343 lines
13 KiB
JavaScript
343 lines
13 KiB
JavaScript
/*
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* Copyright (C) 2016-2021 Yomichan Authors
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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/**
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* Class used to get and mutate generic properties of an object by using path strings.
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*/
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class ObjectPropertyAccessor {
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/**
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* Create a new accessor for a specific object.
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* @param target The object which the getter and mutation methods are applied to.
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* @returns A new ObjectPropertyAccessor instance.
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*/
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constructor(target) {
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this._target = target;
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}
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/**
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* Gets the value at the specified path.
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* @param pathArray The path to the property on the target object.
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* @param pathLength How many parts of the pathArray to use.
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* This parameter is optional and defaults to the length of pathArray.
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* @returns The value found at the path.
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* @throws An error is thrown if pathArray is not valid for the target object.
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*/
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get(pathArray, pathLength) {
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let target = this._target;
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const ii = typeof pathLength === 'number' ? Math.min(pathArray.length, pathLength) : pathArray.length;
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for (let i = 0; i < ii; ++i) {
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const key = pathArray[i];
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if (!ObjectPropertyAccessor.hasProperty(target, key)) {
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throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray.slice(0, i + 1))}`);
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}
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target = target[key];
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}
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return target;
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}
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/**
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* Sets the value at the specified path.
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* @param pathArray The path to the property on the target object.
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* @param value The value to assign to the property.
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* @throws An error is thrown if pathArray is not valid for the target object.
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*/
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set(pathArray, value) {
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const ii = pathArray.length - 1;
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if (ii < 0) { throw new Error('Invalid path'); }
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const target = this.get(pathArray, ii);
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const key = pathArray[ii];
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if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) {
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throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`);
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}
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target[key] = value;
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}
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/**
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* Deletes the property of the target object at the specified path.
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* @param pathArray The path to the property on the target object.
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* @throws An error is thrown if pathArray is not valid for the target object.
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*/
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delete(pathArray) {
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const ii = pathArray.length - 1;
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if (ii < 0) { throw new Error('Invalid path'); }
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const target = this.get(pathArray, ii);
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const key = pathArray[ii];
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if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) {
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throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`);
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}
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if (Array.isArray(target)) {
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throw new Error('Invalid type');
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}
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delete target[key];
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}
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/**
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* Swaps two properties of an object or array.
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* @param pathArray1 The path to the first property on the target object.
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* @param pathArray2 The path to the second property on the target object.
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* @throws An error is thrown if pathArray1 or pathArray2 is not valid for the target object,
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* or if the swap cannot be performed.
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*/
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swap(pathArray1, pathArray2) {
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const ii1 = pathArray1.length - 1;
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if (ii1 < 0) { throw new Error('Invalid path 1'); }
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const target1 = this.get(pathArray1, ii1);
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const key1 = pathArray1[ii1];
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if (!ObjectPropertyAccessor.isValidPropertyType(target1, key1)) { throw new Error(`Invalid path 1: ${ObjectPropertyAccessor.getPathString(pathArray1)}`); }
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const ii2 = pathArray2.length - 1;
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if (ii2 < 0) { throw new Error('Invalid path 2'); }
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const target2 = this.get(pathArray2, ii2);
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const key2 = pathArray2[ii2];
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if (!ObjectPropertyAccessor.isValidPropertyType(target2, key2)) { throw new Error(`Invalid path 2: ${ObjectPropertyAccessor.getPathString(pathArray2)}`); }
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const value1 = target1[key1];
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const value2 = target2[key2];
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target1[key1] = value2;
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try {
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target2[key2] = value1;
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} catch (e) {
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// Revert
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try {
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target1[key1] = value1;
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} catch (e2) {
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// NOP
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}
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throw e;
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}
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}
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/**
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* Converts a path string to a path array.
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* @param pathArray The path array to convert.
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* @returns A string representation of pathArray.
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*/
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static getPathString(pathArray) {
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const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
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let pathString = '';
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let first = true;
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for (let part of pathArray) {
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switch (typeof part) {
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case 'number':
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if (Math.floor(part) !== part || part < 0) {
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throw new Error('Invalid index');
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}
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part = `[${part}]`;
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break;
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case 'string':
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if (!regexShort.test(part)) {
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const escapedPart = part.replace(/["\\]/g, '\\$&');
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part = `["${escapedPart}"]`;
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} else {
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if (!first) {
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part = `.${part}`;
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}
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}
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break;
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default:
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throw new Error(`Invalid type: ${typeof part}`);
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}
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pathString += part;
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first = false;
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}
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return pathString;
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}
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/**
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* Converts a path array to a path string. For the most part, the format of this string
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* matches Javascript's notation for property access.
