96 lines
2.0 KiB
JavaScript
96 lines
2.0 KiB
JavaScript
'use strict';
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function dirtyReporter() {
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const dirty = new Map();
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const onchanges = [];
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function add(obj, value) {
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const saved = dirty.get(obj);
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if (!saved) {
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dirty.set(obj, {type: 'add', newValue: value});
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} else if (saved.type === 'remove') {
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if (saved.savedValue === value) {
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dirty.delete(obj);
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} else {
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saved.newValue = value;
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saved.type = 'modify';
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}
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}
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}
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function remove(obj, value) {
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const saved = dirty.get(obj);
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if (!saved) {
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dirty.set(obj, {type: 'remove', savedValue: value});
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} else if (saved.type === 'add') {
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dirty.delete(obj);
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} else if (saved.type === 'modify') {
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saved.type = 'remove';
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}
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}
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function modify(obj, oldValue, newValue) {
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const saved = dirty.get(obj);
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if (!saved) {
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if (oldValue !== newValue) {
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dirty.set(obj, {type: 'modify', savedValue: oldValue, newValue});
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}
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} else if (saved.type === 'modify') {
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if (saved.savedValue === newValue) {
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dirty.delete(obj);
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} else {
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saved.newValue = newValue;
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}
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} else if (saved.type === 'add') {
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saved.newValue = newValue;
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}
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}
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function clear(obj) {
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if (obj === undefined) {
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dirty.clear();
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} else {
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dirty.delete(obj);
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}
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}
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function isDirty() {
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return dirty.size > 0;
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}
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function onChange(cb) {
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// make sure the callback doesn't throw
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onchanges.push(cb);
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}
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function wrap(obj) {
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for (const key of ['add', 'remove', 'modify', 'clear']) {
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obj[key] = trackChange(obj[key]);
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}
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return obj;
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}
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function emitChange() {
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for (const cb of onchanges) {
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cb();
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}
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}
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function trackChange(fn) {
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return function () {
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const dirty = isDirty();
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const result = fn.apply(null, arguments);
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if (dirty !== isDirty()) {
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emitChange();
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}
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return result;
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};
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}
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function has(key) {
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return dirty.has(key);
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}
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return wrap({add, remove, modify, clear, isDirty, onChange, has});
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}
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