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Merged
dansiegel merged 2 commits into from
May 5, 2024
Merged

chore: enable nullability for mvvm helpers #3131

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f8afe99
chore: enable nullability for mvvm helpers
RLittlesII May 5, 2024
03a11dd
feedback on api surface
RLittlesII May 5, 2024
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6 changes: 6 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -208,3 +208,9 @@ FakesAssemblies/

# Binlog
*.binlog

# macOS
.DS_Store

# VSCode
.mono
78 changes: 40 additions & 38 deletions src/Maui/Prism.Maui/Common/MvvmHelpers.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,6 @@
#nullable enable
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using Prism.Dialogs;
using Prism.Navigation;
Expand All @@ -11,14 +13,14 @@ namespace Prism.Common;

public static class MvvmHelpers
{
public static void InvokeViewAndViewModelAction<T>(object view, Action<T> action) where T : class
public static void InvokeViewAndViewModelAction<T>(object? view, Action<T> action) where T : class
{
if (view is T viewAsT)
{
action(viewAsT);
}

if (view is BindableObject element && element.BindingContext is T viewModelAsT)
if (view is BindableObject { BindingContext: T viewModelAsT })
{
action(viewModelAsT);
}
Expand All @@ -32,14 +34,14 @@ public static void InvokeViewAndViewModelAction<T>(object view, Action<T> action
}
}

public static async Task InvokeViewAndViewModelActionAsync<T>(object view, Func<T, Task> action) where T : class
public static async Task InvokeViewAndViewModelActionAsync<T>(object? view, Func<T, Task> action) where T : class
{
if (view is T viewAsT)
{
await action(viewAsT);
}

if (view is BindableObject element && element.BindingContext is T viewModelAsT)
if (view is BindableObject { BindingContext: T viewModelAsT })
{
await action(viewModelAsT);
}
Expand All @@ -49,11 +51,11 @@ public static async Task InvokeViewAndViewModelActionAsync<T>(object view, Func<
var children = page.GetChildRegions();
if (children is not null)
foreach (var child in children)
await InvokeViewAndViewModelActionAsync<T>(child, action);
await InvokeViewAndViewModelActionAsync(child, action);
}
}

public static void DestroyPage(IView view)
public static void DestroyPage(IView? view)
{
try
{
Expand Down Expand Up @@ -96,7 +98,7 @@ private static void DestroyChildren(IView page)
}
}

public static void DestroyWithModalStack(Page page, IList<Page> modalStack)
public static void DestroyWithModalStack(Page? page, IList<Page?> modalStack)
{
foreach (var childPage in modalStack.Reverse())
{
Expand All @@ -105,15 +107,15 @@ public static void DestroyWithModalStack(Page page, IList<Page> modalStack)
DestroyPage(page);
}

public static T GetImplementerFromViewOrViewModel<T>(object view)
public static T? GetImplementerFromViewOrViewModel<T>(object view)
where T : class
{
if (view is T viewAsT)
{
return viewAsT;
}

if (view is VisualElement element && element.BindingContext is T vmAsT)
if (view is VisualElement { BindingContext: T vmAsT })
{
return vmAsT;
}
Expand All @@ -136,12 +138,12 @@ public static bool IsNavigationTarget(object view, NavigationContext navigationC
return path == viewType.Name || path == viewType.FullName;
}

public static void OnNavigatedFrom(object view, NavigationContext navigationContext)
public static void OnNavigatedFrom(object? view, NavigationContext navigationContext)
{
InvokeViewAndViewModelAction<IRegionAware>(view, x => x.OnNavigatedFrom(navigationContext));
}

public static void OnNavigatedTo(object view, NavigationContext navigationContext)
public static void OnNavigatedTo(object? view, NavigationContext navigationContext)
{
InvokeViewAndViewModelAction<IRegionAware>(view, x => x.OnNavigatedTo(navigationContext));
}
Expand All @@ -161,35 +163,35 @@ private static bool CanNavigate(object page, INavigationParameters parameters)
return implementer?.CanNavigate(parameters) ?? true;
}

public static void OnNavigatedFrom(object page, INavigationParameters parameters)
public static void OnNavigatedFrom(object? page, INavigationParameters parameters)
{
if (page != null)
InvokeViewAndViewModelAction<INavigatedAware>(page, v => v.OnNavigatedFrom(parameters));
}

public static async Task OnInitializedAsync(object page, INavigationParameters parameters)
public static async Task OnInitializedAsync(object? page, INavigationParameters parameters)
{
if (page is null) return;

InvokeViewAndViewModelAction<IInitialize>(page, v => v.Initialize(parameters));
await InvokeViewAndViewModelActionAsync<IInitializeAsync>(page, async v => await v.InitializeAsync(parameters));
}

private static bool HasKey(this IEnumerable<KeyValuePair<string, object>> parameters, string name, out string key)
private static bool HasKey(this IEnumerable<KeyValuePair<string, object>> parameters, string name, [MaybeNullWhen(returnValue: false)] out string key)
{
key = parameters.Select(x => x.Key).FirstOrDefault(k => k.Equals(name, StringComparison.InvariantCultureIgnoreCase));
return !string.IsNullOrEmpty(key);
}

public static void OnNavigatedTo(object page, INavigationParameters parameters)
public static void OnNavigatedTo(object? page, INavigationParameters parameters)
{
if (page != null)
InvokeViewAndViewModelAction<INavigatedAware>(page, v => v.OnNavigatedTo(parameters));
}

public static Page GetOnNavigatedToTarget(Page page, IView mainPage, bool useModalNavigation)
public static Page? GetOnNavigatedToTarget(Page page, IView? mainPage, bool useModalNavigation)
{
Page target;
Page? target;
if (useModalNavigation)
{
var previousPage = GetPreviousPage(page, page.Navigation.ModalStack);
Expand All @@ -210,9 +212,9 @@ public static Page GetOnNavigatedToTarget(Page page, IView mainPage, bool useMod
return target;
}

