2 files changed, 70 insertions, 18 deletions

diff --git a/lisp/progmodes/prolog.el b/lisp/progmodes/prolog.el
index 3d9b0c322ab..ff2769e7493 100644
--- a/lisp/progmodes/prolog.el
+++ b/lisp/progmodes/prolog.el
@@ -840,6 +840,8 @@ This is really kludgy, and unneeded (i.e. obsolete) in Emacs>=24."
 
 (require 'smie)
 
+(defconst prolog-operator-chars "-\\\\#&*+./:<=>?@\\^`~")
+
 (defun prolog-smie-forward-token ()
   ;; FIXME: Add support for 0'<char>, if needed after adding it to
   ;; syntax-propertize-functions.
@@ -848,7 +850,7 @@ This is really kludgy, and unneeded (i.e. obsolete) in Emacs>=24."
    (point)
    (progn (cond
            ((looking-at "[!;]") (forward-char 1))
-           ((not (zerop (skip-chars-forward "#&*+-./:<=>?@\\^`~"))))
+           ((not (zerop (skip-chars-forward prolog-operator-chars))))
            ((not (zerop (skip-syntax-forward "w_'"))))
            ;; In case of non-ASCII punctuation.
            ((not (zerop (skip-syntax-forward ".")))))
@@ -861,8 +863,8 @@ This is really kludgy, and unneeded (i.e. obsolete) in Emacs>=24."
   (buffer-substring-no-properties
    (point)
    (progn (cond
-           ((memq (char-before) '(?! ?\;)) (forward-char -1))
-           ((not (zerop (skip-chars-backward "#&*+-./:<=>?@\\^`~"))))
+           ((memq (char-before) '(?! ?\; ?\,)) (forward-char -1))
+           ((not (zerop (skip-chars-backward prolog-operator-chars))))
            ((not (zerop (skip-syntax-backward "w_'"))))
            ;; In case of non-ASCII punctuation.
            ((not (zerop (skip-syntax-backward ".")))))
@@ -947,12 +949,36 @@ This is really kludgy, and unneeded (i.e. obsolete) in Emacs>=24."
      ;;     ;    c)
      ;;
      ;; based on the space between the open paren and the "a".
-     (unless (and (smie-rule-parent-p "(")
+     (unless (and (smie-rule-parent-p "(" ";")
                   (save-excursion
                     (smie-indent-forward-token)
                     (smie-backward-sexp 'halfsexp)
-                    (not (eq ?\( (char-before)))))
+                    (if (smie-rule-parent-p "(")
+                        (not (eq (char-before) ?\())
+                      (smie-indent-backward-token)
+                      (smie-rule-bolp))))
        prolog-indent-width))
+    (`(:after . ";")
+     ;; Align with same-line comment as in:
+     ;;   ;   %% Toto
+     ;;       foo
+     (and (smie-rule-bolp)
+          (looking-at ";[ \t]*\\(%\\)")
+          (let ((offset (- (save-excursion (goto-char (match-beginning 1))
+                                           (current-column))
+                           (current-column))))
+            ;; Only do it for small offsets, since the comment may actually be
+            ;; an "end-of-line" comment at comment-column!
+            (if (<= offset prolog-indent-width) offset))))
+    (`(:after . ",")
+     ;; Special indent for:
+     ;;    foopredicate(x) :- !,
+     ;;        toto.
+     (and (eq (char-before) ?!)
+          (save-excursion
+            (smie-indent-backward-token) ;Skip !
+            (equal ":-" (car (smie-indent-backward-token))))
+          (smie-rule-parent prolog-indent-width)))
     (`(:after . ,(or `":-" `"-->")) prolog-indent-width)))
 
 
diff --git a/test/indent/prolog.prolog b/test/indent/prolog.prolog
index 6bf9437b883..9ac6df1b6c7 100644
--- a/test/indent/prolog.prolog
+++ b/test/indent/prolog.prolog
@@ -1,16 +1,18 @@
 %% -*- mode: prolog; coding: utf-8; fill-column: 78 -*-
 
 %% bug#21526
-test1 :-
+test21526_1 :-
     (   a ->
-            (   a ->
-                b
-            ;   c
-            )
-    ;   c
+        (   a ->
+            b
+        ;   c
+        )
+    ;   % Toto
+        c ->
+        d
     ).
 
-test2 :-
+test21526_2 :-
     (    a
     ->   (   a,
              b
@@ -19,7 +21,31 @@ test2 :-
          b2
     ;    c1,
          c2
-    )
+    ).
+
+test21526_3 :-
+    X \= Y,
+    \+ a,
+    b,
+    \+ \+ c,
+    d.
+
+test21526_4 :-
+    (   \+ a ->
+        b
+    ;   \+ c,
+        \+ d
+    ).
+
+
+test21526_5 :-
+    (a;
+     b ->
+         c).
+
+test21526_predicate(c) :- !,
+    test_goal1,
+    test_goal2.
 
 %% Testing correct tokenizing.
 foo(X) :- 0'= = X.
@@ -74,11 +100,11 @@ subst(X, V, FV, lambda(Y, Ti, Bi), lambda(Y1, To, Bo)) :-
     %% If X is equal to Y, X is shadowed, so no subst can take place.
     ->  Y1 = Y, Bo = Bi
     ;   (member((Y, _), FV)
-         %% If Y appears in FV, it can appear in V, so we need to
-         %% rename it to avoid name capture.
-         -> new_atom(Y, Y1),
-            subst(Y, Y1, [], Bi, Bi1)
-         ; Y1 = Y, Bi1 = Bi),
+        %% If Y appears in FV, it can appear in V, so we need to
+        %% rename it to avoid name capture.
+        -> new_atom(Y, Y1),
+           subst(Y, Y1, [], Bi, Bi1)
+        ; Y1 = Y, Bi1 = Bi),
         %% Perform substitution on the body.
         subst(X, V, FV, Bi1, Bo)
     ).