src/lex.icl

   1 implementation module lex
   2
   3 import Control.Monad
   4 import Data.Either, Data.Maybe, Data.Map, Data.Func
   5 import StdString
   6 import StdTuple
   7 import StdBool
   8 import StdList
   9 import StdChar
  10
  11 SingleCharTokens :: Map Char TokenValue
  12 SingleCharTokens = fromList [
  13         ('(', BraceOpenToken), (')', BraceCloseToken), ('{', CBraceOpenToken),
  14         ('}', CBraceCloseToken), ('[', SquareOpenToken), (']', SquareCloseToken),
  15         (',', CommaToken), (':', ColonToken), (';', SColonToken),
  16         ('.', DotToken), ('+', PlusToken), ('*', StarToken), ('/', SlashToken),
  17         ('%', PercentToken), ('=', AssignmentToken), ('<', LesserToken),
  18         ('>', BiggerToken), ('!', ExclamationToken)]
  19
  20 EscapeMap :: Map Char Char
  21 EscapeMap = fromList [('a', toChar 7), ('b', '\b'), ('f', '\f'), ('n', '\n'),
  22         ('r', '\r'), ('t', '\t'), ('v', '\v')]
  23
  24 lexer :: [Char] -> LexerOutput
  25 lexer x = lexer` x 1
  26         where
  27                 lexer` :: [Char] Int -> LexerOutput
  28                 lexer` [] i = Right []
  29                 lexer` x i = case lex x i of
  30                         (Right t, rest, i) = lexer` rest i >>= \ts.Right [t:ts]
  31                         (Left e, _, _) = Left e
  32
  33 ret:: TokenValue [Char] Int -> (Either String Token, [Char], Int)
  34 ret tv rest i = (Right (i, tv), rest, i)
  35
  36 err :: String Int -> (Either String Token, [Char], Int)
  37 err s i = (Left ("Line " +++ toString i +++ ": " +++ s), [], i)
  38
  39 lex :: [Char] -> (Int -> (Either String Token, [Char], Int))
  40 lex [] = ret EndOfFileToken []
  41 lex ['/':'/':xs] = lex (dropWhile ((<>) '\n') xs)
  42 lex ['/':'*':xs] =  \i.let (c, r) = span ((<>) ('*','/')) $ zip2 [' ':xs] xs in
  43         lex (tl $ map snd $ tl $ r) (i + length [x\\(x, _)<-c | x == '\n'])
  44 lex ['v':'a':'r':xs] = ret VarToken xs
  45 lex ['V':'o':'i':'d':xs] = ret VoidToken xs
  46 lex ['r':'e':'t':'u':'r':'n':xs] = ret ReturnToken xs
  47 lex ['i':'f':xs] = ret IfToken xs
  48 lex ['e':'l':'s':'e':xs] = ret ElseToken xs
  49 lex ['w':'h':'i':'l':'e':xs] = ret WhileToken xs
  50 lex ['T':'r':'u':'e':xs] = ret TrueToken xs
  51 lex ['F':'a':'l':'s':'e':xs] = ret FalseToken xs
  52 lex ['I':'n':'t':xs] = ret IntTypeToken xs
  53 lex ['C':'h':'a':'r':xs] = ret CharTypeToken xs
  54 lex ['B':'o':'o':'l':xs] = ret BoolTypeToken xs
  55 lex [':':':':xs] = ret DoubleColonToken xs
  56 lex ['!':'=':xs] = ret NotEqualToken xs
  57 lex ['<':'=':xs] = ret LesserEqToken xs
  58 lex ['>':'=':xs] = ret GreaterEqToken xs
  59 lex ['=':'=':xs] = ret EqualsToken xs
  60 lex ['&':'&':xs] = ret AmpersandsToken xs
  61 lex ['|':'|':xs] = ret PipesToken xs
  62 lex ['[':']':xs] = ret EmptyListToken xs
  63 lex ['-':'>':xs] = ret ArrowToken xs
  64 lex ['\'':x:'\'':xs] = ret (CharToken x) xs
  65 lex ['\'':'\\':x:'\'':xs] = case get x EscapeMap of
