mirror of
https://github.com/microsoft/TypeScript.git
synced 2026-03-15 14:05:47 -05:00
Merge branch 'typeguardsByConstructorSigniture' of https://github.com/vvakame/TypeScript into vvakame-typeguardsByConstructorSigniture
This commit is contained in:
@@ -3634,6 +3634,10 @@ module ts {
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return type;
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}
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function getUnionTypeOfSubtypeConstituents(source: UnionType, target: Type): Type {
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return getUnionType(filter(source.types, t => isTypeSubtypeOf(t, target)));
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}
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||||
|
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function getReducedTypeOfUnionType(type: UnionType): Type {
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// If union type was created without subtype reduction, perform the deferred reduction now
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if (!type.reducedType) {
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@@ -5386,17 +5390,35 @@ module ts {
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}
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// Target type is type of prototype property
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let prototypeProperty = getPropertyOfType(rightType, "prototype");
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if (!prototypeProperty) {
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return type;
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if (prototypeProperty) {
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let targetType = getTypeOfSymbol(prototypeProperty);
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if (targetType !== anyType) {
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// Narrow to the target type if it's a subtype of the current type
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if (isTypeSubtypeOf(targetType, type)) {
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return targetType;
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}
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// If the current type is a union type, remove all constituents that aren't subtypes of the target.
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if (type.flags & TypeFlags.Union) {
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return getUnionTypeOfSubtypeConstituents(<UnionType>type, targetType);
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}
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}
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}
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let targetType = getTypeOfSymbol(prototypeProperty);
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// Narrow to target type if it is a subtype of current type
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if (isTypeSubtypeOf(targetType, type)) {
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return targetType;
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// Target type is type of construct signature
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let constructSignatures: Signature[];
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if (rightType.flags & TypeFlags.Interface) {
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constructSignatures = resolveDeclaredMembers(<InterfaceType>rightType).declaredConstructSignatures;
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}
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// If current type is a union type, remove all constituents that aren't subtypes of target type
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if (type.flags & TypeFlags.Union) {
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return getUnionType(filter((<UnionType>type).types, t => isTypeSubtypeOf(t, targetType)));
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else if (rightType.flags & TypeFlags.Anonymous) {
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constructSignatures = getSignaturesOfType(rightType, SignatureKind.Construct);
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}
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if (constructSignatures && constructSignatures.length !== 0) {
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let instanceType = getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature))));
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// Pickup type from union types
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if (type.flags & TypeFlags.Union) {
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return getUnionTypeOfSubtypeConstituents(<UnionType>type, instanceType);
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}
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return instanceType;
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}
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return type;
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}
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@@ -0,0 +1,220 @@
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(12,10): error TS2339: Property 'bar' does not exist on type 'A'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(33,5): error TS2322: Type 'string' is not assignable to type 'number'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(34,10): error TS2339: Property 'bar' does not exist on type 'B<number>'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(63,10): error TS2339: Property 'bar2' does not exist on type 'C1'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(82,10): error TS2339: Property 'bar' does not exist on type 'D'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(109,10): error TS2339: Property 'bar2' does not exist on type 'E1'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(131,11): error TS2339: Property 'foo' does not exist on type 'string | F'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(132,11): error TS2339: Property 'bar' does not exist on type 'string | F'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(157,11): error TS2339: Property 'foo2' does not exist on type 'G1'.
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tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts(179,11): error TS2339: Property 'bar' does not exist on type 'H'.
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==== tests/cases/conformance/expressions/typeGuards/typeGuardsWithInstanceOfByConstructorSignature.ts (10 errors) ====
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interface AConstructor {
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new (): A;
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}
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interface A {
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foo: string;
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}
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declare var A: AConstructor;
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var obj1: A | string;
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if (obj1 instanceof A) { // narrowed to A.
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obj1.foo;
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obj1.bar;
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~~~
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!!! error TS2339: Property 'bar' does not exist on type 'A'.
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}
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var obj2: any;
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if (obj2 instanceof A) { // can't narrow type from 'any'
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obj2.foo;
|
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obj2.bar;
|
||||
}
|
||||
|
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// a construct signature with generics
|
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interface BConstructor {
|
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new <T>(): B<T>;
|
||||
}
|
||||
interface B<T> {
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foo: T;
|
||||
}
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declare var B: BConstructor;
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||||
|
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var obj3: B<number> | string;
|
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if (obj3 instanceof B) { // narrowed to B<number>.
