factor/library/generic/predicate.factor

82 lines
2.7 KiB
Factor

! :folding=indent:collapseFolds=1:
! $Id$
!
! Copyright (C) 2004 Slava Pestov.
!
! Redistribution and use in source and binary forms, with or without
! modification, are permitted provided that the following conditions are met:
!
! 1. Redistributions of source code must retain the above copyright notice,
! this list of conditions and the following disclaimer.
!
! 2. Redistributions in binary form must reproduce the above copyright notice,
! this list of conditions and the following disclaimer in the documentation
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!
! THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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IN: generic
USE: errors
USE: hashtables
USE: kernel
USE: lists
USE: namespaces
USE: parser
USE: strings
USE: words
USE: vectors
! Predicate metaclass for generalized predicate dispatch.
SYMBOL: predicate
: predicate-dispatch ( existing definition class -- dispatch )
[
\ dup , "predicate" word-property , , , \ ifte ,
] make-list ;
: predicate-method ( vtable definition class type# -- )
>r rot r> swap [
vector-nth
( vtable definition class existing )
-rot predicate-dispatch
] 2keep set-vector-nth ;
predicate [
"superclass" word-property builtin-supertypes
] "builtin-supertypes" set-word-property
predicate [
( vtable definition class -- )
dup builtin-supertypes [
( vtable definition class type# )
>r 3dup r> predicate-method
] each 3drop
] "add-method" set-word-property
predicate 25 "priority" set-word-property
: define-predicate ( class predicate definition -- )
rot "superclass" word-property "predicate" word-property
[ \ dup , , , [ drop f ] , \ ifte , ] make-list
define-compound ;
: PREDICATE: ( -- class predicate definition )
#! Followed by a superclass name, then a class name.
scan-word
CREATE
dup rot "superclass" set-word-property
dup predicate "metaclass" set-word-property
dup predicate-word
[ dupd "predicate" set-word-property ] keep
[ define-predicate ] [ ] ; parsing