Merge pull request #6 from mheinzel/bitwise-and-boolean-operators

Improvements for bitwise, logical and comparison operators

Author: mattgreen

src/Hython/Expression.hs

@@ -82,50 +82,30 @@ evalExpr (BinOp (BitOp op) leftExpr rightExpr) = do
             return None
 
 evalExpr (BinOp (BoolOp op) leftExpr rightExpr) = do
-    [lhs, rhs] <- mapM evalExpr [leftExpr, rightExpr]
-    case (op, lhs, rhs) of
-        (And, Bool l, Bool r)   -> newBool (l && r)
-        (And, l, r)             -> do
-            left    <- isTruthy l
-            right   <- isTruthy r
-            return $ if left && right
-                         then r
-                         else l
-        (Or, Bool l, Bool r)    -> newBool (l || r)
-        (Or, l, r)              -> do
-            left    <- isTruthy l
-            return $ if left
-                         then l
-                         else r
-
-evalExpr (BinOp (CompOp op) leftExpr rightExpr) = do
-    [lhs, rhs] <- mapM evalExpr [leftExpr, rightExpr]
-    case (op, lhs, rhs) of
-        (Eq, l, r) -> newBool =<< equal l r
-        (NotEq, l, r) -> do
-            b <- equal l r
-            newBool $ not b
-        (LessThan, Float l, Float r)        -> newBool (l < r)
-        (LessThan, Int l, Int r)            -> newBool (l < r)
-        (LessThanEq, Float l, Float r)      -> newBool (l <= r)
-        (LessThanEq, Int l, Int r)          -> newBool (l <= r)
-        (GreaterThan, Float l, Float r)     -> newBool (l > r)
-        (GreaterThan, Int l, Int r)         -> newBool (l > r)
-        (GreaterThanEq, Int l, Int r)       -> newBool (l >= r)
-        (GreaterThanEq, Float l, Float r)   -> newBool (l >= r)
-        (Is, l, r)                          -> newBool $ l `is` r
-        (IsNot, l, r)                       -> newBool . not $ l `is` r
-        (_, Float _, Int r)                 -> evalExpr (BinOp (CompOp op) leftExpr (constantF r))
-        (_, Int l, Float _)                 -> evalExpr (BinOp (CompOp op) (constantF l) rightExpr)
-        (In, l, r@(Object {}))              -> invoke r "__contains__" [l]
-        (NotIn, _, _)                       -> do
-            (Bool b) <- evalExpr (BinOp (CompOp In) leftExpr rightExpr)
-            newBool (not b)
-        _ -> do
-            raise "SystemError" ("unsupported operand type " ++ show op)
-            return None
+    lhs <- evalExpr leftExpr
+    lTruthy <- isTruthy lhs
+    case (op, lTruthy) of
+        (And, False) -> return lhs
+        (And, True)  -> evalExpr rightExpr
+        (Or,  False) -> evalExpr rightExpr
+        (Or,  True)  -> return lhs
+
+evalExpr (BinOp (CompOp operator) leftExpression rightExpression) = do
+    lhs <- evalExpr leftExpression
+    go operator lhs rightExpression
   where
-    constantF i = Constant $ ConstantFloat $ fromIntegral i
+    go :: (MonadCont m, MonadEnv Object m, MonadIO m, MonadInterpreter m)
+          => ComparisonOperator -> Object -> Expression -> m Object
+    -- for chained comparison, e.g. 1 < 2 < 3
+    go op lhs (BinOp (CompOp rop) rl rr) = do
+        rlhs <- evalExpr rl
+        comp <- compareObjs op lhs rlhs
+        case comp of
+            Bool True -> go rop rlhs rr
+            _         -> newBool False
+    go op lhs rightExpr = do
+        rhs <- evalExpr rightExpr
+        compareObjs op lhs rhs
 
 evalExpr (Call expr argExprs) = do
     target      <- evalExpr expr
@@ -266,6 +246,44 @@ evalParam (DefaultParam param expr) = do
 evalParam (SplatParam param) = return $ SParam param
 evalParam (DoubleSplatParam param) = return $ DSParam param
 
