(PECL weakref >= 0.1.0) Checks whether the object referenced still exists

(PECL weakref >= 0.2.0) Advances to the next map element

(PECL weakref >= 0.1.0) Releases a previously acquired reference

(PECL weakref >= 0.2.0) Returns the value pointed to by a certain object

(PECL weakref >= 0.2.0) Rewinds the iterator to the beginning of the map

(PECL weakref >= 0.1.0) Acquires a strong reference on that object

(PECL weakref >= 0.2.0) Returns whether the iterator is still on a valid map element

(PECL weakref >= 0.2.0) Counts the number of live entries in the map

(PECL weakref >= 0.2.0) Returns the current value under iteration

(PECL weakref >= 0.1.0) Constructs a new weak reference