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obj3.foo = 1;
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obj3.foo = "str";
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~~~~~~~~
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!!! error TS2322: Type 'string' is not assignable to type 'number'.
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obj3.bar = "str";
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~~~
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!!! error TS2339: Property 'bar' does not exist on type 'B<number>'.
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}
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||||
|
||||
var obj4: any;
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if (obj4 instanceof B) { // can't narrow type from 'any'
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obj4.foo = "str";
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obj4.foo = 1;
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obj4.bar = "str";
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||||
}
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||||
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// has multiple construct signature
|
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interface CConstructor {
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new (value: string): C1;
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new (value: number): C2;
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||||
}
|
||||
interface C1 {
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foo: string;
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bar1: number;
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||||
}
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||||
interface C2 {
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foo: string;
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||||
bar2: number;
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}
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declare var C: CConstructor;
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var obj5: C1 | A;
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if (obj5 instanceof C) { // narrowed to C1.
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obj5.foo;
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obj5.bar1;
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obj5.bar2;
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~~~~
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!!! error TS2339: Property 'bar2' does not exist on type 'C1'.
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||||
}
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||||
|
||||
var obj6: any;
|
||||
if (obj6 instanceof C) { // can't narrow type from 'any'
|
||||
obj6.foo;
|
||||
obj6.bar1;
|
||||
obj6.bar2;
|
||||
}
|
||||
|
||||
// with object type literal
|
||||
interface D {
|
||||
foo: string;
|
||||
}
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||||
declare var D: { new (): D; };
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||||
|
||||
var obj7: D | string;
|
||||
if (obj7 instanceof D) { // narrowed to D.
|
||||
obj7.foo;
|
||||
obj7.bar;
|
||||
~~~
|
||||
!!! error TS2339: Property 'bar' does not exist on type 'D'.
|
||||
}
|
||||
|
||||
var obj8: any;
|
||||
if (obj8 instanceof D) { // can't narrow type from 'any'
|
||||
obj8.foo;
|
||||
obj8.bar;
|
||||
}
|
||||
|
||||
// a construct signature that returns a union type
|
||||
interface EConstructor {
|
||||
new (): E1 | E2;
|
||||
}
|
||||
interface E1 {
|
||||
foo: string;
|
||||
bar1: number;
|
||||
}
|
||||
interface E2 {
|
||||
foo: string;
|
||||
bar2: number;
|
||||
}
|
||||
declare var E: EConstructor;
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||||
|
||||
var obj9: E1 | A;
|
||||
if (obj9 instanceof E) { // narrowed to E1.
|
||||
obj9.foo;
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||||
obj9.bar1;
|
||||
obj9.bar2;
|
||||
~~~~
|
||||
!!! error TS2339: Property 'bar2' does not exist on type 'E1'.
|
||||
}
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||||
|
||||
var obj10: any;
|
||||
if (obj10 instanceof E) { // can't narrow type from 'any'
|
||||
obj10.foo;
|
||||
obj10.bar1;
|
||||
obj10.bar2;
|
||||
}
|
||||
|
||||
// a construct signature that returns any
|
||||
interface FConstructor {
|
||||
new (): any;
|
||||
}
|
||||
interface F {
|
||||
foo: string;
|
||||
bar: number;
|
||||
}
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||||
declare var F: FConstructor;
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||||
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||||
var obj11: F | string;
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||||
if (obj11 instanceof F) { // can't type narrowing, construct signature returns any.
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obj11.foo;
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||||
~~~
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||||
!!! error TS2339: Property 'foo' does not exist on type 'string | F'.
|
||||
obj11.bar;
|
||||
~~~
|
||||
!!! error TS2339: Property 'bar' does not exist on type 'string | F'.
|
||||
}
|
||||
|
||||
var obj12: any;
|
||||
if (obj12 instanceof F) { // can't narrow type from 'any'
|
||||
obj12.foo;
|
||||
obj12.bar;
|
||||
}
|
||||
|
||||
// a type with a prototype, it overrides the construct signature
|
||||
interface GConstructor {
|
||||
prototype: G1; // high priority
|
||||
new (): G2; // low priority
|
||||
}
|
||||
interface G1 {
|
||||
foo1: number;
|
||||
}
|
||||
interface G2 {
|
||||
foo2: boolean;
|
||||
}
|
||||
declare var G: GConstructor;
|
||||
|
||||
var obj13: G1 | G2;
|
||||
if (obj13 instanceof G) { // narrowed to G1. G1 is return type of prototype property.
