Add non-Darwin placeholder types and platform failure helper

- OGFPlaceholderTypes.swift: placeholder protocols for OGFGestureNode,
  OGFGestureNodeDelegate, OGFGestureNodeContainer, OGFGestureNodeCoordinator
  on non-Darwin platforms
- OGFGestureFunctions.swift: add #else block with placeholder implementations
  calling _openGesturesPlatformUnimplementedFailure
- Logging.swift: add _openGesturesPlatformUnimplementedFailure helper

Author: Kyle-Ye

Sources/OpenGestures/Extension/OGFGestureFunctions.swift

@@ -36,6 +36,34 @@ public func ogfGestureComponentControllerSetNode(
     preconditionFailure("")
 }
 
+#else
+
+public func OGFGestureNodeDefaultValue() -> Any {
+    ()
+}
+
+public func OGFGestureNodeCreateDefault(_ key: Int) -> any OGFGestureNode {
+    _openGesturesPlatformUnimplementedFailure()
+}
+
+public func OGFGestureNodeCoordinatorCreate(
+    _ willUpdateHandler: (() -> Void)?,
+    _ didUpdateHandler: (() -> Void)?
+) -> any OGFGestureNodeCoordinator {
+    _openGesturesPlatformUnimplementedFailure()
+}
+
+public func OGFGestureComponentControllerSetNode(
+    _ controller: AnyObject,
+    _ node: (any OGFGestureNode)?
+) {
+    _openGesturesPlatformUnimplementedFailure()
+}
+
+public func OGFGestureFailureTypeIsTerminated(_ type: OGFGestureFailureType) -> Bool {
+    ogfGestureFailureTypeIsTerminated(type: type)
+}
+
 #endif
 
 @_cdecl("OGFGestureFailureTypeIsTerminated")

Sources/OpenGestures/Extension/OGFPlaceholderTypes.swift

@@ -0,0 +1,71 @@
+//
+//  OGFPlaceholderTypes.swift
+//  OpenGestures
+//
+//  Placeholder protocol definitions for non-Darwin platforms where
+//  the ObjC protocols from COpenGestures are not available.
+
+#if !canImport(ObjectiveC)
+
+public protocol OGFGestureNode: AnyObject {
+    // weak in ObjC
+    // Swift protocols can't express weak without @objc,
+    /*weak*/ var delegate: (any OGFGestureNodeDelegate)? { get set }
+    /*weak*/ var container: (any OGFGestureNodeContainer)? { get set }
+    var coordinator: (any OGFGestureNodeCoordinator)? { get set }
+    var phase: OGFGesturePhase { get }
+    var isBlocked: Bool { get }
+    var identifier: String { get }
+    var tag: String? { get set }
+    var isDisabled: Bool { get set }
+    var disallowExclusionWithUnresolvedFailureRequirements: Bool { get set }
+    var platformKey: Int { get }
+    var failureReason: (any Error)? { get }
+
+    func abort() throws
+    func addRelation(type: OGFGestureRelationType, role: OGFGestureRelationRole, relatedNode: any OGFGestureNode)
+    func ensureUpdated() throws
+    func fail(reason: Any?, error: inout (any Error)?) throws
+    func removeRelation(type: OGFGestureRelationType, role: OGFGestureRelationRole, relatedNode: any OGFGestureNode)
+    func setTracking(_ tracking: Bool, eventsWithIdentifiers identifiers: [Any])
+    func update(value: Any?, isFinal: Bool) throws
+}
+
+public protocol OGFGestureNodeDelegate: AnyObject {
+    func gestureNode(_ node: any OGFGestureNode, didUpdatePhase phase: OGFGesturePhase)
+    func gestureNode(_ node: any OGFGestureNode, roleForRelationType type: OGFGestureRelationType, relatedNode: any OGFGestureNode) -> Any?
+    func gestureNodeShouldActivate(_ node: any OGFGestureNode) -> Bool
+    func gestureNodeWillUnblock(_ node: any OGFGestureNode)
+
+    // optional in ObjC
+    // Swift protocols can't express optional without @objc,
+    // so we provide default empty implementations below.
+    /*optional*/ func gestureNode(_ node: any OGFGestureNode, didEnqueuePhase phase: OGFGesturePhase)
+    /*optional*/ func gestureNodeWillAbort(_ node: any OGFGestureNode)
+}
+
+extension OGFGestureNodeDelegate {
+    public func gestureNode(_ node: any OGFGestureNode, didEnqueuePhase phase: OGFGesturePhase) {}
+    public func gestureNodeWillAbort(_ node: any OGFGestureNode) {}
+}
+
+public protocol OGFGestureNodeContainer: AnyObject {
+    func indexOfGestureNode(_ node: any OGFGestureNode) -> Int
+    func isDeeperThanContainer(_ container: any OGFGestureNodeContainer, referenceNode: any OGFGestureNode) -> Bool
+    func isDescendantOfContainer(_ container: any OGFGestureNodeContainer, referenceNode: any OGFGestureNode) -> Bool
+}
+
+public protocol OGFGestureNodeCoordinator: AnyObject {
+    var nodes: [any OGFGestureNode] { get }
+    var willUpdateHandler: (() -> Void)? { get set }
+    var willProcessUpdateQueueHandler: (() -> Void)? { get set }
+    var didUpdateHandler: (() -> Void)? { get set }
+
+    func enqueueUpdatesForNodes(_ nodes: [any OGFGestureNode], inBlock block: ([any OGFGestureNode]) -> Void, reason: String)
+    func hasUnresolvedFailureDependenciesForNode(_ node: any OGFGestureNode) -> Bool
+    func updateWithNodes(_ nodes: [any OGFGestureNode], reason: String, updateHandler: ([any OGFGestureNode]) -> Void)
+    func failureDependentsForNode(_ node: any OGFGestureNode) -> [any OGFGestureNode]
+    func processUpdatesWithReason(_ reason: String)
+}
+
+#endif

Sources/OpenGestures/Logging.swift

@@ -14,3 +14,14 @@ package func preconditionFailure(_ message: @autoclosure () -> String, file: Sta
 package func preconditionFailure(_ message: @autoclosure () -> String) -> Never {
     preconditionFailure(message(), file: #fileID, line: #line)
 }
+
+// MARK: - Platform Unimplemented
+
+@_transparent
+package func _openGesturesPlatformUnimplementedFailure(
+    _ function: String = #function,
+    file: StaticString = #fileID,
+    line: UInt = #line
+) -> Never {
+    preconditionFailure("Unimplemented for this platform yet", file: file, line: line)
+}