  66         Just t = ret (CharToken t) xs
  67         _ = err ("Unknown escape: \\" +++ toString x)
  68 lex ['-':t=:[x:xs]]
  69 | isDigit x = let (n, r) = span isDigit t in
  70         ret (NumberToken (toInt $ toString ['-':n])) r
  71 | otherwise = ret DashToken t
  72 lex t=:[x:xs] = case get x SingleCharTokens of
  73         (Just tok) = ret tok xs
  74         Nothing
  75         | x == '\n' = \i.lex xs (i+1)
  76         | isSpace x = lex xs
  77         | isDigit x = let (v, r) = span isDigit t in
  78                 ret (NumberToken (toInt $ toString v)) r
  79         | isAlpha x = let (v, r) = span isIdent t in ret (IdentToken v) r
  80                 with isIdent c = isAlphanum c || c == '_'
  81         | otherwise = err ("Unexpected character: " +++ toString x)
  82
  83
  84 (===) :: TokenValue Token -> Bool
  85 (===) (IdentToken _) (_, IdentToken _) = True
  86 (===) (NumberToken _) (_, NumberToken _) = True
  87 (===) (CharToken _) (_, CharToken _) = True
  88 (===) (VarToken) (_, VarToken) = True
  89 (===) (ReturnToken) (_, ReturnToken) = True
  90 (===) (IfToken) (_, IfToken) = True
  91 (===) (ElseToken) (_, ElseToken) = True
  92 (===) (WhileToken) (_, WhileToken) = True
  93 (===) (TrueToken) (_, TrueToken) = True
  94 (===) (FalseToken) (_, FalseToken) = True
  95 (===) (VoidToken) (_, VoidToken) = True
  96 (===) (IntTypeToken) (_, IntTypeToken) = True
  97 (===) (CharTypeToken) (_, CharTypeToken) = True
  98 (===) (BoolTypeToken) (_, BoolTypeToken) = True
  99 (===) (DoubleColonToken) (_, DoubleColonToken) = True
 100 (===) (NotEqualToken) (_, NotEqualToken) = True
 101 (===) (LesserEqToken) (_, LesserEqToken) = True
 102 (===) (GreaterEqToken) (_, GreaterEqToken) = True
 103 (===) (EqualsToken) (_, EqualsToken) = True
 104 (===) (AmpersandsToken) (_, AmpersandsToken) = True
 105 (===) (PipesToken) (_, PipesToken) = True
 106 (===) (ArrowToken) (_, ArrowToken) = True
 107 (===) (EmptyListToken) (_, EmptyListToken) = True
 108 (===) (BraceOpenToken) (_, BraceOpenToken) = True
 109 (===) (BraceCloseToken) (_, BraceCloseToken) = True
 110 (===) (CBraceOpenToken) (_, CBraceOpenToken) = True
 111 (===) (CBraceCloseToken) (_, CBraceCloseToken) = True
 112 (===) (SquareOpenToken) (_, SquareOpenToken) = True
 113 (===) (SquareCloseToken) (_, SquareCloseToken) = True
 114 (===) (CommaToken) (_, CommaToken) = True
 115 (===) (ColonToken) (_, ColonToken) = True
 116 (===) (SColonToken) (_, SColonToken) = True
 117 (===) (DotToken) (_, DotToken) = True
 118 (===) (PlusToken) (_, PlusToken) = True
 119 (===) (DashToken) (_, DashToken) = True
 120 (===) (StarToken) (_, StarToken) = True
 121 (===) (SlashToken) (_, SlashToken) = True
 122 (===) (PercentToken) (_, PercentToken) = True
 123 (===) (AssignmentToken) (_, AssignmentToken) = True
 124 (===) (LesserToken) (_, LesserToken) = True
 125 (===) (BiggerToken) (_, BiggerToken) = True
 126 (===) (ExclamationToken) (_, ExclamationToken) = True
 127 (===) _ _ = False