39 lines
997 B
Factor
Executable File
39 lines
997 B
Factor
Executable File
! Copyright (C) 2005, 2006 Alex Chapman, Daniel Ehrenberg
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! See http;//factorcode.org/license.txt for BSD license
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USING: kernel sequences math sequences.private strings
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accessors ;
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IN: circular
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! a circular sequence wraps another sequence, but begins at an
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! arbitrary element in the underlying sequence.
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TUPLE: circular seq start ;
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: <circular> ( seq -- circular )
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0 circular boa ;
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: circular-wrap ( n circular -- n circular )
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[ start>> + ] keep
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[ seq>> length rem ] keep ; inline
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M: circular length seq>> length ;
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M: circular virtual@ circular-wrap seq>> ;
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M: circular nth virtual@ nth ;
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M: circular set-nth virtual@ set-nth ;
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M: circular virtual-seq seq>> ;
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: change-circular-start ( n circular -- )
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#! change start to (start + n) mod length
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circular-wrap (>>start) ;
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: push-circular ( elt circular -- )
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[ set-first ] [ 1 swap change-circular-start ] bi ;
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: <circular-string> ( n -- circular )
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0 <string> <circular> ;
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INSTANCE: circular virtual-sequence
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