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108 lines
2.5 KiB
Idris
108 lines
2.5 KiB
Idris
import Data.List1
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import Text.Lexer
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import Text.Parser
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import Text.Parser.Expression
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%default total
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data CalculatorTokenKind
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= CTNum
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| CTPlus
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| CTMinus
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| CTMultiply
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| CTDivide
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| CTOParen
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| CTCParen
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| CTIgnore
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Eq CalculatorTokenKind where
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(==) CTNum CTNum = True
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(==) CTPlus CTPlus = True
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(==) CTMinus CTMinus = True
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(==) CTMultiply CTMultiply = True
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(==) CTDivide CTDivide = True
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(==) CTOParen CTOParen = True
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(==) CTCParen CTCParen = True
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(==) _ _ = False
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Show CalculatorTokenKind where
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show CTNum = "CTNum"
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show CTPlus = "CTPlus"
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show CTMinus = "CTMinus"
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show CTMultiply = "CTMultiply"
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show CTDivide = "CTDivide"
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show CTOParen = "CTOParen"
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show CTCParen = "CTCParen"
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show CTIgnore = "CTIgnore"
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CalculatorToken : Type
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CalculatorToken = Token CalculatorTokenKind
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Show CalculatorToken where
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show (Tok kind text) = "Tok kind: " ++ show kind ++ " text: " ++ text
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TokenKind CalculatorTokenKind where
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TokType CTNum = Double
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TokType _ = ()
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tokValue CTNum s = cast s
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tokValue CTPlus _ = ()
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tokValue CTMinus _ = ()
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tokValue CTMultiply _ = ()
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tokValue CTDivide _ = ()
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tokValue CTOParen _ = ()
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tokValue CTCParen _ = ()
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tokValue CTIgnore _ = ()
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ignored : WithBounds CalculatorToken -> Bool
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ignored (MkBounded (Tok CTIgnore _) _ _) = True
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ignored _ = False
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number : Lexer
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number = digits
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calculatorTokenMap : TokenMap CalculatorToken
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calculatorTokenMap = toTokenMap [
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(spaces, CTIgnore),
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(digits, CTNum),
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(exact "+", CTPlus),
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(exact "-", CTMinus),
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(exact "*", CTMultiply),
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(exact "/", CTDivide)
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]
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lexCalculator : String -> Maybe (List (WithBounds CalculatorToken))
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lexCalculator str =
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case lex calculatorTokenMap str of
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(tokens, _, _, "") => Just tokens
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_ => Nothing
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mutual
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term : Grammar state CalculatorToken True Double
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term = do
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num <- match CTNum
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pure num
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expr : Grammar state CalculatorToken True Double
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expr = buildExpressionParser [
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[ Infix ((*) <$ match CTMultiply) AssocLeft
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, Infix ((/) <$ match CTDivide) AssocLeft
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],
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[ Infix ((+) <$ match CTPlus) AssocLeft
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, Infix ((-) <$ match CTMinus) AssocLeft
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]
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] term
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parseCalculator : List (WithBounds CalculatorToken) -> Either String Double
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parseCalculator toks =
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case parse expr $ filter (not . ignored) toks of
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Right (l, []) => Right l
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Right e => Left "contains tokens that were not consumed"
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Left e => Left (show e)
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parse1 : String -> Either String Double
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parse1 x =
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case lexCalculator x of
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Just toks => parseCalculator toks
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Nothing => Left "Failed to lex."
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