conf: implement snd_config_add_before() and snd_config_add_after()

Signed-off-by: Jaroslav Kysela <perex@perex.cz>

include/conf.h

@@ -114,7 +114,9 @@ int snd_config_expand(snd_config_t *config, snd_config_t *root,
 int snd_config_evaluate(snd_config_t *config, snd_config_t *root,
 			snd_config_t *private_data, snd_config_t **result);
 
-int snd_config_add(snd_config_t *config, snd_config_t *leaf);
+int snd_config_add(snd_config_t *config, snd_config_t *child);
+int snd_config_add_before(snd_config_t *before, snd_config_t *child);
+int snd_config_add_after(snd_config_t *after, snd_config_t *child);
 int snd_config_remove(snd_config_t *config);
 int snd_config_delete(snd_config_t *config);
 int snd_config_delete_compound_members(const snd_config_t *config);

include/list.h

@@ -86,6 +86,21 @@ static inline void list_add_tail(struct list_head *p, struct list_head *list)
 	list->prev = p;
 }
 
+/* list_insert - insert a new list entry between two known consecutive entries
+ * @p: the new entry to be inserted between prev and next
+ * @prev: the left-side entry
+ * @next: the right-side entry
+ */
+static inline void list_insert(struct list_head *p,
+			       struct list_head *prev,
+			       struct list_head *next)
+{
+	next->prev = p;
+	p->next = next;
+	p->prev = prev;
+	prev->next = p;
+}
+
 /* list_del - delete the given list entry */
 static inline void list_del(struct list_head *p)
 {

src/conf.c

@@ -1978,6 +1978,88 @@ int snd_config_add(snd_config_t *parent, snd_config_t *child)
 	return 0;
 }
 
+/**
+ * \brief Adds a child after another child configuration node.
+ * \param after Handle to the start configuration node.
+ * \param child Handle to the configuration node to be added.
+ * \return Zero if successful, otherwise a negative error code.
+ *
+ * This function makes the node \a child a child of the parent of
+ * the node \a after.
+ *
+ * The parent node then owns the child node, i.e., the child node gets
+ * deleted together with its parent.
+ *
+ * \a child must have an id.
+ *
+ * \par Errors:
+ * <dl>
+ * <dt>-EINVAL<dd>\a child does not have an id.
+ * <dt>-EINVAL<dd>\a child already has a parent.
+ * <dt>-EEXIST<dd>\a parent already contains a child node with the same
+ *                id as \a child.
+ * </dl>
+ */
+int snd_config_add_after(snd_config_t *after, snd_config_t *child)
+{
+	snd_config_iterator_t i, next;
+	snd_config_t *parent;
+	assert(after && child);
+	parent = after->parent;
+	assert(parent);
+	if (!child->id || child->parent)
+		return -EINVAL;
+	snd_config_for_each(i, next, parent) {
+		snd_config_t *n = snd_config_iterator_entry(i);
+		if (strcmp(child->id, n->id) == 0)
+			return -EEXIST;
+	}
+	child->parent = parent;
+	list_insert(&child->list, &after->list, after->list.next);
+	return 0;
+}
+
+/**
+ * \brief Adds a child before another child configuration node.
+ * \param before Handle to the start configuration node.
+ * \param child Handle to the configuration node to be added.
+ * \return Zero if successful, otherwise a negative error code.
+ *
+ * This function makes the node \a child a child of the parent of
+ * the node \a before.
+ *
+ * The parent node then owns the child node, i.e., the child node gets
+ * deleted together with its parent.
+ *
+ * \a child must have an id.
+ *
+ * \par Errors:
+ * <dl>
+ * <dt>-EINVAL<dd>\a child does not have an id.
+ * <dt>-EINVAL<dd>\a child already has a parent.
+ * <dt>-EEXIST<dd>\a parent already contains a child node with the same
+ *                id as \a child.
+ * </dl>
+ */
+int snd_config_add_before(snd_config_t *before, snd_config_t *child)
+{
+	snd_config_iterator_t i, next;
+	snd_config_t *parent;
+	assert(before && child);
+	parent = before->parent;
+	assert(parent);
+	if (!child->id || child->parent)
+		return -EINVAL;
+	snd_config_for_each(i, next, parent) {
+		snd_config_t *n = snd_config_iterator_entry(i);
+		if (strcmp(child->id, n->id) == 0)
+			return -EEXIST;
+	}
+	child->parent = parent;
+	list_insert(&child->list, before->list.prev, &before->list);
+	return 0;
+}
+
 /**
  * \brief Removes a configuration node from its tree.
  * \param config Handle to the configuration node to be removed.