corps/json-delta

Json object diff / patching with configurable short-circuit tolerance.

json-delta's Issues

TS2322: Type 'null' is not assignable to type 'void | Diff'

the diff function return type is Diff | void however it returns null in line 152:

json-delta/index.ts

Lines 144 to 154 in 41275a6

	export function diff(
	a: AnyJson,
	b: AnyJson,
	tolerance = Infinity
	): Diff | void {
	let result: Diff = [];
	if (gatherDiff(a, b, tolerance, [], result) || result.length > tolerance)
	return [[[], b]];
	if (result.length === 0) return null;
	return result;
	}

I can prepare a PR if it helps

TS2322: Type '[number, number] | null' is not assignable to type 'void | [number, number]'

the shortestEdit function return type is [number, number] | void however it returns null in line 335:

json-delta/index.ts

Lines 300 to 336 in 41275a6

	let shortestEdit: [number, number] | void = (function() {
	for (var d = 0; d <= tolerance; ++d) {
	for (var k = -d; k <= d; k += 2) {
	let aIdx: number;
	let takeB = aOfDiagonal[k + 1 + tolerance];
	let takeA = aOfDiagonal[k - 1 + tolerance];
	if (k === -d || (k !== d && takeA < takeB)) {
	aIdx = takeB;
	} else {
	aIdx = takeA + 1;
	}
	let bIdx = aIdx - k;
	while (
	aIdx < aLen &&
	bIdx < bLen &&
	deepEqual(a[aIdx], b[bIdx])
	) {
	aIdx++;
	bIdx++;
	}
	aOfDiagonal[k + tolerance] = aIdx;
	if (aIdx >= aLen && bIdx >= bLen) {
	aOfDiagonalForEditSize[d] = aOfDiagonal.slice();
	return [d, k] as [number, number];
	}
	}
	aOfDiagonalForEditSize[d] = aOfDiagonal.slice();
	}
	return null;
	})();

I can prepare a PR if it helps

TS2322: Type 'AnyJson[] | null' is not assignable to type 'void | AnyJson[]'

the lcs function return type is AnyJson[] | void however it returns null in line 282:

json-delta/index.ts

Lines 274 to 283 in 41275a6

	export function lcs(
	a: AnyJson[],
	b: AnyJson[],
	tolerance = a.length + b.length
	): AnyJson[] | void {
	let result: AnyJson[] = [];
	return arrDiff(a, b, tolerance, aIdx => result.push(a[aIdx]))
	? result.reverse()
	: null;
	}

I can prepare a PR if it helps

ReadonlyArray Type not supported

applyDiff creates a shallowCopy so it does not modify the input.
However it does not accept read only data structures.

Would it be possible to change that e.g.:

interface JsonMap {
  [key: string]: Readonly<AnyJson>;
}
interface JsonArray extends ReadonlyArray<AnyJson> {}

It would also be nice to return the input type:

export function applyDiff<T extends AnyJson>(o: T, d: Diff | void): T {