+(defun show-paren--unescaped-p (pos)
+ "Determine whether the paren after POS is unescaped."
+ (save-excursion
+ (goto-char pos)
+ (= (logand (skip-syntax-backward "/\\") 1) 0)))
+
+(defun show-paren--categorize-paren (pos)
+ "Determine whether the character after POS has paren syntax,
+and if so, return a cons (DIR . OUTSIDE), where DIR is 1 for an
+open paren, -1 for a close paren, and OUTSIDE is the buffer
+position of the outside of the paren. If the character isn't a
+paren, or it is an escaped paren, return nil."
+ (cond
+ ((and (eq (syntax-class (syntax-after pos)) 4)
+ (show-paren--unescaped-p pos))
+ (cons 1 pos))
+ ((and (eq (syntax-class (syntax-after pos)) 5)
+ (show-paren--unescaped-p pos))
+ (cons -1 (1+ pos)))))
+
+(defun show-paren--locate-near-paren ()
+ "Locate an unescaped paren \"near\" point to show.
+If one is found, return the cons (DIR . OUTSIDE), where DIR is 1
+for an open paren, -1 for a close paren, and OUTSIDE is the buffer
+position of the outside of the paren. Otherwise return nil."
+ (let* ((ind-pos (save-excursion (back-to-indentation) (point)))
+ (eol-pos
+ (save-excursion
+ (end-of-line) (skip-chars-backward " \t" ind-pos) (point)))
+ (before (show-paren--categorize-paren (1- (point))))
+ (after (show-paren--categorize-paren (point))))
+ (cond
+ ;; Point is immediately outside a paren.
+ ((eq (car before) -1) before)
+ ((eq (car after) 1) after)
+ ;; Point is immediately inside a paren.
+ ((and show-paren-when-point-inside-paren before))
+ ((and show-paren-when-point-inside-paren after))
+ ;; Point is in the whitespace before the code.
+ ((and show-paren-when-point-in-periphery
+ (<= (point) ind-pos))
+ (or (show-paren--categorize-paren ind-pos)
+ (show-paren--categorize-paren (1- eol-pos))))
+ ;; Point is in the whitespace after the code.
+ ((and show-paren-when-point-in-periphery
+ (>= (point) eol-pos))
+ (show-paren--categorize-paren (1- eol-pos))))))
+