popup-matching-paren.el

(require 'cl)

(defvar popup-matching-paren-open-parens "([{\"")
(defvar popup-matching-paren-close-parens ")]}\"")

(defun popup-matching-paren (&optional lines)
  "popup 1+`lines'*2 lines"
  (interactive)
  (unless lines
    (setq lines 0))
  (cond
    ((find (char-before) popup-matching-paren-close-parens)
     (popup-matching-paren-backward lines))
    ((find (char-after) popup-matching-paren-open-parens)
     (popup-matching-paren-forward lines))))


(defun popup-matching-paren-forward (lines)
  (let ((text (save-excursion
               (forward-sexp)
               (unless (and  (<= (window-start) (point))
                             (< (point) (window-end)))
                 (popup-matching-paren-get-lines lines)))))
    (when text
      (popup-tip text))))

(defun popup-matching-paren-backward (lines)
  (let ((text (save-excursion
               (backward-sexp)
               (unless (and  (<= (window-start) (point))
                             (< (point) (window-end)))
                 (popup-matching-paren-get-lines lines)))))
    (when text
      (popup-tip text))))


(defun popup-matching-paren-get-lines (lines)
  (let ((beg (save-excursion (previous-line lines) (line-beginning-position)))
        (end (save-excursion (next-line lines) (line-end-position))))
    (buffer-substring beg end)))