Add unary plus (#253)

compiler/expr_visitor.py

@@ -410,6 +410,7 @@ class ExprVisitor(algorithm.Visitor):
 
   _UNARY_OP_TEMPLATES = {
       ast.Invert: 'πg.Invert(πF, {operand})',
+      ast.UAdd: 'πg.Pos(πF, {operand})',
       ast.USub: 'πg.Neg(πF, {operand})',
   }
 

compiler/expr_visitor_test.py

@@ -220,11 +220,7 @@ class ExprVisitorTest(unittest.TestCase):
 
   testUnaryOpNot = _MakeExprTest('not True')
   testUnaryOpInvert = _MakeExprTest('~4')
-
-  def testUnaryOpNotImplemented(self):
-    self.assertRaisesRegexp(util.ParseError, 'unary op not implemented',
-                            _ParseAndVisitExpr, '+foo')
-
+  testUnaryOpPos = _MakeExprTest('+4')
 
 def _MakeModuleBlock():
   return block.ModuleBlock('__main__', 'grumpy', 'grumpy/lib', '<test>', '',

runtime/core.go

@@ -640,6 +640,16 @@ func Oct(f *Frame, o *Object) (*Object, *BaseException) {
 	return o, nil
 }
 
+// Pos returns the result of o.__pos__ and is equivalent to the Python
+// expression "+o".
+func Pos(f *Frame, o *Object) (*Object, *BaseException) {
+	pos := o.typ.slots.Pos
+	if pos == nil {
+		return nil, f.RaiseType(TypeErrorType, fmt.Sprintf("bad operand type for unary +: '%s'", o.typ.Name()))
+	}
+	return pos.Fn(f, o)
+}
+
 // Print implements the Python print statement. It calls str() on the given args
 // and outputs the results to stdout separated by spaces. Similar to the Python
 // print statement.

runtime/core_test.go

@@ -795,6 +795,26 @@ func TestOct(t *testing.T) {
 	}
 }
 
+func TestPos(t *testing.T) {
+	pos := newTestClass("pos", []*Type{ObjectType}, newStringDict(map[string]*Object{
+		"__pos__": newBuiltinFunction("__pos__", func(f *Frame, _ Args, _ KWArgs) (*Object, *BaseException) {
+			return NewInt(-42).ToObject(), nil
+		}).ToObject(),
+	}))
+	cases := []invokeTestCase{
+		{args: wrapArgs(42), want: NewInt(42).ToObject()},
+		{args: wrapArgs(1.2), want: NewFloat(1.2).ToObject()},
+		{args: wrapArgs(NewLong(big.NewInt(123))), want: NewLong(big.NewInt(123)).ToObject()},
+		{args: wrapArgs(newObject(pos)), want: NewInt(-42).ToObject()},
+		{args: wrapArgs("foo"), wantExc: mustCreateException(TypeErrorType, "bad operand type for unary +: 'str'")},
+	}
+	for _, cas := range cases {
+		if err := runInvokeTestCase(wrapFuncForTest(Pos), &cas); err != "" {
+			t.Error(err)
+		}
+	}
+}
+
 func TestPyPrint(t *testing.T) {
 	fun := wrapFuncForTest(func(f *Frame, args *Tuple, sep, end string) (string, *BaseException) {
 		return captureStdout(f, func() *BaseException {

runtime/float.go

@@ -194,6 +194,10 @@ func floatNonZero(f *Frame, o *Object) (*Object, *BaseException) {
 	return GetBool(toFloatUnsafe(o).Value() != 0).ToObject(), nil
 }
 
+func floatPos(f *Frame, o *Object) (*Object, *BaseException) {
+	return o, nil
+}
+
 func floatPow(f *Frame, v, w *Object) (*Object, *BaseException) {
 	return floatArithmeticOp(f, "__pow__", v, w, func(v, w float64) float64 { return math.Pow(v, w) })
 }
@@ -257,6 +261,7 @@ func initFloatType(dict map[string]*Object) {
 	FloatType.slots.Neg = &unaryOpSlot{floatNeg}
 	FloatType.slots.New = &newSlot{floatNew}
 	FloatType.slots.NonZero = &unaryOpSlot{floatNonZero}
+	FloatType.slots.Pos = &unaryOpSlot{floatPos}
 	FloatType.slots.Pow = &binaryOpSlot{floatPow}
 	FloatType.slots.RAdd = &binaryOpSlot{floatRAdd}
 	FloatType.slots.RDiv = &binaryOpSlot{floatRDiv}

runtime/int.go

@@ -264,6 +264,10 @@ func intOr(f *Frame, v, w *Object) (*Object, *BaseException) {
 	return NewInt(toIntUnsafe(v).Value() | toIntUnsafe(w).Value()).ToObject(), nil
 }
 
+func intPos(f *Frame, o *Object) (*Object, *BaseException) {
+	return o, nil
+}
+
 func intPow(f *Frame, v, w *Object) (*Object, *BaseException) {
 	if w.isInstance(IntType) {
 		// First try to use the faster floating point arithmetic
@@ -388,6 +392,7 @@ func initIntType(dict map[string]*Object) {
 	IntType.slots.NonZero = &unaryOpSlot{intNonZero}
 	IntType.slots.Oct = &unaryOpSlot{intOct}
 	IntType.slots.Or = &binaryOpSlot{intOr}
+	IntType.slots.Pos = &unaryOpSlot{intPos}
 	IntType.slots.Pow = &binaryOpSlot{intPow}
 	IntType.slots.RAdd = &binaryOpSlot{intRAdd}
 	IntType.slots.RAnd = &binaryOpSlot{intAnd}

runtime/long.go

@@ -307,6 +307,10 @@ func longOr(z, x, y *big.Int) {
 	z.Or(x, y)
 }
 
+func longPos(z, x *big.Int) {
+	z.Set(x)
+}
+
 func longRepr(f *Frame, o *Object) (*Object, *BaseException) {
 	return NewStr(toLongUnsafe(o).value.Text(10) + "L").ToObject(), nil
 }
@@ -355,6 +359,7 @@ func initLongType(dict map[string]*Object) {
 	LongType.slots.NonZero = longUnaryBoolOpSlot(longNonZero)
 	LongType.slots.Oct = &unaryOpSlot{longOct}
 	LongType.slots.Or = longBinaryOpSlot(longOr)
+	LongType.slots.Pos = longUnaryOpSlot(longPos)
 	// This operation can return a float, it must use binaryOpSlot directly.
 	LongType.slots.Pow = &binaryOpSlot{longPow}
 	LongType.slots.RAdd = longRBinaryOpSlot(longAdd)

runtime/slots.go

@@ -420,6 +420,7 @@ type typeSlots struct {
 	NonZero      *unaryOpSlot
 	Oct          *unaryOpSlot
 	Or           *binaryOpSlot
+	Pos          *unaryOpSlot
 	Pow          *binaryOpSlot
 	RAdd         *binaryOpSlot
 	RAnd         *binaryOpSlot

testing/op_test.py

@@ -81,5 +81,28 @@ def TestNeg():
   assert -x == -100
 
 
+def TestPos():
+  x = 12
+  assert +x == 12
+
+  x = 1.1
+  assert +x == 1.1
+
+  x = 0.0
+  assert +x == 0.0
+
+  x = float('inf')
+  assert math.isinf(+x)
+
+  x = +float('inf')
+  assert math.isinf(+x)
+
+  x = float('nan')
+  assert math.isnan(+x)
+
+  x = long(100)
+  assert +x == 100
+
+
 if __name__ == '__main__':
   weetest.RunTests()