66 lines
1.9 KiB
Haskell
66 lines
1.9 KiB
Haskell
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module Parse.Pattern (term, expr) where
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import Control.Applicative ((<$>),(<*>),pure)
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import Control.Monad
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import Control.Monad.State
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import Data.Char (isUpper)
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import Data.List (intercalate)
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import Unique
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import Text.Parsec hiding (newline,spaces,State)
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import Text.Parsec.Indent
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import Parse.Helpers
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import Parse.Literal
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import qualified SourceSyntax.Pattern as Pattern
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import SourceSyntax.Everything hiding (tuple)
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basic :: IParser Pattern
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basic = choice
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[ char '_' >> return PAnything
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, do v <- var
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return $ case v of
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"True" -> PLiteral (Boolean True)
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"False" -> PLiteral (Boolean False)
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c : _ -> if isUpper c then PData v [] else PVar v
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, do lit <- literal
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return $ case lit of
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Str s -> foldr combine (PData "[]" []) s
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where combine h t = PData "::" [PLiteral (Chr h),t]
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_ -> PLiteral lit
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]
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asPattern :: Pattern -> IParser Pattern
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asPattern pattern = do
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var <- optionMaybe (try (whitespace >> reserved "as" >> whitespace >> lowVar))
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return $ case var of
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Just v -> PAlias v pattern
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Nothing -> pattern
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record :: IParser Pattern
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record = PRecord <$> brackets (commaSep1 lowVar)
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tuple :: IParser Pattern
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tuple = do ps <- parens (commaSep expr)
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return $ case ps of { [p] -> p; _ -> Pattern.tuple ps }
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list :: IParser Pattern
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list = Pattern.list <$> braces (commaSep expr)
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term :: IParser Pattern
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term =
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(choice [ record, tuple, list, basic ]) <?> "pattern"
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patternConstructor :: IParser Pattern
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patternConstructor = do
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v <- intercalate "." <$> dotSep1 capVar
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case v of
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"True" -> return $ PLiteral (Boolean True)
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"False" -> return $ PLiteral (Boolean False)
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_ -> PData v <$> spacePrefix term
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expr :: IParser Pattern
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expr = do
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patterns <- consSep1 (patternConstructor <|> term)
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asPattern (foldr1 Pattern.cons patterns) <?> "pattern"
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