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// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart = 2.9
// Verify semantics of the ??= operator, including order of operations, by
// keeping track of the operations performed.
import "package:expect/expect.dart";
import "assignment_helper.dart" as h;
bad() {
Expect.fail('Should not be executed');
}
var xGetValue = null;
get x {
h.operations.add('x');
var tmp = xGetValue;
xGetValue = null;
return tmp;
}
void set x(value) {
h.operations.add('x=$value');
}
var yGetValue = null;
get y {
h.operations.add('y');
var tmp = yGetValue;
yGetValue = null;
return tmp;
}
void set y(value) {
h.operations.add('y=$value');
}
var zGetValue = null;
get z {
h.operations.add('z');
var tmp = zGetValue;
zGetValue = null;
return tmp;
}
void set z(value) {
h.operations.add('z=$value');
}
var fValue = null;
f() {
h.operations.add('f()');
var tmp = fValue;
fValue = null;
return tmp;
}
void check(expectedValue, f(), expectedOperations) {
Expect.equals(expectedValue, f());
Expect.listEquals(expectedOperations, h.operations);
h.operations = [];
}
class C {
final String s;
C(this.s);
@override
String toString() => s;
static var xGetValue = null;
static get x {
h.operations.add('C.x');
var tmp = xGetValue;
xGetValue = null;
return tmp;
}
static void set x(value) {
h.operations.add('C.x=$value');
}
var vGetValue = null;
get v {
h.operations.add('$s.v');
var tmp = vGetValue;
vGetValue = null;
return tmp;
}
void set v(value) {
h.operations.add('$s.v=$value');
}
var indexGetValue = null;
operator [](index) {
h.operations.add('$s[$index]');
var tmp = indexGetValue;
indexGetValue = null;
return tmp;
}
void operator []=(index, value) {
h.operations.add('$s[$index]=$value');
}
final finalOne = 1;
final finalNull = null;
void instanceTest() {
// v ??= e is equivalent to ((x) => x == null ? v = e : x)(v)
vGetValue = 1; check(1, () => v ??= bad(), ['$s.v']);
yGetValue = 1; check(1, () => v ??= y, ['$s.v', 'y', '$s.v=1']);
finalOne ??= null;
// ^^^^^^^^
// [analyzer] COMPILE_TIME_ERROR.ASSIGNMENT_TO_FINAL
// [cfe] The setter 'finalOne' isn't defined for the class 'C'.
yGetValue = 1;
}
}
class D extends C {
D(String s) : super(s);
get v => bad();
void set v(value) {
bad();
}
void derivedInstanceTest() {
// super.v ??= e is equivalent to
// ((x) => x == null ? super.v = e : x)(super.v)
vGetValue = 1; check(1, () => super.v ??= bad(), ['$s.v']);
yGetValue = 1; check(1, () => super.v ??= y, ['$s.v', 'y', '$s.v=1']);
}
}
main() {
// Make sure the "none" test fails if "??=" is not implemented. This makes
// status files easier to maintain.
var _;
_ ??= null;
new C('c').instanceTest();
new D('d').derivedInstanceTest();
// v ??= e is equivalent to ((x) => x == null ? v = e : x)(v)
xGetValue = 1; check(1, () => x ??= bad(), ['x']);
yGetValue = 1; check(1, () => x ??= y, ['x', 'y', 'x=1']);
h.xGetValue = 1; check(1, () => h.x ??= bad(), ['h.x']);
yGetValue = 1; check(1, () => h.x ??= y, ['h.x', 'y', 'h.x=1']);
{ var l = 1; check(1, () => l ??= bad(), []); }
{ var l; yGetValue = 1; check(1, () => l ??= y, ['y']); Expect.equals(1, l); }
{ final l = 1; l ??= null; }
// ^
// [analyzer] COMPILE_TIME_ERROR.ASSIGNMENT_TO_FINAL_LOCAL
// [cfe] Can't assign to the final variable 'l'.
C ??= null;
//^
// [analyzer] COMPILE_TIME_ERROR.ASSIGNMENT_TO_TYPE
// [cfe] Can't assign to a type literal.
h ??= null;
//^
// [analyzer] COMPILE_TIME_ERROR.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT
// [cfe] A prefix can't be used as an expression.
h[0] ??= null;
//^
// [analyzer] COMPILE_TIME_ERROR.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT
// [cfe] A prefix can't be used as an expression.
// C.v ??= e is equivalent to ((x) => x == null ? C.v = e : x)(C.v)
C.xGetValue = 1; check(1, () => C.x ??= bad(), ['C.x']);
yGetValue = 1; check(1, () => C.x ??= y, ['C.x', 'y', 'C.x=1']);
h.C.xGetValue = 1; check(1, () => h.C.x ??= bad(), ['h.C.x']);
yGetValue = 1; check(1, () => h.C.x ??= y, ['h.C.x', 'y', 'h.C.x=1']);
// e1.v ??= e2 is equivalent to
// ((x) => ((y) => y == null ? x.v = e2 : y)(x.v))(e1)
xGetValue = new C('x'); xGetValue.vGetValue = 1;
check(1, () => x.v ??= bad(), ['x', 'x.v']);
xGetValue = new C('x'); yGetValue = 1;
check(1, () => x.v ??= y, ['x', 'x.v', 'y', 'x.v=1']);
fValue = new C('f()'); fValue.vGetValue = 1;
check(1, () => f().v ??= bad(), ['f()', 'f().v']);
fValue = new C('f()'); yGetValue = 1;
check(1, () => f().v ??= y, ['f()', 'f().v', 'y', 'f().v=1']);
// e1[e2] ??= e3 is equivalent to
// ((a, i) => ((x) => x == null ? a[i] = e3 : x)(a[i]))(e1, e2)
xGetValue = new C('x'); yGetValue = 1; xGetValue.indexGetValue = 2;
check(2, () => x[y] ??= bad(), ['x', 'y', 'x[1]']);
xGetValue = new C('x'); yGetValue = 1; zGetValue = 2;
check(2, () => x[y] ??= z, ['x', 'y', 'x[1]', 'z', 'x[1]=2']);
// e1?.v ??= e2 is equivalent to ((x) => x == null ? null : x.v ??= e2)(e1).
check(null, () => x?.v ??= bad(), ['x']);
xGetValue = new C('x'); xGetValue.vGetValue = 1;
check(1, () => x?.v ??= bad(), ['x', 'x.v']);
xGetValue = new C('x'); yGetValue = 1;
check(1, () => x?.v ??= y, ['x', 'x.v', 'y', 'x.v=1']);
// C?.v ??= e2 is equivalent to C.v ??= e2.
C.xGetValue = 1;
check(1, () => C?.x ??= bad(), ['C.x']);
h.C.xgetValue = 1;
// ^^^^^^^^^
// [analyzer] COMPILE_TIME_ERROR.UNDEFINED_SETTER
// [cfe] Setter not found: 'xgetValue'.
check(1, () => h.c?.x ??= bad(), ['h.C.x']);
// ^
// [analyzer] COMPILE_TIME_ERROR.UNDEFINED_PREFIXED_NAME
// [cfe] Undefined name 'c'.
yGetValue = 1;
check(1, () => C?.x ??= y, ['C.x', 'y', 'C.x=1']);
yGetValue = 1;
check(1, () => h.C?.x ??= y, ['h.C.x', 'y', 'h.C.x=1']);
}