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141 lines
4.7 KiB
EmacsLisp
141 lines
4.7 KiB
EmacsLisp
;;; compare-w.el --- compare text between windows for Emacs.
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;; Copyright (C) 1986, 1989 Free Software Foundation, Inc.
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;; Maintainer: FSF
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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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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to
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;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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;;; Commentary:
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;; This package provides one entry point, compare-windows. It compares
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;; text starting from point in two adjacent windows, advancing point
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;; until it finds a difference. Option variables permit you to ignore
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;; whitespace differences, or case differences, or both.
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;;; Code:
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(defvar compare-windows-whitespace " \t\n"
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"*String of characters considered whitespace for \\[compare-windows].
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Changes in whitespace are optionally ignored.
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The value of `compare-windows-whitespace' may instead be a function; this
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function is called in each buffer, with point at the current scanning point.
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The function's job is to categorize any whitespace around (including before)
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point; it should also advance past any whitespace.
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The function is passed one argument, the point where `compare-windows'
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was originally called; it should not consider any text before that point.
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If the function returns the same value for both buffers, then the
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whitespace is considered to match, and is skipped.")
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(defvar compare-ignore-case nil
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"*Non-nil means \\[compare-windows] ignores case differences.")
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;;;###autoload
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(defun compare-windows (ignore-whitespace)
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"Compare text in current window with text in next window.
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Compares the text starting at point in each window,
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moving over text in each one as far as they match.
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A prefix arg means ignore changes in whitespace.
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The variable `compare-windows-whitespace' controls how whitespace is skipped.
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If `compare-ignore-case' is non-nil, changes in case are also ignored."
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(interactive "P")
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(let* (p1 p2 maxp1 maxp2 b1 b2 w2
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success size
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(opoint1 (point))
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opoint2
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(skip-whitespace (if ignore-whitespace
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compare-windows-whitespace))
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(skip-whitespace-regexp (concat "[" skip-whitespace "]+")))
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(setq p1 (point) b1 (current-buffer))
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(setq w2 (next-window (selected-window)))
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(if (eq w2 (selected-window))
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(error "No other window"))
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(setq p2 (window-point w2)
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b2 (window-buffer w2))
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(setq opoint2 p2)
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(setq maxp1 (point-max))
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(save-excursion
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(set-buffer b2)
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(setq maxp2 (point-max)))
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(setq success t)
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(while success
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(setq success nil)
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;; if interrupted, show how far we've gotten
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(goto-char p1)
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(set-window-point w2 p2)
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;; If both buffers have whitespace next to point,
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;; optionally skip over it.
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(and skip-whitespace
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(save-excursion
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(let (p1a p2a w1 w2 result1 result2)
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(if (stringp skip-whitespace)
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(progn
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(if (not (eobp))
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(skip-chars-backward skip-whitespace opoint1))
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(and (looking-at skip-whitespace-regexp)
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(setq p1a (match-end 0) result1 t)))
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(setq result1 (funcall skip-whitespace opoint1))
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(setq p1a (point)))
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(set-buffer b2)
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(goto-char p2)
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(if (stringp skip-whitespace)
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(progn
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(if (not (eobp))
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(skip-chars-backward skip-whitespace opoint2))
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(and (looking-at skip-whitespace-regexp)
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(setq p2a (match-end 0) result2 t)))
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(setq result2 (funcall skip-whitespace opoint2))
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(setq p2a (point)))
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(and result1 result2 (eq result1 result2)
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(setq p1 p1a
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p2 p2a)))))
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;; Try advancing comparing 1000 chars at a time.
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;; When that fails, go 500 chars at a time, and so on.
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(let ((size 1000)
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success-1
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(case-fold-search compare-ignore-case))
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(while (> size 0)
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(setq success-1 t)
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;; Try comparing SIZE chars at a time, repeatedly, till that fails.
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(while success-1
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(setq size (min size (- maxp1 p1) (- maxp2 p2)))
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(setq success-1
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(and (> size 0)
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(= 0 (compare-buffer-substrings b2 p2 (+ size p2)
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b1 p1 (+ size p1)))))
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(if success-1
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(setq p1 (+ p1 size) p2 (+ p2 size)
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success t)))
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;; If SIZE chars don't match, try fewer.
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(setq size (/ size 2)))))
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(goto-char p1)
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(set-window-point w2 p2)
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(if (= (point) opoint1)
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(ding))))
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(provide 'compare-w)
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;;; compare-w.el ends here
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