From 0ea7a871ce923dfb13d36e7f06e283b0ac24d886 Mon Sep 17 00:00:00 2001
From: Thomas Nind <31306100+tznind@users.noreply.github.com>
Date: Sun, 21 May 2023 22:26:50 +0100
Subject: [PATCH] Adds TreeView MaxDepth (#2651)

---
 Terminal.Gui/Views/TreeView/Branch.cs   |  9 ++-
 Terminal.Gui/Views/TreeView/TreeView.cs |  5 ++
 UnitTests/Views/TreeViewTests.cs        | 95 ++++++++++++++++++++++++-
 3 files changed, 107 insertions(+), 2 deletions(-)

diff --git a/Terminal.Gui/Views/TreeView/Branch.cs b/Terminal.Gui/Views/TreeView/Branch.cs
index 795e06268..aeb556288 100644
--- a/Terminal.Gui/Views/TreeView/Branch.cs
+++ b/Terminal.Gui/Views/TreeView/Branch.cs
@@ -61,8 +61,15 @@ namespace Terminal.Gui {
 				return;
 			}
 
-			var children = tree.TreeBuilder.GetChildren (this.Model) ?? Enumerable.Empty<T> ();
+			IEnumerable<T> children;
 
+			if (Depth >= tree.MaxDepth) {
+				children = Enumerable.Empty<T> ();
+			}
+			else {
+				children = tree.TreeBuilder.GetChildren (this.Model) ?? Enumerable.Empty<T> ();
+			}
+			
 			this.ChildBranches = children.ToDictionary (k => k, val => new Branch<T> (tree, this, val));
 		}
 
diff --git a/Terminal.Gui/Views/TreeView/TreeView.cs b/Terminal.Gui/Views/TreeView/TreeView.cs
index d4e7f4bea..14645539d 100644
--- a/Terminal.Gui/Views/TreeView/TreeView.cs
+++ b/Terminal.Gui/Views/TreeView/TreeView.cs
@@ -85,6 +85,11 @@ namespace Terminal.Gui {
 		/// <value></value>
 		public bool MultiSelect { get; set; } = true;
 
+		/// <summary>
+		/// Maximum number of nodes that can be expanded in any given branch.
+		/// </summary>
+		public int MaxDepth { get; set; } = 100;
+
 		/// <summary>
 		/// True makes a letter key press navigate to the next visible branch that begins with
 		/// that letter/digit.
diff --git a/UnitTests/Views/TreeViewTests.cs b/UnitTests/Views/TreeViewTests.cs
index 585b41b64..0644fac65 100644
--- a/UnitTests/Views/TreeViewTests.cs
+++ b/UnitTests/Views/TreeViewTests.cs
@@ -131,7 +131,7 @@ namespace Terminal.Gui.ViewsTests {
 		{
 			var tree = CreateTree (out Factory f, out Car car1, out Car car2);
 			tree.BeginInit (); tree.EndInit ();
-			
+
 			// control only allows 1 row to be viewed at once
 			tree.Bounds = new Rect (0, 0, 20, 1);
 
@@ -902,6 +902,99 @@ namespace Terminal.Gui.ViewsTests {
 				new [] { tv.ColorScheme.Normal, pink });
 		}
 
+		[Fact, AutoInitShutdown]
+		public void TestBottomlessTreeView_MaxDepth_5 ()
+		{
+			var tv = new TreeView<string> () { Width = 20, Height = 10 };
+
+			tv.TreeBuilder = new DelegateTreeBuilder<string> (
+				(s) => new [] { (int.Parse (s) + 1).ToString () }
+				);
+
+			tv.AddObject ("1");
+			tv.ColorScheme = new ColorScheme ();
+
+			tv.LayoutSubviews ();
+			tv.Draw ();
+
+			// Nothing expanded
+			TestHelpers.AssertDriverContentsAre (
+@"└+1
+", output);
+			tv.MaxDepth = 5;
+			tv.ExpandAll ();
+
+			tv.Draw ();
+
+			// Normal drawing of the tree view
+			TestHelpers.AssertDriverContentsAre (
+@"    
+└-1
+  └-2
+    └-3
+      └-4
+        └-5
+          └─6
+", output);
+			Assert.False (tv.CanExpand ("6"));
+			Assert.False (tv.IsExpanded ("6"));
+
+			tv.Collapse("6");
+
+			Assert.False (tv.CanExpand ("6"));
+			Assert.False (tv.IsExpanded ("6"));
+
+			tv.Collapse ("5");
+
+			Assert.True (tv.CanExpand ("5"));
+			Assert.False (tv.IsExpanded ("5"));
+
+			tv.Draw ();
+
+			// Normal drawing of the tree view
+			TestHelpers.AssertDriverContentsAre (
+@"    
+└-1
+  └-2
+    └-3
+      └-4
+        └+5
+", output);
+		}
+
+		[Fact, AutoInitShutdown]
+		public void TestBottomlessTreeView_MaxDepth_3 ()
+		{
+			var tv = new TreeView<string> () { Width = 20, Height = 10 };
+
+			tv.TreeBuilder = new DelegateTreeBuilder<string> (
+				(s) => new [] { (int.Parse (s) + 1).ToString () }
+				);
+
+			tv.AddObject ("1");
+			tv.ColorScheme = new ColorScheme ();
+
+			tv.LayoutSubviews ();
+			tv.Draw ();
+
+			// Nothing expanded
+			TestHelpers.AssertDriverContentsAre (
+@"└+1
+", output);
+			tv.MaxDepth = 3;
+			tv.ExpandAll ();
+			tv.Draw ();
+
+			// Normal drawing of the tree view
+			TestHelpers.AssertDriverContentsAre (
+@"    
+└-1
+  └-2
+    └-3
+      └─4
+", output);
+		}
+
 		[Fact, AutoInitShutdown]
 		public void TestTreeView_Filter ()
 		{