21 lines
628 B
Factor
21 lines
628 B
Factor
! Copyright (C) 2008 Chris Double.
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! See http://factorcode.org/license.txt for BSD license.
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USING: kernel arrays strings math.parser sequences
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peg peg.ebnf peg.parsers memoize math accessors ;
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IN: peg.expr
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EBNF: expr
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digit = [0-9] => [[ digit> ]]
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number = (digit)+ => [[ 10 digits>integer ]]
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value = number
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| ("(" exp ")") => [[ second ]]
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fac = fac "*" value => [[ first3 nip * ]]
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| fac "/" value => [[ first3 nip / ]]
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| number
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exp = exp "+" fac => [[ first3 nip + ]]
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| exp "-" fac => [[ first3 nip - ]]
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| fac
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;EBNF
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