X-Git-Url: http://git.lukelau.me/?a=blobdiff_plain;f=AST.hs;h=e491b648a7d45f7bd3b419b0e3ff6a8c215cbd83;hb=2f3c8f5cb6c8b9e6f5be02b20910f8105a9011a6;hp=5b22ea6c662714d483f1dd1ec51755e5f4b7dc7a;hpb=d6cecbbf067560322e391363250fd3c5d45bfbec;p=kaleidoscope-hs.git

diff --git a/AST.hs b/AST.hs
index 5b22ea6..e491b64 100644
--- a/AST.hs
+++ b/AST.hs
@@ -1,9 +1,11 @@
 module AST where
 
+import Data.Char
 import Text.Read 
 import Text.ParserCombinators.ReadP hiding ((+++), choice)
 
 data Expr = Num Float
+          | Var String
           | BinOp BinOp Expr Expr
   deriving Show
 
@@ -11,16 +13,15 @@ data BinOp = Add | Sub | Mul | Cmp Ordering
   deriving Show
 
 instance Read Expr where
-  readPrec = choice [ parseNum
+  readPrec = parens $ choice [ parseNum
+                             , parseVar
                              , parseBinOp "<" 10 (Cmp LT)
                              , parseBinOp "+" 20 Add
                              , parseBinOp "-" 20 Sub
                              , parseBinOp "*" 40 Mul
                              ]
     where parseNum = Num <$> readPrec
-          -- use 'prec 1' and 'step' so that parsing 'a'
-          -- can only go one step deep, to prevent ininfite
-          -- recursion
+          parseVar = Var <$> lift (munch1 isAlpha)
           parseBinOp s prc op = prec prc $ do
             a <- step readPrec
             lift $ do
@@ -30,3 +31,27 @@ instance Read Expr where
             b <- readPrec
             return (BinOp op a b)
             
+data Prototype = Prototype String [String]
+  deriving Show
+
+instance Read Prototype where
+  readPrec = lift $ do
+    name <- munch1 isAlpha
+    params <- between (char '(') (char ')') $
+                sepBy (munch1 isAlpha) skipSpaces
+    return (Prototype name params)
+
+data AST = Function Prototype Expr
+         | Extern Prototype
+         | TopLevelExpr Expr
+  deriving Show
+
+instance Read AST where
+  readPrec = parseFunction +++ parseExtern +++ parseTopLevel
+    where parseFunction = do
+            lift $ string "def" >> skipSpaces
+            Function <$> readPrec <*> readPrec
+          parseExtern = do
+            lift $ string "extern" >> skipSpaces
+            Extern <$> readPrec
+          parseTopLevel = TopLevelExpr <$> readPrec