43 lines
1.2 KiB
Factor
Executable File
43 lines
1.2 KiB
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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generic.standard namespaces arrays math quotations ;
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IN: classes.union
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PREDICATE: class union-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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: small-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 first "predicate" word-prop swap
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[ >r "predicate" word-prop [ dup ] swap append r> ]
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assoc-map alist>quot
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] if ;
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: big-union-predicate-quot ( members -- quot )
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[ small-union-predicate-quot ] [ dup ]
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class-hash-dispatch-quot ;
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: union-predicate-quot ( members -- quot )
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[ [ drop t ] ] { } map>assoc
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dup length 4 <= [
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small-union-predicate-quot
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] [
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flatten-methods
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big-union-predicate-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-predicate define-union-predicate ;
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: define-union-class ( class members -- )
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dupd f union-class define-class define-union-predicate ;
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M: union-class reset-class
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{ "metaclass" "members" } reset-props ;
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