示例#1
0
文件: expr.go 项目: tintohill/pythia
func (check *Checker) comparison(x, y *operand, op token.Token) {
	// spec: "In any comparison, the first operand must be assignable
	// to the type of the second operand, or vice versa."
	err := ""
	if x.assignableTo(check.conf, y.typ) || y.assignableTo(check.conf, x.typ) {
		defined := false
		switch op {
		case token.EQL, token.NEQ:
			// spec: "The equality operators == and != apply to operands that are comparable."
			defined = Comparable(x.typ) || x.isNil() && hasNil(y.typ) || y.isNil() && hasNil(x.typ)
		case token.LSS, token.LEQ, token.GTR, token.GEQ:
			// spec: The ordering operators <, <=, >, and >= apply to operands that are ordered."
			defined = isOrdered(x.typ)
		default:
			unreachable()
		}
		if !defined {
			typ := x.typ
			if x.isNil() {
				typ = y.typ
			}
			err = check.sprintf("operator %s not defined for %s", op, typ)
		}
	} else {
		err = check.sprintf("mismatched types %s and %s", x.typ, y.typ)
	}

	if err != "" {
		check.errorf(x.pos(), "cannot compare %s %s %s (%s)", x.expr, op, y.expr, err)
		x.mode = invalid
		return
	}

	if x.mode == constant && y.mode == constant {
		x.val = exact.MakeBool(exact.Compare(x.val, op, y.val))
		// The operands are never materialized; no need to update
		// their types.
	} else {
		x.mode = value
		// The operands have now their final types, which at run-
		// time will be materialized. Update the expression trees.
		// If the current types are untyped, the materialized type
		// is the respective default type.
		check.updateExprType(x.expr, defaultType(x.typ), true)
		check.updateExprType(y.expr, defaultType(y.typ), true)
	}

	// spec: "Comparison operators compare two operands and yield
	//        an untyped boolean value."
	x.typ = Typ[UntypedBool]
}
示例#2
0
func checkConstValue(t *testing.T, prog *ssa.Program, obj *types.Const) {
	c := prog.ConstValue(obj)
	// fmt.Printf("ConstValue(%s) = %s\n", obj, c) // debugging
	if c == nil {
		t.Errorf("ConstValue(%s) == nil", obj)
		return
	}
	if !types.Identical(c.Type(), obj.Type()) {
		t.Errorf("ConstValue(%s).Type() == %s", obj, c.Type())
		return
	}
	if obj.Name() != "nil" {
		if !exact.Compare(c.Value, token.EQL, obj.Val()) {
			t.Errorf("ConstValue(%s).Value (%s) != %s",
				obj, c.Value, obj.Val())
			return
		}
	}
}