31 lines
948 B
Factor
31 lines
948 B
Factor
! Copyright (C) 2004, 2008 Slava Pestov.
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! See http://factorcode.org/license.txt for BSD license.
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USING: words sequences kernel assocs combinators classes
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namespaces arrays math quotations ;
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IN: classes.intersection
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PREDICATE: intersection-class < class
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"metaclass" word-prop intersection-class eq? ;
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: intersection-predicate-quot ( members -- quot )
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dup empty? [
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drop [ drop t ]
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] [
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unclip "predicate" word-prop swap [
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"predicate" word-prop [ dup ] swap [ not ] 3append
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[ drop f ]
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] { } map>assoc alist>quot
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] if ;
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: define-intersection-predicate ( class -- )
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dup participants intersection-predicate-quot define-predicate ;
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M: intersection-class update-class define-intersection-predicate ;
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: define-intersection-class ( class participants -- )
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[ f f rot intersection-class define-class ]
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[ drop update-classes ]
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2bi ;
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M: intersection-class rank-class drop 2 ;
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