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+/*
+ * Copyright (C) 2019-2021 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/>.
+ */
+
+/**
+ * Converts an `Error` object to a serializable JSON object.
+ * @param error An error object to convert.
+ * @returns A simple object which can be serialized by `JSON.stringify()`.
+ */
+function serializeError(error) {
+ try {
+ if (typeof error === 'object' && error !== null) {
+ return {
+ name: error.name,
+ message: error.message,
+ stack: error.stack,
+ data: error.data
+ };
+ }
+ } catch (e) {
+ // NOP
+ }
+ return {
+ value: error,
+ hasValue: true
+ };
+}
+
+/**
+ * Converts a serialized erorr into a standard `Error` object.
+ * @param serializedError A simple object which was initially generated by serializeError.
+ * @returns A new `Error` instance.
+ */
+function deserializeError(serializedError) {
+ if (serializedError.hasValue) {
+ return serializedError.value;
+ }
+ const error = new Error(serializedError.message);
+ error.name = serializedError.name;
+ error.stack = serializedError.stack;
+ error.data = serializedError.data;
+ return error;
+}
+
+/**
+ * Checks whether a given value is a non-array object.
+ * @param value The value to check.
+ * @returns `true` if the value is an object and not an array, `false` otherwise.
+ */
+function isObject(value) {
+ return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+/**
+ * Converts any string into a form that can be passed into the RegExp constructor.
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
+ * @param string The string to convert to a valid regular expression.
+ * @returns The escaped string.
+ */
+function escapeRegExp(string) {
+ return string.replace(/[.*+\-?^${}()|[\]\\]/g, '\\$&');
+}
+
+/**
+ * Reverses a string.
+ * @param string The string to reverse.
+ * @returns The returned string, which retains proper UTF-16 surrogate pair order.
+ */
+function stringReverse(string) {
+ return [...string].reverse().join('');
+}
+
+/**
+ * Creates a deep clone of an object or value. This is similar to `JSON.parse(JSON.stringify(value))`.
+ * @param value The value to clone.
+ * @returns A new clone of the value.
+ * @throws An error if the value is circular and cannot be cloned.
+ */
+const clone = (() => {
+ // eslint-disable-next-line no-shadow
+ function clone(value) {
+ if (value === null) { return null; }
+ switch (typeof value) {
+ case 'boolean':
+ case 'number':
+ case 'string':
+ case 'bigint':
+ case 'symbol':
+ case 'undefined':
+ return value;
+ default:
+ return cloneInternal(value, new Set());
+ }
+ }
+
+ function cloneInternal(value, visited) {
+ if (value === null) { return null; }
+ switch (typeof value) {
+ case 'boolean':
+ case 'number':
+ case 'string':
+ case 'bigint':
+ case 'symbol':
+ case 'undefined':
+ return value;
+ case 'function':
+ return cloneObject(value, visited);
+ case 'object':
+ return Array.isArray(value) ? cloneArray(value, visited) : cloneObject(value, visited);
+ }
+ }
+
+ function cloneArray(value, visited) {
+ if (visited.has(value)) { throw new Error('Circular'); }
+ try {
+ visited.add(value);
+ const result = [];
+ for (const item of value) {
+ result.push(cloneInternal(item, visited));
+ }
+ return result;
+ } finally {
+ visited.delete(value);
+ }
+ }
+
+ function cloneObject(value, visited) {
+ if (visited.has(value)) { throw new Error('Circular'); }
+ try {
+ visited.add(value);
+ const result = {};
+ for (const key in value) {
+ if (Object.prototype.hasOwnProperty.call(value, key)) {
+ result[key] = cloneInternal(value[key], visited);
+ }
+ }
+ return result;
+ } finally {
+ visited.delete(value);
+ }
+ }
+
+ return clone;
+})();
+
+/**
+ * Checks if an object or value is deeply equal to another object or value.
+ * @param value1 The first value to check.
+ * @param value2 The second value to check.
+ * @returns `true` if the values are the same object, or deeply equal without cycles. `false` otherwise.
