ladybird/Userland/Libraries/LibGUI/UndoStack.cpp
Andreas Kling ff912946ae LibGUI: Support merging of adjacent commands on the UndoStack
When pushing a new command on an undo stack, we will now attempt to
merge it into the stack's current command.

Merging is implemented by overriding the "merge_with(Command const&)"
virtual on GUI::Command. :^)
2021-05-08 22:17:50 +02:00

146 lines
3 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibGUI/Command.h>
#include <LibGUI/UndoStack.h>
namespace GUI {
UndoStack::UndoStack()
{
}
UndoStack::~UndoStack()
{
}
bool UndoStack::can_undo() const
{
return m_stack_index > 0 || (m_stack.size() == 1 && m_stack[0].commands.size() > 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;
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();
if (on_state_change)
on_state_change();
}
void UndoStack::redo()
{
if (!can_redo())
return;
auto& commands = m_stack[m_stack_index++].commands;
for (auto& command : commands)
command.redo();
if (on_state_change)
on_state_change();
}
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();
// 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();
}
finalize_current_combo();
}
if (!m_stack.last().commands.is_empty()) {
bool merged = m_stack.last().commands.last().merge_with(*command);
if (merged)
return;
}
m_stack.last().commands.append(move(command));
if (on_state_change)
on_state_change();
}
void UndoStack::finalize_current_combo()
{
if (m_stack.is_empty()) {
m_stack.append(make<Combo>());
return;
}
if (!m_stack.last().commands.is_empty()) {
m_stack.append(make<Combo>());
m_stack_index = m_stack.size() - 1;
if (on_state_change)
on_state_change();
}
}
void UndoStack::set_current_unmodified()
{
finalize_current_combo();
if (m_clean_index.has_value() && m_clean_index.value() == m_stack_index)
return;
m_clean_index = m_stack_index;
if (on_state_change)
on_state_change();
}
bool UndoStack::is_current_modified() const
{
if (!m_clean_index.has_value())
return true;
if (m_stack_index != m_clean_index.value())
return true;
if (m_stack.is_empty())
return false;
if (m_stack_index == m_stack.size() - 1 && !m_stack[m_stack_index].commands.is_empty())
return true;
return false;
}
void UndoStack::clear()
{
if (m_stack.is_empty() && m_stack_index == 0 && !m_clean_index.has_value())
return;
m_stack.clear();
m_stack_index = 0;
m_clean_index.clear();
if (on_state_change)
on_state_change();
}
}