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* @param pathString The path string to convert.
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* @returns An array representation of pathString.
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*/
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static getPathArray(pathString) {
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const pathArray = [];
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let state = 'empty';
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let quote = 0;
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let value = '';
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let escaped = false;
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for (const c of pathString) {
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const v = c.codePointAt(0);
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switch (state) {
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case 'empty': // Empty
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case 'id-start': // Expecting identifier start
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if (v === 0x5b) { // '['
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if (state === 'id-start') {
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throw new Error(`Unexpected character: ${c}`);
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}
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state = 'open-bracket';
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} else if (
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(v >= 0x41 && v <= 0x5a) || // ['A', 'Z']
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(v >= 0x61 && v <= 0x7a) || // ['a', 'z']
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v === 0x5f // '_'
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) {
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state = 'id';
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value += c;
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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case 'id': // Identifier
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if (
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(v >= 0x41 && v <= 0x5a) || // ['A', 'Z']
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(v >= 0x61 && v <= 0x7a) || // ['a', 'z']
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(v >= 0x30 && v <= 0x39) || // ['0', '9']
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v === 0x5f // '_'
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) {
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value += c;
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} else if (v === 0x5b) { // '['
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pathArray.push(value);
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value = '';
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state = 'open-bracket';
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} else if (v === 0x2e) { // '.'
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pathArray.push(value);
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value = '';
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state = 'id-start';
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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case 'open-bracket': // Open bracket
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if (v === 0x22 || v === 0x27) { // '"' or '\''
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quote = v;
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state = 'string';
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} else if (v >= 0x30 && v <= 0x39) { // ['0', '9']
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state = 'number';
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value += c;
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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case 'string': // Quoted string
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if (escaped) {
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value += c;
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escaped = false;
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} else if (v === 0x5c) { // '\\'
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escaped = true;
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} else if (v !== quote) {
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value += c;
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} else {
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state = 'close-bracket';
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}
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break;
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case 'number': // Number
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if (v >= 0x30 && v <= 0x39) { // ['0', '9']
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value += c;
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} else if (v === 0x5d) { // ']'
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pathArray.push(Number.parseInt(value, 10));
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value = '';
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state = 'next';
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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case 'close-bracket': // Expecting closing bracket after quoted string
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if (v === 0x5d) { // ']'
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pathArray.push(value);
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value = '';
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state = 'next';
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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case 'next': // Expecting . or [
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if (v === 0x5b) { // '['
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state = 'open-bracket';
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} else if (v === 0x2e) { // '.'
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state = 'id-start';
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} else {
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throw new Error(`Unexpected character: ${c}`);
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}
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break;
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}
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}
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switch (state) {
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case 'empty':
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case 'next':
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break;
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case 'id':
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pathArray.push(value);
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value = '';
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break;
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default:
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throw new Error('Path not terminated correctly');
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}
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return pathArray;
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}
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/**
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* Checks whether an object or array has the specified property.
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* @param object The object to test.
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* @param property The property to check for existence.
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* This value should be a string if the object is a non-array object.
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* For arrays, it should be an integer.
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* @returns true if the property exists, otherwise false.
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*/
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static hasProperty(object, property) {
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switch (typeof property) {
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case 'string':
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return (
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typeof object === 'object' &&
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object !== null &&
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!Array.isArray(object) &&
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Object.prototype.hasOwnProperty.call(object, property)
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);
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case 'number':
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return (
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Array.isArray(object) &&
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property >= 0 &&
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property < object.length &&
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property === Math.floor(property)
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);
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default:
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return false;
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}
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}
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/**
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* Checks whether a property is valid for the given object
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* @param object The object to test.
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* @param property The property to check for existence.
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* @returns true if the property is correct for the given object type, otherwise false.
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* For arrays, this means that the property should be a positive integer.
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* For non-array objects, the property should be a string.
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*/
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static isValidPropertyType(object, property) {
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switch (typeof property) {
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case 'string':
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return (
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typeof object === 'object' &&
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object !== null &&
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!Array.isArray(object)
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);
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case 'number':
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return (
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Array.isArray(object) &&
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property >= 0 &&
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property === Math.floor(property)
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);
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default:
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return false;
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}
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}
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}
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