1 files changed, 121 insertions, 0 deletions
diff --git a/hs/AST.hs b/hs/AST.hs
new file mode 100644
index 0000000..a809d6e
--- /dev/null
+++ b/hs/AST.hs
@@ -0,0 +1,121 @@
+module AST where
+
+import Data.List
+import qualified GCStore as GCS (Id)
+
+
+type Name = String
+
+data Program = Program Block
+  deriving (Show)
+
+data Block = Block [Statement]
+  deriving (Show)
+
+data Statement
+    = Declaration Name Expression
+    | Assignment Name Expression
+    | Condition Expression Block Block
+    | Dive Name [Expression] Block
+    | Expr Expression
+  deriving (Show)
+
+data Expression
+    = EBin BinaryOp Expression Expression
+    | EUn UnaryOp Expression
+    | ELit Literal
+  deriving (Show)
+
+data Literal
+    = LNum Double
+    | LStr String
+    | LVar Name
+    | LBlock BlockType ArgList Block
+    | LGCSId GCS.Id
+    | LNil
+  deriving (Show)
+
+type ArgList = [Name]
+
+data BlockType = BT0 | BT1 | BT2  -- the number of ?'s
+  deriving (Show, Enum, Eq)
+
+data BinaryOp
+    = BOPlus | BOMinus | BOMul | BODiv | BOMod | BOPow
+    | BOLess | BOGreater | BOEqual | BOLEq | BOGEq
+    | BOBoolAnd | BOBoolOr
+  deriving (Show, Eq)
+
+data UnaryOp
+    = UONeg | UONot
+  deriving (Show, Eq)
+
+
+class ASTPretty a where
+    astPrettyI :: Int -> a -> String
+
+    astPretty :: a -> String
+    astPretty = astPrettyI 0
+
+
+indent :: Int -> String
+indent n = replicate (4*n) ' '
+
+instance ASTPretty Program where
+    astPrettyI i (Program (Block sts)) =
+        let pr = map (astPrettyI i) sts
+        in intercalate "\n" $ map (uncurry (++)) $ zip ("" : cycle [indent i]) pr
+
+instance ASTPretty Block where
+    astPrettyI _ (Block []) = "{}"
+    astPrettyI i (Block sts) =
+        let lns = map (('\n' : indent (i+1)) ++) $ map (astPrettyI (i+1)) sts
+        in "{" ++ concat lns ++ "\n" ++ indent i ++ "}"
+
+instance ASTPretty Statement where
+    astPrettyI i (Declaration n e) = n ++ " := " ++ astPrettyI i e ++ ";"
+    astPrettyI i (Assignment n e) = n ++ " = " ++ astPrettyI i e ++ ";"
+    astPrettyI i (Condition c b1 b2) =
+        "if " ++ astPrettyI i c ++ " " ++ astPrettyI i b1 ++ " else " ++ astPrettyI i b2
+    astPrettyI i (Dive n [] b) = n ++ " " ++ astPrettyI i b
+    astPrettyI i (Dive n al b) =
+        n ++ "(" ++ intercalate ", " (map (astPrettyI i) al) ++ ") " ++ astPrettyI i b
+    astPrettyI i (Expr e) = astPrettyI i e ++ ";"
+
+instance ASTPretty Expression where
+    astPrettyI i (EBin bo e1 e2) =
+        "(" ++ astPrettyI i e1 ++ ") " ++ astPrettyI i bo ++ " (" ++ astPrettyI i e2 ++ ")"
+    astPrettyI i (EUn uo e) =
+        astPrettyI i uo ++ "(" ++ astPrettyI i e ++ ")"
+    astPrettyI i (ELit l) = astPrettyI i l
+
+instance ASTPretty Literal where
+    astPrettyI _ (LNum m) = show m
+    astPrettyI _ (LStr s) = show s
+    astPrettyI _ (LVar n) = n
+    astPrettyI i (LBlock bt [] b) = replicate (fromEnum bt) '?' ++ astPrettyI i b
+    astPrettyI i (LBlock bt al b) =
+        replicate (fromEnum bt) '?' ++ "(" ++ intercalate ", " al ++ ")" ++ astPrettyI i b
+    astPrettyI _ (LGCSId d) = "<[" ++ show d ++ "]>"
+    astPrettyI _ LNil = "nil"
+
+instance ASTPretty BinaryOp where
+    astPrettyI _ bo = case bo of
+        BOPlus -> "+"
+        BOMinus -> "-"
+        BOMul -> "*"
+        BODiv -> "/"
+        BOMod -> "%"
+        BOPow -> "**"
+        BOLess -> "<"
+        BOGreater -> ">"
+        BOEqual -> "=="
+        BOLEq -> "<="
+        BOGEq -> ">="
+        BOBoolAnd -> "&&"
+        BOBoolOr -> "||"
+
+instance ASTPretty UnaryOp where
+    astPrettyI _ uo = case uo of
+        UONeg -> "-"
+        UONot -> "!"