Add standard library

[kaleidoscope-hs.git] / AST.hs

diff --git a/AST.hs b/AST.hs
index 5628e7c7cd74c8d0f04d5b4e9c908e245e5696f6..b019a2a2078f91c18a5046f63e10676f2c40d5aa 100644 (file)
--- a/AST.hs
+++ b/AST.hs
@@ -1,23 +1,89 @@
 module AST where
 
+import Data.Char
 import Text.Read 
-import Text.ParserCombinators.ReadP hiding ((+++))
+import Text.ParserCombinators.ReadP hiding ((+++), (<++), choice)
 
-data Expr = Num Float
-          | Add Expr Expr
+data Expr = Num Double
+          | Var String
+          | BinOp BinOp Expr Expr
+          | Call String [Expr]
+          | If Expr Expr Expr
+          | For String Expr Expr (Maybe Expr) Expr
+  deriving Show
+
+data BinOp = Add | Sub | Mul | Cmp Ordering
   deriving Show
 
 instance Read Expr where
-  readPrec = parseNum +++ parseAdd
+  readPrec = parens $ choice [ parseNum
+                             , parseVar
+                             , parseCall
+                             , parseIf
+                             , parseFor
+                             , parseBinOp "<" 10 (Cmp LT)
+                             , parseBinOp ">" 10 (Cmp GT)
+                             , parseBinOp "==" 10 (Cmp EQ)
+                             , 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
-          parseAdd = prec 1 $ do
+          parseVar = Var <$> lift (munch1 isAlpha)
+          parseBinOp s prc op = prec prc $ do
             a <- step readPrec
-            lift $ do
-              skipSpaces
-              char '+'
-              skipSpaces
+            spaced $ string s
             b <- readPrec
-            return (Add a b)
+            return (BinOp op a b)
+          parseCall = do
+            func <- lift (munch1 isAlpha)
+            params <- lift $ between (char '(') (char ')') $
+                        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)
+          parseFor = do
+            spaced $ string "for"
+            identifier <- lift (munch1 isAlpha)
+            spaced $ char '='
+            start <- readPrec
+            spaced $ char ','
+            cond <- readPrec
+            stp <- (spaced (char ',') >> Just <$> step readPrec)
+                     <++ pure Nothing
+            spaced $ string "in"
+            body <- readPrec
+            return (For identifier start cond stp body)
+          spaced f = lift $ skipSpaces >> f >> skipSpaces
+            
+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