|
||||
obj13.foo1;
|
||||
obj13.foo2;
|
||||
~~~~
|
||||
!!! error TS2339: Property 'foo2' does not exist on type 'G1'.
|
||||
}
|
||||
|
||||
var obj14: any;
|
||||
if (obj14 instanceof G) { // can't narrow type from 'any'
|
||||
obj14.foo1;
|
||||
obj14.foo2;
|
||||
}
|
||||
|
||||
// a type with a prototype that has any type
|
||||
interface HConstructor {
|
||||
prototype: any; // high priority, but any type is ignored. interface has implicit `prototype: any`.
|
||||
new (): H; // low priority
|
||||
}
|
||||
interface H {
|
||||
foo: number;
|
||||
}
|
||||
declare var H: HConstructor;
|
||||
|
||||
var obj15: H | string;
|
||||
if (obj15 instanceof H) { // narrowed to H.
|
||||
obj15.foo;
|
||||
obj15.bar;
|
||||
~~~
|
||||
!!! error TS2339: Property 'bar' does not exist on type 'H'.
|
||||
}
|
||||
|
||||
var obj16: any;
|
||||
if (obj16 instanceof H) { // can't narrow type from 'any'
|
||||
obj16.foo1;
|
||||
obj16.foo2;
|
||||
}
|
||||
|
||||
@@ -0,0 +1,276 @@
|
||||
//// [typeGuardsWithInstanceOfByConstructorSignature.ts]
|
||||
interface AConstructor {
|
||||
new (): A;
|
||||
}
|
||||
interface A {
|
||||
foo: string;
|
||||
}
|
||||
declare var A: AConstructor;
|
||||
|
||||
var obj1: A | string;
|
||||
if (obj1 instanceof A) { // narrowed to A.
|
||||
obj1.foo;
|
||||
obj1.bar;
|
||||
}
|
||||
|
||||
var obj2: any;
|
||||
if (obj2 instanceof A) { // can't narrow type from 'any'
|
||||
obj2.foo;
|
||||
obj2.bar;
|
||||
}
|
||||
|
||||
// a construct signature with generics
|
||||
interface BConstructor {
|
||||
new <T>(): B<T>;
|
||||
}
|
||||
interface B<T> {
|
||||
foo: T;
|
||||
}
|
||||
declare var B: BConstructor;
|
||||
|
||||
var obj3: B<number> | string;
|
||||
if (obj3 instanceof B) { // narrowed to B<number>.
|
||||
obj3.foo = 1;
|
||||
obj3.foo = "str";
|
||||
obj3.bar = "str";
|
||||
}
|
||||
|
||||
var obj4: any;
|
||||
if (obj4 instanceof B) { // can't narrow type from 'any'
|
||||
obj4.foo = "str";
|
||||
obj4.foo = 1;
|
||||
obj4.bar = "str";
|
||||
}
|
||||
|
||||
// has multiple construct signature
|
||||
interface CConstructor {
|
||||
new (value: string): C1;
|
||||
new (value: number): C2;
|
||||
}
|
||||
interface C1 {
|
||||
foo: string;
|
||||
bar1: number;
|
||||
}
|
||||
interface C2 {
|
||||
foo: string;
|
||||
bar2: number;
|
||||
}
|
||||
declare var C: CConstructor;
|
||||
|
||||
var obj5: C1 | A;
|
||||
if (obj5 instanceof C) { // narrowed to C1.
|
||||
obj5.foo;
|
||||
obj5.bar1;
|
||||
obj5.bar2;
|
||||
}
|
||||
|
||||
var obj6: any;
|
||||
if (obj6 instanceof C) { // can't narrow type from 'any'
|
||||
obj6.foo;
|
||||
obj6.bar1;
|
||||
obj6.bar2;
|
||||
}
|
||||
|
||||
// with object type literal
|
||||
interface D {
|
||||
foo: string;
|
||||
}
|
||||
declare var D: { new (): D; };
|
||||
|
||||
var obj7: D | string;
|
||||
if (obj7 instanceof D) { // narrowed to D.
