line))))
 177
 178 ;;  Sexps
 179
 180 (defun in-string-p ()
 181   "Return non-nil if point is in a string.
 182 \[This is an internal function.]"
 183   (let ((orig (point)))
 184     (save-excursion
 185       (beginning-of-defun)
 186       (nth 3 (parse-partial-sexp (point) orig)))))
 187
 188 (defun end-of-sexp ()
 189   "Move point to the end of the current sexp.
 190 \[This is an internal function.]"
 191   (let ((char-syntax (syntax-after (point))))
 192     (if (or (eq char-syntax ?\))
 193             (and (eq char-syntax ?\") (in-string-p)))
 194         (forward-char 1)
 195       (forward-sexp 1))))
 196
 197 (put 'sexp 'end-op 'end-of-sexp)
 198
 199 (defun beginning-of-sexp ()
 200   "Move point to the beginning of the current sexp.
 201 \[This is an internal function.]"
 202   (let ((char-syntax (char-syntax (char-before))))
 203     (if (or (eq char-syntax ?\()
 204             (and (eq char-syntax ?\") (in-string-p)))
 205         (forward-char -1)
 206       (forward-sexp -1))))
 207
 208 (put 'sexp 'beginning-op 'beginning-of-sexp)
 209
 210 ;;  Lists
 211
 212 (put 'list 'bounds-of-thing-at-point 'thing-at-point-bounds-of-list-at-point)
 213
 214 (defun thing-at-point-bounds-of-list-at-point ()
 215   "Return the bounds of the list at point.
 216 \[Internal function used by `bounds-of-thing-at-point'.]"
 217   (save-excursion
 218     (let ((opoint (point))
 219           (beg (ignore-errors
 220                  (up-list -1)
 221                  (point))))
 222       (ignore-errors
 223         (if beg
 224             (progn (forward-sexp)
 225                    (cons beg (point)))
 226           ;; Are we are at the beginning of a top-level sexp?
 227           (forward-sexp)
 228           (let ((end (point)))
 229             (backward-sexp)
 230             (if (>= opoint (point))
 231                 (cons opoint end))))))))
 232
 233 ;; Defuns
 234
 235 (put 'defun 'beginning-op 'beginning-of-defun)
 236 (put 'defun 'end-op       'end-of-defun)
 237 (put 'defun 'forward-op   'end-of-defun)
 238
 239 ;;  Filenames
 240
 241 (defvar thing-at-point-file-name-chars "-~/[:alnum:]_.${}#%,:"
 242   "Characters allowable in filenames.")
 243
 244 (put 'filename 'end-op
 245      (lambda ()
 246        (re-search-forward (concat "\\=[" thing-at-point-file-name-chars "]*")
 247                           nil t)))
 248 (put 'filename 'beginning-op
 249      (lambda ()
 250        (if (re-search-backward (concat "[^" thing-at-point-file-name-chars "]")
 251                                nil t)
 252            (forward-char)
 253          (goto-char (point-min)))))
 254
 255 ;;  URIs
 256
 257 (defvar thing-at-point-beginning-of-url-regexp nil
 258   "Regexp matching the beginning of a well-formed URI.
 259 If nil, construct the regexp from `thing-at-point-uri-schemes'.")
 260
 261 (defvar thing-at-point-url-path-regexp
 262   "[^]\t\n \"'<>[^`{}]*[^]\t\n \"'<>[^`{}.,;]+"
 263   "Regexp matching the host and filename or e-mail part of a URL.")
 264
 265 (defvar thing-at-point-short-url-regexp
 266   (concat "[-A-Za-z0-9]+\\.[-A-Za-z0-9.]+" thing-at-point-url-path-regexp)
 267   "Regexp matching a URI without a scheme component.")
