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Arithmetic evaluation: Difference between revisions
Added Factor.
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(Added Factor.) |
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Line 638:
? arithEvaluate("(1 + 2 / 2) * (5 + 5)")
# value: 20.0</lang>
=={{header|Factor}}==
<lang factor>USING: accessors kernel locals math math.parser peg.ebnf ;
IN: rosetta.arith
TUPLE: operator left right ;
TUPLE: add < operator ; C: <add> add
TUPLE: sub < operator ; C: <sub> sub
TUPLE: mul < operator ; C: <mul> mul
TUPLE: div < operator ; C: <div> div
EBNF: expr-ast
spaces = [\n\t ]*
digit = [0-9]
number = (digit)+ => [[ string>number ]]
value = spaces number:n => [[ n ]]
| spaces "(" exp:e spaces ")" => [[ e ]]
fac = fac:a spaces "*" value:b => [[ a b <mul> ]]
| fac:a spaces "/" value:b => [[ a b <div> ]]
| value
exp = exp:a spaces "+" fac:b => [[ a b <add> ]]
| exp:a spaces "-" fac:b => [[ a b <sub> ]]
| fac
main = exp:e spaces !(.) => [[ e ]]
;EBNF
GENERIC: eval-ast ( ast -- result )
M: number eval-ast ;
: recursive-eval ( ast -- left-result right-result )
[ left>> eval-ast ] [ right>> eval-ast ] bi ;
M: add eval-ast recursive-eval + ;
M: sub eval-ast recursive-eval - ;
M: mul eval-ast recursive-eval * ;
M: div eval-ast recursive-eval / ;
: evaluate ( string -- result )
expr-ast eval-ast ;</lang>
=={{header|Haskell}}==
Line 669 ⟶ 713:
Right expr -> evaluate expr
Left _ -> error "Did not parse"</lang>
=={{header|J}}==
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