Support for SwiftUI

BGSwift/Classes/BGExtent.swift

@@ -163,7 +163,7 @@ public class BGExtentBuilderGeneric {
         return state(value) { lhs, rhs in
             lhs.bg_unwrapped === rhs.bg_unwrapped
         }
-    }
+    }    
 }
 
 public class BGExtentBuilder<Extent: BGExtent>: BGExtentBuilderGeneric {

BGSwift/Classes/BGResource.swift

@@ -249,14 +249,32 @@ public enum BGStateComparison {
     public enum Identical { case identical }
 }
 
-public class BGState<Type>: BGResource, BGResourceInternal, TransientResource {
+public class BGState<Type>: BGResource, BGResourceInternal, TransientResource, ObservableObject {
     var subsequents = Set<BGSubsequentLink>()
     weak var supplier: BGBehavior?
     weak var owner: BGExtent?
     var debugName: String?
     var _event: BGEvent = .unknownPast
     var _prevEvent: BGEvent = .unknownPast
 
+    // These properties support combine and swiftui
+    public weak var bindingInput: BGState? // could even be ourselves for two way binding
+    private var _observableUpdated: BGEvent = .unknownPast
+    private var _observableAccessed: Bool = false
+    public var observableValue: Type {
+        get {
+            _observableAccessed = true
+            if _event.sequence > _observableUpdated.sequence {
+                return traceValue
+            } else {
+                return value
+            }
+        }
+        set {
+            bindingInput?.updateWithAction(newValue)
+        }
+    }
+
     var _value: Type
     var _prevValue: Type?
     private var comparison: ((Type, Type) -> Bool)?
@@ -294,6 +312,14 @@ public class BGState<Type>: BGResource, BGResourceInternal, TransientResource {
         }
 
         if !valueEquals(newValue) {
+            if _observableAccessed {
+                owner?.sideEffect { [weak self] in
+                    if let self {
+                        self.objectWillChange.send()
+                        self._observableUpdated = self.event
+                    }
+                }
+            }
             _prevValue = _value;
             _prevEvent = _event;
 
@@ -338,6 +364,7 @@ public class BGState<Type>: BGResource, BGResourceInternal, TransientResource {
     func clearTransientValue() {
         _prevValue = nil
     }
+
 }
 
 public protocol BGDemandable {
@@ -356,3 +383,4 @@ extension BGDemandable {
         }
     }
 }
+

Example/BGSwift.xcodeproj/project.pbxproj

@@ -72,6 +72,7 @@
 		739FF919270F98F4000DACD1 /* BGExtentTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BGExtentTests.swift; sourceTree = "<group>"; };
 		739FF91B270F9D00000DACD1 /* BGGraphTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BGGraphTests.swift; sourceTree = "<group>"; };
 		739FF91E270FAF6A000DACD1 /* EventTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EventTests.swift; sourceTree = "<group>"; };
+		73E0B6492960F75100912A22 /* Package.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; name = Package.swift; path = ../Package.swift; sourceTree = "<group>"; };
 		8A12E8DD9E2CF2B6B45E7835 /* Pods_BGSwift_Example.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_BGSwift_Example.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		8A2F667ABE5A14147F7D89E8 /* Pods_BGSwift_Tests.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_BGSwift_Tests.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		DBFB91C16E7BCE9F06B08EE1 /* Pods-BGSwift-Example.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-BGSwift-Example.debug.xcconfig"; path = "Target Support Files/Pods-BGSwift-Example/Pods-BGSwift-Example.debug.xcconfig"; sourceTree = "<group>"; };
@@ -100,6 +101,7 @@
 		5A0BB796270517E40043E632 = {
 			isa = PBXGroup;
 			children = (
+				73E0B6492960F75100912A22 /* Package.swift */,
 				5AC349BC2705259F00289AD2 /* BGSwift */,
 				5A0BB7A1270517E40043E632 /* Example */,
 				5A0BB7B8270517E60043E632 /* Tests */,

Package.swift

@@ -0,0 +1,30 @@
+// swift-tools-version:5.3
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "BGSwift",
+    platforms: [
+        .macOS(.v10_15), // These are where Combine becomes available which we will use in SwiftPM compatibility
+        .iOS(.v13)
+    ],
+    products: [
+        // Products define the executables and libraries a package produces, and make them visible to other packages.
+        .library(
+            name: "BGSwift",
+            targets: ["BGSwift"]),
+    ],
+    dependencies: [
+        // Dependencies declare other packages that this package depends on.
+        // .package(url: /* package url */, from: "1.0.0"),
+    ],
+    targets: [
+        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
+        // Targets can depend on other targets in this package, and on products in packages this package depends on.
+        .target(
+            name: "BGSwift",
+            path: "BGSwift/Classes"),
+    ],
+    swiftLanguageVersions: [.v5]
+)