 268
 269 (defvar thing-at-point-uri-schemes
 270   ;; Officials from http://www.iana.org/assignments/uri-schemes.html
 271   '("aaa://" "about:" "acap://" "apt:" "bzr://" "bzr+ssh://"
 272     "attachment:/" "chrome://" "cid:" "content://" "crid://" "cvs://"
 273     "data:" "dav:" "dict://" "doi:" "dns:" "dtn:" "feed:" "file:/"
 274     "finger://" "fish://" "ftp://" "geo:" "git://" "go:" "gopher://"
 275     "h323:" "http://" "https://" "im:" "imap://" "info:" "ipp:"
 276     "irc://" "irc6://" "ircs://" "iris.beep:" "jar:" "ldap://"
 277     "ldaps://" "mailto:" "mid:"  "mtqp://" "mupdate://" "news:"
 278     "nfs://" "nntp://" "opaquelocktoken:" "pop://" "pres:"
 279     "resource://" "rmi://" "rsync://" "rtsp://" "rtspu://" "service:"
 280     "sftp://" "sip:" "sips:" "smb://" "sms:" "snmp://" "soap.beep://"
 281     "soap.beeps://" "ssh://" "svn://" "svn+ssh://" "tag:" "tel:"
 282     "telnet://" "tftp://" "tip://" "tn3270://" "udp://" "urn:"
 283     "uuid:" "vemmi://"  "webcal://" "xri://" "xmlrpc.beep://"
 284     "xmlrpc.beeps://" "z39.50r://" "z39.50s://" "xmpp:"
 285     ;; Compatibility
 286     "fax:" "mms://" "mmsh://" "modem:" "prospero:" "snews:"
 287     "wais://")
 288   "List of URI schemes recognized by `thing-at-point-url-at-point'.
 289 Each string in this list should correspond to the start of a
 290 URI's scheme component, up to and including the trailing // if
 291 the scheme calls for that to be present.")
 292
 293 (defvar thing-at-point-markedup-url-regexp "<URL:\\([^<>\n]+\\)>"
 294   "Regexp matching a URL marked up per RFC1738.
 295 This kind of markup was formerly recommended as a way to indicate
 296 URIs, but as of RFC 3986 it is no longer recommended.
 297 Subexpression 1 should contain the delimited URL.")
 298
 299 (defvar thing-at-point-newsgroup-regexp
 300   "\\`[[:lower:]]+\\.[-+[:lower:]_0-9.]+\\'"
 301   "Regexp matching a newsgroup name.")
 302
 303 (defvar thing-at-point-newsgroup-heads
 304   '("alt" "comp" "gnu" "misc" "news" "sci" "soc" "talk")
 305   "Used by `thing-at-point-newsgroup-p' if gnus is not running.")
 306
 307 (defvar thing-at-point-default-mail-uri-scheme "mailto"
 308   "Default scheme for ill-formed URIs that look like <foo@example.com>.
 309 If nil, do not give such URIs a scheme.")
 310
 311 (put 'url 'bounds-of-thing-at-point 'thing-at-point-bounds-of-url-at-point)
 312
 313 (defun thing-at-point-bounds-of-url-at-point (&optional lax)
 314   "Return a cons cell containing the start and end of the URI at point.
 315 Try to find a URI using `thing-at-point-markedup-url-regexp'.
 316 If that fails, try with `thing-at-point-beginning-of-url-regexp'.
 317 If that also fails, and optional argument LAX is non-nil, return
 318 the bounds of a possible ill-formed URI (one lacking a scheme)."
 319   ;; Look for the old <URL:foo> markup.  If found, use it.
 320   (or (thing-at-point--bounds-of-markedup-url)
 321       ;; Otherwise, find the bounds within which a URI may exist.  The
 322       ;; method is similar to `ffap-string-at-point'.  Note that URIs
 323       ;; may contain parentheses but may not contain spaces (RFC3986).
 324       (let* ((allowed-chars "--:=&?$+@-Z_[:alpha:]~#,%;*()!'")
 325              (skip-before "^[0-9a-zA-Z]")
 326              (skip-after  ":;.,!?")
