isFull

isFull is a boolean predicate or method used in data structures to indicate that a bounded container has no remaining capacity for additional elements. It is most commonly associated with fixed-size structures such as queues, stacks, buffers, circular buffers, and resource pools.

Semantics and scope

isFull returns true when the container’s current number of elements equals its capacity, and false otherwise. In some implementations fullness may be defined as current size greater than or equal to capacity. isFull is typically the complement of isEmpty, which checks for zero elements.

Typical usage

isFull is used to guard insertion or allocation actions. If isFull is true, a program may block the producer, throw an exception, return an error, or trigger a resize/reallocation. In systems that require backpressure, isFull helps regulate flow by signaling that no additional items can be accepted temporarily.

Implementation considerations

In concurrent or multi-threaded contexts, checking isFull and updating the container size must be atomic or properly synchronized to avoid race conditions. Capacity and size are core factors; overflow must be prevented. In dynamic structures that resize automatically (such as arrays with automatic growth), isFull may never be true in practice, or its meaning may be tied to a fixed portion of capacity before triggering a resize.

Language and library notes

Not all languages or standard libraries expose an isFull method. Some provide size and capacity, remainingCapacity, or a fixed-capacity container where fullness is implicit. When implementing isFull, a common pattern is to compare currentSize with capacity, e.g., return size == capacity. See also isEmpty, capacity, size, remainingCapacity.