|
||||
obj7.foo;
|
||||
obj7.bar;
|
||||
}
|
||||
|
||||
var obj8: any;
|
||||
if (obj8 instanceof D) { // can't narrow type from 'any'
|
||||
obj8.foo;
|
||||
obj8.bar;
|
||||
}
|
||||
|
||||
// a construct signature that returns a union type
|
||||
interface EConstructor {
|
||||
new (): E1 | E2;
|
||||
}
|
||||
interface E1 {
|
||||
foo: string;
|
||||
bar1: number;
|
||||
}
|
||||
interface E2 {
|
||||
foo: string;
|
||||
bar2: number;
|
||||
}
|
||||
declare var E: EConstructor;
|
||||
|
||||
var obj9: E1 | A;
|
||||
if (obj9 instanceof E) { // narrowed to E1.
|
||||
obj9.foo;
|
||||
obj9.bar1;
|
||||
obj9.bar2;
|
||||
}
|
||||
|
||||
var obj10: any;
|
||||
if (obj10 instanceof E) { // can't narrow type from 'any'
|
||||
obj10.foo;
|
||||
obj10.bar1;
|
||||
obj10.bar2;
|
||||
}
|
||||
|
||||
// a construct signature that returns any
|
||||
interface FConstructor {
|
||||
new (): any;
|
||||
}
|
||||
interface F {
|
||||
foo: string;
|
||||
bar: number;
|
||||
}
|
||||
declare var F: FConstructor;
|
||||
|
||||
var obj11: F | string;
|
||||
if (obj11 instanceof F) { // can't type narrowing, construct signature returns any.
|
||||
obj11.foo;
|
||||
obj11.bar;
|
||||
}
|
||||
|
||||
var obj12: any;
|
||||
if (obj12 instanceof F) { // can't narrow type from 'any'
|
||||
obj12.foo;
|
||||
obj12.bar;
|
||||
}
|
||||
|
||||
// a type with a prototype, it overrides the construct signature
|
||||
interface GConstructor {
|
||||
prototype: G1; // high priority
|
||||
new (): G2; // low priority
|
||||
}
|
||||
interface G1 {
|
||||
foo1: number;
|
||||
}
|
||||
interface G2 {
|
||||
foo2: boolean;
|
||||
}
|
||||
declare var G: GConstructor;
|
||||
|
||||
var obj13: G1 | G2;
|
||||
if (obj13 instanceof G) { // narrowed to G1. G1 is return type of prototype property.
|
||||
obj13.foo1;
|
||||
obj13.foo2;
|
||||
}
|
||||
|
||||
var obj14: any;
|
||||
if (obj14 instanceof G) { // can't narrow type from 'any'
|
||||
obj14.foo1;
|
||||
obj14.foo2;
|
||||
}
|
||||
|
||||
// a type with a prototype that has any type
|
||||
interface HConstructor {
|
||||
prototype: any; // high priority, but any type is ignored. interface has implicit `prototype: any`.
|
||||
new (): H; // low priority
|
||||
}
|
||||
interface H {
|
||||
foo: number;
|
||||
}
|
||||
declare var H: HConstructor;
|
||||
|
||||
var obj15: H | string;
|
||||
if (obj15 instanceof H) { // narrowed to H.