 327              (pt (point))
 328              (beg (save-excursion
 329                     (skip-chars-backward allowed-chars)
 330                     (skip-chars-forward skip-before pt)
 331                     (point)))
 332              (end (save-excursion
 333                     (skip-chars-forward allowed-chars)
 334                     (skip-chars-backward skip-after pt)
 335                     (point))))
 336         (or (thing-at-point--bounds-of-well-formed-url beg end pt)
 337             (if lax (cons beg end))))))
 338
 339 (defun thing-at-point--bounds-of-markedup-url ()
 340   (when thing-at-point-markedup-url-regexp
 341     (let ((case-fold-search t)
 342           (pt (point))
 343           (beg (line-beginning-position))
 344           (end (line-end-position))
 345           found)
 346       (save-excursion
 347         (goto-char beg)
 348         (while (and (not found)
 349                     (<= (point) pt)
 350                     (< (point) end))
 351           (and (re-search-forward thing-at-point-markedup-url-regexp
 352                                   end 1)
 353                (> (point) pt)
 354                (setq found t))))
 355       (if found
 356           (cons (match-beginning 1) (match-end 1))))))
 357
 358 (defun thing-at-point--bounds-of-well-formed-url (beg end _pt)
 359   (save-excursion
 360     (goto-char beg)
 361     (let (url-beg paren-end regexp)
 362       (save-restriction
 363         (narrow-to-region beg end)
 364         ;; The scheme component must either match at BEG, or have no
 365         ;; other alphanumerical ASCII characters before it.
 366         (setq regexp (concat "\\(?:\\`\\|[^a-zA-Z0-9]\\)\\("
 367                              (or thing-at-point-beginning-of-url-regexp
 368                                  (regexp-opt thing-at-point-uri-schemes))
 369                              "\\)"))
 370         (and (re-search-forward regexp end t)
 371              ;; URI must have non-empty contents.
 372              (< (point) end)
 373              (setq url-beg (match-beginning 1))))
 374       (when url-beg
 375         ;; If there is an open paren before the URI, truncate to the
 376         ;; matching close paren.
 377         (and (> url-beg (point-min))
 378              (eq (car-safe (syntax-after (1- url-beg))) 4)
 379              (save-restriction
 380                (narrow-to-region (1- url-beg) (min end (point-max)))
 381                (setq paren-end (ignore-errors
 382                                  (scan-lists (1- url-beg) 1 0))))
 383              (not (blink-matching-check-mismatch (1- url-beg) paren-end))
 384              (setq end (1- paren-end)))
 385         (cons url-beg end)))))
 386
 387 (put 'url 'thing-at-point 'thing-at-point-url-at-point)
 388
 389 (defun thing-at-point-url-at-point (&optional lax bounds)
 390   "Return the URL around or before point.
 391 If no URL is found, return nil.
 392
 393 If optional argument LAX is non-nil, look for URLs that are not
 394 well-formed, such as foo@bar or <nobody>.
 395
 396 If optional arguments BOUNDS are non-nil, it should be a cons
 397 cell of the form (START . END), containing the beginning and end
 398 positions of the URI.  Otherwise, these positions are detected
 399 automatically from the text around point.
 400
 401 If the scheme component is absent, either because a URI delimited
 402 with <url:...> lacks one, or because an ill-formed URI was found
 403 with LAX or BEG and END, try to add a scheme in the returned URI.
 404 The scheme is chosen heuristically: \"mailto:\" if the address
 405 looks like an email address, \"ftp://\" if it starts with
 406 \"ftp\", etc."
 407   (unless bounds
 408     (setq bounds (thing-at-point-bounds-of-url-at-point lax)))
 409   (when (and bounds (< (car bounds) (cdr bounds)))
 410     (let ((str (buffer-substring-no-properties (car bounds) (cdr bounds))))
 411       ;; If there is no scheme component, try to add one.
 412       (unless (string-match "\\`[a-zA-Z][-a-zA-Z0-9+.]*:" str)
 413         (or
 414          ;; If the URI has the form <foo@bar>, treat it according to
 415          ;; `thing-at-point-default-mail-uri-scheme'.  If there are
 416          ;; no angle brackets, it must be mailto.
