mirror of
https://github.com/JohnEstropia/CoreStore.git
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404 lines
16 KiB
Swift
404 lines
16 KiB
Swift
//
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// Field.Virtual.swift
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// CoreStore
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//
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// Copyright © 2020 John Rommel Estropia
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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//
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import CoreData
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import Foundation
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// MARK: - FieldContainer
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extension FieldContainer {
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// MARK: - Virtual
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/**
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The containing type for computed property values. Because this value is not persisted to the backing store, any type is supported. `Field.Virtual` properties are not allowed to have initial values, including `nil` for optional types.
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```
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class Animal: CoreStoreObject {
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@Field.Virtual(
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"pluralName",
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customGetter: { (object, field) in
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return object.$species.value + "s"
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}
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)
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var pluralName: String
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@Field.Stored("species")
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var species: String = ""
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}
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```
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- Important: `Field` properties are required to be used as `@propertyWrapper`s. Any other declaration not using the `@Field.Virtual(...) var` syntax will be ignored.
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*/
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@propertyWrapper
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public struct Virtual<V>: AttributeKeyPathStringConvertible, FieldAttributeProtocol {
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/**
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Initializes the metadata for the property. `Field.Virtual` properties are not allowed to have initial values, including `nil` for optional types.
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```
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class Person: CoreStoreObject {
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@Field.Virtual(
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"pluralName",
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customGetter: { (object, field) in
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return object.$species.value + "s"
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}
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)
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var pluralName: String
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@Field.Stored("species")
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var species: String = ""
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}
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```
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- parameter keyPath: the permanent attribute name for this property.
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- parameter customGetter: use this closure as an "override" for the default property getter. The closure receives a `ObjectProxy<O>`, which acts as a type-safe proxy for the receiver. When accessing the property value from `ObjectProxy<O>`, make sure to use `field.primitiveValue` instead of `field.value`, which would unintentionally execute the same closure again recursively. Do not make assumptions on the thread/queue that the closure is executed on; accessors may be called from `NSError` logs for example.
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- parameter customSetter: use this closure as an "override" for the default property setter. The closure receives a `ObjectProxy<O>`, which acts as a fast, type-safe KVC interface for `CoreStoreObject`. The reason a `CoreStoreObject` instance is not passed directly is because the Core Data runtime is not aware of `CoreStoreObject` properties' static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as `ListMonitor` observing.) When accessing the property value from `ObjectProxy<O>`, make sure to use `field.primitiveValue` instead of `field.value`, which would unintentionally execute the same closure again recursively.
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- parameter affectedByKeyPaths: a set of key paths for properties whose values affect the value of the receiver. This is similar to `NSManagedObject.keyPathsForValuesAffectingValue(forKey:)`.
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*/
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public init(
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_ keyPath: KeyPathString,
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customGetter: @escaping (_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>) -> V,
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customSetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>,
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_ newValue: V
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) -> Void
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)? = nil,
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affectedByKeyPaths: @autoclosure @escaping () -> Set<KeyPathString> = []) {
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self.init(
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keyPath: keyPath,
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customGetter: customGetter,
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customSetter: customSetter,
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affectedByKeyPaths: affectedByKeyPaths
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)
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}
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/**
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Overload for compiler error message only
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*/
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@available(*, unavailable, message: "Field.Virtual properties are not allowed to have initial values, including `nil`.")
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public init(
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wrappedValue initial: @autoclosure @escaping () -> V,
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_ keyPath: KeyPathString,
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versionHashModifier: @autoclosure @escaping () -> String? = nil,
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customGetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>
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) -> V
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)? = nil,
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customSetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>,
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_ newValue: V
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) -> Void
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)? = nil,
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affectedByKeyPaths: @autoclosure @escaping () -> Set<KeyPathString> = []) {
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fatalError()
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}
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// MARK: @propertyWrapper
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@available(*, unavailable)
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public var wrappedValue: V {
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get { fatalError() }
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set { fatalError() }
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}
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public var projectedValue: Self {
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return self
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}
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public static subscript(
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_enclosingInstance instance: O,
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wrapped wrappedKeyPath: ReferenceWritableKeyPath<O, V>,
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storage storageKeyPath: ReferenceWritableKeyPath<O, Self>
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) -> V {
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get {
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Internals.assert(
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instance.rawObject != nil,
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"Attempted to access values from a \(Internals.typeName(O.self)) meta object. Meta objects are only used for querying keyPaths and infering types."
