1/*
2 * Copyright (C) 2006, 2007 Apple, Inc.  All rights reserved.
3 * Copyright (C) 2012 Google, Inc.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
15 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
21 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
22 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include "config.h"
28#include "core/editing/UndoStack.h"
29
30#include "core/dom/ContainerNode.h"
31#include "core/editing/UndoStep.h"
32#include "platform/EventDispatchForbiddenScope.h"
33#include "wtf/TemporaryChange.h"
34
35namespace blink {
36
37// Arbitrary depth limit for the undo stack, to keep it from using
38// unbounded memory. This is the maximum number of distinct undoable
39// actions -- unbroken stretches of typed characters are coalesced
40// into a single action.
41static const size_t maximumUndoStackDepth = 1000;
42
43UndoStack::UndoStack()
44    : m_inRedo(false)
45{
46}
47
48DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(UndoStack)
49
50PassOwnPtrWillBeRawPtr<UndoStack> UndoStack::create()
51{
52    return adoptPtrWillBeNoop(new UndoStack());
53}
54
55void UndoStack::registerUndoStep(PassRefPtrWillBeRawPtr<UndoStep> step)
56{
57    if (m_undoStack.size() == maximumUndoStackDepth)
58        m_undoStack.removeFirst(); // drop oldest item off the far end
59    if (!m_inRedo)
60        m_redoStack.clear();
61    m_undoStack.append(step);
62}
63
64void UndoStack::registerRedoStep(PassRefPtrWillBeRawPtr<UndoStep> step)
65{
66    m_redoStack.append(step);
67}
68
69void UndoStack::didUnloadFrame(const LocalFrame& frame)
70{
71    EventDispatchForbiddenScope assertNoEventDispatch;
72    filterOutUndoSteps(m_undoStack, frame);
73    filterOutUndoSteps(m_redoStack, frame);
74}
75
76void UndoStack::filterOutUndoSteps(UndoStepStack& stack, const LocalFrame& frame)
77{
78    UndoStepStack newStack;
79    while (!stack.isEmpty()) {
80        UndoStep* step = stack.first().get();
81        if (!step->belongsTo(frame))
82            newStack.append(step);
83        stack.removeFirst();
84    }
85    stack.swap(newStack);
86}
87
88bool UndoStack::canUndo() const
89{
90    return !m_undoStack.isEmpty();
91}
92
93bool UndoStack::canRedo() const
94{
95    return !m_redoStack.isEmpty();
96}
97
98void UndoStack::undo()
99{
100    if (canUndo()) {
101        UndoStepStack::iterator back = --m_undoStack.end();
102        RefPtrWillBeRawPtr<UndoStep> step(back->get());
103        m_undoStack.remove(back);
104        step->unapply();
105        // unapply will call us back to push this command onto the redo stack.
106    }
107}
108
109void UndoStack::redo()
110{
111    if (canRedo()) {
112        UndoStepStack::iterator back = --m_redoStack.end();
113        RefPtrWillBeRawPtr<UndoStep> step(back->get());
114        m_redoStack.remove(back);
115
116        ASSERT(!m_inRedo);
117        TemporaryChange<bool> redoScope(m_inRedo, true);
118        step->reapply();
119        // reapply will call us back to push this command onto the undo stack.
120    }
121}
122
123void UndoStack::trace(Visitor* visitor)
124{
125    visitor->trace(m_undoStack);
126    visitor->trace(m_redoStack);
127}
128
129} // namespace blink
130