+ */
+const deepEqual = (() => {
+ // eslint-disable-next-line no-shadow
+ function deepEqual(value1, value2) {
+ if (value1 === value2) { return true; }
+
+ const type = typeof value1;
+ if (typeof value2 !== type) { return false; }
+
+ switch (type) {
+ case 'object':
+ case 'function':
+ return deepEqualInternal(value1, value2, new Set());
+ default:
+ return false;
+ }
+ }
+
+ function deepEqualInternal(value1, value2, visited1) {
+ if (value1 === value2) { return true; }
+
+ const type = typeof value1;
+ if (typeof value2 !== type) { return false; }
+
+ switch (type) {
+ case 'object':
+ case 'function':
+ {
+ if (value1 === null || value2 === null) { return false; }
+ const array = Array.isArray(value1);
+ if (array !== Array.isArray(value2)) { return false; }
+ if (visited1.has(value1)) { return false; }
+ visited1.add(value1);
+ return array ? areArraysEqual(value1, value2, visited1) : areObjectsEqual(value1, value2, visited1);
+ }
+ default:
+ return false;
+ }
+ }
+
+ function areObjectsEqual(value1, value2, visited1) {
+ const keys1 = Object.keys(value1);
+ const keys2 = Object.keys(value2);
+ if (keys1.length !== keys2.length) { return false; }
+
+ const keys1Set = new Set(keys1);
+ for (const key of keys2) {
+ if (!keys1Set.has(key) || !deepEqualInternal(value1[key], value2[key], visited1)) { return false; }
+ }
+
+ return true;
+ }
+
+ function areArraysEqual(value1, value2, visited1) {
+ const length = value1.length;
+ if (length !== value2.length) { return false; }
+
+ for (let i = 0; i < length; ++i) {
+ if (!deepEqualInternal(value1[i], value2[i], visited1)) { return false; }
+ }
+
+ return true;
+ }
+
+ return deepEqual;
+})();
+
+/**
+ * Creates a new base-16 (lower case) string of a sequence of random bytes of the given length.
+ * @param length The number of bytes the string represents. The returned string's length will be twice as long.
+ * @returns A string of random characters.
+ */
+function generateId(length) {
+ const array = new Uint8Array(length);
+ crypto.getRandomValues(array);
+ let id = '';
+ for (const value of array) {
+ id += value.toString(16).padStart(2, '0');
+ }
+ return id;
+}
+
+/**
+ * Creates an unresolved promise that can be resolved later, outside the promise's executor function.
+ * @returns An object `{promise, resolve, reject}`, containing the promise and the resolve/reject functions.
+ */
+function deferPromise() {
+ let resolve;
+ let reject;
+ const promise = new Promise((resolve2, reject2) => {
+ resolve = resolve2;
+ reject = reject2;
+ });
+ return {promise, resolve, reject};
+}
+
+/**
+ * Creates a promise that is resolved after a set delay.
+ * @param delay How many milliseconds until the promise should be resolved. If 0, the promise is immediately resolved.
+ * @param resolveValue Optional; the value returned when the promise is resolved.
+ * @returns A promise with two additional properties: `resolve` and `reject`, which can be used to complete the promise early.
+ */
+function promiseTimeout(delay, resolveValue) {
+ if (delay <= 0) {
+ const promise = Promise.resolve(resolveValue);
+ promise.resolve = () => {}; // NOP
+ promise.reject = () => {}; // NOP
+ return promise;
+ }
+
+ let timer = null;
+ let {promise, resolve, reject} = deferPromise();
+
+ const complete = (callback, value) => {
+ if (callback === null) { return; }
+ if (timer !== null) {
+ clearTimeout(timer);
+ timer = null;
+ }
+ resolve = null;
+ reject = null;
+ callback(value);
+ };
+
+ const resolveWrapper = (value) => complete(resolve, value);
+ const rejectWrapper = (value) => complete(reject, value);
+
+ timer = setTimeout(() => {
+ timer = null;
+ resolveWrapper(resolveValue);
+ }, delay);
+
+ promise.resolve = resolveWrapper;
+ promise.reject = rejectWrapper;
+
+ return promise;
+}
+
+/**
+ * Creates a promise that will resolve after the next animation frame, using `requestAnimationFrame`.
+ * @param timeout Optional; a maximum duration (in milliseconds) to wait until the promise resolves. If null or omitted, no timeout is used.
+ * @returns A promise that is resolved with `{time, timeout}`, where `time` is the timestamp from `requestAnimationFrame`,
+ * and `timeout` is a boolean indicating whether the cause was a timeout or not.
+ * @throws The promise throws an error if animation is not supported in this context, such as in a service worker.