|
||||
obj15.foo;
|
||||
obj15.bar;
|
||||
}
|
||||
|
||||
var obj16: any;
|
||||
if (obj16 instanceof H) { // can't narrow type from 'any'
|
||||
obj16.foo1;
|
||||
obj16.foo2;
|
||||
}
|
||||
|
||||
|
||||
//// [typeGuardsWithInstanceOfByConstructorSignature.js]
|
||||
var obj1;
|
||||
if (obj1 instanceof A) {
|
||||
obj1.foo;
|
||||
obj1.bar;
|
||||
}
|
||||
var obj2;
|
||||
if (obj2 instanceof A) {
|
||||
obj2.foo;
|
||||
obj2.bar;
|
||||
}
|
||||
var obj3;
|
||||
if (obj3 instanceof B) {
|
||||
obj3.foo = 1;
|
||||
obj3.foo = "str";
|
||||
obj3.bar = "str";
|
||||
}
|
||||
var obj4;
|
||||
if (obj4 instanceof B) {
|
||||
obj4.foo = "str";
|
||||
obj4.foo = 1;
|
||||
obj4.bar = "str";
|
||||
}
|
||||
var obj5;
|
||||
if (obj5 instanceof C) {
|
||||
obj5.foo;
|
||||
obj5.bar1;
|
||||
obj5.bar2;
|
||||
}
|
||||
var obj6;
|
||||
if (obj6 instanceof C) {
|
||||
obj6.foo;
|
||||
obj6.bar1;
|
||||
obj6.bar2;
|
||||
}
|
||||
var obj7;
|
||||
if (obj7 instanceof D) {
|
||||
obj7.foo;
|
||||
obj7.bar;
|
||||
}
|
||||
var obj8;
|
||||
if (obj8 instanceof D) {
|
||||
obj8.foo;
|
||||
obj8.bar;
|
||||
}
|
||||
var obj9;
|
||||
if (obj9 instanceof E) {
|
||||
obj9.foo;
|
||||
obj9.bar1;
|
||||
obj9.bar2;
|
||||
}
|
||||
var obj10;
|
||||
if (obj10 instanceof E) {
|
||||
obj10.foo;
|
||||
obj10.bar1;
|
||||
obj10.bar2;
|
||||
}
|
||||
var obj11;
|
||||
if (obj11 instanceof F) {
|
||||
obj11.foo;
|
||||
obj11.bar;
|
||||
}
|
||||
var obj12;
|
||||
if (obj12 instanceof F) {
|
||||
obj12.foo;
|
||||
obj12.bar;
|
||||
}
|
||||
var obj13;
|
||||
if (obj13 instanceof G) {
|
||||
obj13.foo1;
|
||||
obj13.foo2;
|
||||
}
|
||||
var obj14;
|
||||
if (obj14 instanceof G) {
|
||||
obj14.foo1;
|
||||
obj14.foo2;
|
||||
}
|
||||
var obj15;
|
||||
if (obj15 instanceof H) {
|
||||
obj15.foo;
|
||||
obj15.bar;
|
||||
}
|
||||
var obj16;
|
||||
if (obj16 instanceof H) {
|
||||
obj16.foo1;
|
||||
obj16.foo2;
|
||||
}
|
||||
@@ -0,0 +1,186 @@
|
||||
interface AConstructor {
|
||||
new (): A;
|
||||
}
|
||||
interface A {
|
||||
foo: string;
|
||||
}
|
||||
declare var A: AConstructor;
|
||||
|
||||
var obj1: A | string;
|
||||
if (obj1 instanceof A) { // narrowed to A.
|
||||
obj1.foo;
|
||||
obj1.bar;
|
||||
}
|
||||
|
||||
var obj2: any;
|
||||
if (obj2 instanceof A) { // can't narrow type from 'any'
|
||||
obj2.foo;
|
||||
obj2.bar;
|
||||
}
|
||||
|
||||
// a construct signature with generics
|
||||
interface BConstructor {
|
||||
new <T>(): B<T>;
|
||||
}
|
||||
interface B<T> {
|
||||
foo: T;
|
||||
}
|
||||
declare var B: BConstructor;
|
||||
|
||||
var obj3: B<number> | string;
|
||||
if (obj3 instanceof B) { // narrowed to B<number>.
|
||||
obj3.foo = 1;
|
||||
obj3.foo = "str";
|
||||
obj3.bar = "str";
|
||||
}
|
||||
|
||||
var obj4: any;
|
||||
if (obj4 instanceof B) { // can't narrow type from 'any'
|
||||
obj4.foo = "str";
|
||||
obj4.foo = 1;
|
||||
obj4.bar = "str";
|
||||
}
|
||||
|
||||
// has multiple construct signature
|
||||
interface CConstructor {
|
||||
new (value: string): C1;
|
||||
new (value: number): C2;
|
||||
}
|
||||
interface C1 {
|
||||
foo: string;
|
||||
bar1: number;
|
||||
}
|
||||
interface C2 {
|
||||
foo: string;
|
||||
bar2: number;
|
||||
}
|
||||
declare var C: CConstructor;
|
||||
|
||||
var obj5: C1 | A;
|
||||
if (obj5 instanceof C) { // narrowed to C1.
