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;;; thingatpt.el --- Get the `thing' at point
;; Copyright (C) 1991,1992,1993 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
;; it's 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 %ss" THING))))
;;=== General routines ====================================================
;;;###autoload
(defun bounds-of-thing-at-point (THING)
"Determine the start and end buffer locations for the THING at point,
where THING is an entity for which there is a either a corresponding
forward-THING operation, or corresponding beginning-of-THING and
end-of-THING operations, eg. 'word, 'sentence, 'defun.
Return a cons cell '(start . end) giving the start and end positions."
(let ((orig (point)))
(condition-case nil
(save-excursion
(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 (and beg end (<= beg orig) (< orig end))
(cons beg end))))
(error nil))))
;;;###autoload
(defun thing-at-point (THING)
"Return the THING at point, where THING is an entity defined by
bounds-of-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 =======================================================
;;--- 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)
;;--- Lists ---
(put 'list 'end-op (function (lambda () (up-list 1))))
(put 'list 'beginning-op 'backward-sexp)
;;--- Filenames ---
(defvar file-name-chars "~/A-Za-z0-9---_.${}#%,"
"Characters allowable in filenames.")
(put 'filename 'end-op
(function (lambda () (skip-chars-forward file-name-chars))))
(put 'filename 'beginning-op
(function (lambda () (skip-chars-backward file-name-chars (point-min)))))
;;--- Whitespace ---
(defun forward-whitespace (ARG)
(interactive "p")
(if (natnump ARG)
(re-search-forward "[ \t]+\\|\n" nil nil ARG)
(while (< ARG 0)
(if (re-search-backward "[ \t]+\\|\n" nil nil)
(or (eq (char-after (match-beginning 0)) 10)
(skip-chars-backward " \t")))
(setq ARG (1+ ARG)))))
;;--- Buffer ---
(put 'buffer 'end-op 'end-of-buffer)
(put 'buffer 'beginning-op 'beginning-of-buffer)
;;--- Symbols ---
(defun forward-symbol (ARG)
(interactive "p")
(if (natnump ARG)
(re-search-forward "\\(\\sw\\|\\s_\\)+" nil nil ARG)
(while (< ARG 0)
(if (re-search-backward "\\(\\sw\\|\\s_\\)+" nil nil)
(skip-syntax-backward "w_"))
(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, signalling 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.
|
