Reorganisation of the source tree

[ghc-hetmet.git] / utils / ext-core / Lex.hs

diff --git a/utils/ext-core/Lex.hs b/utils/ext-core/Lex.hs
new file mode 100644 (file)
index 0000000..ad9d2eb
--- /dev/null
+++ b/utils/ext-core/Lex.hs
@@ -0,0 +1,92 @@
+module Lex where
+
+import ParseGlue
+import Ratio
+import Char
+
+isNameChar c = isAlpha c || isDigit c || (c == '_') || (c == '\'') 
+isKeywordChar c = isAlpha c || (c == '_') 
+
+lexer :: (Token -> P a) -> P a 
+lexer cont [] = cont TKEOF []
+lexer cont ('\n':cs) = \line -> lexer cont cs (line+1)
+lexer cont ('-':'>':cs) = cont TKrarrow cs
+lexer cont (c:cs) 
+      | isSpace c = lexer cont cs
+      | isLower c || (c == '_') = lexName cont TKname (c:cs)
+      | isUpper c = lexName cont TKcname (c:cs)
+      | isDigit c || (c == '-') = lexNum cont (c:cs)
+lexer cont ('%':cs) = lexKeyword cont cs
+lexer cont ('\'':cs) = lexChar cont cs
+lexer cont ('\"':cs) = lexString [] cont cs 
+lexer cont ('#':cs) = cont TKhash cs
+lexer cont ('(':cs) = cont TKoparen cs
+lexer cont (')':cs) = cont TKcparen cs
+lexer cont ('{':cs) = cont TKobrace cs
+lexer cont ('}':cs) = cont TKcbrace cs
+lexer cont ('=':cs) = cont TKeq cs
+lexer cont (':':':':cs) = cont TKcoloncolon cs
+lexer cont ('*':cs) = cont TKstar cs
+lexer cont ('.':cs) = cont TKdot cs
+lexer cont ('\\':cs) = cont TKlambda cs
+lexer cont ('/':'\\':cs) = cont TKbiglambda cs
+lexer cont ('@':cs) = cont TKat cs
+lexer cont ('?':cs) = cont TKquestion cs
+lexer cont (';':cs) = cont TKsemicolon cs
+lexer cont (c:cs) = failP "invalid character" [c]
+
+lexChar cont ('\\':'x':h1:h0:'\'':cs)
+       | isHexEscape [h1,h0] =  cont (TKchar (hexToChar h1 h0)) cs
+lexChar cont ('\\':cs) = failP "invalid char character" ('\\':(take 10 cs))
+lexChar cont ('\'':cs) = failP "invalid char character" ['\'']
+lexChar cont ('\"':cs) = failP "invalid char character" ['\"']
+lexChar cont (c:'\'':cs) = cont (TKchar c) cs
+
+lexString s cont ('\\':'x':h1:h0:cs) 
+       | isHexEscape [h1,h0] = lexString (s++[hexToChar h1 h0]) cont cs
+lexString s cont ('\\':cs) = failP "invalid string character" ['\\']
+lexString s cont ('\'':cs) = failP "invalid string character" ['\'']
+lexString s cont ('\"':cs) = cont (TKstring s) cs
+lexString s cont (c:cs) = lexString (s++[c]) cont cs
+
+isHexEscape = all (\c -> isHexDigit c && (isDigit c || isLower c))
+
+hexToChar h1 h0 = 
+       chr(
+       (digitToInt h1) * 16 + 
+       (digitToInt h0))
+
+
+lexNum cont cs =
+  case cs of
+     ('-':cs) ->  f (-1) cs
+     _ -> f 1 cs
+ where f sgn cs = 
+         case span isDigit cs of
+          (digits,'.':c:rest) | isDigit c -> 
+            cont (TKrational (numer % denom)) rest'
+              where (fpart,rest') = span isDigit (c:rest)
+                    denom = 10^(length fpart)
+                    numer = sgn * ((read digits) * denom + (read fpart))
+          (digits,rest) -> cont (TKinteger (sgn * (read digits))) rest
+
+lexName cont cstr cs = cont (cstr name) rest
+   where (name,rest) = span isNameChar cs
+
+lexKeyword cont cs = 
+   case span isKeywordChar cs of
+      ("module",rest) -> cont TKmodule rest
+      ("data",rest)  -> cont TKdata rest
+      ("newtype",rest) -> cont TKnewtype rest
+      ("forall",rest) -> cont TKforall rest    
+      ("rec",rest) -> cont TKrec rest  
+      ("let",rest) -> cont TKlet rest  
+      ("in",rest) -> cont TKin rest    
+      ("case",rest) -> cont TKcase rest        
+      ("of",rest) -> cont TKof rest    
+      ("coerce",rest) -> cont TKcoerce rest    
+      ("note",rest) -> cont TKnote rest        
+      ("external",rest) -> cont TKexternal rest
+      ("_",rest) -> cont TKwild rest
+      _ -> failP "invalid keyword" ('%':cs) 
+