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)
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Internals.assert(
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instance.rawObject?.isRunningInAllowedQueue() == true,
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"Attempted to access \(Internals.typeName(O.self))'s value outside it's designated queue."
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)
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return self.read(field: instance[keyPath: storageKeyPath], for: instance.rawObject!) as! V
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}
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set {
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Internals.assert(
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instance.rawObject != nil,
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"Attempted to access values from a \(Internals.typeName(O.self)) meta object. Meta objects are only used for querying keyPaths and infering types."
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)
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Internals.assert(
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instance.rawObject?.isRunningInAllowedQueue() == true,
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"Attempted to access \(Internals.typeName(O.self))'s value outside it's designated queue."
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)
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return self.modify(field: instance[keyPath: storageKeyPath], for: instance.rawObject!, newValue: newValue)
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}
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}
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// MARK: AnyKeyPathStringConvertible
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public var cs_keyPathString: String {
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return self.keyPath
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}
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// MARK: KeyPathStringConvertible
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public typealias ObjectType = O
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public typealias DestinationValueType = V
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// MARK: AttributeKeyPathStringConvertible
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public typealias ReturnValueType = DestinationValueType
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// MARK: PropertyProtocol
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internal let keyPath: KeyPathString
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// MARK: FieldProtocol
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internal static var dynamicObjectType: CoreStoreObject.Type {
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return ObjectType.self
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}
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internal static func read(
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field: FieldProtocol,
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for rawObject: CoreStoreManagedObject
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) -> Any? {
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let field = field as! Self
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if let customGetter = field.customGetter {
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return customGetter(
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ObjectProxy<O>(rawObject),
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ObjectProxy<O>.FieldProxy<V>(rawObject: rawObject, field: field)
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)
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}
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let keyPath = field.keyPath
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switch rawObject.value(forKey: keyPath) {
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case let rawValue as V:
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return rawValue
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default:
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return nil
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}
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}
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internal static func modify(
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field: FieldProtocol,
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for rawObject: CoreStoreManagedObject,
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newValue: Any?
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) {
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Internals.assert(
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rawObject.isEditableInContext() == true,
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"Attempted to update a \(Internals.typeName(O.self))'s value from outside a transaction."
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)
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let newValue = newValue as! V
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let field = field as! Self
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let keyPath = field.keyPath
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if let customSetter = field.customSetter {
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return customSetter(
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ObjectProxy<O>(rawObject),
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ObjectProxy<O>.FieldProxy<V>(rawObject: rawObject, field: field),
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newValue
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)
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}
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return rawObject.setValue(newValue, forKey: keyPath)
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}
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// MARK: FieldAttributeProtocol
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internal let entityDescriptionValues: () -> FieldAttributeProtocol.EntityDescriptionValues
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internal var getter: CoreStoreManagedObject.CustomGetter? {
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guard let customGetter = self.customGetter else {
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return nil
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}
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let keyPath = self.keyPath
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return { (_ id: Any) -> Any? in
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let rawObject = id as! CoreStoreManagedObject
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rawObject.willAccessValue(forKey: keyPath)
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defer {
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rawObject.didAccessValue(forKey: keyPath)
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}
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return customGetter(
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ObjectProxy<O>(rawObject),
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ObjectProxy<O>.FieldProxy<V>(rawObject: rawObject, field: self)
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)
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}
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}
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internal var setter: CoreStoreManagedObject.CustomSetter? {
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guard let customSetter = self.customSetter else {
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return nil
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}
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let keyPath = self.keyPath
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return { (_ id: Any, _ newValue: Any?) -> Void in
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let rawObject = id as! CoreStoreManagedObject
