47 lines
1.8 KiB
Scheme
47 lines
1.8 KiB
Scheme
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; Copyright (c) 2003 RT Happe <rthappe at web de>
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; See the file COPYING distributed with the Scheme Untergrund Library
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;;; a uniform framework for sequence as data + behaviour
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;;; in other words: mucho indirection here [ could reduce it ]
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;; such records represent behavioural sequence types S
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;; maker : integer [t] -> S -- like MAKE-VECTOR
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;; predicate : any -> boolean -- like VECTOR?
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;; getter : S integer --> any -- like VECTOR-REF
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;; setter : S integer any --> unspecified -- like VECTOR-SET!
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;; meter : S --> integer -- like VECTOR-LENGTH
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(define-record-type :sequence-type
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(make-sequence-type maker predicate getter setter meter)
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sequence-type?
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(maker sequence-type:maker)
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(predicate sequence-type:predicate)
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(getter sequence-type:getter)
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(setter sequence-type:setter)
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(meter sequence-type:meter))
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;; underlying sequence data + behavioural sequence type
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(define-record-type :behaved-sequence
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;; avoiding the make-behaved-sequence namning pattern for good reason
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(make-behaved-sequence-record type instance)
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behaved-sequence?
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(type behaved-sequence:type)
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(instance behaved-sequence:instance))
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(define (behaved-sequence-ref s k)
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((sequence-type:getter (behaved-sequence:type s))
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(behaved-sequence:instance s) k))
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(define (behaved-sequence-set! s k x)
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((sequence-type:setter (behaved-sequence:type s))
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(behaved-sequence:instance s) k x))
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(define (behaved-sequence-length s)
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((sequence-type:meter (behaved-sequence:type s))
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(behaved-sequence:instance s)))
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;; note the necessary TYPE arg contrasting with MAKE-VECTOR etc.
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(define (make-behaved-sequence type k . maybe-fill)
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(make-behaved-sequence-record type
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(apply (sequence-type:maker type)
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k maybe-fill)))
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