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LibGUI: Reverse internal direction of GUI::UndoStack

Browse source 
The undo stack was very difficult to understand as it grew by adding
new undo commands to the front of the internal vector. This meant we
had to keep updating indices as the stack grew and shrank.

This patch makes the internal vector grow by appending instead.
This commit is contained in:
Andreas Kling 2021-05-08 13:09:24 +02:00
parent 2ef4fbc5c1
commit 74a4571f02
2 changed files with 46 additions and 51 deletions
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91
Userland/Libraries/LibGUI/UndoStack.cpp
View file

@ -17,29 +17,27 @@ UndoStack::~UndoStack()
{
}
bool UndoStack::can_undo() const
{
return m_stack_index > 0;
}
bool UndoStack::can_redo() const
{
if (m_stack.is_empty())
return false;
return m_stack_index != m_stack.size() - 1;
}
void UndoStack::undo()
{
if (!can_undo())
return;
auto pop_container_and_undo = [this]() {
for (;;) {
if (m_stack_index >= m_stack.size())
break;
auto& combo = m_stack[m_stack_index++];
if (combo.commands.size() == 0)
continue;
for (auto& command : combo.commands)
command.undo();
break;
}
};
// If this is the first undo, finish off our current combo
if (m_stack_index == 0)
finalize_current_combo();
pop_container_and_undo();
finalize_current_combo();
auto& combo = m_stack[--m_stack_index];
for (auto i = static_cast<ssize_t>(combo.commands.size()) - 1; i >= 0; i--)
combo.commands[i].undo();
}
void UndoStack::redo()
@ -47,61 +45,56 @@ void UndoStack::redo()
if (!can_redo())
return;
m_stack_index -= 1;
auto& commands = m_stack[m_stack_index].commands;
for (int i = commands.size() - 1; i >= 0; i--)
commands[i].redo();
auto& commands = m_stack[m_stack_index++].commands;
for (auto& command : commands)
command.redo();
}
void UndoStack::pop()
{
VERIFY(!m_stack.is_empty());
m_stack.take_last();
if (m_clean_index.has_value() && m_clean_index.value() > m_stack.size())
m_clean_index = {};
}
void UndoStack::push(NonnullOwnPtr<Command>&& command)
{
if (m_stack.is_empty())
finalize_current_combo();
m_stack.append(make<Combo>());
if (m_stack_index > 0) {
for (size_t i = 0; i < m_stack_index; i++)
m_stack.remove(0);
if (m_clean_index.has_value()) {
if (m_clean_index.value() < m_stack_index)
m_clean_index.clear();
else
m_clean_index = m_clean_index.value() - m_stack_index;
// If the stack cursor is behind the top of the stack, nuke everything from here to the top.
if (m_stack_index != m_stack.size() - 1) {
while (m_stack.size() != m_stack_index) {
pop();
}
m_stack_index = 0;
finalize_current_combo();
}
m_stack.first().commands.prepend(move(command));
m_stack.last().commands.append(move(command));
}
void UndoStack::finalize_current_combo()
{
if (m_stack_index > 0)
return;
if (m_stack.size() != 0 && m_stack.first().commands.size() == 0)
if (m_stack.is_empty()) {
m_stack.append(make<Combo>());
return;
}
auto undo_commands_container = make<Combo>();
m_stack.prepend(move(undo_commands_container));
if (m_clean_index.has_value())
m_clean_index = m_clean_index.value() + 1;
if (!m_stack.last().commands.is_empty()) {
m_stack.append(make<Combo>());
m_stack_index = m_stack.size() - 1;
}
}
void UndoStack::set_current_unmodified()
{
// Skip empty container
if (can_undo() && m_stack[m_stack_index].commands.is_empty())
m_clean_index = m_stack_index + 1;
else
m_clean_index = m_stack_index;
m_clean_index = m_stack_index;
}
bool UndoStack::is_current_modified() const
{
return !m_clean_index.has_value() || m_stack_index != m_clean_index.value();
return !(m_clean_index.has_value() && m_clean_index.value() == m_stack_index);
}
void UndoStack::clear()