+
+compareObjs :: MonadInterpreter m => ComparisonOperator -> Object -> Object -> m Object
+compareObjs op lhs rhs = case (op, lhs, rhs) of
+    -- equality
+    (Eq,    l, r)             -> newBool =<< equal l r
+    (NotEq, l, r)             -> newBool . not =<< equal l r
+    -- "is", "is not", "in", "not in"
+    (Is,    l, r)             -> newBool $ l `is` r
+    (IsNot, l, r)             -> newBool . not $ l `is` r
+    (In,    l, r)             -> invoke r "__contains__" [l]
+    (NotIn, l, r)             -> do
+        Bool b <- invoke r "__contains__" [l]
+        newBool (not b)
+    -- conversion
+    (_, Bool l, _)          -> compareObjs op (Float (boolToFloat l)) rhs
+    (_, Int  l, _)          -> compareObjs op (Float (fromIntegral l)) rhs
+    (_, _, Bool r)          -> compareObjs op lhs (Float (boolToFloat r))
+    (_, _, Int  r)          -> compareObjs op lhs (Float (fromIntegral r))
+    -- comparison
+    (_, Bytes  l, Bytes  r)   -> applyOp op l r
+    (_, Float  l, Float  r)   -> applyOp op l r
+    (_, String l, String r)   -> applyOp op l r
+    -- error cases
+    _ -> do
+        raise "TypeError" "unorderable types"
+        return None
+  where
+    boolToFloat True  = 1
+    boolToFloat False = 0
+    applyOp :: (Ord a, MonadInterpreter m) => ComparisonOperator -> a -> a -> m Object
+    applyOp c a b = newBool $ compOp c a b
+    compOp LessThan = (<)
+    compOp LessThanEq = (<=)
+    compOp GreaterThan = (>)
+    compOp GreaterThanEq = (>=)
+    compOp _ = error "compOp: Eq, NotEq, Is, IsNot, In, NotIn should be handled"
+
+
 is :: Object -> Object -> Bool
 is None None                = True
 is (Bool l) (Bool r)        = l == r

src/Hython/Types.hs

@@ -223,27 +223,34 @@ isNone (None) = True
 isNone _ = False
 
 equal :: MonadInterpreter m => Object -> Object -> m Bool
-equal (Bool l) (Bool r)             = return $ l == r
-equal (Bytes l) (Bytes r)           = return $ l == r
-equal (Float l) (Float r)           = return $ l == r
-equal (Imaginary l) (Imaginary r)   = return $ l == r
-equal (Int l) (Int r)               = return $ l == r
-equal (String l) (String r)         = return $ l == r
-equal (BuiltinFn l) (BuiltinFn r)   = return $ l == r
-equal (Dict l) (Dict r) = do
-    left    <- readRef l
-    right   <- readRef r
-    if IntMap.size left /= IntMap.size right
-        then return False
-        else do
-            results <- zipWithM pairEqual (IntMap.elems left) (IntMap.elems right)
-            return $ all (== True) results
+equal lhs rhs = case (lhs, rhs) of
+    -- conversion
+    (Bool l, _) -> equal (Float (boolToFloat  l)) rhs
+    (Int  l, _) -> equal (Float (fromIntegral l)) rhs
+    (_, Bool r) -> equal lhs (Float (boolToFloat  r))
+    (_, Int  r) -> equal lhs (Float (fromIntegral r))
+    (None,        None       ) -> return True
+    (Bytes     l, Bytes     r) -> return $ l == r
+    (Float     l, Float     r) -> return $ l == r
+    (Imaginary l, Imaginary r) -> return $ l == r
+    (String    l, String    r) -> return $ l == r
+    (BuiltinFn l, BuiltinFn r) -> return $ l == r
+    (Dict      l, Dict      r) -> do
+        left    <- readRef l
+        right   <- readRef r
+        if IntMap.size left /= IntMap.size right
+            then return False
+            else do
+                results <- zipWithM pairEqual (IntMap.elems left) (IntMap.elems right)
+                return $ all (== True) results
+    (_, _) -> return False
   where
+    boolToFloat False = 0.0
+    boolToFloat True  = 1.0
     pairEqual (lk, lv) (rk, rv) = do
         k <- equal lk rk
         v <- equal lv rv
         return $ k && v
-equal _ _                           = return False
 
