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;;; expand-region-core.el --- Increase selected region by semantic units.
;; Copyright (C) 2011-2013 Magnar Sveen
;; Author: Magnar Sveen <>
;; Keywords: marking region
;; This program 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 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <>.
;;; Commentary:
;; The core functionality of expand-region.
;; See
;;; Code:
(eval-when-compile (require 'cl))
(require 'expand-region-custom)
(declare-function er/expand-region "expand-region")
(defvar er/history '()
"A history of start and end points so we can contract after expanding.")
;; history is always local to a single buffer
(make-variable-buffer-local 'er/history)
(defvar er--space-str " \t\n")
(defvar er--blank-list (append er--space-str nil))
(set-default 'er--show-expansion-message nil)
(defvar er/try-expand-list nil
"A list of functions that are tried when expanding.")
(defun er--prepare-expanding ()
(when (and (er--first-invocation)
(not (use-region-p)))
(push-mark nil t) ;; one for keeping starting position
(push-mark nil t)) ;; one for replace by set-mark in expansions
(when (not (eq t transient-mark-mode))
(setq transient-mark-mode (cons 'only transient-mark-mode))))
(defun er--copy-region-to-register ()
(when (and (stringp expand-region-autocopy-register)
(> (length expand-region-autocopy-register) 0))
(set-register (aref expand-region-autocopy-register 0)
(filter-buffer-substring (region-beginning) (region-end)))))
;; save-mark-and-excursion in Emacs 25 works like save-excursion did before
(when (< emacs-major-version 25)
(defmacro save-mark-and-excursion (&rest body)
`(save-excursion ,@body))))
(defun er--expand-region-1 ()
"Increase selected region by semantic units.
Basically it runs all the mark-functions in `er/try-expand-list'
and chooses the one that increases the size of the region while
moving point or mark as little as possible."
(let* ((p1 (point))
(p2 (if (use-region-p) (mark) (point)))
(start (min p1 p2))
(end (max p1 p2))
(try-list er/try-expand-list)
(best-start (point-min))
(best-end (point-max))
(set-mark-default-inactive nil))
;; add hook to clear history on buffer changes
(unless er/history
(add-hook 'after-change-functions 'er/clear-history t t))
;; remember the start and end points so we can contract later
;; unless we're already at maximum size
(unless (and (= start best-start)
(= end best-end))
(push (cons start end) er/history))
(when (and expand-region-skip-whitespace
(= start end))
(skip-chars-forward er--space-str)
(setq start (point)))
(while try-list
(funcall (car try-list))
(when (and (region-active-p)
(er--this-expansion-is-better start end best-start best-end))
(setq best-start (point))
(setq best-end (mark))
(when (and er--show-expansion-message (not (minibufferp)))
(message "%S" (car try-list))))))
(setq try-list (cdr try-list)))
(setq deactivate-mark nil)
(goto-char best-start)
(set-mark best-end)
(when (and (= best-start (point-min))
(= best-end (point-max))) ;; We didn't find anything new, so exit early
(defun er--this-expansion-is-better (start end best-start best-end)
"t if the current region is an improvement on previous expansions.
This is provided as a separate function for those that would like
to override the heuristic."
(<= (point) start)
(>= (mark) end)
(> (- (mark) (point)) (- end start))
(or (> (point) best-start)
(and (= (point) best-start)
(< (mark) best-end)))))
(defun er/contract-region (arg)
"Contract the selected region to its previous size.
With prefix argument contracts that many times.
If prefix argument is negative calls `er/expand-region'.
If prefix argument is 0 it resets point and mark to their state
before calling `er/expand-region' for the first time."
(interactive "p")
(if (< arg 0)
(er/expand-region (- arg))
(when er/history
;; Be sure to reset them all if called with 0
(when (= arg 0)
(setq arg (length er/history)))
(when (not transient-mark-mode)
(setq transient-mark-mode (cons 'only transient-mark-mode)))
;; Advance through the list the desired distance
(while (and (cdr er/history)
(> arg 1))
(setq arg (- arg 1))
(setq er/history (cdr er/history)))
;; Reset point and mark
(let* ((last (pop er/history))
(start (car last))
(end (cdr last)))
(goto-char start)
(set-mark end)
(when (eq start end)
(defun er/prepare-for-more-expansions-internal (repeat-key-str)
"Return bindings and a message to inform user about them"
(let ((msg (format "Type %s to expand again" repeat-key-str))
(bindings (list (cons repeat-key-str '(er/expand-region 1)))))
;; If contract and expand are on the same binding, ignore contract
(unless (string-equal repeat-key-str expand-region-contract-fast-key)
(setq msg (concat msg (format ", %s to contract" expand-region-contract-fast-key)))
(push (cons expand-region-contract-fast-key '(er/contract-region 1)) bindings))
;; If reset and either expand or contract are on the same binding, ignore reset
(unless (or (string-equal repeat-key-str expand-region-reset-fast-key)
(string-equal expand-region-contract-fast-key expand-region-reset-fast-key))
(setq msg (concat msg (format ", %s to reset" expand-region-reset-fast-key)))
(push (cons expand-region-reset-fast-key '(er/expand-region 0)) bindings))
(cons msg bindings)))
(defun er/prepare-for-more-expansions ()
"Let one expand more by just pressing the last key."
