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feat(collection): [#29] Allow for any kind of Index #40

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merged 2 commits into from
May 14, 2023
Merged

feat(collection): [#29] Allow for any kind of Index #40

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0e896b7
[#29] allow for any kind of Index for collections
pjechris May 14, 2023
19a615c
[doc] update README
pjechris May 14, 2023
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10 changes: 3 additions & 7 deletions README.md
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Expand Up @@ -127,7 127,7 @@ identityMap.find(Book.self, id: 1)?

### Relational objects

To store objects containing other objects you need to make them conform to one protocol: `Aggregate`.
To store objects containing nested identity objects you need to make them conform to one protocol: `Aggregate`.

```swift
struct AuthorBooks: Aggregate {
Expand Down Expand Up @@ -167,7 167,7 @@ identityMap.find(Book.self, id: "ACK") // A Clash of Kings
identityMap.find(Book.self, id: "ADD") // A Dance with Dragons
```

You can also modify any of them however you want:
You can also modify any of them however you want. Notice the change is visible from the object itself AND from aggregate objects:

```swift
let newAuthor = Author(id: 1, name: "George R.R MartinI")
Expand All @@ -178,7 178,7 @@ identityMap.find(Author.self, id: 1) // George R.R MartinI
identityMap.find(AuthorBooks.self, id: 1) // George R.R MartinI [A Clash of Kings, A Dance with Dragons]
```

> You might think about storing books on `Author` directly (`author.books`). In this case `Author` would need to implement `Aggregate` and declare `books` are nested entity.
> You might think about storing books on `Author` directly (`author.books`). In this case `Author` needs to implement `Aggregate` and declare `books` as nested entity.
>
> However I strongly advise you to not nest `Identifiable` objects into other `Identifiable` objects. Read [Handling relationships](https://swiftunwrap.com/article/modeling-done-right/) article if you want to know more about this subject.

Expand Down Expand Up @@ -269,10 269,6 @@ identityMap.find(Book.self, id: "ACK") // return "A Clash of Kings" because canc

## Known limitations

### Custom collections are not supported

Custom collections are actually supported but for now you need to import `Accelerate` and conform to `AccelerateMutableBuffer`. Hopefully this restriction will be lifted.

### Associated value enums require double update

Let's say you have an enum with `Identifiable`/`Aggregate`:
Expand Down
4 changes: 2 additions & 2 deletions Sources/CohesionKit/KeyPath/PartialIdentifiableKeyPath.swift
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Expand Up @@ -45,7 45,7 @@ public struct PartialIdentifiableKeyPath<Root> {
}
}

public init<C: MutableCollection>(_ keyPath: KeyPath<Root, C>) where C.Element: Identifiable, C.Index == Int {
public init<C: MutableCollection>(_ keyPath: KeyPath<Root, C>) where C.Element: Identifiable, C.Index: Hashable {
self.keyPath = keyPath
self.accept = { parent, root, stamp, visitor in
visitor.visit(
Expand All @@ -55,7 55,7 @@ public struct PartialIdentifiableKeyPath<Root> {
}
}

public init<C: MutableCollection>(_ keyPath: KeyPath<Root, C>) where C.Element: Aggregate, C.Index == Int {
public init<C: MutableCollection>(_ keyPath: KeyPath<Root, C>) where C.Element: Aggregate, C.Index: Hashable {
self.keyPath = keyPath
self.accept = { parent, root, stamp, visitor in
visitor.visit(
Expand Down
22 changes: 13 additions & 9 deletions Sources/CohesionKit/KeyPath/UnsafeMutablePointer KeyPath.swift
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Expand Up @@ -4,20 4,24 @@ extension UnsafeMutablePointer {

func assign<Value>(_ value: Value, to keyPath: KeyPath<Pointee, Value>) {

guard let unsafePointer = UnsafeMutablePointer<Value>(mutating: pointer(to: keyPath)) else {
fatalError("cannot update value for KeyPath<\(Pointee.self), \(Value.self)>. Computed properties are not supported.")
guard let unsafeValuePointer = UnsafeMutablePointer<Value>(mutating: pointer(to: keyPath)) else {
fatalError("cannot update value for KeyPath<\(Pointee.self), \(Value.self)>: failed to access memory pointer.")
}

unsafePointer.pointee = value
unsafeValuePointer.pointee = value
}

func assign<C: MutableCollection>(_ value: C.Element, to keyPath: KeyPath<Pointee, C>, index: C.Index)
where C.Index == Int {

guard let unsafePointer = UnsafeMutablePointer<C>(mutating: pointer(to: keyPath)) else {
fatalError("cannot update value for KeyPath<\(Pointee.self), \(C.self)>. Computed properties are not supported.")
func assign<C: MutableCollection>(_ value: C.Element, to keyPath: KeyPath<Pointee, C>, index: C.Index) {

guard let unsafeCollectionPointer = UnsafeMutablePointer<C>(mutating: pointer(to: keyPath)) else {
fatalError("cannot update value for KeyPath<\(Pointee.self), \(C.self)>: failed to access memory pointer.")
}

unsafePointer.pointee.withContiguousMutableStorageIfAvailable { $0[index] = value }
/// calculate the distance in memory where the object is located to update it
let distance = unsafeCollectionPointer
.pointee
.distance(from: unsafeCollectionPointer.pointee.startIndex, to: index)

unsafeCollectionPointer.pointee.withContiguousMutableStorageIfAvailable { $0[distance] = value }
}
}
2 changes: 1 addition & 1 deletion Sources/CohesionKit/Storage/EntityNode.swift
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Expand Up @@ -61,7 61,7 @@ class EntityNode<T>: AnyEntityNode {