 isTruthy :: MonadInterpreter m => Object -> m Bool
 isTruthy (None) = return False

src/Language/Python/Parser.y

@@ -458,28 +458,25 @@ lambdef_nocond
     : LAMBDA varargslist ':' test_nocond    { LambdaExpr $2 $4 }
 
 -- or_test: and_test ('or' and_test)*
--- TODO: implement 0-n clauses
 or_test
     : and_test              { $1 }
-    | or_test OR and_test  { BinOp (BoolOp Or) $1 $3 }
+    | or_test OR and_test   { BinOp (BoolOp Or) $1 $3 }
 
 -- and_test: not_test ('and' not_test)*
--- TODO: implement 0-n clauses
 and_test
     : not_test              { $1 }
     | and_test AND not_test { BinOp (BoolOp And) $1 $3 }
 
 -- not_test: 'not' not_test | comparison
--- TODO: implement 0-n clauses
 not_test
     : NOT not_test          { UnaryOp Not $2 }
     | comparison            { $1 }
 
 -- comparison: expr (comp_op expr)*
--- TODO: implement 0-n clauses
+-- NOTE: right-recursive, because of 1 < 2 < 3 etc.
 comparison
-    : expr                  { $1 }
-    | expr comp_op expr     { BinOp (CompOp $2) $1 $3 }
+    : expr                     { $1 }
+    | expr comp_op comparison  { BinOp (CompOp $2) $1 $3 }
 
 -- comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
 comp_op
@@ -500,29 +497,25 @@ star_expr
     : '*' expr      { undefined }
 
 -- expr: xor_expr ('|' xor_expr)*
--- TODO: implement 0-n handling
 expr
     : xor_expr                      { $1 }
-    | xor_expr '|' xor_expr         { BinOp (BitOp BitOr) $1 $3 }
+    | expr '|' xor_expr             { BinOp (BitOp BitOr) $1 $3 }
 
 -- xor_expr: and_expr ('^' and_expr)*
--- TODO: implement 0-n handling
 xor_expr
     : and_expr                      { $1 }
-    | and_expr '^' and_expr         { BinOp (BitOp BitXor) $1 $3 }
+    | xor_expr '^' and_expr         { BinOp (BitOp BitXor) $1 $3 }
 
 -- and_expr: shift_expr ('&' shift_expr)*
--- TODO: implement 0-n handling
 and_expr
     : shift_expr                    { $1 }
-    | shift_expr '&' shift_expr     { BinOp (BitOp BitAnd) $1 $3 }
+    | and_expr '&' shift_expr       { BinOp (BitOp BitAnd) $1 $3 }
 
 -- shift_expr: arith_expr (('<<'|'>>') arith_expr)*
--- TODO: implement 0-n handling
 shift_expr
     : arith_expr                    { $1 }
-    | arith_expr '<<' arith_expr    { BinOp (BitOp LShift) $1 $3 }
-    | arith_expr '>>' arith_expr    { BinOp (BitOp RShift) $1 $3 }
+    | shift_expr '<<' arith_expr    { BinOp (BitOp LShift) $1 $3 }
+    | shift_expr '>>' arith_expr    { BinOp (BitOp RShift) $1 $3 }
 
