Introduce Sendable SharedRepository (#14)

# Introduce Sendable SharedRepository

## ♻️ Current situation & Problem
Until now, `Sendable` conformance for values stored in the
`ValueRepository` (the builtin `SharedRepository` implementation) never
checked if values do indeed conform to Sendable. Implementors were
always required

## ⚙️ Release Notes 
* Introduced new `SendableSharedRepository` and
`SendableValueRepository` variant.

### Breaking Changes
* Computed KnowledgeSources now need to specify the type of the
SharedRepository via an associated type.
* The `HeapRepository` was removed. 

## 📚 Documentation
Documentation was updated.


## ✅ Testing
Additional unit testing was added for the new sendable shared repository
variants.


## 📝 Code of Conduct & Contributing Guidelines 

By submitting creating this pull request, you agree to follow our [Code
of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md):
- [x] I agree to follow the [Code of
Conduct](https://github.com/StanfordSpezi/.github/blob/main/CODE_OF_CONDUCT.md)
and [Contributing
Guidelines](https://github.com/StanfordSpezi/.github/blob/main/CONTRIBUTING.md).

Package.swift

@@ -69,7 +69,7 @@ func swiftLintPlugin() -> [Target.PluginUsage] {
 
 func swiftLintPackage() -> [PackageDescription.Package.Dependency] {
     if ProcessInfo.processInfo.environment["SPEZI_DEVELOPMENT_SWIFTLINT"] != nil {
-        [.package(url: "https://github.com/realm/SwiftLint.git", .upToNextMinor(from: "0.55.1"))]
+        [.package(url: "https://github.com/realm/SwiftLint.git", from: "0.55.1")]
     } else {
         []
     }

Sources/SpeziFoundation/SharedRepository/RepositoryValue.swift → Sources/SpeziFoundation/SharedRepository/Builtin/RepositoryValue.swift

@@ -7,33 +7,40 @@
 //
 
 
-/// Represents type erased ``RepositoryValue``.
+/// Represents type erased `RepositoryValue`.
+///
+/// Refer to ``RepositoryValue``.
 public protocol AnyRepositoryValue {
-    /// This property gives access to a type-erased version of ``RepositoryValue/Source``
+    /// This property gives access to a type-erased version of `Source`.
     var anySource: any KnowledgeSource.Type { get }
     /// This property gives access to a type-erased version of ``RepositoryValue/value``.
     var anyValue: Any { get }
 }
 
 
-/// A type that represents a stored value inside a ``SharedRepository``.
+/// A stored value in a shared repository.
 ///
-/// You may also think of it as a stored instance of a ``KnowledgeSource``.
-public protocol RepositoryValue<Source>: AnyRepositoryValue {
-    /// The ``KnowledgeSource`` for which the value is stored.
-    associatedtype Source: KnowledgeSource
+/// This container type contains the stored value an type information of the associated ``KnowledgeSource``.
+public struct RepositoryValue<Source: KnowledgeSource> {
+    /// The value of the knowledge source.
+    public let value: Source.Value
+
+    /// Initialize a new repository value.
+    /// - Parameter value: The value instance.
+    init(_ value: Source.Value) {
+        self.value = value
+    }
+}
 
 
-    /// The value instance of the ``KnowledgeSource``.
-    var value: Source.Value { get }
+extension RepositoryValue: AnyRepositoryValue {}
 
 
-    init(_ value: Source.Value)
-}
+extension RepositoryValue: Sendable where Source.Value: Sendable {}
 
 
 extension RepositoryValue {
-    /// The type erased ``RepositoryValue/Source``.
+    /// The type erased `Source`.
     public var anySource: any KnowledgeSource.Type {
         Source.self
     }

Sources/SpeziFoundation/SharedRepository/Builtin/SendableValueRepository.swift

@@ -0,0 +1,56 @@
+//
+// This source file is part of the Stanford Spezi open-source project
+//
+// SPDX-FileCopyrightText: 2023 Stanford University and the project authors (see CONTRIBUTORS.md)
+//
+// SPDX-License-Identifier: MIT
+//
+
+
+/// A Sendable Shared Repository.
+public struct SendableValueRepository<Anchor> {
+    private var storage: [ObjectIdentifier: AnyRepositoryValue & Sendable] = [:]
+
+
+    /// Initializes an empty shared repository.
+    public init() {}
+}
+
+
+extension SendableValueRepository: SendableSharedRepository {
+    public func get<Source: KnowledgeSource<Anchor>>(_ source: Source.Type) -> Source.Value? where Source.Value: Sendable {
+        (storage[ObjectIdentifier(source)] as? RepositoryValue<Source>)?.value
+    }
+
+    public mutating func set<Source: KnowledgeSource<Anchor>>(_ source: Source.Type, value newValue: Source.Value?) where Source.Value: Sendable {
+        storage[ObjectIdentifier(source)] = newValue.map { RepositoryValue<Source>($0) }
+    }
+
+    public func collect<Value>(allOf type: Value.Type) -> [Value] {
+        storage.values.compactMap { value in
+            value.anyValue as? Value
+        }
+    }
+}
+
+
+extension SendableValueRepository: Collection {
+    public typealias Index = Dictionary<ObjectIdentifier, AnyRepositoryValue & Sendable>.Index
+
+    public var startIndex: Index {
+        storage.values.startIndex
+    }
+
+    public var endIndex: Index {
+        storage.values.endIndex
+    }
+
+    public func index(after index: Index) -> Index {
+        storage.values.index(after: index)
+    }
+
+
+    public subscript(position: Index) -> AnyRepositoryValue & Sendable {
+        storage.values[position]
+    }
+}

