! Copyright (C) 2004, 2008 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays definitions assocs kernel kernel.private
slots.private namespaces sequences strings words vectors math
quotations combinators sorting effects graphs vocabs ;
IN: classes

SYMBOL: class<-cache
SYMBOL: class-not-cache
SYMBOL: classes-intersect-cache
SYMBOL: class-and-cache
SYMBOL: class-or-cache

: init-caches ( -- )
    H{ } clone class<-cache set
    H{ } clone class-not-cache set
    H{ } clone classes-intersect-cache set
    H{ } clone class-and-cache set
    H{ } clone class-or-cache set ;

: reset-caches ( -- )
    class<-cache get clear-assoc
    class-not-cache get clear-assoc
    classes-intersect-cache get clear-assoc
    class-and-cache get clear-assoc
    class-or-cache get clear-assoc ;

PREDICATE: class < word ( obj -- ? ) "class" word-prop ;

SYMBOL: update-map
SYMBOL: builtins

PREDICATE: builtin-class < class
    "metaclass" word-prop builtin-class eq? ;

PREDICATE: tuple-class < class
    "metaclass" word-prop tuple-class eq? ;

: classes ( -- seq ) all-words [ class? ] subset ;

: type>class ( n -- class ) builtins get-global nth ;

: bootstrap-type>class ( n -- class ) builtins get nth ;

: predicate-word ( word -- predicate )
    [ word-name "?" append ] keep word-vocabulary create ;

: predicate-effect 1 { "?" } <effect> ;

PREDICATE: predicate < word "predicating" word-prop >boolean ;

: define-predicate ( class quot -- )
    >r "predicate" word-prop first
    r> predicate-effect define-declared ;

: superclass ( class -- super )
    #! Output f for non-classes to work with algebra code
    dup class? [ "superclass" word-prop ] [ drop f ] if ;

: members ( class -- seq )
    #! Output f for non-classes to work with algebra code
    dup class? [ "members" word-prop ] [ drop f ] if ;

GENERIC: reset-class ( class -- )

M: word reset-class drop ;

<PRIVATE

! update-map
: class-uses ( class -- seq )
    dup members swap superclass [ add ] when* ;

: class-usages ( class -- assoc )
    [ update-map get at ] closure ;

: update-map+ ( class -- )
    dup class-uses update-map get add-vertex ;

: update-map- ( class -- )
    dup class-uses update-map get remove-vertex ;

PRIVATE>

: define-class-props ( members superclass metaclass -- assoc )
    [
        "metaclass" set
        dup [ bootstrap-word ] when "superclass" set
        [ bootstrap-word ] map "members" set
    ] H{ } make-assoc ;

: (define-class) ( word props -- )
    over reset-class
    over deferred? [ over define-symbol ] when
    >r dup word-props r> union over set-word-props
    dup predicate-word 2dup 1quotation "predicate" set-word-prop
    over "predicating" set-word-prop
    t "class" set-word-prop ;

GENERIC: update-predicate ( class -- )

M: class update-predicate drop ;

: update-predicates ( assoc -- )
    [ drop update-predicate ] assoc-each ;

GENERIC: update-methods ( assoc -- )

: define-class ( word members superclass metaclass -- )
    #! If it was already a class, update methods after.
    reset-caches
    define-class-props
    over update-map-
    dupd (define-class)
    dup update-map+
    class-usages dup update-predicates update-methods ;

GENERIC: class ( object -- class ) inline

M: object class type type>class ;