83 lines
1.8 KiB
JavaScript
83 lines
1.8 KiB
JavaScript
export function PropertyMixin(key, meta = {}) {
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if (!meta || 'object' !== typeof meta) {
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throw new TypeError(
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`Expected meta for Property(${
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key
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}) to be object. ${
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JSON.stringify(meta)
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} given.`
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);
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}
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return (Superclass) => {
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if (Superclass.prototype[key]) {
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throw new TypeError(`can't redefine Avocado property "${key}"`);
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}
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if ('identity' === meta.transformProperty) {
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meta.transformProperty = (key) => key;
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}
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else if (!meta.transformProperty) {
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meta.transformProperty = (key) => `${key}_PRIVATE_PROPERTY`;
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}
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meta.emit = meta.emit || function(...args) {
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if (this.emit) {
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this.emit(...args);
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}
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}
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meta.eq = meta.eq || function (l, r) {
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return l === r;
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}
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meta.get = meta.get || function(value) {
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return this[meta.transformProperty(key)];
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}
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meta.set = meta.set || function(value) {
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this[meta.transformProperty(key)] = value;
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}
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let metaDefault;
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if (null === meta.default) {
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metaDefault = null;
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}
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else if (undefined === meta.default) {
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metaDefault = undefined;
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}
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else {
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metaDefault = JSON.parse(JSON.stringify(meta.default));
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}
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class Property extends Superclass {
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constructor(...args) {
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super(...args);
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if (undefined !== metaDefault) {
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meta.set.call(this, metaDefault);
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}
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}
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}
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Object.defineProperty(Property.prototype, key, {
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enumerable: true,
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get: function() {
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return meta.get.call(this);
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},
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set: function (value) {
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const old = meta.get.call(this);
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meta.set.call(this, value);
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if (meta.track && meta.emit && !meta.eq.call(this, old, value)) {
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meta.emit.call(this, `${key}Changed`, old, value);
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}
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},
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});
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return Property;
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}
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}
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