 417          (when (string-match "\\`[^:</>@]+@[-.0-9=&?$+A-Z_a-z~#,%;*]" str)
 418            (let ((scheme (if (and (eq (char-before (car bounds)) ?<)
 419                                   (eq (char-after  (cdr bounds)) ?>))
 420                              thing-at-point-default-mail-uri-scheme
 421                            "mailto")))
 422              (if scheme
 423                  (setq str (concat scheme ":" str)))))
 424          ;; If the string is like <FOO>, where FOO is an existing user
 425          ;; name on the system, treat that as an email address.
 426          (and (string-match "\\`[[:alnum:]]+\\'" str)
 427               (eq (char-before (car bounds)) ?<)
 428               (eq (char-after  (cdr bounds)) ?>)
 429               (not (string-match "~" (expand-file-name (concat "~" str))))
 430               (setq str (concat "mailto:" str)))
 431          ;; If it looks like news.example.com, treat it as news.
 432          (if (thing-at-point-newsgroup-p str)
 433              (setq str (concat "news:" str)))
 434          ;; If it looks like ftp.example.com. treat it as ftp.
 435          (if (string-match "\\`ftp\\." str)
 436              (setq str (concat "ftp://" str)))
 437          ;; If it looks like www.example.com. treat it as http.
 438          (if (string-match "\\`www\\." str)
 439              (setq str (concat "http://" str)))
 440          ;; Otherwise, it just isn't a URI.
 441          (setq str nil)))
 442       str)))
 443
 444 (defun thing-at-point-newsgroup-p (string)
 445   "Return STRING if it looks like a newsgroup name, else nil."
 446   (and
 447    (string-match thing-at-point-newsgroup-regexp string)
 448    (let ((htbs '(gnus-active-hashtb gnus-newsrc-hashtb gnus-killed-hashtb))
 449          (heads thing-at-point-newsgroup-heads)
 450          htb ret)
 451      (while htbs
 452        (setq htb (car htbs) htbs (cdr htbs))
 453        (ignore-errors
 454          ;; errs: htb symbol may be unbound, or not a hash-table.
 455          ;; gnus-gethash is just a macro for intern-soft.
 456          (and (symbol-value htb)
 457               (intern-soft string (symbol-value htb))
 458               (setq ret string htbs nil))
 459          ;; If we made it this far, gnus is running, so ignore "heads":
 460          (setq heads nil)))
 461      (or ret (not heads)
 462          (let ((head (string-match "\\`\\([[:lower:]]+\\)\\." string)))
 463            (and head (setq head (substring string 0 (match-end 1)))
 464                 (member head heads)
 465                 (setq ret string))))
 466      ret)))
 467
 468 (put 'url 'end-op (lambda () (end-of-thing 'url)))
 469
 470 (put 'url 'beginning-op (lambda () (end-of-thing 'url)))
 471
 472 ;; The normal thingatpt mechanism doesn't work for complex regexps.
 473 ;; This should work for almost any regexp wherever we are in the
 474 ;; match.  To do a perfect job for any arbitrary regexp would mean
 475 ;; testing every position before point.  Regexp searches won't find
 476 ;; matches that straddle the start position so we search forwards once
 477 ;; and then back repeatedly and then back up a char at a time.
 478
 479 (defun thing-at-point-looking-at (regexp &optional distance)
 480   "Return non-nil if point is in or just after a match for REGEXP.
 481 Set the match data from the earliest such match ending at or after
 482 point."
 483   (save-excursion
 484     (let ((old-point (point))
 485           (forward-bound (and distance (+ (point) distance)))
 486           (backward-bound (and distance (- (point) distance)))
 487           match)
 488       (and (looking-at regexp)
 489            (>= (match-end 0) old-point)
 490            (setq match (point)))
 491       ;; Search back repeatedly from end of next match.
 492       ;; This may fail if next match ends before this match does.