(let* ((repeat-key (event-basic-type last-input-event))
(repeat-key-str (single-key-description repeat-key))
(msg-and-bindings (er/prepare-for-more-expansions-internal repeat-key-str))
(msg (car msg-and-bindings))
(bindings (cdr msg-and-bindings)))
(when repeat-key
(let ((map (make-sparse-keymap)))
(dolist (binding bindings map)
(define-key map (read-kbd-macro (car binding))
`(lambda ()
(setq this-command `,(cadr ',binding))
(or (minibufferp) (message "%s" ,msg))
(eval `,(cdr ',binding))))))
(or (minibufferp) (message "%s" msg)))))
(if (fboundp 'set-temporary-overlay-map)
(fset 'er/set-temporary-overlay-map 'set-temporary-overlay-map)
;; Backport this function from newer emacs versions
(defun er/set-temporary-overlay-map (map &optional keep-pred)
"Set a new keymap that will only exist for a short period of time.
The new keymap to use must be given in the MAP variable. When to
remove the keymap depends on user input and KEEP-PRED:
- if KEEP-PRED is nil (the default), the keymap disappears as
soon as any key is pressed, whether or not the key is in MAP;
- if KEEP-PRED is t, the keymap disappears as soon as a key *not*
in MAP is pressed;
- otherwise, KEEP-PRED must be a 0-arguments predicate that will
decide if the keymap should be removed (if predicate returns
nil) or kept (otherwise). The predicate will be called after
each key sequence."
(let* ((clearfunsym (make-symbol "clear-temporary-overlay-map"))
(overlaysym (make-symbol "t"))
(alist (list (cons overlaysym map)))
`(lambda ()
(unless ,(cond ((null keep-pred) nil)
((eq t keep-pred)
`(eq this-command
(lookup-key ',map
(t `(funcall ',keep-pred)))
(remove-hook 'pre-command-hook ',clearfunsym)
(setq emulation-mode-map-alists
(delq ',alist emulation-mode-map-alists))))))
(set overlaysym overlaysym)
(fset clearfunsym clearfun)
(add-hook 'pre-command-hook clearfunsym)
(push alist emulation-mode-map-alists))))
(defadvice keyboard-quit (before collapse-region activate)
(when (memq last-command '(er/expand-region er/contract-region))
(er/contract-region 0)))
(defadvice minibuffer-keyboard-quit (around collapse-region activate)
(if (memq last-command '(er/expand-region er/contract-region))
(er/contract-region 0)
(defadvice cua-cancel (before collapse-region activate)
(when (memq last-command '(er/expand-region er/contract-region))
(er/contract-region 0)))
(defun er/clear-history (&rest args)
"Clear the history."
(setq er/history '())
(remove-hook 'after-change-functions 'er/clear-history t))
(defsubst er--first-invocation ()
"t if this is the first invocation of er/expand-region or er/contract-region"
(not (memq last-command '(er/expand-region er/contract-region))))
(defun er--point-is-surrounded-by-white-space ()
(and (or (memq (char-before) er--blank-list)
(eq (point) (point-min)))
(memq (char-after) er--blank-list)))
(defun er/enable-mode-expansions (mode add-fn)
(add-hook (intern (format "%s-hook" mode)) add-fn)
(dolist (buffer (buffer-list))
(with-current-buffer buffer
(when (derived-mode-p mode)
(funcall add-fn))))))
;; Some more performant version of `looking-back'
(defun er/looking-back-on-line (regexp)
"Version of `looking-back' that only checks current line."
(looking-back regexp (line-beginning-position)))
(defun er/looking-back-exact (s)
"Version of `looking-back' that only looks for exact matches, no regexp."
(string= s (buffer-substring (- (point) (length s))
(defun er/looking-back-max (regexp count)
"Version of `looking-back' that only check COUNT chars back."
(looking-back regexp (max 1 (- (point) count))))
(provide 'expand-region-core)
;;; expand-region-core.el ends here
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