Support setting the route without navigating

Necessary for mutating route specific data without causing navigation changes.
The desired usage here would be that `oldState.map { $0.instanceIdentifier } == newState.map { $0.instanceIdentifier}`, and has significant side effects (described below) if not the case.

Note this carries a risk of having unintended effects if the user uses this incorrectly as it could cause the UI & navigationState to go out-of-sync if one changes the actual segments in the route.

However, the above side effect also Fixes #26, in that one can use this to react to UIKit based changes to the route. (IE system UINavigationBar back button)

ReSwiftRouter/NavigationActions.swift

@@ -42,10 +42,12 @@ public struct SetRouteAction: Action {
 
     let route: [RouteSegment]
     let animated: Bool
+    let navigate: Bool
 
     public init(route: [RouteSegment], animated: Bool = true, navigate: Bool = true) {
         self.route = route
         self.animated = animated
+        self.navigate = navigate
     }
 }
 

ReSwiftRouter/NavigationReducer.swift

@@ -22,6 +22,8 @@ public struct NavigationReducer {
         switch action {
         case let action as SetRouteAction:
             return self.setRoute(state: state, action: action)
+        case let action as MutateRouteSegmentAction:
+            return self.mutateComponent(state: state, action: action)
         default: break
         }
 
@@ -33,6 +35,18 @@ public struct NavigationReducer {
 
         state.route = action.route
         state.changeRouteAnimated = action.animated
+        state.shouldNavigate = action.navigate
+
+        return state
+    }
+
+    private static func mutateComponent(state: NavigationState, action: MutateRouteSegmentAction) -> NavigationState {
+        guard let index = state.route.index(where: { $0.instanceIdentifier == action.component.instanceIdentifier }) else { return state }
+
+        var state = state
+
+        state.route[index] = action.component
+        state.shouldNavigate = false
 
         return state
     }

ReSwiftRouter/NavigationState.swift

@@ -13,6 +13,7 @@ public struct NavigationState {
 
     public var route: [RouteSegment] = []
     var changeRouteAnimated: Bool = true
+    var shouldNavigate: Bool = true // Set to false if the router should not respond to state change
 
     public func segmentWith(instanceIdentifier: UUID) -> RouteSegment? {
         return self.route.first(where: { $0.instanceIdentifier == instanceIdentifier })

ReSwiftRouter/Router.swift

@@ -26,6 +26,10 @@ open class Router<State: StateType>: StoreSubscriber {
     }
 
     open func newState(state: NavigationState) {
+        guard state.shouldNavigate == true else {
+            return
+        }
+
         let routingActions = Router.routingActionsForTransitionFrom(
             lastNavigationState.route, newRoute: state.route)
 

ReSwiftRouterTests/ReSwiftRouterIntegrationTests.swift

@@ -291,7 +291,33 @@ class SwiftFlowRouterIntegrationTests: QuickSpec {
             }
         }
 
+        describe("changing route without navigating") {
+            var store: Store<FakeAppState>!
+            var mockRoutable: MockRoutable!
+            var router: Router<FakeAppState>!
+            let someRoute = MockRouteSegment()
+
+            beforeEach {
+                store = Store(reducer: AppReducer(), state: nil)
+                mockRoutable = MockRoutable()
+                router = Router(store: store, rootRoutable: mockRoutable) { state in
+                    state.navigationState
+                }
 
+                // silence router not read warning, need to keep router alive via reference
+                _ = router
+            }
+
+            context("when dispatching a route change with navigation: false") {
+                beforeEach {
+                    store.dispatch(SetRouteAction(route: [someRoute], navigate: false))
+                }
+
+                it("does not call to push route segment") {
+                    expect(mockRoutable.callsToPushRouteSegment).toEventually(beEmpty())
+                }
+            }
+        }
     }
 
 }