+ */
+function promiseAnimationFrame(timeout=null) {
+ return new Promise((resolve, reject) => {
+ if (typeof cancelAnimationFrame !== 'function' || typeof requestAnimationFrame !== 'function') {
+ reject(new Error('Animation not supported in this context'));
+ return;
+ }
+
+ let timer = null;
+ let frameRequest = null;
+ const onFrame = (time) => {
+ frameRequest = null;
+ if (timer !== null) {
+ clearTimeout(timer);
+ timer = null;
+ }
+ resolve({time, timeout: false});
+ };
+ const onTimeout = () => {
+ timer = null;
+ if (frameRequest !== null) {
+ // eslint-disable-next-line no-undef
+ cancelAnimationFrame(frameRequest);
+ frameRequest = null;
+ }
+ resolve({time: performance.now(), timeout: true});
+ };
+
+ // eslint-disable-next-line no-undef
+ frameRequest = requestAnimationFrame(onFrame);
+ if (typeof timeout === 'number') {
+ timer = setTimeout(onTimeout, timeout);
+ }
+ });
+}
+
+/**
+ * Base class controls basic event dispatching.
+ */
+class EventDispatcher {
+ /**
+ * Creates a new instance.
+ */
+ constructor() {
+ this._eventMap = new Map();
+ }
+
+ /**
+ * Triggers an event with the given name and specified argument.
+ * @param eventName The string representing the event's name.
+ * @param details Optional; the argument passed to the callback functions.
+ * @returns `true` if any callbacks were registered, `false` otherwise.
+ */
+ trigger(eventName, details) {
+ const callbacks = this._eventMap.get(eventName);
+ if (typeof callbacks === 'undefined') { return false; }
+
+ for (const callback of callbacks) {
+ callback(details);
+ }
+ return true;
+ }
+
+ /**
+ * Adds a single event listener to a specific event.
+ * @param eventName The string representing the event's name.
+ * @param callback The event listener callback to add.
+ */
+ on(eventName, callback) {
+ let callbacks = this._eventMap.get(eventName);
+ if (typeof callbacks === 'undefined') {
+ callbacks = [];
+ this._eventMap.set(eventName, callbacks);
+ }
+ callbacks.push(callback);
+ }
+
+ /**
+ * Removes a single event listener from a specific event.
+ * @param eventName The string representing the event's name.
+ * @param callback The event listener callback to add.
+ * @returns `true` if the callback was removed, `false` otherwise.
+ */
+ off(eventName, callback) {
+ const callbacks = this._eventMap.get(eventName);
+ if (typeof callbacks === 'undefined') { return true; }
+
+ const ii = callbacks.length;
+ for (let i = 0; i < ii; ++i) {
+ if (callbacks[i] === callback) {
+ callbacks.splice(i, 1);
+ if (callbacks.length === 0) {
+ this._eventMap.delete(eventName);
+ }
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Checks if an event has any listeners.
+ * @param eventName The string representing the event's name.
+ * @returns `true` if the event has listeners, `false` otherwise.
+ */
+ hasListeners(eventName) {
+ const callbacks = this._eventMap.get(eventName);
+ return (typeof callbacks !== 'undefined' && callbacks.length > 0);
+ }
+}
+
+/**
+ * Class which stores event listeners added to various objects, making it easy to remove them in bulk.
+ */
+class EventListenerCollection {
+ /**
+ * Creates a new instance.
+ */
+ constructor() {
+ this._eventListeners = [];
+ }
+
+ /**
+ * Returns the number of event listeners that are currently in the object.
+ * @returns The number of event listeners that are currently in the object.
+ */
+ get size() {
+ return this._eventListeners.length;
+ }
+
+ /**
+ * Adds an event listener of a generic type.
+ * @param type The type of event listener, which can be 'addEventListener', 'addListener', or 'on'.
+ * @param object The object to add the event listener to.
+ * @param args The argument array passed to the object's event listener adding function.
+ * @throws An error if type is not an expected value.
+ */
+ addGeneric(type, object, ...args) {
+ switch (type) {
+ case 'addEventListener': return this.addEventListener(object, ...args);
+ case 'addListener': return this.addListener(object, ...args);
+ case 'on': return this.on(object, ...args);
+ default: throw new Error(`Invalid type: ${type}`);
+ }
+ }
+
+ /**
+ * Adds an event listener using `object.addEventListener`. The listener will later be removed using `object.removeEventListener`.
+ * @param object The object to add the event listener to.
+ * @param args The argument array passed to the `addEventListener`/`removeEventListener` functions.
