iterator: add a generic GPtrArray iterator implementation

lib/wp/iterator.c

@@ -189,3 +189,108 @@ wp_iterator_foreach (WpIterator *self, WpIteratorForeachFunc func,
 
   return wp_iterator_default_foreach (self, func, data);
 }
+
+struct ptr_array_iterator_data
+{
+  GPtrArray *array;
+  GType item_type;
+  guint index;
+  void (*set_value) (GValue *, gpointer);
+};
+
+static void
+ptr_array_iterator_reset (WpIterator *it)
+{
+  struct ptr_array_iterator_data *it_data = wp_iterator_get_user_data (it);
+  it_data->index = 0;
+}
+
+static gboolean
+ptr_array_iterator_next (WpIterator *it, GValue *item)
+{
+  struct ptr_array_iterator_data *it_data = wp_iterator_get_user_data (it);
+
+  if (it_data->index < it_data->array->len) {
+    gpointer ptr = g_ptr_array_index (it_data->array, it_data->index++);
+    g_value_init (item, it_data->item_type);
+    it_data->set_value (item, ptr);
+    return TRUE;
+  }
+  return FALSE;
+}
+
+static gboolean
+ptr_array_iterator_fold (WpIterator *it, WpIteratorFoldFunc func, GValue *ret,
+    gpointer data)
+{
+  struct ptr_array_iterator_data *it_data = wp_iterator_get_user_data (it);
+  gpointer *ptr, *base;
+  guint len;
+
+  ptr = base = it_data->array->pdata;
+  len = it_data->array->len;
+
+  while ((ptr - base) < len) {
+    g_auto (GValue) item = G_VALUE_INIT;
+    g_value_init (&item, it_data->item_type);
+    it_data->set_value (&item, *ptr);
+    if (!func (&item, ret, data))
+      return FALSE;
+    ptr++;
+  }
+  return TRUE;
+}
+
+static void
+ptr_array_iterator_finalize (WpIterator *it)
+{
+  struct ptr_array_iterator_data *it_data = wp_iterator_get_user_data (it);
+  g_ptr_array_unref (it_data->array);
+}
+
+static const WpIteratorMethods ptr_array_iterator_methods = {
+  .reset = ptr_array_iterator_reset,
+  .next = ptr_array_iterator_next,
+  .fold = ptr_array_iterator_fold,
+  .finalize = ptr_array_iterator_finalize,
+};
+
+/**
+ * wp_iterator_new_ptr_array:
+ * @items: (transfer full): the items to iterate over
+ * @item_type: the type of each item
+ *
+ * Returns: (transfer full): a new iterator that iterates over @items
+ */
+WpIterator *
+wp_iterator_new_ptr_array (GPtrArray * items, GType item_type)
+{
+  g_autoptr (WpIterator) it = NULL;
+  struct ptr_array_iterator_data *it_data;
+
+  g_return_val_if_fail (items != NULL, NULL);
+
+  it = wp_iterator_new (&ptr_array_iterator_methods,
+      sizeof (struct ptr_array_iterator_data));
+  it_data = wp_iterator_get_user_data (it);
+  it_data->array = items;
+  it_data->item_type = item_type;
+  it_data->index = 0;
+
+  if (g_type_is_a (item_type, G_TYPE_POINTER))
+    it_data->set_value = g_value_set_pointer;
+  else if (g_type_is_a (item_type, G_TYPE_BOXED))
+    it_data->set_value = (void (*) (GValue *, gpointer)) g_value_set_boxed;
+  else if (g_type_is_a (item_type, G_TYPE_OBJECT))
+    it_data->set_value = g_value_set_object;
+  else if (g_type_is_a (item_type, G_TYPE_INTERFACE))
+    it_data->set_value = g_value_set_object;
+  else if (g_type_is_a (item_type, G_TYPE_VARIANT))
+    it_data->set_value = (void (*) (GValue *, gpointer)) g_value_set_variant;
+  else if (g_type_is_a (item_type, G_TYPE_STRING))
+    it_data->set_value = (void (*) (GValue *, gpointer)) g_value_set_string;
+  else
+    g_return_val_if_reached (NULL);
+
+  return g_steal_pointer (&it);
+}

lib/wp/iterator.h

@@ -47,12 +47,16 @@ GType wp_iterator_get_type (void);
 
 typedef struct _WpIterator WpIterator;
 
+/* ref count */
+
 WP_API
 WpIterator *wp_iterator_ref (WpIterator *self);
 
 WP_API
 void wp_iterator_unref (WpIterator *self);
 
+/* iteration api */
+
 WP_API
 void wp_iterator_reset (WpIterator *self);
 
@@ -67,6 +71,11 @@ WP_API
 gboolean wp_iterator_foreach (WpIterator *self, WpIteratorForeachFunc func,
     gpointer data);
 
+/* constructors */
+
+WP_API
+WpIterator * wp_iterator_new_ptr_array (GPtrArray * items, GType item_type);
+
 G_DEFINE_AUTOPTR_CLEANUP_FUNC (WpIterator, wp_iterator_unref)
 
 G_END_DECLS