public static Page GetOnNavigatedToTargetFromChild(IView target)
public static Page? GetOnNavigatedToTargetFromChild(IView? target)
{
Page child = null;
Page? child = null;

if (target is FlyoutPage flyout)
child = flyout.Detail;
Expand All @@ -230,9 +232,9 @@ public static Page GetOnNavigatedToTargetFromChild(IView target)
return null;
}

public static Page GetPreviousPage(Page currentPage, System.Collections.Generic.IReadOnlyList<Page> navStack)
public static Page? GetPreviousPage(Page currentPage, IReadOnlyList<Page?> navStack)
{
Page previousPage = null;
Page? previousPage = null;

int currentPageIndex = GetCurrentPageIndex(currentPage, navStack);
int previousPageIndex = currentPageIndex - 1;
Expand All @@ -242,7 +244,7 @@ public static Page GetPreviousPage(Page currentPage, System.Collections.Generic.
return previousPage;
}

public static int GetCurrentPageIndex(Page currentPage, System.Collections.Generic.IReadOnlyList<Page> navStack)
public static int GetCurrentPageIndex(Page currentPage, IReadOnlyList<Page?> navStack)
{
int stackCount = navStack.Count;
for (int x = 0; x < stackCount; x++)
Expand All @@ -255,14 +257,14 @@ public static int GetCurrentPageIndex(Page currentPage, System.Collections.Gener
return stackCount - 1;
}

public static Page GetCurrentPage(Page mainPage) =>
public static Page? GetCurrentPage(Page mainPage) =>
_getCurrentPage(mainPage);

[EditorBrowsable(EditorBrowsableState.Never)]
public static void SetCurrentPageDelegate(Func<Page, Page> getCurrentPageDelegate) =>
public static void SetCurrentPageDelegate(Func<Page, Page?> getCurrentPageDelegate) =>
_getCurrentPage = getCurrentPageDelegate;

private static Func<Page, Page> _getCurrentPage = mainPage =>
private static Func<Page, Page?> _getCurrentPage = mainPage =>
{
var page = mainPage;

Expand All @@ -273,7 +275,7 @@ public static void SetCurrentPageDelegate(Func<Page, Page> getCurrentPageDelegat
return EvaluateCurrentPage(page);
};

private static Page GetTarget(Page target)
private static Page? GetTarget(Page? target)
{
return target switch
{
Expand All @@ -285,14 +287,14 @@ private static Page GetTarget(Page target)
};
}

private static Page EvaluateCurrentPage(Page target)
private static Page? EvaluateCurrentPage(Page? target)
{
Page child = GetTarget(target);
Page? child = GetTarget(target);

if (child is not null)
target = GetOnNavigatedToTargetFromChild(child);

if (target is Page page)
if (target is { } page)
{
if (target is IDialogContainer)
{
Expand All @@ -319,9 +321,9 @@ public static async Task HandleNavigationPageGoBack(NavigationPage navigationPag
{
var navigationService = Navigation.Xaml.Navigation.GetNavigationService(navigationPage.CurrentPage);
var result = await navigationService.GoBackAsync();
if (result.Exception is NavigationException navEx && navEx.Message == NavigationException.CannotPopApplicationMainPage)
if (result.Exception is NavigationException { Message: NavigationException.CannotPopApplicationMainPage })
{
Application.Current.Quit();
Application.Current?.Quit();
}
}

Expand All @@ -335,13 +337,13 @@ public static async Task HandleNavigationPageSwipedAway(NavigationPage navigatio
},
};
var result = await navigationService.GoBackAsync(navParams);
if (result.Exception is NavigationException navEx && navEx.Message == NavigationException.CannotPopApplicationMainPage)
if (result.Exception is NavigationException { Message: NavigationException.CannotPopApplicationMainPage })
{
Application.Current.Quit();
Application.Current?.Quit();
}
}

public static void HandleSystemGoBack(IView previousPage, IView currentPage)
public static void HandleSystemGoBack(IView? previousPage, IView? currentPage)
{
var parameters = new NavigationParameters();
parameters.GetNavigationParametersInternal().Add(KnownInternalParameters.NavigationMode, NavigationMode.Back);
Expand All @@ -352,22 +354,22 @@ public static void HandleSystemGoBack(IView previousPage, IView currentPage)

internal static bool HasDirectNavigationPageParent(Page page)
{
return page?.Parent != null && page?.Parent is NavigationPage;
return page.Parent is NavigationPage;
}

internal static bool HasNavigationPageParent(Page page) =>
HasNavigationPageParent(page, out var _);

internal static bool HasNavigationPageParent(Page page, out NavigationPage navigationPage)
internal static bool HasNavigationPageParent(Page page, out NavigationPage? navigationPage)
{
if (page?.Parent != null)
if (page.Parent != null)
{
if (page.Parent is NavigationPage navParent)
{
navigationPage = navParent;
return true;
}
else if ((page.Parent is TabbedPage) && page.Parent?.Parent is NavigationPage navigationParent)
else if (page.Parent is TabbedPage && page.Parent?.Parent is NavigationPage navigationParent)
{
navigationPage = navigationParent;
return true;
Expand Down
2 changes: 1 addition & 1 deletion src/Prism.Core/Navigation/NavigationResult.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ public NavigationResult(bool success)
/// Initializes a new NavigationResult with an <see cref="Exception"/>
/// </summary>
/// <param name="ex">The <see cref="Exception"/> encountered as part of the navigation.</param>
public NavigationResult(Exception ex)
public NavigationResult(Exception? ex)
{
Exception = ex;
}
Expand Down