39 lines
977 B
Factor
39 lines
977 B
Factor
! Copyright (C) 2006 Chris Double.
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! See http://factorcode.org/license.txt for BSD license.
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!
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! Based on pattern matching code from Paul Graham's book 'On Lisp'.
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IN: match
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USING: kernel words sequences namespaces hashtables ;
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SYMBOL: _
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: match-var? ( symbol -- bool )
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dup word? [
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word-name first CHAR: ? =
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] [
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drop f
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] if ;
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: (match) ( seq1 seq2 -- matched? )
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{
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{ [ 2dup = ] [ 2drop t ] }
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{ [ over _ = ] [ 2drop t ] }
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{ [ dup _ = ] [ 2drop t ] }
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{ [ dup match-var? ] [ set t ] }
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{ [ over match-var? ] [ swap set t ] }
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{ [ over sequence? over sequence? and [ over first over first (match) ] [ f ] if ] [ >r 1 tail r> 1 tail (match) ] }
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{ [ t ] [ 2drop f ] }
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} cond ;
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: match ( seq1 seq2 -- bindings )
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[ (match) ] make-hash swap [ drop f ] unless ;
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SYMBOL: result
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: match-cond ( seq assoc -- )
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[
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[ first over match dup result set ] find 2nip dup [ result get [ second call ] bind ] [ no-cond ] if
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] with-scope ;
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