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store_contains(+StoreHandle, ++Key)

Check for an entry in a store object

StoreHandle: A store handle or store name
Key: A ground term

Description

This checks whether a given store object contains an entry for a given key. If so, the predicate succeeds, otherwise it fails.

The key can be arbitrarily complex, but must be a ground term.

The complexity of this operation is linear in the size of the key, since the key needs to be compared. For indexing purposes, a hash value is computed from the key, and the full depth of the key is taken into account.

Note: If StoreHandle is not a handle, then it must be an atom or a compound term, and the store is identified by this term's toplevel functor together with the context module.

Modes and Determinism

store_contains(+, ++) is semidet

Modules

This predicate is sensitive to its module context (tool predicate, see @/2).

Fail Conditions

The store does not contain an entry for Key

Exceptions

(4) instantiation fault: StoreHandle is uninstantiated
(4) instantiation fault: Key is not ground
(5) type error: StoreHandle is neither atom nor compound term nor store handle
(45) named object does not exist: StoreHandle is not the name of a store

Examples


    ?- store_create(Handle),
       store_set(Handle, tom, 12345),
       store_contains(Handle, tom).

    Yes (0.00s cpu)


    ?- store_create(Handle),
       store_set(Handle, tom, 12345),
       store_contains(Handle, harry).

    No (0.00s cpu)