yomichan/ext/mixed/js/dom-data-binder.js
2020-10-08 17:38:18 -04:00

356 lines
11 KiB
JavaScript

/*
* Copyright (C) 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/>.
*/
/* global
* TaskAccumulator
*/
class DOMDataBinder {
constructor({selector, ignoreSelectors=[], createElementMetadata, compareElementMetadata, getValues, setValues, onError=null}) {
this._selector = selector;
this._ignoreSelectors = ignoreSelectors;
this._createElementMetadata = createElementMetadata;
this._compareElementMetadata = compareElementMetadata;
this._getValues = getValues;
this._setValues = setValues;
this._onError = onError;
this._updateTasks = new TaskAccumulator(this._onBulkUpdate.bind(this));
this._assignTasks = new TaskAccumulator(this._onBulkAssign.bind(this));
this._mutationObserver = new MutationObserver(this._onMutation.bind(this));
this._observingElement = null;
this._elementMap = new Map(); // Map([element => observer]...)
this._elementAncestorMap = new Map(); // Map([element => Set([observer]...))
}
observe(element) {
if (this._isObserving) { return; }
this._observingElement = element;
this._mutationObserver.observe(element, {
attributes: true,
attributeOldValue: true,
childList: true,
subtree: true
});
this._onMutation([{
type: 'childList',
target: element.parentNode,
addedNodes: [element],
removedNodes: []
}]);
}
disconnect() {
if (!this._isObserving) { return; }
this._mutationObserver.disconnect();
this._observingElement = null;
for (const observer of this._elementMap.values()) {
this._removeObserver(observer);
}
}
async refresh() {
await this._updateTasks.enqueue(null, {all: true});
}
// Private
_onMutation(mutationList) {
for (const mutation of mutationList) {
switch (mutation.type) {
case 'childList':
this._onChildListMutation(mutation);
break;
case 'attributes':
this._onAttributeMutation(mutation);
break;
}
}
}
_onChildListMutation({addedNodes, removedNodes, target}) {
const selector = this._selector;
const ELEMENT_NODE = Node.ELEMENT_NODE;
for (const node of removedNodes) {
const observers = this._elementAncestorMap.get(node);
if (typeof observers === 'undefined') { continue; }
for (const observer of observers) {
this._removeObserver(observer);
}
}
for (const node of addedNodes) {
if (node.nodeType !== ELEMENT_NODE) { continue; }
if (node.matches(selector)) {
this._createObserver(node);
}
for (const childNode of node.querySelectorAll(selector)) {
this._createObserver(childNode);
}
}
if (addedNodes.length !== 0 || addedNodes.length !== 0) {
const observer = this._elementMap.get(target);
if (typeof observer !== 'undefined' && observer.hasValue) {
this._setElementValue(observer.element, observer.value);
}
}
}
_onAttributeMutation({target}) {
const selector = this._selector;
const observers = this._elementAncestorMap.get(target);
if (typeof observers !== 'undefined') {
for (const observer of observers) {
const element = observer.element;
if (
!element.matches(selector) ||
this._shouldIgnoreElement(element) ||
this._isObserverStale(observer)
) {
this._removeObserver(observer);
}
}
}
if (target.matches(selector)) {
this._createObserver(target);
}
}
async _onBulkUpdate(tasks) {
let all = false;
const targets = [];
for (const [observer, task] of tasks) {
if (observer === null) {
if (task.data.all) {
all = true;
break;
}
} else {
targets.push([observer, task]);
}
}
if (all) {
targets.length = 0;
for (const observer of this._elementMap.values()) {
targets.push([observer, null]);
}
}
const args = targets.map(([observer]) => ({
element: observer.element,
metadata: observer.metadata
}));
const responses = await this._getValues(args);
this._applyValues(targets, responses, true);
}
async _onBulkAssign(tasks) {
const targets = tasks;
const args = targets.map(([observer, task]) => ({
element: observer.element,
metadata: observer.metadata,
value: task.data.value
}));
const responses = await this._setValues(args);
this._applyValues(targets, responses, false);
}
_onElementChange(observer) {
const value = this._getElementValue(observer.element);
observer.value = value;