+ */
+ addEventListener(object, ...args) {
+ object.addEventListener(...args);
+ this._eventListeners.push(['removeEventListener', object, ...args]);
+ }
+
+ /**
+ * Adds an event listener using `object.addListener`. The listener will later be removed using `object.removeListener`.
+ * @param object The object to add the event listener to.
+ * @param args The argument array passed to the `addListener`/`removeListener` function.
+ */
+ addListener(object, ...args) {
+ object.addListener(...args);
+ this._eventListeners.push(['removeListener', object, ...args]);
+ }
+
+ /**
+ * Adds an event listener using `object.on`. The listener will later be removed using `object.off`.
+ * @param object The object to add the event listener to.
+ * @param args The argument array passed to the `on`/`off` function.
+ */
+ on(object, ...args) {
+ object.on(...args);
+ this._eventListeners.push(['off', object, ...args]);
+ }
+
+ /**
+ * Removes all event listeners added to objects for this instance and clears the internal list of event listeners.
+ */
+ removeAllEventListeners() {
+ if (this._eventListeners.length === 0) { return; }
+ for (const [removeFunctionName, object, ...args] of this._eventListeners) {
+ switch (removeFunctionName) {
+ case 'removeEventListener':
+ object.removeEventListener(...args);
+ break;
+ case 'removeListener':
+ object.removeListener(...args);
+ break;
+ case 'off':
+ object.off(...args);
+ break;
+ default:
+ throw new Error(`Unknown remove function: ${removeFunctionName}`);
+ }
+ }
+ this._eventListeners = [];
+ }
+}
+
+/**
+ * Class representing a generic value with an override stack.
+ * Changes can be observed by listening to the 'change' event.
+ */
+class DynamicProperty extends EventDispatcher {
+ /**
+ * Creates a new instance with the specified value.
+ * @param value The value to assign.
+ */
+ constructor(value) {
+ super();
+ this._value = value;
+ this._defaultValue = value;
+ this._overrides = [];
+ }
+
+ /**
+ * Gets the default value for the property, which is assigned to the
+ * public value property when no overrides are present.
+ */
+ get defaultValue() {
+ return this._defaultValue;
+ }
+
+ /**
+ * Assigns the default value for the property. If no overrides are present
+ * and if the value is different than the current default value,
+ * the 'change' event will be triggered.
+ * @param value The value to assign.
+ */
+ set defaultValue(value) {
+ this._defaultValue = value;
+ if (this._overrides.length === 0) { this._updateValue(); }
+ }
+
+ /**
+ * Gets the current value for the property, taking any overrides into account.
+ */
+ get value() {
+ return this._value;
+ }
+
+ /**
+ * Gets the number of overrides added to the property.
+ */
+ get overrideCount() {
+ return this._overrides.length;
+ }
+
+ /**
+ * Adds an override value with the specified priority to the override stack.
+ * Values with higher priority will take precedence over those with lower.
+ * For tie breaks, the override value added first will take precedence.
+ * If the newly added override has the highest priority of all overrides
+ * and if the override value is different from the current value,
+ * the 'change' event will be fired.
+ * @param value The override value to assign.
+ * @param priority The priority value to use, as a number.
+ * @returns A string token which can be passed to the clearOverride function
+ * to remove the override.
+ */
+ setOverride(value, priority=0) {
+ const overridesCount = this._overrides.length;
+ let i = 0;
+ for (; i < overridesCount; ++i) {
+ if (priority > this._overrides[i].priority) { break; }
+ }
+ const token = generateId(16);
+ this._overrides.splice(i, 0, {value, priority, token});
+ if (i === 0) { this._updateValue(); }
+ return token;
+ }
+
+ /**
+ * Removes a specific override value. If the removed override
+ * had the highest priority, and the new value is different from
+ * the previous value, the 'change' event will be fired.
+ * @param token The token for the corresponding override which is to be removed.
+ * @returns true if an override was returned, false otherwise.
+ */
+ clearOverride(token) {
+ for (let i = 0, ii = this._overrides.length; i < ii; ++i) {
+ if (this._overrides[i].token === token) {
+ this._overrides.splice(i, 1);
+ if (i === 0) { this._updateValue(); }
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /**
+ * Updates the current value using the current overrides and default value.
+ * If the new value differs from the previous value, the 'change' event will be fired.
+ */
+ _updateValue() {
+ const value = this._overrides.length > 0 ? this._overrides[0].value : this._defaultValue;
+ if (this._value === value) { return; }
+ this._value = value;
+ this.trigger('change', {value});
+ }
+}