From 510551bb4f7c7fd325b753b5654174d4baaa5464 Mon Sep 17 00:00:00 2001
From: thankyouverycool <66646555+thankyouverycool@users.noreply.github.com>
Date: Mon, 4 Jul 2022 21:36:30 -0400
Subject: [PATCH] LibGUI: Add fallible try_push() variant to UndoStack

---
 Userland/Libraries/LibGUI/UndoStack.cpp | 13 ++++++++++---
 Userland/Libraries/LibGUI/UndoStack.h   |  1 +
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibGUI/UndoStack.cpp b/Userland/Libraries/LibGUI/UndoStack.cpp
index 6ac2205648..cb273f4d37 100644
--- a/Userland/Libraries/LibGUI/UndoStack.cpp
+++ b/Userland/Libraries/LibGUI/UndoStack.cpp
@@ -46,7 +46,7 @@ void UndoStack::redo()
         on_state_change();
 }
 
-void UndoStack::push(NonnullOwnPtr<Command> command)
+ErrorOr<void> UndoStack::try_push(NonnullOwnPtr<Command> command)
 {
     // If the stack cursor is behind the top of the stack, nuke everything from here to the top.
     while (m_stack.size() != m_stack_index)
@@ -57,14 +57,21 @@ void UndoStack::push(NonnullOwnPtr<Command> command)
 
     if (!m_stack.is_empty() && is_current_modified()) {
         if (m_stack.last().merge_with(*command))
-            return;
+            return {};
     }
 
-    m_stack.append(move(command));
+    TRY(m_stack.try_append(move(command)));
     m_stack_index = m_stack.size();
 
     if (on_state_change)
         on_state_change();
+
+    return {};
+}
+
+void UndoStack::push(NonnullOwnPtr<Command> command)
+{
+    MUST(try_push(move(command)));
 }
 
 void UndoStack::set_current_unmodified()
diff --git a/Userland/Libraries/LibGUI/UndoStack.h b/Userland/Libraries/LibGUI/UndoStack.h
index ab58d140e5..4ed787975b 100644
--- a/Userland/Libraries/LibGUI/UndoStack.h
+++ b/Userland/Libraries/LibGUI/UndoStack.h
@@ -20,6 +20,7 @@ public:
     ~UndoStack() = default;
 
     void push(NonnullOwnPtr<Command>);
+    ErrorOr<void> try_push(NonnullOwnPtr<Command>);
 
     bool can_undo() const;
     bool can_redo() const;