|
||||
obj5.foo;
|
||||
obj5.bar1;
|
||||
obj5.bar2;
|
||||
}
|
||||
|
||||
var obj6: any;
|
||||
if (obj6 instanceof C) { // can't narrow type from 'any'
|
||||
obj6.foo;
|
||||
obj6.bar1;
|
||||
obj6.bar2;
|
||||
}
|
||||
|
||||
// with object type literal
|
||||
interface D {
|
||||
foo: string;
|
||||
}
|
||||
declare var D: { new (): D; };
|
||||
|
||||
var obj7: D | string;
|
||||
if (obj7 instanceof D) { // narrowed to D.
|
||||
obj7.foo;
|
||||
obj7.bar;
|
||||
}
|
||||
|
||||
var obj8: any;
|
||||
if (obj8 instanceof D) { // can't narrow type from 'any'
|
||||
obj8.foo;
|
||||
obj8.bar;
|
||||
}
|
||||
|
||||
// a construct signature that returns a union type
|
||||
interface EConstructor {
|
||||
new (): E1 | E2;
|
||||
}
|
||||
interface E1 {
|
||||
foo: string;
|
||||
bar1: number;
|
||||
}
|
||||
interface E2 {
|
||||
foo: string;
|
||||
bar2: number;
|
||||
}
|
||||
declare var E: EConstructor;
|
||||
|
||||
var obj9: E1 | A;
|
||||
if (obj9 instanceof E) { // narrowed to E1.
|
||||
obj9.foo;
|
||||
obj9.bar1;
|
||||
obj9.bar2;
|
||||
}
|
||||
|
||||
var obj10: any;
|
||||
if (obj10 instanceof E) { // can't narrow type from 'any'
|
||||
obj10.foo;
|
||||
obj10.bar1;
|
||||
obj10.bar2;
|
||||
}
|
||||
|
||||
// a construct signature that returns any
|
||||
interface FConstructor {
|
||||
new (): any;
|
||||
}
|
||||
interface F {
|
||||
foo: string;
|
||||
bar: number;
|
||||
}
|
||||
declare var F: FConstructor;
|
||||
|
||||
var obj11: F | string;
|
||||
if (obj11 instanceof F) { // can't type narrowing, construct signature returns any.
|
||||
obj11.foo;
|
||||
obj11.bar;
|
||||
}
|
||||
|
||||
var obj12: any;
|
||||
if (obj12 instanceof F) { // can't narrow type from 'any'
|
||||
obj12.foo;
|
||||
obj12.bar;
|
||||
}
|
||||
|
||||
// a type with a prototype, it overrides the construct signature
|
||||
interface GConstructor {
|
||||
prototype: G1; // high priority
|
||||
new (): G2; // low priority
|
||||
}
|
||||
interface G1 {
|
||||
foo1: number;
|
||||
}
|
||||
interface G2 {
|
||||
foo2: boolean;
|
||||
}
|
||||
declare var G: GConstructor;
|
||||
|
||||
var obj13: G1 | G2;
|
||||
if (obj13 instanceof G) { // narrowed to G1. G1 is return type of prototype property.
|
||||
obj13.foo1;
|
||||
obj13.foo2;
|
||||
}
|
||||
|
||||
var obj14: any;
|
||||
if (obj14 instanceof G) { // can't narrow type from 'any'
|
||||
obj14.foo1;
|
||||
obj14.foo2;
|
||||
}
|
||||
|
||||
// a type with a prototype that has any type
|
||||
interface HConstructor {
|
||||
prototype: any; // high priority, but any type is ignored. interface has implicit `prototype: any`.
|
||||
new (): H; // low priority
|
||||
}
|
||||
interface H {
|
||||
foo: number;
|
||||
}
|
||||
declare var H: HConstructor;
|
||||
|
||||
var obj15: H | string;
|
||||
if (obj15 instanceof H) { // narrowed to H.
|
||||
obj15.foo;
|
||||
obj15.bar;
|
||||
}
|
||||
|
||||
var obj16: any;
|
||||
if (obj16 instanceof H) { // can't narrow type from 'any'
|
||||
obj16.foo1;
|
||||
obj16.foo2;
|
||||
}
|
||||
Reference in New Issue
Block a user