module.exports = {
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diff: diff,
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jsonPatchPathConverter: jsonPatchPathConverter,
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};
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/*
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const obj1 = {a: 4, b: 5};
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const obj2 = {a: 3, b: 5};
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const obj3 = {a: 4, c: 5};
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diff(obj1, obj2);
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[
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{ "op": "replace", "path": ['a'], "value": 3 }
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]
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diff(obj2, obj3);
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[
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{ "op": "remove", "path": ['b'] },
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{ "op": "replace", "path": ['a'], "value": 4 }
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{ "op": "add", "path": ['c'], "value": 5 }
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]
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// using converter to generate jsPatch standard paths
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// see http://jsonpatch.com
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import {diff, jsonPatchPathConverter} from 'just-diff'
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diff(obj1, obj2, jsonPatchPathConverter);
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[
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{ "op": "replace", "path": '/a', "value": 3 }
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]
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diff(obj2, obj3, jsonPatchPathConverter);
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[
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{ "op": "remove", "path": '/b' },
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{ "op": "replace", "path": '/a', "value": 4 }
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{ "op": "add", "path": '/c', "value": 5 }
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]
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// arrays
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const obj4 = {a: 4, b: [1, 2, 3]};
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const obj5 = {a: 3, b: [1, 2, 4]};
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const obj6 = {a: 3, b: [1, 2, 4, 5]};
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diff(obj4, obj5);
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[
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{ "op": "replace", "path": ['a'], "value": 3 }
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{ "op": "replace", "path": ['b', 2], "value": 4 }
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]
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diff(obj5, obj6);
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[
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{ "op": "add", "path": ['b', 3], "value": 5 }
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]
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// nested paths
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const obj7 = {a: 4, b: {c: 3}};
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const obj8 = {a: 4, b: {c: 4}};
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const obj9 = {a: 5, b: {d: 4}};
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diff(obj7, obj8);
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[
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{ "op": "replace", "path": ['b', 'c'], "value": 4 }
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]
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diff(obj8, obj9);
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[
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{ "op": "replace", "path": ['a'], "value": 5 }
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{ "op": "remove", "path": ['b', 'c']}
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{ "op": "add", "path": ['b', 'd'], "value": 4 }
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]
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*/
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function diff(obj1, obj2, pathConverter) {
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if (!obj1 || typeof obj1 != 'object' || !obj2 || typeof obj2 != 'object') {
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throw new Error('both arguments must be objects or arrays');
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}
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pathConverter ||
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(pathConverter = function(arr) {
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return arr;
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});
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function getDiff({obj1, obj2, basePath, basePathForRemoves, diffs}) {
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var obj1Keys = Object.keys(obj1);
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var obj1KeysLength = obj1Keys.length;
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var obj2Keys = Object.keys(obj2);
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var obj2KeysLength = obj2Keys.length;
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var path;
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var lengthDelta = obj1.length - obj2.length;
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if (trimFromRight(obj1, obj2)) {
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for (var i = 0; i < obj1KeysLength; i++) {
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var key = Array.isArray(obj1) ? Number(obj1Keys[i]) : obj1Keys[i];
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if (!(key in obj2)) {
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path = basePathForRemoves.concat(key);
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diffs.remove.push({
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op: 'remove',
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path: pathConverter(path),
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});
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}
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}
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for (var i = 0; i < obj2KeysLength; i++) {
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var key = Array.isArray(obj2) ? Number(obj2Keys[i]) : obj2Keys[i];
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pushReplaces({
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key,
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obj1,
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obj2,
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path: basePath.concat(key),
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pathForRemoves: basePath.concat(key),
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diffs,
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});
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}
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} else {
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// trim from left, objects are both arrays
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for (var i = 0; i < lengthDelta; i++) {
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path = basePathForRemoves.concat(i);
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diffs.remove.push({
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op: 'remove',
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path: pathConverter(path),
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});
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}
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// now make a copy of obj1 with excess elements left trimmed and see if there any replaces
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var obj1Trimmed = obj1.slice(lengthDelta);;
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for (var i = 0; i < obj2KeysLength; i++) {
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pushReplaces({
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key: i,
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obj1: obj1Trimmed,
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obj2,
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path: basePath.concat(i),
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// since list of removes are reversed before presenting result,
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// we need to ignore existing parent removes when doing nested removes
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pathForRemoves: basePath.concat(i + lengthDelta),
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diffs,
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});
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}
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}
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}
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var diffs = {remove: [], replace: [], add: []};
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getDiff({
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obj1,
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obj2,
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basePath: [],
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basePathForRemoves: [],
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diffs,
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});
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// reverse removes since we want to maintain indexes
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return diffs.remove
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.reverse()
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.concat(diffs.replace)
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.concat(diffs.add);
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function pushReplaces({key, obj1, obj2, path, pathForRemoves, diffs}) {
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var obj1AtKey = obj1[key];
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var obj2AtKey = obj2[key];
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if(!(key in obj1) && (key in obj2)) {
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var obj2Value = obj2AtKey;
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diffs.add.push({
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op: 'add',
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path: pathConverter(path),
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value: obj2Value,
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});
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} else if(obj1AtKey !== obj2AtKey) {
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if(Object(obj1AtKey) !== obj1AtKey ||
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Object(obj2AtKey) !== obj2AtKey || differentTypes(obj1AtKey, obj2AtKey)
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) {
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pushReplace(path, diffs, obj2AtKey);
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} else {
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if(!Object.keys(obj1AtKey).length &&
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!Object.keys(obj2AtKey).length &&
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String(obj1AtKey) != String(obj2AtKey)) {
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pushReplace(path, diffs, obj2AtKey);
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} else {
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getDiff({
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obj1: obj1[key],
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obj2: obj2[key],
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basePath: path,
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basePathForRemoves: pathForRemoves,
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diffs});
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}
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}
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}
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}
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function pushReplace(path, diffs, newValue) {
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diffs.replace.push({
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op: 'replace',
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path: pathConverter(path),
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value: newValue,
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});
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}
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}
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function jsonPatchPathConverter(arrayPath) {
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return [''].concat(arrayPath).join('/');
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}
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function differentTypes(a, b) {
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return Object.prototype.toString.call(a) != Object.prototype.toString.call(b);
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}
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function trimFromRight(obj1, obj2) {
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var lengthDelta = obj1.length - obj2.length;
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if (Array.isArray(obj1) && Array.isArray(obj2) && lengthDelta > 0) {
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var leftMatches = 0;
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var rightMatches = 0;
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for (var i = 0; i < obj2.length; i++) {
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if (String(obj1[i]) === String(obj2[i])) {
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leftMatches++;
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} else {
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break;
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}
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}
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for (var j = obj2.length; j > 0; j--) {
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if (String(obj1[j + lengthDelta]) === String(obj2[j])) {
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rightMatches++;
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} else {
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break;
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}
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}
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// bias to trim right becase it requires less index shifting
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return leftMatches >= rightMatches;
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}
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return true;
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}
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