/* * Copyright (C) 2016-2020 Yomichan Authors * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <https://www.gnu.org/licenses/>. */ /** * Class used to get and mutate generic properties of an object by using path strings. */ class ObjectPropertyAccessor { /** * Create a new accessor for a specific object. * @param target The object which the getter and mutation methods are applied to. * @returns A new ObjectPropertyAccessor instance. */ constructor(target) { this._target = target; } /** * Gets the value at the specified path. * @param pathArray The path to the property on the target object. * @param pathLength How many parts of the pathArray to use. * This parameter is optional and defaults to the length of pathArray. * @returns The value found at the path. * @throws An error is thrown if pathArray is not valid for the target object. */ get(pathArray, pathLength) { let target = this._target; const ii = typeof pathLength === 'number' ? Math.min(pathArray.length, pathLength) : pathArray.length; for (let i = 0; i < ii; ++i) { const key = pathArray[i]; if (!ObjectPropertyAccessor.hasProperty(target, key)) { throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray.slice(0, i + 1))}`); } target = target[key]; } return target; } /** * Sets the value at the specified path. * @param pathArray The path to the property on the target object. * @param value The value to assign to the property. * @throws An error is thrown if pathArray is not valid for the target object. */ set(pathArray, value) { const ii = pathArray.length - 1; if (ii < 0) { throw new Error('Invalid path'); } const target = this.get(pathArray, ii); const key = pathArray[ii]; if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) { throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`); } target[key] = value; } /** * Deletes the property of the target object at the specified path. * @param pathArray The path to the property on the target object. * @throws An error is thrown if pathArray is not valid for the target object. */ delete(pathArray) { const ii = pathArray.length - 1; if (ii < 0) { throw new Error('Invalid path'); } const target = this.get(pathArray, ii); const key = pathArray[ii]; if (!ObjectPropertyAccessor.isValidPropertyType(target, key)) { throw new Error(`Invalid path: ${ObjectPropertyAccessor.getPathString(pathArray)}`); } if (Array.isArray(target)) { throw new Error('Invalid type'); } delete target[key]; } /** * Swaps two properties of an object or array. * @param pathArray1 The path to the first property on the target object. * @param pathArray2 The path to the second property on the target object. * @throws An error is thrown if pathArray1 or pathArray2 is not valid for the target object, * or if the swap cannot be performed. */ swap(pathArray1, pathArray2) { const ii1 = pathArray1.length - 1; if (ii1 < 0) { throw new Error('Invalid path 1'); } const target1 = this.get(pathArray1, ii1); const key1 = pathArray1[ii1]; if (!ObjectPropertyAccessor.isValidPropertyType(target1, key1)) { throw new Error(`Invalid path 1: ${ObjectPropertyAccessor.getPathString(pathArray1)}`); } const ii2 = pathArray2.length - 1; if (ii2 < 0) { throw new Error('Invalid path 2'); } const target2 = this.get(pathArray2, ii2); const key2 = pathArray2[ii2]; if (!ObjectPropertyAccessor.isValidPropertyType(target2, key2)) { throw new Error(`Invalid path 2: ${ObjectPropertyAccessor.getPathString(pathArray2)}`); } const value1 = target1[key1]; const value2 = target2[key2]; target1[key1] = value2; try { target2[key2] = value1; } catch (e) { // Revert try { target1[key1] = value1; } catch (e2) { // NOP } throw e; } } /** * Converts a path string to a path array. * @param pathArray The path array to convert. * @returns A string representation of pathArray. */ static getPathString(pathArray) { const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/; let pathString = ''; let first = true; for (let part of pathArray) { switch (typeof part) { case 'number': if (Math.floor(part) !== part || part < 0) { throw new Error('Invalid index'); } part = `[${part}]`; break; case 'string': if (!regexShort.test(part)) { const escapedPart = part.replace(/["\\]/g, '\\$&'); part = `["${escapedPart}"]`; } else { if (!first) { part = `.