vis: implement intersection of selections

main.c

@@ -80,6 +80,8 @@ static const char *selections_save(Vis*, const char *keys, const Arg *arg);
 static const char *selections_restore(Vis*, const char *keys, const Arg *arg);
 /* union selections */
 static const char *selections_union(Vis*, const char *keys, const Arg *arg);
+/* intersect selections */
+static const char *selections_intersect(Vis*, const char *keys, const Arg *arg);
 /* adjust current used count according to keys */
 static const char *count(Vis*, const char *keys, const Arg *arg);
 /* move to the count-th line or if not given either to the first (arg->i < 0)
@@ -285,6 +287,7 @@ enum {
 	VIS_ACTION_SELECTIONS_SAVE,
 	VIS_ACTION_SELECTIONS_RESTORE,
 	VIS_ACTION_SELECTIONS_UNION,
+	VIS_ACTION_SELECTIONS_INTERSECT,
 	VIS_ACTION_TEXT_OBJECT_WORD_OUTER,
 	VIS_ACTION_TEXT_OBJECT_WORD_INNER,
 	VIS_ACTION_TEXT_OBJECT_LONGWORD_OUTER,
@@ -1060,6 +1063,11 @@ static const KeyAction vis_action[] = {
 		VIS_HELP("Add selections from register")
 		selections_union
 	},
+	[VIS_ACTION_SELECTIONS_INTERSECT] = {
+		"vis-selections-intersect",
+		VIS_HELP("Intersect selections with register")
+		selections_intersect
+	},
 	[VIS_ACTION_TEXT_OBJECT_WORD_OUTER] = {
 		"vis-textobject-word-outer",
 		VIS_HELP("A word leading and trailing whitespace included")
@@ -1671,6 +1679,40 @@ static const char *selections_union(Vis *vis, const char *keys, const Arg *arg)
 	return keys;
 }
 
+static void intersect(Array *ret, Array *a, Array *b) {
+	size_t i = 0, j = 0;
+	Filerange *r1 = array_get(a, i), *r2 = array_get(b, j);
+	while (r1 && r2) {
+		if (text_range_overlap(r1, r2)) {
+			Filerange new = text_range_intersect(r1, r2);
+			array_add(ret, &new);
+		}
+		if (r1->end < r2->end)
+			r1 = array_get(a, ++i);
+		else
+			r2 = array_get(b, ++j);
+	}
+}
+
+static const char *selections_intersect(Vis *vis, const char *keys, const Arg *arg) {
+	View *view = vis_view(vis);
+	enum VisRegister reg = vis_register_used(vis);
+	Array a = vis_register_selections_get(vis, reg);
+	Array b = view_selections_get_all(view);
+	Array sel;
+	array_init_from(&sel, &a);
+
+	intersect(&sel, &a, &b);
+	view_selections_set_all(view, &sel);
+	vis_cancel(vis);
+
+	array_release(&a);
+	array_release(&b);
+	array_release(&sel);
+
+	return keys;
+}
+
 static const char *replace(Vis *vis, const char *keys, const Arg *arg) {
 	if (!keys[0]) {
 		vis_keymap_disable(vis);