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Fixed out of spec behavior of array.reduce #731

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Merged
Perryvw merged 6 commits into from
Oct 5, 2019
Merged

Fixed out of spec behavior of array.reduce #731

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603c124
Fixed out of spec behavior of array.reduce
Perryvw Oct 3, 2019
cbc6acc
Moved select declarations from ArrayReduce to lualib declaration files
Perryvw Oct 3, 2019
826b878
Fixed issue in reduce with undefined returning callback
Perryvw Oct 5, 2019
f905134
Changed reduce loop from while to for for performance reasons
Perryvw Oct 5, 2019
5711abc
Cleaned up code a little from PR feedback
Perryvw Oct 5, 2019
2ab6c5b
testcase formatting
Perryvw Oct 5, 2019
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25 changes: 13 additions & 12 deletions src/lualib/ArrayReduce.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,25 +3,26 @@ function __TS__ArrayReduce<T>(
this: void,
arr: T[],
callbackFn: (accumulator: T, currentValue: T, index: number, array: T[]) => T,
initial?: T
...initial: Vararg<T>
): T {
const len = arr.length;

if (len === 0 && initial === undefined) {
// tslint:disable-next-line: no-string-throw
throw "Reduce of empty array with no initial value";
}

let k = 0;
let accumulator = initial;
if (initial === undefined) {
let accumulator = undefined;

// Check if initial value is present in function call
if (select("#", ...initial) !== 0) {
accumulator = select(1, ...initial);
} else if (len > 0) {
accumulator = arr[0];
k++;
k = 1;
} else {
// tslint:disable-next-line: no-string-throw
throw "Reduce of empty array with no initial value";
}

while (k < len) {
accumulator = callbackFn(accumulator, arr[k], k, arr);
k = k + 1;
for (const i of forRange(k, len - 1)) {
accumulator = callbackFn(accumulator, arr[i], i, arr);
}

return accumulator;
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3 changes: 3 additions & 0 deletions src/lualib/declarations/global.d.ts
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Expand Up @@ -16,3 +16,6 @@ declare function rawset<T, K extends keyof T>(table: T, key: K, val: T[K]): void
declare function next<K, V>(table: Record<any, V>, index?: K): [K, V];
declare function pcall(func: () => any): any;
declare function unpack<T>(list: T[], i?: number, j?: number): T[];

declare function select<T>(index: number, ...args: T[]): T;
declare function select<T>(index: "#", ...args: T[]): number;
6 changes: 6 additions & 0 deletions src/lualib/declarations/tstl.d.ts
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@@ -1,5 +1,11 @@
/** @noSelfInFile */

/** @vararg */
interface Vararg<T> extends Array<T> {}

/** @forRange */
declare function forRange(start: number, limit: number, step?: number): number[];

interface LuaClass {
prototype: LuaObject;
____super?: LuaClass;
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16 changes: 16 additions & 0 deletions test/unit/builtins/array.spec.ts
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Expand Up @@ -486,6 +486,22 @@ test.each<[[(total: number, currentItem: number, index: number, array: number[])
util.testExpression`[1, 3, 5, 7].reduce(${util.valuesToString(args)})`.expectToMatchJsResult();
});

test("array.reduce empty undefined initial", () => {
util.testExpression`[].reduce(() => {}, undefined)`.expectToMatchJsResult();
});

test("array.reduce empty no initial", () => {
util.testExpression`[].reduce(() => {})`.expectToMatchJsResult(true);
});

test("array.reduce undefined returning callback", () => {
util.testFunction`
const calls: Array<{ a: void, b: string }> = [];
["a", "b"].reduce<void>((a, b) => { calls.push({ a, b }) }, undefined);
return calls;
`.expectToMatchJsResult();
});

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