src/lex.icl

   1 implementation module lex
   2
   3 import Control.Monad, Control.Applicative
   4 import Data.Either, Data.Func
   5 from StdFunc import o
   6 import StdBool
   7 import StdList
   8 import StdChar
   9
  10 import yard
  11
  12 lexer :: [Char] -> LexerOutput
  13 lexer r = case runParser lexProgram r of
  14         (Right p, _) = Right p
  15         (Left e, _) = Left $ toString e
  16
  17 lexProgram :: Parser Char [Token]
  18 lexProgram = some lexToken <* many (satisfy isSpace) <* eof
  19         >>= \ts->pure (map (\t->(0, 0, t)) ts)
  20
  21 lexToken :: Parser Char TokenValue
  22 lexToken =
  23         //Keyword tokens
  24         (lexKw "var" VarToken) <|>
  25         (lexKw "Void" VoidToken) <|>
  26         (lexKw "return" ReturnToken) <|>
  27         (lexKw "if" IfToken) <|>
  28         (lexKw "else" ElseToken) <|>
  29         (lexKw "while" WhileToken) <|>
  30         (lexKw "True" TrueToken) <|>
  31         (lexKw "False" FalseToken) <|>
  32         (lexKw "Int" IntTypeToken) <|>
  33         (lexKw "Bool" BoolTypeToken) <|>
  34         (lexKw "Char" CharTypeToken) <|>
  35         //Escape chars tokens
  36         (liftM CharToken $ item '\'' *> item '\\' *> lexEscape <* item '\'') <|>
  37         //Normal chars tokens
  38         (liftM CharToken $ item '\'' *> satisfy ((<>) '\'') <* item '\'') <|>
  39         //Two char ops tokens
  40         (lexOp "::" DoubleColonToken) <|> (lexOp "!=" NotEqualToken) <|>
  41         (lexOp "<=" LesserEqToken) <|> (lexOp ">=" GreaterEqToken) <|>
  42         (lexOp "==" EqualsToken) <|> (lexOp "&&" AmpersandsToken) <|>
  43         (lexOp "||" PipesToken) <|> (lexOp "[]" EmptyListToken) <|>
  44         (lexOp "->" ArrowToken) <|> (lexOp "(" BraceOpenToken) <|>
  45         //One char ops tokens
  46         (lexOp ")" BraceCloseToken) <|> (lexOp "{" CBraceOpenToken) <|>
  47         (lexOp "}" CBraceCloseToken) <|> (lexOp "[" SquareOpenToken) <|>
  48         (lexOp "]" SquareCloseToken) <|> (lexOp "," CommaToken) <|>
  49         (lexOp ":" ColonToken) <|> (lexOp ";" SColonToken) <|>
  50         (lexOp "." DotToken) <|> (lexOp "+" PlusToken) <|>
  51         (lexOp "*" StarToken) <|> (lexOp "/" SlashToken) <|>
  52         (lexOp "%" PercentToken) <|> (lexOp "=" AssignmentToken) <|>
  53         (lexOp "<" LesserToken) <|> (lexOp ">" BiggerToken) <|>
  54         (lexOp "!" ExclamationToken) <|> (lexOp "-" DashToken) <|>
  55         //Number tokens
  56         (liftM (NumberToken o toInt o toString) $ some $ satisfy isDigit) <|>
  57         //Ident tokens
  58         (liftM IdentToken $ some $ satisfy isIdentChar) <|>
  59         (satisfy isSpace >>| lexToken) //<|>
  60 //      (eof >>| pure EndOfFileToken)
  61         where
  62                 isIdentChar c = isAlphanum c || c == '_'
  63                 lexOp s tv = list (fromString s) >>| pure tv
  64                 lexKw kw tv = lexOp kw tv <* check (not o isIdentChar) >>| pure tv
  65                 lexEscape = (
  66                         lexOp "a" (toChar 7) <|> lexOp "b" '\b' <|> lexOp "f" '\f' <|>
  67                         lexOp "n" '\n' <|> lexOp "r" '\t' <|> lexOp "v" '\v' <|>
  68                         lexOp "'" '\'') <?> ("Unknown escape", 0)