Generate code for if statements

[kaleidoscope-hs.git] / AST.hs

diff --git a/AST.hs b/AST.hs
index 9ff555a74d10c6d970fc8b7df0a37c1d98fdbffc..ae18a52347ce91c37336a06f891bae690ba691ec 100644 (file)
--- a/AST.hs
+++ b/AST.hs
@@ -8,6 +8,7 @@ data Expr = Num Double
           | Var String
           | BinOp BinOp Expr Expr
           | Call String [Expr]
+          | If Expr Expr Expr
   deriving Show
 
 data BinOp = Add | Sub | Mul | Cmp Ordering
@@ -17,6 +18,7 @@ instance Read Expr where
   readPrec = parens $ choice [ parseNum
                              , parseVar
                              , parseCall
+                             , parseIf
                              , parseBinOp "<" 10 (Cmp LT)
                              , parseBinOp ">" 10 (Cmp GT)
                              , parseBinOp "==" 10 (Cmp EQ)
@@ -28,10 +30,7 @@ instance Read Expr where
           parseVar = Var <$> lift (munch1 isAlpha)
           parseBinOp s prc op = prec prc $ do
             a <- step readPrec
-            lift $ do
-              skipSpaces
-              string s
-              skipSpaces
+            spaced $ string s
             b <- readPrec
             return (BinOp op a b)
           parseCall = do
@@ -40,6 +39,15 @@ instance Read Expr where
                         sepBy (readS_to_P reads)
                               (skipSpaces >> char ',' >> skipSpaces)
             return (Call func params)
+          parseIf = do
+            spaced $ string "if" 
+            cond <- readPrec
+            spaced $ string "then"
+            thenE <- readPrec
+            spaced $ string "else"
+            elseE <- readPrec
+            return (If cond thenE elseE)
+          spaced f = lift $ skipSpaces >> f >> skipSpaces
             
 data Prototype = Prototype String [String]
   deriving Show