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Merged
Perryvw merged 2 commits into from
May 5, 2019
Merged

Support for spread operator on iterables #569

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62a6cb8
Support for spread operator on iterables
tomblind May 5, 2019
d143dad
adressing feedback on test
tomblind May 5, 2019
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2 changes: 2 additions & 0 deletions src/LuaLib.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ export enum LuaLibFeature {
WeakMap = "WeakMap",
WeakSet = "WeakSet",
SourceMapTraceBack = "SourceMapTraceBack",
Spread = "Spread",
StringConcat = "StringConcat",
StringEndsWith = "StringEndsWith",
StringReplace = "StringReplace",
Expand All @@ -62,6 +63,7 @@ const luaLibDependencies: {[lib in LuaLibFeature]?: LuaLibFeature[]} = {
Set: [LuaLibFeature.InstanceOf, LuaLibFeature.Iterator, LuaLibFeature.Symbol],
WeakMap: [LuaLibFeature.InstanceOf, LuaLibFeature.Iterator, LuaLibFeature.Symbol],
WeakSet: [LuaLibFeature.InstanceOf, LuaLibFeature.Iterator, LuaLibFeature.Symbol],
Spread: [LuaLibFeature.Iterator],
SymbolRegistry: [LuaLibFeature.Symbol],
};

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7 changes: 6 additions & 1 deletion src/LuaTransformer.ts
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Expand Up @@ -4561,9 +4561,14 @@ export class LuaTransformer {
const innerExpression = this.expectExpression(this.transformExpression(expression.expression));
if (tsHelper.isTupleReturnCall(expression.expression, this.checker)) {
return innerExpression;
} else {
}

const type = this.checker.getTypeAtLocation(expression.expression);
if (tsHelper.isArrayType(type, this.checker, this.program)) {
return this.createUnpackCall(innerExpression, expression);
}

return this.transformLuaLibFunction(LuaLibFeature.Spread, expression, innerExpression);
}

public transformStringLiteral(literal: ts.StringLiteralLike): ExpressionVisitResult {
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13 changes: 13 additions & 0 deletions src/lualib/Spread.ts
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@@ -0,0 +1,13 @@
declare function unpack<T>(this: void, list: T[], i?: number, j?: number): T[];

declare namespace table {
export function unpack<T>(this: void, list: T[], i?: number, j?: number): T[];
}

function __TS__Spread<T>(this: void, iterable: Iterable<T>): T[] {
const arr: T[] = [];
for (const item of iterable) {
arr[arr.length] = item;
}
return (table.unpack || unpack)(arr);
}
20 changes: 20 additions & 0 deletions test/unit/spreadElement.spec.ts
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Expand Up @@ -47,3 +47,23 @@ test("Spread Element Lua JIT", () => {
const lua = util.transpileString(`[...[0, 1, 2]]`, options);
expect(lua).toBe("local ____ = {unpack({\n 0,\n 1,\n 2,\n})}");
});

test("Spread Element Iterable", () => {
const code = `
const it = {
i: -1,
[Symbol.iterator]() {
return this;
},
next() {
++this.i;
return {
value: 2 ** this.i,
done: this.i == 9,
}
}
};
const arr = [...it];
return JSONStringify(arr)`;
expect(JSON.parse(util.transpileAndExecute(code))).toEqual([1, 2, 4, 8, 16, 32, 64, 128, 256]);
});