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+/*
+ * Copyright (C) 2016-2021 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;
+ }
+ }
+}