From 18cf19f4d12dbe95b952b895c85579bb41801602 Mon Sep 17 00:00:00 2001 From: Taylor R Campbell Date: Sun, 7 Apr 2013 16:42:21 +0000 Subject: Implement `paredit-preserving-column'. --- paredit.el | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/paredit.el b/paredit.el index e2d3f78..80d83d5 100644 --- a/paredit.el +++ b/paredit.el @@ -173,6 +173,21 @@ Signal an error if no clause matches." (put 'paredit-ignore-sexp-errors 'lisp-indent-function 0) + (defmacro paredit-preserving-column (&rest body) + "Evaluate BODY and restore point to former column, relative to code. +Assumes BODY will change only indentation. +If point was on code, it moves with the code. +If point was on indentation, it stays in indentation." + (let ((column (make-symbol "column")) + (indentation (make-symbol "indentation"))) + `(let ((,column (current-column)) + (,indentation (paredit-current-indentation))) + (let ((value (progn ,@body))) + (paredit-restore-column ,column ,indentation) + value)))) + + (put 'paredit-preserving-column 'lisp-indent-function 0) + nil) ;;;; Minor Mode Definition @@ -2611,6 +2626,20 @@ This is independent of context -- it doesn't check what state the (save-excursion (back-to-indentation) (current-column))) + +(defun paredit-restore-column (column indentation) + ;; Preserve the point's position either in the indentation or in the + ;; code: if on code, move with the code; if in indentation, leave it + ;; in the indentation, either where it was (if still on indentation) + ;; or at the end of the indentation (if the code moved far enough + ;; left). + (let ((indentation* (paredit-current-indentation))) + (goto-char + (+ (point-at-bol) + (cond ((not (< column indentation)) + (+ column (- indentation* indentation))) + ((<= indentation* column) indentation*) + (t column)))))) ;;;; Initialization -- cgit v1.2.1