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  6 Iteration   6.1 The LOOP Facility   6.1.2 Variable Initialization and Stepping Clauses   6.1.2.1 Iteration Control

6.1.2.1.6 The for-as-hash subclause

In the for-as-hash subclause the for or as construct iterates over the elements, keys, and values of a hash-table. In this syntax, a compound preposition is used to designate access to a hash table. The variable var takes on the value of each hash key or hash value in the supplied hash-table. The following loop keywords serve as valid prepositions within this syntax:

  • being

    The keyword being introduces either the Loop schema hash-key or hash-value.

  • each, the

    The loop keyword each follows the loop keyword being when hash-key or hash-value is used. The loop keyword the is used with hash-keys and hash-values only for ease of reading. This agreement isn't required.

  • hash-key, hash-keys

    These loop keywords access each key entry of the hash table. If the name hash-value is supplied in a using construct with one of these Loop schemas, the iteration can optionally access the keyed value. The order in which the keys are accessed is undefined; empty slots in the hash table are ignored.

  • hash-value, hash-values

    These loop keywords access each value entry of a hash table. If the name hash-key is supplied in a using construct with one of these Loop schemas, the iteration can optionally access the key that corresponds to the value. The order in which the keys are accessed is undefined; empty slots in the hash table are ignored.

  • using

    The loop keyword using introduces the optional key or the keyed value to be accessed. It allows access to the hash key if iteration is over the hash values, and the hash value if iteration is over the hash keys.

  • in, of

    These loop prepositions introduce hash-table.

In effect

being {each | the} {hash-value | hash-values | hash-key | hash-keys} {in | of}

is a compound preposition.

Iteration stops when there are no more hash keys or hash values to be referenced in the supplied hash-table.


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