@stryke/json/dist/pointer/find-reference.mjs

A package containing JSON parsing/stringify utilities used by Storm Software.

import { isSetObject } from "@stryke/type-checks/is-set-object";
import { isString } from "@stryke/type-checks/is-string";

//#region src/pointer/find-reference.ts
const { isArray } = Array;
/**
* Finds a target in document specified by JSON Pointer. Also returns the
* object containing the target and key used to reference that object.
*
* Throws Error('NOT_FOUND') if pointer does not result into a value in the middle
* of the path. If the last element of the path does not result into a value, the
* lookup succeeds with `val` set to `undefined`. It can be used to discriminate
* missing values, because `undefined` is not a valid JSON value.
*
* If last element in array is targeted using "-", e.g. "/arr/-", use
* `isArrayEnd` to verify that:
*
* ```js
* const ref = find({arr: [1, 2, 3], ['arr', '-']});
* if (isArrayReference(ref)) {
*   if (isArrayEnd(ref)) {
*     // ...
*   }
* }
* ```
*
* @param val - Document to search in.
* @param path - JSON Pointer path.
* @returns Reference to the target.
*/
const find = (val, path) => {
	const pathLength = path.length;
	if (!pathLength) return { val };
	let obj;
	let key;
	for (let i = 0; i < pathLength; i++) {
		obj = val;
		key = path[i];
		if (isArray(obj)) {
			const length = obj.length;
			if (key === "-") key = length;
			else if (isString(key)) {
				const key2 = Math.trunc(Number.parseInt(key));
				if (String(key2) !== key) throw new Error("INVALID_INDEX");
				key = key2;
				if (key < 0) throw new Error("INVALID_INDEX");
			}
			if (key) val = obj[key];
		} else if (isSetObject(obj)) val = key && key in obj ? obj[key] : void 0;
		else throw new Error("NOT_FOUND");
	}
	return {
		val,
		obj,
		key
	};
};
const isArrayReference = (ref) => isArray(ref.obj) && typeof ref.key === "number";
const isArrayEnd = (ref) => ref.obj.length === ref.key;
const isObjectReference = (ref) => typeof ref.obj === "object" && typeof ref.key === "string";

//#endregion
export { find, isArrayEnd, isArrayReference, isObjectReference };
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