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| /* @flow */ | |
| type MutablePropertyValues<Props: {[string]: mixed}> | |
| = $Exact<$ObjMap<Props, <T,R>(p: Property<T, R>) => PropertyValue<T, R>>> | |
| type PropertyValues<Props: {[string]: mixed}> | |
| = $ReadOnly<MutablePropertyValues<Props>>; | |
| interface Layout<Props: {[string]: mixed}> { | |
| getValue<S: string>(name: S): $ElementType<PropertyValues<Props>, S>; | |
| getMutable(): MutableLayout<Props>; | |
| } | |
| interface MutableLayout<Props: {[string]: mixed}> extends Layout<Props> { | |
| setValue<S: string>(name: S, value: $ElementType<PropertyValues<Props>, S>): void; | |
| } | |
| class Layer { | |
| layout: Layout<any>; | |
| constructor(layout: *) { | |
| this.layout = layout; | |
| } | |
| setLayoutProperty(name: string, value: any) { | |
| // Direct mutation not allowed: | |
| // this.layout.setValue(name, value); | |
| // Also not allowed: | |
| // this.layout._values[name] = value; | |
| // Instead: | |
| const nextLayout = this.layout.getMutable(); | |
| nextLayout.setValue(name, value); | |
| this.layout = nextLayout; | |
| } | |
| } | |
| class LayoutImpl<Props: {[string]: mixed}> implements Layout<Props>, MutableLayout<Props> { | |
| _properties: Properties<Props>; | |
| _values: MutablePropertyValues<Props>; | |
| constructor(properties: Properties<Props>) { | |
| this._properties = properties; | |
| this._values = cloneAsMutable(properties._defaultValues); | |
| } | |
| getValue<S: string>(name: S): $ElementType<PropertyValues<Props>, S> { | |
| return this._values[name]; | |
| } | |
| setValue<S: string>(name: S, value: $ElementType<PropertyValues<Props>, S>) { | |
| this._values[name] = value; | |
| } | |
| getMutable(): MutableLayout<Props> { | |
| const copy = new LayoutImpl(this._properties); | |
| copy._values = cloneAsMutable(this._values); | |
| return copy; | |
| } | |
| } | |
| class BasicProperty<T> implements Property<T, T> { constructor(value: T) {} } | |
| class Properties<Props: {[string]: mixed}> { | |
| _properties: Props; | |
| _defaultValues: PropertyValues<Props>; | |
| constructor(properties: Props) { /* ... */ } | |
| } | |
| const layoutProperties = new Properties({ | |
| size: new BasicProperty(0), | |
| anchor: new BasicProperty('top') | |
| }); | |
| const layer = new Layer(new LayoutImpl(layoutProperties)); | |
| layer.setLayoutProperty('size', 2); | |
| const prevLayout = layer.layout; | |
| layer.setLayoutProperty('size', 3); | |
| console.log(prevLayout.getValue('size')); // => 2 | |
| console.log(layer.layout.getValue('size')); // => 3 | |
| console.log(prevLayout === layer.layout); // => false | |
| // --------------------------------------------------------------------------- | |
| interface Property<T, R> { /* ... */ } | |
| class PropertyValue<T, R> { | |
| property: Property<T, R>; | |
| value: PropertyValueSpecification<T>; | |
| constructor(property: *, value: *) { | |
| this.property = property; | |
| this.value = value; | |
| } | |
| /* ... */ | |
| } | |
| declare type CameraFunctionSpecification<T> = | |
| | {| type: 'exponential', stops: Array<[number, T]> |} | |
| | {| type: 'interval', stops: Array<[number, T]> |}; | |
| declare type PropertyValueSpecification<T> = | |
| | T | |
| | CameraFunctionSpecification<T> | |
| | Array<mixed>; | |
| function cloneAsMutable<T: Object>(x: $ReadOnly<T>): T { | |
| const result = {}; | |
| for (let key in x) { | |
| result[key] = x[key]; | |
| } | |
| return (result: any); | |
| } | |
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