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219 lines
6.6 KiB
EmacsLisp
219 lines
6.6 KiB
EmacsLisp
;;; thingatpt.el --- Get the `thing' at point
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;; Copyright (C) 1991,1992,1993,1994,1995 Free Software Foundation, Inc.
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;; Author: Mike Williams <mikew@gopher.dosli.govt.nz>
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;; Keywords: extensions, matching, mouse
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;; Created: Thu Mar 28 13:48:23 1991
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;; Commentary:
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;; This file provides routines for getting the `thing' at the location of
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;; point, whatever that `thing' happens to be. The `thing' is defined by
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;; it's beginning and end positions in the buffer.
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;;
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;; The function bounds-of-thing-at-point finds the beginning and end
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;; positions by moving first forward to the end of the `thing', and then
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;; backwards to the beginning. By default, it uses the corresponding
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;; forward-`thing' operator (eg. forward-word, forward-line).
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;;
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;; Special cases are allowed for using properties associated with the named
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;; `thing':
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;;
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;; forward-op Function to call to skip forward over a `thing' (or
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;; with a negative argument, backward).
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;;
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;; beginning-op Function to call to skip to the beginning of a `thing'.
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;; end-op Function to call to skip to the end of a `thing'.
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;;
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;; Reliance on existing operators means that many `things' can be accessed
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;; without further code: eg.
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;; (thing-at-point 'line)
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;; (thing-at-point 'page)
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;;; Code:
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(provide 'thingatpt)
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;; Basic movement
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;;;###autoload
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(defun forward-thing (THING &optional N)
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"Move forward to the end of the next THING."
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(let ((forward-op (or (get THING 'forward-op)
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(intern-soft (format "forward-%s" THING)))))
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(if (fboundp forward-op)
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(funcall forward-op (or N 1))
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(error "Can't determine how to move over %ss" THING))))
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;; General routines
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;;;###autoload
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(defun bounds-of-thing-at-point (THING)
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"Determine the start and end buffer locations for the THING at point,
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where THING is an entity for which there is a either a corresponding
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forward-THING operation, or corresponding beginning-of-THING and
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end-of-THING operations, eg. 'word, 'sentence, 'defun.
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Return a cons cell '(start . end) giving the start and end positions."
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(let ((orig (point)))
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(condition-case nil
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(save-excursion
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(let ((end (progn
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(funcall
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(or (get THING 'end-op)
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(function (lambda () (forward-thing THING 1)))))
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(point)))
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(beg (progn
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(funcall
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(or (get THING 'beginning-op)
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(function (lambda () (forward-thing THING -1)))))
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(point))))
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(if (and beg end (<= beg orig) (< orig end))
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(cons beg end))))
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(error nil))))
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;;;###autoload
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(defun thing-at-point (THING)
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"Return the THING at point, where THING is an entity defined by
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bounds-of-thing-at-point."
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(let ((bounds (bounds-of-thing-at-point THING)))
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(if bounds
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(buffer-substring (car bounds) (cdr bounds)))))
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;; Go to beginning/end
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(defun beginning-of-thing (THING)
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(let ((bounds (bounds-of-thing-at-point THING)))
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(or bounds (error "No %s here" THING))
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(goto-char (car bounds))))
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(defun end-of-thing (THING)
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(let ((bounds (bounds-of-thing-at-point THING)))
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(or bounds (error "No %s here" THING))
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(goto-char (cdr bounds))))
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;; Special cases
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;; Lines
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;; bolp will be false when you click on the last line in the buffer
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;; and it has no final newline.
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(put 'line 'beginning-op
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(function (lambda () (if (bolp) (forward-line -1) (beginning-of-line)))))
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;; Sexps
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(defun in-string-p ()
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(let ((orig (point)))
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(save-excursion
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(beginning-of-defun)
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(nth 3 (parse-partial-sexp (point) orig)))))
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(defun end-of-sexp ()
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(let ((char-syntax (char-syntax (char-after (point)))))
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(if (or (eq char-syntax ?\))
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(and (eq char-syntax ?\") (in-string-p)))
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(forward-char 1)
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(forward-sexp 1))))
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(put 'sexp 'end-op 'end-of-sexp)
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;; Lists
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(put 'list 'end-op (function (lambda () (up-list 1))))
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(put 'list 'beginning-op 'backward-sexp)
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;; Filenames
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(defvar file-name-chars "~/A-Za-z0-9---_.${}#%,"
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"Characters allowable in filenames.")
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(put 'filename 'end-op
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(function (lambda () (skip-chars-forward file-name-chars))))
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(put 'filename 'beginning-op
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(function (lambda () (skip-chars-backward file-name-chars (point-min)))))
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;; Whitespace
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(defun forward-whitespace (ARG)
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(interactive "p")
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(if (natnump ARG)
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(re-search-forward "[ \t]+\\|\n" nil nil ARG)
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(while (< ARG 0)
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(if (re-search-backward "[ \t]+\\|\n" nil nil)
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(or (eq (char-after (match-beginning 0)) 10)
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(skip-chars-backward " \t")))
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(setq ARG (1+ ARG)))))
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;; Buffer
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(put 'buffer 'end-op 'end-of-buffer)
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(put 'buffer 'beginning-op 'beginning-of-buffer)
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;; Symbols
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(defun forward-symbol (ARG)
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(interactive "p")
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(if (natnump ARG)
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(re-search-forward "\\(\\sw\\|\\s_\\)+" nil nil ARG)
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(while (< ARG 0)
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(if (re-search-backward "\\(\\sw\\|\\s_\\)+" nil nil)
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(skip-syntax-backward "w_"))
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(setq ARG (1+ ARG)))))
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;; Syntax blocks
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(defun forward-same-syntax (&optional arg)
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(interactive "p")
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(while (< arg 0)
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(skip-syntax-backward
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(char-to-string (char-syntax (char-after (1- (point))))))
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(setq arg (1+ arg)))
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(while (> arg 0)
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(skip-syntax-forward (char-to-string (char-syntax (char-after (point)))))
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(setq arg (1- arg))))
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;; Aliases
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(defun word-at-point () (thing-at-point 'word))
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(defun sentence-at-point () (thing-at-point 'sentence))
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(defun read-from-whole-string (STR)
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"Read a lisp expression from STR, signaling an error if the entire string
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was not used."
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(let* ((read-data (read-from-string STR))
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(more-left
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(condition-case nil
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(progn (read-from-string (substring STR (cdr read-data)))
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t)
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(end-of-file nil))))
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(if more-left
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(error "Can't read whole string")
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(car read-data))))
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(defun form-at-point (&optional THING PRED)
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(let ((sexp (condition-case nil
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(read-from-whole-string (thing-at-point (or THING 'sexp)))
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(error nil))))
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(if (or (not PRED) (funcall PRED sexp)) sexp)))
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(defun sexp-at-point () (form-at-point 'sexp))
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(defun symbol-at-point () (form-at-point 'sexp 'symbolp))
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(defun number-at-point () (form-at-point 'sexp 'numberp))
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(defun list-at-point () (form-at-point 'list 'listp))
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;; thingatpt.el ends here.
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