1 ! Copyright (C) 2006 Chris Double.
2 ! See http://factorcode.org/license.txt for BSD license.
4 ! Based on pattern matching code from Paul Graham's book 'On Lisp'.
5 USING: assocs classes classes.tuple combinators kernel lexer
6 macros make namespaces parser quotations sequences summary words
12 : define-match-var ( name -- )
14 dup t "match-var" set-word-prop
15 dup [ get ] curry ( -- value ) define-declared ;
17 : define-match-vars ( seq -- )
18 [ define-match-var ] each ;
20 SYNTAX: MATCH-VARS: ! vars ...
21 ";" [ define-match-var ] each-token ;
23 PREDICATE: match-var < word "match-var" word-prop ;
25 : set-match-var ( value var -- ? )
26 building get ?at [ = ] [ ,, t ] if ;
28 : (match) ( value1 value2 -- matched? )
30 { [ dup match-var? ] [ set-match-var ] }
31 { [ over match-var? ] [ swap set-match-var ] }
32 { [ 2dup = ] [ 2drop t ] }
33 { [ 2dup [ _ eq? ] either? ] [ 2drop t ] }
34 { [ 2dup [ sequence? ] both? ] [
35 2dup [ length ] same? [
38 { [ 2dup [ tuple? ] both? ] [
39 2dup [ class-of ] same? [
40 [ tuple-slots ] bi@ [ (match) ] 2all?
45 : match ( value1 value2 -- bindings )
46 [ (match) ] H{ } make swap [ drop f ] unless ;
48 ERROR: no-match-cond ;
50 M: no-match-cond summary drop "Fall-through in match-cond" ;
52 MACRO: match-cond ( assoc -- quot )
54 dup ?first callable? [ unclip ] [ [ no-match-cond ] ] if
57 [ [ dupd match ] curry ] dip
58 [ with-variables ] curry rot
62 GENERIC: replace-patterns ( object -- result )
63 M: object replace-patterns ;
64 M: match-var replace-patterns get ;
65 M: sequence replace-patterns [ replace-patterns ] map ;
66 M: tuple replace-patterns tuple>array replace-patterns >tuple ;
68 : match-replace ( object pattern1 pattern2 -- result )
69 [ match [ "Pattern does not match" throw ] unless* ] dip swap
70 [ replace-patterns ] with-variables ;
72 : ?rest ( seq -- tailseq/f )
73 [ f ] [ rest ] if-empty ;
75 : (match-first) ( seq pattern-seq -- bindings leftover/f )
79 2dup length head over match
80 [ swap ?rest ] [ [ rest ] dip (match-first) ] ?if
83 : match-first ( seq pattern-seq -- bindings )
86 : (match-all) ( seq pattern-seq -- )
87 [ (match-first) ] keep
88 [ , [ swap (match-all) ] [ drop ] if* ] [ 2drop ] if* ;
90 : match-all ( seq pattern-seq -- bindings-seq )
91 [ (match-all) ] { } make ;