Emacs:删除空格或单词

Question

如何将 emacs 配置为与按 Alt+D 或 Alt+Backspace 删除相邻空格或单个单词的其他现代编辑器相同的方式工作？默认情况下，emacs 总是删除一个单词。

Answer 1

(defvar movement-syntax-table
  (let ((st (make-syntax-table)))
    ;; ` default = punctuation
    ;; ' default = punctuation
    ;; , default = punctuation
    ;; ; default = punctuation
    (modify-syntax-entry ?{ "." st)  ;; { = punctuation
    (modify-syntax-entry ?} "." st)  ;; } = punctuation
    (modify-syntax-entry ?\" "." st) ;; " = punctuation
    (modify-syntax-entry ?\\ "_" st) ;; \ = symbol
    (modify-syntax-entry ?\$ "_" st) ;; $ = symbol
    (modify-syntax-entry ?\% "_" st) ;; % = symbol
    st)
  "Syntax table used while executing custom movement functions.")

(defun delete-word-or-whitespace (&optional arg)
"http://stackoverflow.com/a/20456861/2112489"
(interactive "P")
  (with-syntax-table movement-syntax-table
    (let* (
        beg
        end
        (word-regexp "\\sw")
        (punctuation-regexp "\\s.")
        (symbol-regexp "\\s_\\|\\s(\\|\\s)"))
      (cond
        ;; Condition # 1
        ;; right of cursor = word or punctuation or symbol
        ((or
            (save-excursion (< 0 (skip-syntax-forward "w")))
            (save-excursion (< 0 (skip-syntax-forward ".")))
            (save-excursion (< 0 (skip-syntax-forward "_()"))))
          ;; Condition #1 -- Step 1 of 2
          (cond
            ;; right of cursor = word
            ((save-excursion (< 0 (skip-syntax-forward "w")))
              (skip-syntax-forward "w")
              (setq end (point))
              (while (looking-back word-regexp)
                (backward-char))
              (setq beg (point))
              (delete-region beg end))
            ;; right of cursor = punctuation
            ((save-excursion (< 0 (skip-syntax-forward ".")))
              (skip-syntax-forward ".")
              (setq end (point))
              (while (looking-back punctuation-regexp)
                (backward-char))
              (setq beg (point))
              (delete-region beg end))
            ;; right of cursor = symbol
            ((save-excursion (< 0 (skip-syntax-forward "_()")))
              (skip-syntax-forward "_()")
              (setq end (point))
              (while (looking-back symbol-regexp)
                (backward-char))
              (setq beg (point))
              (delete-region beg end)))
          ;; Condition #1 -- Step 2 of 2
          (cond
            ;; right of cursor = whitespace
            ;; left of cursor = not word / not symbol / not punctuation = whitespace or bol
            ((and
                (save-excursion (< 0 (skip-chars-forward "\s\t")))
                (not (save-excursion (> 0 (skip-syntax-backward "w"))))
                (not (save-excursion (> 0 (skip-syntax-backward "."))))
                (not (save-excursion (> 0 (skip-syntax-backward "_()")))))
              (setq beg (point))
              (skip-chars-forward "\s\t")
              (setq end (point))
              (delete-region beg end))
            ;; right of cursor = whitespace
            ;; left of cursor = word or symbol or punctuation
            ((and
                (save-excursion (< 0 (skip-chars-forward "\s\t")))
                (or
                  (save-excursion (> 0 (skip-syntax-backward "w")))
                  (save-excursion (> 0 (skip-syntax-backward ".")))
                  (save-excursion (> 0 (skip-syntax-backward "_()")))))
              (fixup-whitespace))))
        ;; Condition # 2
        ;; right of cursor = whitespace
        ;; left of cursor = bol | left of cursor = whitespace | right of cursor = whitespace + eol
        ((and 
            (save-excursion (< 0 (skip-chars-forward "\s\t")))
            (or
