Introduce option tree shadowing

Introduce get_option_shadow.  This routine takes an option, the tree under which that option resides, and another tree.  It returns a corresponding option with parallel ancestry in the second tree, creating that option and ancestry if it does not already exist.

Add enum copy_option_flags.

Add the CO_NO_LISTBOX_ITEM flag, which is used to suppress listbox creation for shadowed trees.

Add the CO_SHALLOW flag, which is used to suppress the duplication of unwanted children for shadowed trees.

Add a flags parameter to copy_option and tree_dup (and out of necessity, struct option_type_info and str_dup).

src/config/options.c

@@ -210,7 +210,7 @@ get_opt_rec(struct option *tree, const unsigned char *name_)
 		 * option. By having _template_ OPT_AUTOCREATE and _template_
 		 * inside, you can have even multi-level autocreating. */
 
-		option = copy_option(template);
+		option = copy_option(template, 0);
 		if (!option) {
 			mem_free(aname);
 			return NULL;
@@ -618,7 +618,7 @@ delete_option(struct option *option)
 }
 
 struct option *
-copy_option(struct option *template)
+copy_option(struct option *template, int flags)
 {
 	struct option *option = mem_calloc(1, sizeof(*option));
 
@@ -633,7 +633,8 @@ copy_option(struct option *template)
 	option->desc = template->desc;
 	option->change_hook = template->change_hook;
 
-	option->box_item = init_option_listbox_item(option);
+	if (!(flags & CO_NO_LISTBOX_ITEM))
+		option->box_item = init_option_listbox_item(option);
 	if (option->box_item) {
 		if (template->box_item) {
 			option->box_item->type = template->box_item->type;
@@ -642,7 +643,7 @@ copy_option(struct option *template)
 	}
 
 	if (option_types[template->type].dup) {
-		option_types[template->type].dup(option, template);
+		option_types[template->type].dup(option, template, flags);
 	} else {
 		option->value = template->value;
 	}
@@ -650,6 +651,48 @@ copy_option(struct option *template)
 	return option;
 }
 
+/* Return the shadow option in @shadow_tree of @option in @tree. If @option
+ * isn't yet shadowed in @shadow_tree, shadow it (i.e. create a copy
+ * in @shadow_tree) along with any ancestors that aren't shadowed. */
+struct option *
+get_option_shadow(struct option *option, struct option *tree,
+                  struct option *shadow_tree)
+{
+
+	struct option *shadow_option = NULL;
+
+	assert(option);
+	assert(tree);
+	assert(shadow_tree);
+
+	if (option == tree) {
+		shadow_option = shadow_tree;
+	} else if (option->root && option->name) {
+		struct option *shadow_root;
+
+		shadow_root = get_option_shadow(option->root, tree,
+		                                shadow_tree);
+		if (!shadow_root) return NULL;
+
+		shadow_option = get_opt_rec_real(shadow_root, option->name);
+		if (!shadow_option) {
+			shadow_option = copy_option(option,
+			                            CO_SHALLOW
+			                             | CO_NO_LISTBOX_ITEM);
+			if (shadow_option) {
+				shadow_option->root = shadow_root;
+				/* No need to sort, is there? It isn't shown
+				 * in the options manager. -- Miciah */
+				add_to_list_end(*shadow_root->value.tree,
+				                shadow_option);
+			}
+
+		}
+	}
+
+	return shadow_option;
+}
+
 LIST_OF(struct option) *
 init_options_tree(void)
 {

src/config/options.h

@@ -169,7 +169,17 @@ extern void smart_config_string(struct string *, int, int,
 				void (*)(struct string *, struct option *,
 					 unsigned char *, int, int, int, int));
 
-extern struct option *copy_option(struct option *);
+enum copy_option_flags {
+	/* Do not create a listbox option for the new option. */
+	CO_NO_LISTBOX_ITEM = (1 << 0),
+
+	/* Do not copy children. */
+	CO_SHALLOW         = (1 << 1),
+};
+
+extern struct option *copy_option(struct option *, int);
+struct option *get_option_shadow(struct option *, struct option *,
+                                 struct option *);
 extern void delete_option(struct option *);
 void mark_option_as_deleted(struct option *);
 

src/config/opttypes.c

@@ -295,7 +295,7 @@ str_wr(struct option *o, struct string *s)
 }
 
 static void
-str_dup(struct option *opt, struct option *template)
+str_dup(struct option *opt, struct option *template, int flags)
 {
 	unsigned char *new = mem_alloc(MAX_STR_LEN);
 
@@ -366,7 +366,7 @@ color_wr(struct option *opt, struct string *str)
 }
 
 static void
-tree_dup(struct option *opt, struct option *template)
+tree_dup(struct option *opt, struct option *template, int flags)
 {
 	LIST_OF(struct option) *new = init_options_tree();
 	LIST_OF(struct option) *tree = template->value.tree;
@@ -375,8 +375,10 @@ tree_dup(struct option *opt, struct option *template)
 	if (!new) return;
 	opt->value.tree = new;
 
+	if (flags & CO_SHALLOW) return;
+
 	foreachback (option, *tree) {
-		struct option *new_opt = copy_option(option);
+		struct option *new_opt = copy_option(option, flags);
 
 		if (!new_opt) continue;
 		object_nolock(new_opt, "option");

src/config/opttypes.h

@@ -9,7 +9,7 @@ struct option_type_info {
 	unsigned char *(*cmdline)(struct option *, unsigned char ***, int *);
 	unsigned char *(*read)(struct option *, unsigned char **, int *);
 	void (*write)(struct option *, struct string *);
-	void (*dup)(struct option *, struct option *);
+	void (*dup)(struct option *, struct option *, int);
 	int (*set)(struct option *, unsigned char *);
 	unsigned char *help_str;
 };