observer.hasValue = true;
this._assignTasks.enqueue(observer, {value});
}
_applyValues(targets, response, ignoreStale) {
if (!Array.isArray(response)) { return; }
for (let i = 0, ii = targets.length; i < ii; ++i) {
const [observer, task] = targets[i];
const {error, result} = response[i];
const stale = (task !== null && task.stale);
if (error) {
if (typeof this._onError === 'function') {
this._onError(error, stale, observer.element, observer.metadata);
}
continue;
}
if (stale && !ignoreStale) { continue; }
observer.value = result;
observer.hasValue = true;
this._setElementValue(observer.element, result);
}
}
_createObserver(element) {
if (this._elementMap.has(element) || this._shouldIgnoreElement(element)) { return; }
const metadata = this._createElementMetadata(element);
const nodeName = element.nodeName.toUpperCase();
const ancestors = this._getAncestors(element);
const observer = {
element,
ancestors,
type: (nodeName === 'INPUT' ? element.type : null),
value: null,
hasValue: false,
onChange: null,
metadata
};
observer.onChange = this._onElementChange.bind(this, observer);
this._elementMap.set(element, observer);
element.addEventListener('change', observer.onChange, false);
for (const ancestor of ancestors) {
let observers = this._elementAncestorMap.get(ancestor);
if (typeof observers === 'undefined') {
observers = new Set();
this._elementAncestorMap.set(ancestor, observers);
}
observers.add(observer);
}
this._updateTasks.enqueue(observer);
}
_removeObserver(observer) {
const {element, ancestors} = observer;
element.removeEventListener('change', observer.onChange, false);
observer.onChange = null;
this._elementMap.delete(element);
for (const ancestor of ancestors) {
const observers = this._elementAncestorMap.get(ancestor);
if (typeof observers === 'undefined') { continue; }
observers.delete(observer);
if (observers.size === 0) {
this._elementAncestorMap.delete(ancestor);
}
}
}
_isObserverStale(observer) {
const {element, type, metadata} = observer;
const nodeName = element.nodeName.toUpperCase();
return !(
type === (nodeName === 'INPUT' ? element.type : null) &&
this._compareElementMetadata(metadata, this._createElementMetadata(element))
);
}
_shouldIgnoreElement(element) {
for (const selector of this._ignoreSelectors) {
if (element.matches(selector)) {
return true;
}
}
return false;
}
_getAncestors(node) {
const root = this._observingElement;
const results = [];
while (true) {
results.push(node);
if (node === root) { break; }
node = node.parentNode;
if (node === null) { break; }
}
return results;
}
_setElementValue(element, value) {
switch (element.nodeName.toUpperCase()) {
case 'INPUT':
switch (element.type) {
case 'checkbox':
element.checked = value;
break;
case 'text':
case 'number':
element.value = value;
break;
}
break;
case 'TEXTAREA':
case 'SELECT':
element.value = value;
break;
}
const event = new CustomEvent('settingChanged', {detail: {value}});
element.dispatchEvent(event);
}
_getElementValue(element) {
switch (element.nodeName.toUpperCase()) {
case 'INPUT':
switch (element.type) {
case 'checkbox':
return !!element.checked;
case 'text':
return `${element.value}`;
case 'number':
return DOMDataBinder.convertToNumber(element.value, element);
}
break;
case 'TEXTAREA':
case 'SELECT':
return element.value;
}
return null;
}
// Utilities
static convertToNumber(value, constraints) {
value = parseFloat(value);
if (!Number.isFinite(value)) { return 0; }
let {min, max, step} = constraints;
min = DOMDataBinder.convertToNumberOrNull(min);
max = DOMDataBinder.convertToNumberOrNull(max);
step = DOMDataBinder.convertToNumberOrNull(step);
if (typeof min === 'number') { value = Math.max(value, min); }
if (typeof max === 'number') { value = Math.min(value, max); }
if (typeof step === 'number' && step !== 0) { value = Math.round(value / step) * step; }
return value;
}
static convertToNumberOrNull(value) {
if (typeof value !== 'number') {
if (typeof value !== 'string' || value.length === 0) {
return null;
}
value = parseFloat(value);
}
return !Number.isNaN(value) ? value : null;
}
}