${part}`; } } break; default: throw new Error(`Invalid type: ${typeof part}`); } pathString += part; first = false; } return pathString; } /** * Converts a path array to a path string. For the most part, the format of this string * matches Javascript's notation for property access. * @param pathString The path string to convert. * @returns An array representation of pathString. */ static getPathArray(pathString) { const pathArray = []; let state = 'empty'; let quote = 0; let value = ''; let escaped = false; for (const c of pathString) { const v = c.codePointAt(0); switch (state) { case 'empty': // Empty case 'id-start': // Expecting identifier start if (v === 0x5b) { // '[' if (state === 'id-start') { throw new Error(`Unexpected character: ${c}`); } state = 'open-bracket'; } else if ( (v >= 0x41 && v <= 0x5a) || // ['A', 'Z'] (v >= 0x61 && v <= 0x7a) || // ['a', 'z'] v === 0x5f // '_' ) { state = 'id'; value += c; } else { throw new Error(`Unexpected character: ${c}`); } break; case 'id': // Identifier if ( (v >= 0x41 && v <= 0x5a) || // ['A', 'Z'] (v >= 0x61 && v <= 0x7a) || // ['a', 'z'] (v >= 0x30 && v <= 0x39) || // ['0', '9'] v === 0x5f // '_' ) { value += c; } else if (v === 0x5b) { // '[' pathArray.push(value); value = ''; state = 'open-bracket'; } else if (v === 0x2e) { // '.' pathArray.push(value); value = ''; state = 'id-start'; } else { throw new Error(`Unexpected character: ${c}`); } break; case 'open-bracket': // Open bracket if (v === 0x22 || v === 0x27) { // '"' or '\'' quote = v; state = 'string'; } else if (v >= 0x30 && v <= 0x39) { // ['0', '9'] state = 'number'; value += c; } else { throw new Error(`Unexpected character: ${c}`); } break; case 'string': // Quoted string if (escaped) { value += c; escaped = false; } else if (v === 0x5c) { // '\\' escaped = true; } else if (v !== quote) { value += c; } else { state = 'close-bracket'; } break; case 'number': // Number if (v >= 0x30 && v <= 0x39) { // ['0', '9'] value += c; } else if (v === 0x5d) { // ']' pathArray.push(Number.parseInt(value, 10)); value = ''; state = 'next'; } else { throw new Error(`Unexpected character: ${c}`); } break; case 'close-bracket': // Expecting closing bracket after quoted string if (v === 0x5d) { // ']' pathArray.push(value); value = ''; state = 'next'; } else { throw new Error(`Unexpected character: ${c}`); } break; case 'next': // Expecting . or [ if (v === 0x5b) { // '[' state = 'open-bracket'; } else if (v === 0x2e) { // '.' state = 'id-start'; } else { throw new Error(`Unexpected character: ${c}`); } break; } } switch (state) { case 'empty': case 'next': break; case 'id': pathArray.push(value); value = ''; break; default: throw new Error('Path not terminated correctly'); } return pathArray; } /** * Checks whether an object or array has the specified property. * @param object The object to test. * @param property The property to check for existence. * This value should be a string if the object is a non-array object. * For arrays, it should be an integer. * @returns true if the property exists, otherwise false. */ static hasProperty(object, property) { switch (typeof property) { case 'string': return ( typeof object === 'object' && object !== null && !Array.isArray(object) && Object.prototype.hasOwnProperty.call(object, property) ); case 'number': return ( Array.isArray(object) && property >= 0 && property < object.length && property === Math.floor(property) ); default: return false; } } /** * Checks whether a property is valid for the given object * @param object The object to test. * @param property The property to check for existence. * @returns true if the property is correct for the given object type, otherwise false. * For arrays, this means that the property should be a positive integer. * For non-array objects, the property should be a string. */ static isValidPropertyType(object, property) { switch (typeof property) { case 'string': return ( typeof object === 'object' && object !== null && !Array.isArray(object) ); case 'number': return ( Array.isArray(object) && property >= 0 && property === Math.floor(property) ); default: return false; } } }