              (bolp)
              (save-excursion (> 0 (skip-chars-backward "\s\t")))
              (save-excursion (< 0 (skip-chars-forward "\s\t")) (eolp))))
          (setq beg (point))
          (skip-chars-forward "\s\t")
          (setq end (point))
          (delete-region beg end))
        ;; Condition # 3
        ;; right of cursor = whitespace or eol
        ;; left of cursor = word or symbol or punctuation
        ;; not bol + word or symbol or punctuation
        ;; not bol + whitespace + word or symbol or punctuation
        ((and 
            (or (save-excursion (< 0 (skip-chars-forward "\s\t"))) (eolp))
            (or
              (save-excursion (> 0 (skip-syntax-backward "w")))
              (save-excursion (> 0 (skip-syntax-backward ".")))
              (save-excursion (> 0 (skip-syntax-backward "_()"))))
            (not (save-excursion (> 0 (skip-syntax-backward "w")) (bolp)))
            (not (save-excursion (> 0 (skip-syntax-backward ".")) (bolp)))
            (not (save-excursion (> 0 (skip-syntax-backward "_()")) (bolp)))
            (not (save-excursion (and (> 0 (skip-syntax-backward "w")) (> 0 (skip-chars-backward "\s\t")) (bolp))))
            (not (save-excursion (and (> 0 (skip-syntax-backward ".")) (> 0 (skip-chars-backward "\s\t")) (bolp))))
            (not (save-excursion (and (> 0 (skip-syntax-backward "_()")) (> 0 (skip-chars-backward "\s\t")) (bolp)))))
          (setq end (point))
          (cond
            ((save-excursion (> 0 (skip-syntax-backward "w")))
              (while (looking-back word-regexp)
                (backward-char)))
            ((save-excursion (> 0 (skip-syntax-backward ".")))
              (while (looking-back punctuation-regexp)
                (backward-char)))
            ((save-excursion (> 0 (skip-syntax-backward "_()")))
              (while (looking-back symbol-regexp)
                (backward-char))))
          (setq beg (point))
          (when (save-excursion (> 0 (skip-chars-backward "\s\t")))
            (skip-chars-backward "\s\t")
            (setq beg (point)))
          (delete-region beg end)
          (skip-chars-forward "\s\t"))
        ;; Condition # 4
        ;; not bol = eol
        ;; left of cursor = bol + word or symbol or punctuation | bol + whitespace + word or symbol or punctuation
        ((and
            (not (and (bolp) (eolp)))
            (or
              (save-excursion (> 0 (skip-syntax-backward "w")) (bolp))
              (save-excursion (> 0 (skip-syntax-backward ".")) (bolp))
              (save-excursion (> 0 (skip-syntax-backward "_()")) (bolp))
              (save-excursion (and (> 0 (skip-syntax-backward "w")) (> 0 (skip-chars-backward "\s\t")) (bolp)))
              (save-excursion (and (> 0 (skip-syntax-backward ".")) (> 0 (skip-chars-backward "\s\t")) (bolp)))
              (save-excursion (and (> 0 (skip-syntax-backward "_()")) (> 0 (skip-chars-backward "\s\t")) (bolp)))))
          (skip-chars-forward "\s\t")
          (setq end (point))
          (setq beg (point-at-bol))
          (delete-region beg end))
        ;; Condition # 5
        ;; point = eol
        ;; not an empty line
        ;; whitespace to the left of eol
        ((and
            (not (and (bolp) (eolp)))
            (eolp)
            (save-excursion (> 0 (skip-chars-backward "\s\t"))))
          (setq end (point))
          (skip-chars-backward "\s\t")
          (setq beg (point))
          (delete-region beg end))
        ;; Condition # 6
        ;; point = not eob
        ;; point = bolp and eolp
        ;; universal argument = C-u = '(4)
        ((and
            (not (eobp))
            (and (bolp) (eolp))
            (equal arg '(4)))
          (delete-forward-char 1))) )))