Sources/SpeziFoundation/SharedRepository/Builtin/ValueRepository.swift

@@ -7,33 +7,33 @@
 //
 
 
-/// A ``ValueRepository`` that allows to store any ``KnowledgeSource``s.
-public typealias UniversalValueRepository = ValueRepository<Any>
-
-
-/// A ``SharedRepository`` implementation that itself is a value type.
-///
-/// - Note: The ``ValueRepository`` is considered `Sendable` if the ``RepositoryAnchor`` conforms to `Sendable`.
-public struct ValueRepository<Anchor>: SharedRepository, BuiltinRepository {
-    var storage: Container = [:]
+/// A Shared Repository.
+public struct ValueRepository<Anchor> {
+    private var storage: [ObjectIdentifier: AnyRepositoryValue] = [:]
 
 
+    /// Initializes an empty shared repository.
     public init() {}
+}
 
 
+extension ValueRepository: SharedRepository {
     public func get<Source: KnowledgeSource<Anchor>>(_ source: Source.Type) -> Source.Value? {
-        get0(source)
+        (storage[ObjectIdentifier(source)] as? RepositoryValue<Source>)?.value
     }
 
     public mutating func set<Source: KnowledgeSource<Anchor>>(_ source: Source.Type, value newValue: Source.Value?) {
-        set0(source, value: newValue)
+        self.storage[ObjectIdentifier(source)] = newValue.map { RepositoryValue<Source>($0) }
     }
 
     public func collect<Value>(allOf type: Value.Type) -> [Value] {
-        collect0(allOf: type)
+        storage.values.compactMap { value in
+            value.anyValue as? Value
+        }
     }
 }
 
+
 extension ValueRepository: Collection {
     public typealias Index = Dictionary<ObjectIdentifier, AnyRepositoryValue>.Index
 
@@ -54,6 +54,3 @@ extension ValueRepository: Collection {
         storage.values[position]
     }
 }
-
-
-extension ValueRepository: @unchecked Sendable where Anchor: Sendable {}

Sources/SpeziFoundation/SharedRepository/KnowledgeSource/ComputedKnowledgeSource.swift

@@ -8,11 +8,14 @@
 
 
 /// A ``KnowledgeSource`` that allows to compose it's values from it's surrounding knowledge environment.
-public protocol ComputedKnowledgeSource<Anchor>: SomeComputedKnowledgeSource {
+public protocol ComputedKnowledgeSource<Anchor, Repository>: SomeComputedKnowledgeSource {
+    associatedtype Repository
+
     /// Computes the value of the ``KnowledgeSource``.
     ///
     /// - Note: The implementation of this method must be deterministic.
     /// - Parameter repository: The repository to use for computation.
     /// - Returns: Returns the computed value.
-    static func compute<Repository: SharedRepository<Anchor>>(from repository: Repository) -> Value
+    @Sendable
+    static func compute(from repository: Repository) -> Value
 }

Sources/SpeziFoundation/SharedRepository/KnowledgeSource/KnowledgeSource.swift

@@ -16,23 +16,4 @@ public protocol KnowledgeSource<Anchor> {
     associatedtype Value = Self
     /// The ``RepositoryAnchor`` to which this `KnowledgeSource` is anchored to.
     associatedtype Anchor: RepositoryAnchor
-
-
-    /// Optional reduction algorithm to handle overriding existing entries.
-    ///
-    /// The default implementation overrides the existing value.
-    /// - Parameters:
-    ///   - value: The existing value to reduce into.
-    ///   - nextValue: The next value.
-    static func reduce(value: inout Self.Value, nextValue: Self.Value)
-}
-
-extension KnowledgeSource {
-    /// The default implementation override the current value.
-    /// - Parameters:
-    ///   - value: The existing value to reduce into.
-    ///   - nextValue: The next value.
-    public static func reduce(value: inout Self.Value, nextValue: Self.Value) {
-        value = nextValue
-    }
 }

Sources/SpeziFoundation/SharedRepository/KnowledgeSource/OptionalComputedKnowledgeSource.swift

@@ -9,11 +9,14 @@
 
 /// A ``KnowledgeSource`` that allows to compose it's values from it's surrounding knowledge environment
 /// but may deliver a optional value.
-public protocol OptionalComputedKnowledgeSource<Anchor>: SomeComputedKnowledgeSource {
+public protocol OptionalComputedKnowledgeSource<Anchor, Repository>: SomeComputedKnowledgeSource {
+    associatedtype Repository
+
     /// Computes the value of the ``KnowledgeSource``.
     ///
     /// - Note: The implementation of this method must be deterministic.
     /// - Parameter repository: The repository to use for computation.
     /// - Returns: Returns the computed value or nil if nothing could be computed.
-    static func compute<Repository: SharedRepository<Anchor>>(from repository: Repository) -> Value?
+    @Sendable
+    static func compute(from repository: Repository) -> Value?
 }