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Implement array.entries() #1031

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Merged
Perryvw merged 4 commits into from
Jun 12, 2021
Merged

Implement array.entries() #1031

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d466631
Implement array.entries
Perryvw Jun 12, 2021
63e66d6
Added extra test for indirect use of array.entries()
Perryvw Jun 12, 2021
4796215
Added destructuring test for array.entries
Perryvw Jun 12, 2021
2e0939d
Fix prettier
Perryvw Jun 12, 2021
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1 change: 1 addition & 0 deletions src/LuaLib.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import { EmitHost } from "./transpilation";

export enum LuaLibFeature {
ArrayConcat = "ArrayConcat",
ArrayEntries = "ArrayEntries",
ArrayEvery = "ArrayEvery",
ArrayFilter = "ArrayFilter",
ArrayForEach = "ArrayForEach",
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14 changes: 14 additions & 0 deletions src/lualib/ArrayEntries.ts
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@@ -0,0 +1,14 @@
// https://262.ecma-international.org/10.0/#sec-array.prototype.entries
function __TS__ArrayEntries<T>(this: void, array: T[]): IterableIterator<[number, T]> {
let key = 0;
return {
[Symbol.iterator](): IterableIterator<[number, T]> {
return this;
},
next(): IteratorResult<[number, T]> {
const result = { done: array[key] === undefined, value: [key, array[key]] as [number, T] };
key++;
return result;
},
};
}
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@tomblind tomblind Jun 12, 2021

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Why not just this?

function __TS__ArrayEntries<T>(this: void, array: T[]) {
    return ipairs(array);
}

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@Perryvw Perryvw Jun 12, 2021

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Because TS defines the type of entries as returning IterableIterator<[number, T]>, and I don't think ipairs LuaIterable<LuaMultiReturn<[number, NonNullable<T>]>> is 1:1 assignable to that since it's a different iterator kind and also the lack of LuaMultiReturn.

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@tomblind tomblind Jun 12, 2021

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Ah yeah, that would be a problem if used indirectly. It's a shame since this version is so much more complex.

It might be good to add a test for indirect use:

...
const entries = array.entries();
for (const [i, v] of entries) {
...

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@Perryvw Perryvw Jun 12, 2021

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Good call, added a test for indirect use as well as destructuring, those both fail if ipairs is used

2 changes: 2 additions & 0 deletions src/transformation/builtins/array.ts
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Expand Up @@ -36,6 +36,8 @@ export function transformArrayPrototypeCall(
switch (expressionName) {
case "concat":
return transformLuaLibFunction(context, LuaLibFeature.ArrayConcat, node, caller, ...params);
case "entries":
return transformLuaLibFunction(context, LuaLibFeature.ArrayEntries, node, caller);
case "push":
return transformLuaLibFunction(context, LuaLibFeature.ArrayPush, node, caller, ...params);
case "reverse":
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29 changes: 29 additions & 0 deletions test/unit/builtins/array.spec.ts
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Expand Up @@ -594,6 +594,35 @@ describe.each(["reduce", "reduceRight"])("array.%s", reduce => {
});
});

test.each([{ array: [] }, { array: ["a", "b", "c"] }, { array: [{ foo: "foo" }, { bar: "bar" }] }])(
"array.entries (%p)",
({ array }) => {
util.testFunction`
const array = ${util.formatCode(array)};
const result = [];
for (const [i, v] of array.entries()) {
result.push([i, v]);
}
return result;
`.expectToMatchJsResult();
}
);

test("array.entries indirect use", () => {
util.testFunction`
const entries = ["a", "b", "c"].entries();
const result = [];
for (const [i, v] of entries) {
result.push([i, v]);
}
return result;
`.expectToMatchJsResult();
});

test("array.entries destructured", () => {
util.testExpression`[...["a", "b", "c"].entries()]`.expectToMatchJsResult();
});

const genericChecks = [
"function generic<T extends number[]>(array: T)",
"function generic<T extends [...number[]]>(array: T)",
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