 493       (re-search-forward regexp forward-bound 'limit)
 494       (while (and (re-search-backward regexp backward-bound t)
 495                   (or (> (match-beginning 0) old-point)
 496                       (and (looking-at regexp)  ; Extend match-end past search start
 497                            (>= (match-end 0) old-point)
 498                            (setq match (point))))))
 499       (if (not match) nil
 500         (goto-char match)
 501         ;; Back up a char at a time in case search skipped
 502         ;; intermediate match straddling search start pos.
 503         (while (and (not (bobp))
 504                     (progn (backward-char 1) (looking-at regexp))
 505                     (>= (match-end 0) old-point)
 506                     (setq match (point))))
 507         (goto-char match)
 508         (looking-at regexp)))))
 509
 510 ;;   Email addresses
 511 (defvar thing-at-point-email-regexp
 512   "<?[-+_.~a-zA-Z][-+_.~:a-zA-Z0-9]*@[-.a-zA-Z0-9]+>?"
 513   "A regular expression probably matching an email address.
 514 This does not match the real name portion, only the address, optionally
 515 with angle brackets.")
 516
 517 ;; Haven't set 'forward-op on 'email nor defined 'forward-email' because
 518 ;; not sure they're actually needed, and URL seems to skip them too.
 519 ;; Note that (end-of-thing 'email) and (beginning-of-thing 'email)
 520 ;; work automagically, though.
 521
 522 (put 'email 'bounds-of-thing-at-point
 523      (lambda ()
 524        (let ((thing (thing-at-point-looking-at
 525                      thing-at-point-email-regexp 500)))
 526          (if thing
 527              (let ((beginning (match-beginning 0))
 528                    (end (match-end 0)))
 529                (cons beginning end))))))
 530
 531 (put 'email 'thing-at-point
 532      (lambda ()
 533        (let ((boundary-pair (bounds-of-thing-at-point 'email)))
 534          (if boundary-pair
 535              (buffer-substring-no-properties
 536               (car boundary-pair) (cdr boundary-pair))))))
 537
 538 ;;  Buffer
 539
 540 (put 'buffer 'end-op (lambda () (goto-char (point-max))))
 541 (put 'buffer 'beginning-op (lambda () (goto-char (point-min))))
 542
 543 ;;  Aliases
 544
 545 (defun word-at-point ()
 546   "Return the word at point.  See `thing-at-point'."
 547   (thing-at-point 'word))
 548
 549 (defun sentence-at-point ()
 550   "Return the sentence at point.  See `thing-at-point'."
 551   (thing-at-point 'sentence))
 552
 553 (defun read-from-whole-string (str)
 554   "Read a Lisp expression from STR.
 555 Signal an error if the entire string was not used."
 556   (let* ((read-data (read-from-string str))
 557          (more-left
 558           (condition-case nil
 559               ;; The call to `ignore' suppresses a compiler warning.
 560               (progn (ignore (read-from-string (substring str (cdr read-data))))
 561                      t)
 562             (end-of-file nil))))
 563     (if more-left
 564         (error "Can't read whole string")
 565       (car read-data))))
 566
 567 (defun form-at-point (&optional thing pred)
 568   (let ((sexp (ignore-errors
 569                 (read-from-whole-string (thing-at-point (or thing 'sexp))))))
 570     (if (or (not pred) (funcall pred sexp)) sexp)))
 571
 572 ;;;###autoload
 573 (defun sexp-at-point ()
 574   "Return the sexp at point, or nil if none is found."
 575   (form-at-point 'sexp))
 576 ;;;###autoload
 577 (defun symbol-at-point ()
 578   "Return the symbol at point, or nil if none is found."
 579   (let ((thing (thing-at-point 'symbol)))
 580     (if thing (intern thing))))
 581 ;;;###autoload
 582 (defun number-at-point ()
 583   "Return the number at point, or nil if none is found."
 584   (form-at-point 'sexp 'numberp))
 585 (put 'number 'thing-at-point 'number-at-point)
 586 ;;;###autoload
 587 (defun list-at-point ()
 588   "Return the Lisp list at point, or nil if none is found."
 589   (form-at-point 'list 'listp))
 590
 591 ;;; thingatpt.el ends here