/// observe one of the node child whose type is a collection
func observeChild<C: MutableCollection>(_ childNode: EntityNode<C.Element>, for keyPath: KeyPath<T, C>, index: C.Index)
where C.Index == Int {
where C.Index: Hashable {
observeChild(childNode, identity: keyPath.appending(path: \C[index])) { pointer, newValue in
pointer.assign(newValue, to: keyPath, index: index)
}
Expand Down
4 changes: 2 additions & 2 deletions Sources/CohesionKit/Visitor/IdentityMapStoreVisitor.swift
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Expand Up @@ -33,7 33,7 @@ struct IdentityMapStoreVisitor: NestedEntitiesVisitor {
}

func visit<Root, C: MutableCollection>(context: EntityContext<Root, C>, entities: C)
where C.Element: Identifiable, C.Index == Int {
where C.Element: Identifiable, C.Index: Hashable {

for index in entities.indices {
context.parent.observeChild(
Expand All @@ -45,7 45,7 @@ struct IdentityMapStoreVisitor: NestedEntitiesVisitor {
}

func visit<Root, C: MutableCollection>(context: EntityContext<Root, C>, entities: C)
where C.Element: Aggregate, C.Index == Int {
where C.Element: Aggregate, C.Index: Hashable {

for index in entities.indices {
context.parent.observeChild(
Expand Down
4 changes: 2 additions & 2 deletions Sources/CohesionKit/Visitor/NestedEntitiesVisitor.swift
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Expand Up @@ -9,8 9,8 @@ protocol NestedEntitiesVisitor {
func visit<Root, T: Aggregate>(context: EntityContext<Root, T?>, entity: T?)

func visit<Root, C: MutableCollection>(context: EntityContext<Root, C>, entities: C)
where C.Element: Identifiable, C.Index == Int
where C.Element: Identifiable, C.Index: Hashable

func visit<Root, C: MutableCollection>(context: EntityContext<Root, C>, entities: C)
where C.Element: Aggregate, C.Index == Int
where C.Element: Aggregate, C.Index: Hashable
}
20 changes: 16 additions & 4 deletions Tests/CohesionKitTests/KeyPath/UnsafeMutablePointerTests.swift
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Expand Up @@ -3,7 3,7 @@ import XCTest

class UnsafeMutablePointerTests: XCTestCase {
func test_assign_propertyIsImmutable_propertyIsChanged() {
var hello = Hello()
var hello = Hello(collection: [], singleValue: "hello")

withUnsafeMutablePointer(to: &hello) {
$0.assign("world", to: \Hello.singleValue)
Expand All @@ -13,17 13,29 @@ class UnsafeMutablePointerTests: XCTestCase {
}

func test_assign_keyPathIsCollection_propertyIsImmutable_collectionIsChangedAtIndex() {
var hello = Hello()
var hello = Hello(collection: [1, 2, 3, 4], singleValue: "")

withUnsafeMutablePointer(to: &hello) {
$0.assign(5, to: \Hello.collection, index: 3)
}

XCTAssertEqual(hello.collection, [1, 2, 3, 5])
}

func test_assign_keyPathIsCollection_mutipleAssignments_colllectionIsChanged() {
var hello = Hello(collection: [1, 2, 3, 4], singleValue: "")

withUnsafeMutablePointer(to: &hello) {
$0.assign(4, to: \Hello.collection, index: 0)
$0.assign(3, to: \Hello.collection, index: 0)
$0.assign(2, to: \Hello.collection, index: 0)
}

XCTAssertEqual(hello.collection, [2, 2, 3, 4])
}
}

private struct Hello {
let collection = [1, 2, 3, 4]
let singleValue = "hello"
let collection: [Int]
let singleValue: String
}
4 changes: 2 additions & 2 deletions Tests/CohesionKitTests/Visitor/IdentityMapStoreVisitorTests.swift
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Expand Up @@ -57,14 57,14 @@ class IdentityMapStoreVisitorTests: XCTestCase {
}

private class EntityNodeStub<T>: EntityNode<T> {
var observeChildKeyPathIndexCalled: (AnyEntityNode, PartialKeyPath<T>, Int) -> Void = { _, _, _ in }
var observeChildKeyPathIndexCalled: (AnyEntityNode, PartialKeyPath<T>, Any) -> Void = { _, _, _ in }
var observeChildKeyPathOptionalCalled: (AnyEntityNode, PartialKeyPath<T>) -> Void = { _, _ in }

override func observeChild<C: MutableCollection>(
_ childNode: EntityNode<C.Element>,
for keyPath: KeyPath<T, C>,
index: C.Index
) where C.Index == Int {
) {
observeChildKeyPathIndexCalled(childNode, keyPath, index)
}

Expand Down