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rawObject.willChangeValue(forKey: keyPath)
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defer {
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rawObject.didChangeValue(forKey: keyPath)
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}
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return customSetter(
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ObjectProxy<O>(rawObject),
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ObjectProxy<O>.FieldProxy<V>(rawObject: rawObject, field: self),
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newValue as! V
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)
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}
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}
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let initializer: CoreStoreManagedObject.CustomInitializer? = nil
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// MARK: FilePrivate
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fileprivate init(
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keyPath: KeyPathString,
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customGetter: ((_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>) -> V)?,
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customSetter: ((_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>, _ newValue: V) -> Void)? ,
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affectedByKeyPaths: @escaping () -> Set<KeyPathString>
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) {
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self.keyPath = keyPath
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self.entityDescriptionValues = {
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(
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attributeType: .undefinedAttributeType,
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isOptional: true,
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isTransient: true,
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allowsExternalBinaryDataStorage: false,
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versionHashModifier: nil,
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renamingIdentifier: nil,
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valueTransformer: nil,
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affectedByKeyPaths: affectedByKeyPaths(),
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defaultValue: nil
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)
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}
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self.customGetter = customGetter
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self.customSetter = customSetter
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}
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// MARK: Private
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private let customGetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>
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) -> V
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)?
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private let customSetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>,
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_ newValue: V
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) -> Void
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)?
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}
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}
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// MARK: - FieldContainer.Virtual where V: FieldOptionalType
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extension FieldContainer.Virtual where V: FieldOptionalType {
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/**
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Initializes the metadata for the property. `Field.Virtual` properties are not allowed to have initial values, including `nil` for optional types.
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```
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class Person: CoreStoreObject {
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@Field.Virtual(
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"pluralName",
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customGetter: { (object, field) in
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return object.$species.value + "s"
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}
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)
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var pluralName: String?
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@Field.Stored("species")
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var species: String = ""
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}
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```
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- parameter keyPath: the permanent attribute name for this property.
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- parameter customGetter: use this closure as an "override" for the default property getter. The closure receives a `ObjectProxy<O>`, which acts as a type-safe proxy for the receiver. When accessing the property value from `ObjectProxy<O>`, make sure to use `field.primitiveValue` instead of `field.value`, which would unintentionally execute the same closure again recursively. Do not make assumptions on the thread/queue that the closure is executed on; accessors may be called from `NSError` logs for example.
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- parameter customSetter: use this closure as an "override" for the default property setter. The closure receives a `ObjectProxy<O>`, which acts as a fast, type-safe KVC interface for `CoreStoreObject`. The reason a `CoreStoreObject` instance is not passed directly is because the Core Data runtime is not aware of `CoreStoreObject` properties' static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as `ListMonitor` observing.) When accessing the property value from `ObjectProxy<O>`, make sure to use `field.primitiveValue` instead of `field.value`, which would unintentionally execute the same closure again recursively.
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- parameter affectedByKeyPaths: a set of key paths for properties whose values affect the value of the receiver. This is similar to `NSManagedObject.keyPathsForValuesAffectingValue(forKey:)`.
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*/
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public init(
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_ keyPath: KeyPathString,
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customGetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>
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) -> V
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)? = nil,
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customSetter: (
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(
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_ object: ObjectProxy<O>,
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_ field: ObjectProxy<O>.FieldProxy<V>,
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_ newValue: V
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) -> Void
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)? = nil,
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affectedByKeyPaths: @autoclosure @escaping () -> Set<KeyPathString> = []) {
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self.init(
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keyPath: keyPath,
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customGetter: customGetter,
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customSetter: customSetter,
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affectedByKeyPaths: affectedByKeyPaths
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)
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}
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}
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