jiff/lib/jsonPatch.js

JSON diff and patch based on rfc6902

/** @license MIT License (c) copyright 2010-2014 original author or authors */
/** @author Brian Cavalier */
/** @author John Hann */

var patches = require('./patches');
var clone = require('./clone');
var InvalidPatchOperationError = require('./InvalidPatchOperationError');

exports.apply = patch;
exports.applyInPlace = patchInPlace;
exports.clone = clone;
exports.isValidObject = isValidObject;
exports.defaultHash = defaultHash;

var defaultOptions = {};

/**
 * Apply the supplied JSON Patch to x
 * @param {array} changes JSON Patch
 * @param {object|array|string|number} x object/array/value to patch
 * @param {object} options
 * @param {function(index:Number, array:Array, context:object):Number} options.findContext
 *  function used adjust array indexes for smarty/fuzzy patching, for
 *  patches containing context
 * @returns {object|array|string|number} patched version of x. If x is
 *  an array or object, it will be mutated and returned. Otherwise, if
 *  x is a value, the new value will be returned.
 */
function patch(changes, x, options) {
	return patchInPlace(changes, clone(x), options);
}

function patchInPlace(changes, x, options) {
	if(!options) {
		options = defaultOptions;
	}

	// TODO: Consider throwing if changes is not an array
	if(!Array.isArray(changes)) {
		return x;
	}

	var patch, p;
	for(var i=0; i<changes.length; ++i) {
		p = changes[i];
		patch = patches[p.op];

		if(patch === void 0) {
			throw new InvalidPatchOperationError('invalid op ' + JSON.stringify(p));
		}

		x = patch.apply(x, p, options);
	}

	return x;
}

function defaultHash(x) {
	return isValidObject(x) || isArray(x) ? JSON.stringify(x) : x;
}

function isValidObject (x) {
	return x !== null && Object.prototype.toString.call(x) === '[object Object]';
}

function isArray (x) {
	return Object.prototype.toString.call(x) === '[object Array]';
}