X-Git-Url: https://git.lukelau.me/?p=kaleidoscope-hs.git;a=blobdiff_plain;f=AST.hs;h=7dad3a19e91eab9f12657101bd224b5c81742d07;hp=5b22ea6c662714d483f1dd1ec51755e5f4b7dc7a;hb=8a66ac4f81c3d1eab3b13a9e58cee0098573eff1;hpb=d6cecbbf067560322e391363250fd3c5d45bfbec

diff --git a/AST.hs b/AST.hs
index 5b22ea6..7dad3a1 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
 
@@ -12,15 +14,14 @@ data BinOp = Add | Sub | Mul | Cmp Ordering
 
 instance Read Expr where
   readPrec = 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