1 ! Copyright (C) 2008 Slava Pestov.
2 ! See http://factorcode.org/license.txt for BSD license.
3 USING: arrays assocs math math.intervals kernel accessors
4 sequences namespaces classes classes.algebra
5 combinators words combinators.short-circuit
7 compiler.tree.propagation.info
8 compiler.tree.propagation.copy ;
9 IN: compiler.tree.propagation.constraints
11 ! A constraint is a statement about a value.
13 ! Maps constraints to constraints ("A implies B")
16 GENERIC: assume* ( constraint -- )
17 GENERIC: satisfied? ( constraint -- ? )
21 ! satisfied? is inaccurate. It's just used to prevent infinite
22 ! loops so its only implemented for true-constraints and
24 M: object satisfied? drop f ;
26 : assume ( constraint -- ) dup satisfied? [ drop ] [ assume* ] if ;
29 TUPLE: true-constraint value ;
31 : =t ( value -- constraint ) resolve-copy true-constraint boa ;
33 : follow-implications ( constraint -- )
34 constraints get assoc-stack [ assume ] when* ;
36 M: true-constraint assume*
37 [ \ f class-not <class-info> swap value>> refine-value-info ]
38 [ follow-implications ]
41 M: true-constraint satisfied?
42 value>> value-info class>>
43 { [ true-class? ] [ null-class? not ] } 1&& ;
45 TUPLE: false-constraint value ;
47 : =f ( value -- constriant ) resolve-copy false-constraint boa ;
49 M: false-constraint assume*
50 [ \ f <class-info> swap value>> refine-value-info ]
51 [ follow-implications ]
54 M: false-constraint satisfied?
55 value>> value-info class>>
56 { [ false-class? ] [ null-class? not ] } 1&& ;
59 TUPLE: class-constraint value class ;
61 : is-instance-of ( value class -- constraint )
62 [ resolve-copy ] dip class-constraint boa ;
64 M: class-constraint assume*
65 [ class>> <class-info> ] [ value>> ] bi refine-value-info ;
67 ! Interval constraints
68 TUPLE: interval-constraint value interval ;
70 : is-in-interval ( value interval -- constraint )
71 [ resolve-copy ] dip interval-constraint boa ;
73 M: interval-constraint assume*
74 [ interval>> <interval-info> ] [ value>> ] bi refine-value-info ;
77 TUPLE: literal-constraint value literal ;
79 : is-equal-to ( value literal -- constraint )
80 [ resolve-copy ] dip literal-constraint boa ;
82 M: literal-constraint assume*
83 [ literal>> <literal-info> ] [ value>> ] bi refine-value-info ;
85 ! Implication constraints
86 TUPLE: implication p q ;
90 : assume-implication ( q p -- )
91 [ constraints get [ assoc-stack swap suffix ] 2keep last set-at ]
92 [ satisfied? [ assume ] [ drop ] if ] 2bi ;
94 M: implication assume*
95 [ q>> ] [ p>> ] bi assume-implication ;
97 ! Equivalence constraints
98 TUPLE: equivalence p q ;
102 M: equivalence assume*
104 [ assume-implication ]
105 [ swap assume-implication ] 2bi ;
107 ! Conjunction constraints -- sequences act as conjunctions
108 M: sequence assume* [ assume ] each ;
110 : /\ ( p q -- constraint ) 2array ;
113 : t--> ( constraint boolean-value -- constraint' ) =t swap --> ;
115 : f--> ( constraint boolean-value -- constraint' ) =f swap --> ;