Add support for exclusive mode

src/Spectre.Console/Internal/Backends/AnsiConsoleFacade.cs

@@ -13,9 +13,10 @@ namespace Spectre.Console
         public Profile Profile { get; }
         public IAnsiConsoleCursor Cursor => GetBackend().Cursor;
         public IAnsiConsoleInput Input { get; }
+        public IExclusivityMode ExclusivityMode { get; }
         public RenderPipeline Pipeline { get; }
 
-        public AnsiConsoleFacade(Profile profile)
+        public AnsiConsoleFacade(Profile profile, IExclusivityMode exclusivityMode)
         {
             _renderLock = new object();
             _ansiBackend = new AnsiConsoleBackend(profile);
@@ -23,6 +24,7 @@ namespace Spectre.Console
 
             Profile = profile ?? throw new ArgumentNullException(nameof(profile));
             Input = new DefaultInput(Profile);
+            ExclusivityMode = exclusivityMode ?? throw new ArgumentNullException(nameof(exclusivityMode));
             Pipeline = new RenderPipeline();
         }
 

src/Spectre.Console/Internal/Cell.cs

@@ -1,4 +1,3 @@
-using System.Linq;
 using Spectre.Console.Rendering;
 using Wcwidth;
 

src/Spectre.Console/Internal/DefaultExclusivityMode.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Spectre.Console.Internal
+{
+    internal sealed class DefaultExclusivityMode : IExclusivityMode
+    {
+        private static readonly SemaphoreSlim _semaphore;
+
+        static DefaultExclusivityMode()
+        {
+            _semaphore = new SemaphoreSlim(1, 1);
+        }
+
+        public T Run<T>(Func<T> func)
+        {
+            // Try aquiring the exclusivity semaphore
+            if (!_semaphore.Wait(0))
+            {
+                throw new InvalidOperationException(
+                    "Trying to run one or more interactive functions concurrently. " +
+                    "Operations with dynamic displays (e.g. a prompt and a progress display) " +
+                    "cannot be running at the same time.");
+            }
+
+            try
+            {
+                return func();
+            }
+            finally
+            {
+                _semaphore.Release(1);
+            }
+        }
+
+        public async Task<T> Run<T>(Func<Task<T>> func)
+        {
+            // Try aquiring the exclusivity semaphore
+            if (!await _semaphore.WaitAsync(0).ConfigureAwait(false))
+            {
+                // TODO: Need a better message here
+                throw new InvalidOperationException(
+                    "Could not aquire the interactive semaphore");
+            }
+
+            try
+            {
+                return await func();
+            }
+            finally
+            {
+                _semaphore.Release(1);
+            }
+        }
+    }
+}