[PATCH v4 1/2] menu: Add a function to set the default by matching the item data

[Schrempf Frieder]

From: Frieder Schrempf <frieder.schrempf at kontron.de>

In order to make it possible to auto select a default entry by
matching the data of the menu entries by an external matching
function, we add some helpers and expose the
menu_set_default_by_item_data_match() function.

Signed-off-by: Frieder Schrempf <frieder.schrempf at kontron.de>
---
Changes in v4:
* Use the proper style for the function description
* Move the comment for the function description to the header file

Changes in v3:
* Add a full function comment to describe menu_set_default_by_item_data_match().

Changes in v2:
* Keep the menu structs private and instead only expose one additional
  function, that sets the default by calling an external matching
  function on each entry.
* Change the title and commit message to reflect the changes.
---
 common/menu.c  | 40 ++++++++++++++++++++++++++++++++++++++++
 include/menu.h | 19 +++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/common/menu.c b/common/menu.c
index 7b66d199a9..e16a0a4a50 100644
--- a/common/menu.c
+++ b/common/menu.c
@@ -160,6 +160,46 @@ static inline struct menu_item *menu_item_by_key(struct menu *m,
 	return menu_items_iter(m, menu_item_key_match, item_key);
 }
 
+/*
+ * Find the first matching item, if any exists by calling a matching function
+ * on the items data field.
+ */
+static inline struct menu_item *menu_item_by_matching_fn(struct menu *m,
+			int match(void *, void *), void * extra)
+{
+	struct list_head *pos, *n;
+	struct menu_item *item;
+	int ret;
+
+	list_for_each_safe(pos, n, &m->items) {
+		item = list_entry(pos, struct menu_item, list);
+		if (item->key) {
+			ret = match(item->data, extra);
+			if (ret == 1)
+				return item;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Sets a menu default option by calling a matching function on each of the
+ * menu items data field.
+ */
+int menu_set_default_by_item_data_match(struct menu *m,
+			int match(void *, void *), void *extra, char **key)
+{
+	struct menu_item *item = menu_item_by_matching_fn(m, match, extra);
+
+	if (!item)
+		return -ENOENT;
+
+	*key = item->key;
+	m->default_item = item;
+	return 0;
+}
+
 /*
  * Set *choice to point to the default item's data, if any default item was
  * set, and returns 1. If no default item was set, returns -ENOENT.
diff --git a/include/menu.h b/include/menu.h
index 2d227c20bd..96c9fcac03 100644
--- a/include/menu.h
+++ b/include/menu.h
@@ -19,6 +19,25 @@ int menu_destroy(struct menu *m);
 void menu_display_statusline(struct menu *m);
 int menu_default_choice(struct menu *m, void **choice);
 
+/**
+ * menu_set_default_by_item_data_match() - - sets a menu default option by
+ * calling a matching function on each of the menu items data field.
+ *
+ * @m: Points to a menu created by menu_create().
+ * @match: Points to a function that is passed a pointer to the items data field
+ *         and a pointer to extra data to compare with. It should return 1 on a
+ *         match.
+ * @extra: Points to some data that is passed as a second parameter to the
+ *         matching function.
+ * @key: Points to a char array that will be set to hold the key of the matched
+ *       menu item.
+ * @return 0 if a matching item was found,
+ *	   -ENOENT if no matching item was found
+ */
+int menu_set_default_by_item_data_match(struct menu *m,
+					int match(void *, void *), void *extra,
+					char **key);
+
 /**
  * menu_show() Show a boot menu
  *
-- 
2.17.1