33 lines
941 B
Factor
Executable File
33 lines
941 B
Factor
Executable File
! 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.union
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PREDICATE: union-class < class
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"metaclass" word-prop union-class eq? ;
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! Union classes for dispatch on multiple classes.
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: union-predicate-quot ( members -- quot )
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dup empty? [
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drop [ drop f ]
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] [
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unclip "predicate" word-prop swap [
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"predicate" word-prop [ dup ] prepend
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[ drop t ]
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] { } map>assoc alist>quot
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] if ;
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: define-union-predicate ( class -- )
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dup members union-predicate-quot define-predicate ;
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M: union-class update-class define-union-predicate ;
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: define-union-class ( class members -- )
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[ f swap union-class define-class ]
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[ drop update-classes ]
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2bi ;
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M: union-class reset-class
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{ "class" "metaclass" "members" } reset-props ;
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