103 lines
2.5 KiB
Idris
103 lines
2.5 KiB
Idris
module Quox.Lexer
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import public Quox.Token
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import Data.String
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import Data.String.Extra
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import public Text.Lexer
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import public Text.Lexer.Tokenizer
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import Control.Monad.Either
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import Generics.Derive
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%default total
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%language ElabReflection
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public export
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record Error where
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constructor Err
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reason : StopReason
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line, col : Int
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char : Char
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nameStart = pred $ \c => isAlpha c || c == '_'
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nameCont = pred $ \c => isAlphaNum c || c == '_' || c == '\''
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name = nameStart <+> many nameCont <+> reject nameCont
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wild = is '_' <+> reject nameCont
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%hide Text.Lexer.symbol
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symbol = is '\'' <+> name
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decimal = some digit <+> reject nameCont
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natToNumber : Nat -> Number
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natToNumber 0 = Zero
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natToNumber 1 = One
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natToNumber k = Other k
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skip : Lexer -> Tokenizer (Maybe a)
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skip lex = match lex $ const Nothing
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simple : Char -> a -> Tokenizer (Maybe a)
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simple ch = match (is ch) . const . Just
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keyword : String -> Keyword -> Tokenizer (Maybe Token)
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keyword str = match (exact str <+> reject nameCont) . const . Just . K
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choice : (xs : List (Tokenizer a)) -> {auto 0 _ : NonEmpty xs} -> Tokenizer a
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choice (t :: ts) = foldl (\a, b => a <|> b) t ts
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match : Lexer -> (String -> a) -> Tokenizer (Maybe a)
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match lex f = Tokenizer.match lex (Just . f)
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%hide Tokenizer.match
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tokens : Tokenizer (Maybe Token)
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tokens = choice [
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skip $ lineComment $ exact "--",
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skip $ blockComment (exact "{-") (exact "-}"),
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skip spaces,
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simple '(' $ P LParen, simple ')' $ P RParen,
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simple '[' $ P LSquare, simple ']' $ P RSquare,
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simple '{' $ P LBrace, simple '}' $ P RBrace,
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simple ',' $ P Comma,
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simple '∷' $ P DblColon,
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simple ':' $ P Colon, -- needs to be after '::'
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simple '.' $ P Dot,
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simple '→' $ P Arrow,
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simple '⇒' $ P DblArrow,
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simple '×' $ P Times,
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simple '⊲' $ P Triangle,
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match wild $ const $ P Wild,
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keyword "λ" Lam,
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keyword "let" Let, keyword "in" In,
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keyword "case" Case, keyword "of" Of,
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keyword "ω" Omega,
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keyword "Π" Pi, keyword "Σ" Sigma, keyword "W" W,
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match name $ Name,
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match symbol $ Symbol . assert_total strTail,
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match decimal $ N . natToNumber . cast,
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match (is '★' <+> decimal) $ TYPE . cast . assert_total strTail
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]
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export
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lex : String -> Either Error (List BToken)
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lex str =
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let (res, (reason, line, col, str)) = lex tokens str in
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case reason of
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EndInput => Right $ mapMaybe sequence res
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_ => let char = assert_total strIndex str 0 in
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Left $ Err {reason, line, col, char}
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