bug#10181: 24.0.92; [wishlist] split `diff-refine-change' in several faces

[Juri Linkov]

> Please, split the `diff-refine-change' face in several faces: one for
> each of the possible "surrounding" face:
> * for `diff-changed', define `diff-changed-refined'.
> * for `diff-removed', define `diff-removed-refined'.
> * for `diff-added', define `diff-added-refined'.
>
> Why? --> Because users (like me) may want to define such "refined"
> faces based on the "not-refined" ones.  Currently this is not
> possible, so I cannot obtain a satisfactory aspect of the refined hunks.

This could be implemented exactly the same way as currently other
diff faces are implemented where `diff-removed' and `diff-added'
both inherit from `diff-changed' by default.  Anyone wishing to use
different faces to highlight removed and added lines can customize
`diff-removed' and `diff-added' to not inherit from `diff-changed'.

`diff-indicator-changed', `diff-indicator-removed' and
`diff-indicator-added' are defined with inheritance as well.

So the following patch does the same by defining new faces
`diff-refine-removed' and `diff-refine-added' inheriting from
`diff-refine-change'.  And `smerge-refined-removed' with
`smerge-refined-added' inheriting from `smerge-refined-change'
by default:

=== modified file 'lisp/vc/diff-mode.el'
--- lisp/vc/diff-mode.el        2012-05-01 02:48:41 +0000
+++ lisp/vc/diff-mode.el        2012-05-17 00:27:59 +0000
@@ -1866,6 +1873,18 @@ (defface diff-refine-change
   "Face used for char-based changes shown by `diff-refine-hunk'."
   :group 'diff-mode)
 
+(defface diff-refine-removed
+  '((t :inherit diff-refine-change))
+  "Face used for removed characters shown by `diff-refine-hunk'."
+  :group 'diff-mode
+  :version "24.2")
+
+(defface diff-refine-added
+  '((t :inherit diff-refine-change))
+  "Face used for added characters shown by `diff-refine-hunk'."
+  :group 'diff-mode
+  :version "24.2")
+
 (defun diff-refine-preproc ()
   (while (re-search-forward "^[+>]" nil t)
     ;; Remove spurious changes due to the fact that one side of the hunk is
@@ -1879,7 +1898,7 @@ (defun diff-refine-preproc ()
   )
 
 (declare-function smerge-refine-subst "smerge-mode"
-                  (beg1 end1 beg2 end2 props &optional preproc))
+                  (beg1 end1 beg2 end2 props &optional preproc props2))
 
 (defun diff-refine-hunk ()
   "Highlight changes of hunk at point at a finer granularity."
@@ -1890,7 +1909,8 @@ (defun diff-refine-hunk ()
     (let* ((start (point))
            (style (diff-hunk-style))    ;Skips the hunk header as well.
            (beg (point))
-           (props '((diff-mode . fine) (face diff-refine-change)))
+           (props  '((diff-mode . fine) (face diff-refine-removed)))
+           (props2 '((diff-mode . fine) (face diff-refine-added)))
            ;; Be careful to go back to `start' so diff-end-of-hunk gets
            ;; to read the hunk header's line info.
            (end (progn (goto-char start) (diff-end-of-hunk) (point))))
@@ -1904,7 +1924,7 @@ (defun diff-refine-hunk ()
                                    end t)
            (smerge-refine-subst (match-beginning 0) (match-end 1)
                                 (match-end 1) (match-end 0)
-                                props 'diff-refine-preproc)))
+                                props 'diff-refine-preproc props2)))
         (context
          (let* ((middle (save-excursion (re-search-forward "^---")))
                 (other middle))
@@ -1916,14 +1936,14 @@ (defun diff-refine-hunk ()
                                     (setq other (match-end 0))
                                     (match-beginning 0))
                                   other
-                                  props 'diff-refine-preproc))))
+                                  props 'diff-refine-preproc props2))))
         (t ;; Normal diffs.
          (let ((beg1 (1+ (point))))
            (when (re-search-forward "^---.*\n" end t)
              ;; It's a combined add&remove, so there's something to do.
              (smerge-refine-subst beg1 (match-beginning 0)
                                   (match-end 0) end
-                                  props 'diff-refine-preproc))))))))
+                                  props 'diff-refine-preproc props2))))))))
 
 (defun diff-undo (&optional arg)
   "Perform `undo', ignoring the buffer's read-only status."

=== modified file 'lisp/vc/smerge-mode.el'
--- lisp/vc/smerge-mode.el      2012-05-04 23:16:47 +0000
+++ lisp/vc/smerge-mode.el      2012-05-17 00:28:03 +0000
@@ -128,6 +128,18 @@ (defface smerge-refined-change
   "Face used for char-based changes shown by `smerge-refine'."
   :group 'smerge)
 
+(defface smerge-refined-removed
+  '((t :inherit smerge-refined-change))
+  "Face used for removed characters shown by `smerge-refine'."
+  :group 'smerge
+  :version "24.2")
+
+(defface smerge-refined-added
+  '((t :inherit smerge-refined-change))
+  "Face used for added characters shown by `smerge-refine'."
+  :group 'smerge
+  :version "24.2")
+
 (easy-mmode-defmap smerge-basic-map
   `(("n" . smerge-next)
     ("p" . smerge-prev)
@@ -980,9 +992,11 @@ (defun smerge-refine-highlight-change (b
           (dolist (x props) (overlay-put ol (car x) (cdr x)))
           ol)))))
 
-(defun smerge-refine-subst (beg1 end1 beg2 end2 props &optional preproc)
+(defun smerge-refine-subst (beg1 end1 beg2 end2 props &optional preproc props2)
   "Show fine differences in the two regions BEG1..END1 and BEG2..END2.
-PROPS is an alist of properties to put (via overlays) on the changes.
+PROPS is an alist of properties to put (via overlays) on the changes,
+or only on removed characters when PROPS2 is non-nil.
+PROPS2 is an alist of properties to put on added characters.
 If non-nil, PREPROC is called with no argument in a buffer that contains
 a copy of a region, just before preparing it to for `diff'.  It can be
 used to replace chars to try and eliminate some spurious differences."
@@ -1029,7 +1043,7 @@ (defun smerge-refine-subst (beg1 end1 be
                         (smerge-refine-highlight-change buf beg1 m1 m2 props)))
                 (when (memq op '(?a ?c))
                   (setq last2
-                        (smerge-refine-highlight-change buf beg2 m4 m5 
props))))
+                        (smerge-refine-highlight-change buf beg2 m4 m5 (or 
props2 props)))))
               (forward-line 1)                            ;Skip hunk header.
               (and (re-search-forward "^[0-9]" nil 'move) ;Skip hunk body.
                    (goto-char (match-beginning 0))))
@@ -1091,7 +1105,10 @@ (defun smerge-refine (&optional part)
     (smerge-refine-subst (match-beginning n1) (match-end n1)
                          (match-beginning n2)  (match-end n2)
                          '((smerge . refine)
-                           (face . smerge-refined-change)))))
+                           (face . smerge-refined-removed))
+                        nil
+                        '((smerge . refine)
+                           (face . smerge-refined-added)))))
 
 (defun smerge-diff (n1 n2)
   (smerge-match-conflict)