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Improve generic type signature of Iterator.from() #59927

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4e547ba
Improve generic type signature of Iterator.from()
nikolaybotev Sep 10, 2024
d8fcd4f
Add TNext argument and default value for TReturn
nikolaybotev Sep 10, 2024
c073b9f
Update baselines
nikolaybotev Sep 10, 2024
667ef7f
Add test case for iterator returned from Iterator.from() passing alon…
nikolaybotev Sep 10, 2024
36bedbf
Rename type parameter TResult in Iterator class to TReturn for consis…
nikolaybotev Sep 10, 2024
80a059e
Revert addition of TNext type argument to Iterator.from
nikolaybotev Sep 10, 2024
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Add test case for iterator returned from Iterator.from() passing alon… 
…g the return value of the wrapped iterator
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@nikolaybotev
nikolaybotev committed Sep 10, 2024
commit 667ef7fb4d506fa4fafeb7015795e0bba4ec7357
11 changes: 10 additions & 1 deletion tests/baselines/reference/builtinIterator.errors.txt
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Expand Up @@ -142,4 +142,13 @@ builtinIterator.ts(73,35): error TS2322: Type 'Generator<string, number, boolean
!!! error TS2322: Type '[undefined]' is not assignable to type '[] | [boolean]'.
!!! error TS2322: Type '[undefined]' is not assignable to type '[boolean]'.
!!! error TS2322: Type 'undefined' is not assignable to type 'boolean'.
!!! related TS6502 lib.esnext.iterator.d.ts:--:--: The expected type comes from the return type of this signature.
!!! related TS6502 lib.esnext.iterator.d.ts:--:--: The expected type comes from the return type of this signature.

// Iterator.from pass-through of return value
const customGenerator = function* () {
return 42;
}();
const withHelpers = Iterator.from(customGenerator);
const result = withHelpers.next();
const resultValue: number = result.value; // this should work

18 changes: 17 additions & 1 deletion tests/baselines/reference/builtinIterator.js
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Expand Up @@ -73,7 +73,16 @@ declare const g1: Generator<string, number, boolean>;
const iter1 = Iterator.from(g1);

declare const iter2: IteratorObject<string>;
const iter3 = iter2.flatMap(() => g1);
const iter3 = iter2.flatMap(() => g1);

// Iterator.from pass-through of return value
const customGenerator = function* () {
return 42;
}();
const withHelpers = Iterator.from(customGenerator);
const result = withHelpers.next();
const resultValue: number = result.value; // this should work


//// [builtinIterator.js]
"use strict";
Expand Down Expand Up @@ -134,3 +143,10 @@ class BadIterator3 extends Iterator {
}
const iter1 = Iterator.from(g1);
const iter3 = iter2.flatMap(() => g1);
// Iterator.from pass-through of return value
const customGenerator = function* () {
return 42;
}();
const withHelpers = Iterator.from(customGenerator);
const result = withHelpers.next();
const resultValue = result.value; // this should work
25 changes: 25 additions & 0 deletions tests/baselines/reference/builtinIterator.symbols
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Expand Up @@ -193,3 +193,28 @@ const iter3 = iter2.flatMap(() => g1);
>flatMap : Symbol(IteratorObject.flatMap, Decl(lib.esnext.iterator.d.ts, --, --))
>g1 : Symbol(g1, Decl(builtinIterator.ts, 68, 13))

// Iterator.from pass-through of return value
const customGenerator = function* () {
>customGenerator : Symbol(customGenerator, Decl(builtinIterator.ts, 75, 5))

return 42;
}();
const withHelpers = Iterator.from(customGenerator);
>withHelpers : Symbol(withHelpers, Decl(builtinIterator.ts, 78, 5))
>Iterator.from : Symbol(IteratorConstructor.from, Decl(lib.esnext.iterator.d.ts, --, --))
>Iterator : Symbol(Iterator, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.esnext.iterator.d.ts, --, --))
>from : Symbol(IteratorConstructor.from, Decl(lib.esnext.iterator.d.ts, --, --))
>customGenerator : Symbol(customGenerator, Decl(builtinIterator.ts, 75, 5))

const result = withHelpers.next();
>result : Symbol(result, Decl(builtinIterator.ts, 79, 5))
>withHelpers.next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))
>withHelpers : Symbol(withHelpers, Decl(builtinIterator.ts, 78, 5))
>next : Symbol(Iterator.next, Decl(lib.es2015.iterable.d.ts, --, --))

const resultValue: number = result.value; // this should work
>resultValue : Symbol(resultValue, Decl(builtinIterator.ts, 80, 5))
>result.value : Symbol(value, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --))
>result : Symbol(result, Decl(builtinIterator.ts, 79, 5))
>value : Symbol(value, Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --))

50 changes: 50 additions & 0 deletions tests/baselines/reference/builtinIterator.types
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Expand Up @@ -426,3 +426,53 @@ const iter3 = iter2.flatMap(() => g1);
>g1 : Generator<string, number, boolean>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

// Iterator.from pass-through of return value
const customGenerator = function* () {
>customGenerator : Generator<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>function* () { return 42;}() : Generator<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>function* () { return 42;} : () => Generator<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

return 42;
>42 : 42
> : ^^

}();
const withHelpers = Iterator.from(customGenerator);
>withHelpers : IteratorObject<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Iterator.from(customGenerator) : IteratorObject<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>Iterator.from : <T, TReturn = any, TNext = any>(value: Iterator<T, TReturn, TNext> | Iterable<T, TReturn, TNext>) => IteratorObject<T, TReturn, unknown>
> : ^ ^^ ^^^^^^^^ ^^^^^^^^ ^^ ^^^^^
>Iterator : IteratorConstructor
> : ^^^^^^^^^^^^^^^^^^^
>from : <T, TReturn = any, TNext = any>(value: Iterator<T, TReturn, TNext> | Iterable<T, TReturn, TNext>) => IteratorObject<T, TReturn, unknown>
> : ^ ^^ ^^^^^^^^ ^^^^^^^^ ^^ ^^^^^
>customGenerator : Generator<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

const result = withHelpers.next();
>result : IteratorResult<never, number>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>withHelpers.next() : IteratorResult<never, number>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>withHelpers.next : (...[value]: [] | [unknown]) => IteratorResult<never, number>
> : ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>withHelpers : IteratorObject<never, number, unknown>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>next : (...[value]: [] | [unknown]) => IteratorResult<never, number>
> : ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

const resultValue: number = result.value; // this should work
>resultValue : number
> : ^^^^^^
>result.value : number
> : ^^^^^^
>result : IteratorResult<never, number>
> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>value : number
> : ^^^^^^

10 changes: 9 additions & 1 deletion tests/cases/compiler/builtinIterator.ts
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Expand Up @@ -73,4 +73,12 @@ declare const g1: Generator<string, number, boolean>;
const iter1 = Iterator.from(g1);

declare const iter2: IteratorObject<string>;
const iter3 = iter2.flatMap(() => g1);
const iter3 = iter2.flatMap(() => g1);

// Iterator.from pass-through of return value
const customGenerator = function* () {
return 42;
}();
const withHelpers = Iterator.from(customGenerator);
const result = withHelpers.next();
const resultValue: number = result.value; // this should work