 -- arith_expr: term (('+'|'-') term)*
 arith_expr

test/operators/arithmetic.py

@@ -0,0 +1,48 @@
+# Integral arithmetic
+print(+5)
+print(-5)
+
+print(1+1)
+print(3-5)
+print(2*4)
+print(3/5)
+print(5%2)
+print(5//2)
+print(5**3)
+print(0**0)
+
+# Floating point arithmetic
+print(+5.0)
+print(-5.0)
+print(1.0 + 2.0)
+print(2.0 - 0.5)
+print(1.0 * 1.6)
+print(1.0 / 4.8)
+print(5.0 % 2.0)
+print(5.0 // 2.0)
+print(5.0 ** 3.4)
+print(0.0 ** 0.0)
+
+# Mixed integral / floating point
+print(1 + 2.0)
+print(1.7 - 2)
+print(17.24 * 4)
+print(2 / 0.3)
+print(5.4 % 2)
+print(7 // 1.7)
+print(9.1 ** 3)
+print(2 ** 3.14159)
+
+# Precedence
+print(2**-1)
+
+print(3 - 2 + 1)
+print(1 + 2.2 * 3)
+print((1 + 2.2) * 3)
+print(3 + 5 % 2)
+print(10 / 3 // 2)
+print(4 + 2 ** 7)
+
+
+# TODO: imaginary number arithmetic
+#print(3.14j + 1.0)

test/operators/bitwise.py

@@ -4,3 +4,11 @@
 print(22 ^ 5)
 print(2 << 4)
 print(16 >> 2)
+
+# multiple
+print(~~19)
+print(197 & 92 & 345)
+print(197 | 92 | 345)
+print(197 ^ 92 ^ 345)
+print(1   << 2 << 3)
+print(256 >> 4 >> 3)

test/operators/comparison.py

@@ -0,0 +1,98 @@
+# Boolean operations
+print(42 == 42)
+print(42 != 18)
+
+# Integer boolean operations
+print(5 > 1)
+print(5 >= 5)
+print(4 < 1)
+print(4 <= 4)
+
+# Float boolean operators
+print(5.0 > 1.0)
+print(4.0 < 1.0)
+print(5.0 >= 5.0)
+print(4.0 <= 4.0)
+
+# Mixed int/float with operators
+print(5 == 1.0)
+print(4 != 1.0)
+print(5 > 1.0)
+print(4 < 1.0)
+print(5 >= 5.0)
+print(4 <= 4.0)
+
+print(5.0 == 1)
+print(4.0 != 1)
+print(5.0 > 1)
+print(4.0 < 1)
+print(5.0 >= 5)
+print(4.0 <= 4)
+
+
+# On strings
+print("test" == "test")
+print("" == "test")
+print("a" < "b")
+print("b" < "a")
+print("abc" < "abcde")
+
+
+# On bytes
+print(b'test' == b'test')
+print(b'' == b'test')
+print(b'a' < b'b')
+print(b'b' < b'a')
+print(b'abc' < b'abcde')
+
+
+# Mixed
+print("mixed!")
+elements = [-3, -0.00001, 0, 0.0, 1, 1.0, 32, "", "foo", b'fo', b'foo', False, True, None]
+for a in elements:
+    for b in elements:
+        try:
+            print("comparison")
+            print(a == b)
+            print(a != b)
+            print(a < b)
+            print(a > b)
+            print(a <= b)
+            print(a >= b)
+        except TypeError:
+            print("TypeError")
+
+
+# Chaining comparison operators
+print("chained")
+print(3 == 3 != 3)
+print(4 == 4 > 2)
+print(1 < 2 < 3 < 4)
+print(2 > 3 > -1)
+print(3 <= 10 > 17)
+print(-3 < 10 >= 10)
+
+# Mixed with other operators
+print(3 < 2 * 2 < 5)
+print(4 // 2 == 2 < 3)
+print(7 > 6 > 7 - 1 and (True and False) < True)
+
+def p(n):
+    print(n)
+    return n
+
+# Only evaluate each element once
+print(p(1) < p(2) < p(3) < p(4))
+
+# Stop after first wrong comparison
+print(p(7) < p(6) < p(8) < p(9))
+
+
+
+# TODO: is
+# TODO: Chained comparison operators
+# TODO: Comparison of lists, tuples
+# TODO: Equality of sets, dicts
+# TODO: Imaginary
+# TODO: objects with __eq__() etc.
+