Source/WebCore/editing/ModifySelectionListLevel.cpp

/*
 * Copyright (C) 2006, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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#include "config.h"
#include "ModifySelectionListLevel.h"

#include "Document.h"
#include "Editing.h"
#include "Frame.h"
#include "FrameSelection.h"
#include "HTMLOListElement.h"
#include "HTMLUListElement.h"
#include "RenderObject.h"

namespace WebCore {

ModifySelectionListLevelCommand::ModifySelectionListLevelCommand(Document& document)
    : CompositeEditCommand(document)
{
}

bool ModifySelectionListLevelCommand::preservesTypingStyle() const
{
    return true;
}

// This needs to be static so it can be called by canIncreaseSelectionListLevel and canDecreaseSelectionListLevel
static bool getStartEndListChildren(const VisibleSelection& selection, Node*& start, Node*& end)
{
    if (selection.isNone())
        return false;

    // start must be in a list child
    Node* startListChild = enclosingListChild(selection.start().anchorNode());
    if (!startListChild)
        return false;

    // end must be in a list child
    Node* endListChild = selection.isRange() ? enclosingListChild(selection.end().anchorNode()) : startListChild;
    if (!endListChild)
        return false;
    
    // For a range selection we want the following behavior:
    //      - the start and end must be within the same overall list
    //      - the start must be at or above the level of the rest of the range
    //      - if the end is anywhere in a sublist lower than start, the whole sublist gets moved
    // In terms of this function, this means:
    //      - endListChild must start out being be a sibling of startListChild, or be in a
    //         sublist of startListChild or a sibling
    //      - if endListChild is in a sublist of startListChild or a sibling, it must be adjusted
    //         to be the ancestor that is startListChild or its sibling
    while (startListChild->parentNode() != endListChild->parentNode()) {
        endListChild = endListChild->parentNode();
        if (!endListChild)
            return false;
    }
    
    // if the selection ends on a list item with a sublist, include the entire sublist
    if (endListChild->renderer()->isListItem()) {
        RenderObject* r = endListChild->renderer()->nextSibling();
        if (r && isListHTMLElement(r->node()))
            endListChild = r->node();
    }

    start = startListChild;
    end = endListChild;
    return true;
}

void ModifySelectionListLevelCommand::insertSiblingNodeRangeBefore(Node* startNode, Node* endNode, Node* refNode)
{
    Node* node = startNode;
    while (1) {
        Node* next = node->nextSibling();
        removeNode(*node);
        insertNodeBefore(*node, *refNode);

        if (node == endNode)
            break;

        node = next;
    }
}

void ModifySelectionListLevelCommand::insertSiblingNodeRangeAfter(Node* startNode, Node* endNode, Node* refNode)
{
    Node* node = startNode;
    while (1) {
        Node* next = node->nextSibling();
        removeNode(*node);
        insertNodeAfter(*node, *refNode);

        if (node == endNode)
            break;

        refNode = node;
        node = next;
    }
}

void ModifySelectionListLevelCommand::appendSiblingNodeRange(Node* startNode, Node* endNode, Element* newParent)
{
    Node* node = startNode;
    while (1) {
        Node* next = node->nextSibling();
        removeNode(*node);
        appendNode(*node, *newParent);

        if (node == endNode)
            break;

        node = next;
    }
}

IncreaseSelectionListLevelCommand::IncreaseSelectionListLevelCommand(Document& document, Type listType)
    : ModifySelectionListLevelCommand(document)
    , m_listType(listType)
{
}

// This needs to be static so it can be called by canIncreaseSelectionListLevel
static bool canIncreaseListLevel(const VisibleSelection& selection, Node*& start, Node*& end)
{
    if (!getStartEndListChildren(selection, start, end))
        return false;
        
    // start must not be the first child (because you need a prior one
    // to increase relative to)
    if (!start->renderer()->previousSibling())
        return false;
    
    return true;
}

// For the moment, this is SPI and the only client (Mail.app) is satisfied.
// Here are two things to re-evaluate when making into API.
// 1. Currently, InheritedListType uses clones whereas OrderedList and
// UnorderedList create a new list node of the specified type.  That is
// inconsistent wrt style.  If that is not OK, here are some alternatives:
//  - new nodes always inherit style (probably the best choice)
//  - new nodes have always have no style
//  - new nodes of the same type inherit style
// 2. Currently, the node we return may be either a pre-existing one or
// a new one. Is it confusing to return the pre-existing one without
// somehow indicating that it is not new?  If so, here are some alternatives:
//  - only return the list node if we created it
//  - indicate whether the list node is new or pre-existing
//  - (silly) client specifies whether to return pre-existing list nodes
void IncreaseSelectionListLevelCommand::doApply()
{
    Node* startListChild;
    Node* endListChild;
    if (!canIncreaseListLevel(endingSelection(), startListChild, endListChild))
        return;

    Node* previousItem = startListChild->renderer()->previousSibling()->node();
    if (isListHTMLElement(previousItem)) {
        // move nodes up into preceding list
        appendSiblingNodeRange(startListChild, endListChild, downcast<Element>(previousItem));
        m_listElement = previousItem;
    } else {
        // create a sublist for the preceding element and move nodes there
        RefPtr<Element> newParent;
        switch (m_listType) {
        case Type::InheritedListType:
            newParent = startListChild->parentElement();
            if (newParent)
                newParent = newParent->cloneElementWithoutChildren(document());
            break;
        case Type::OrderedList:
            newParent = HTMLOListElement::create(document());
            break;
        case Type::UnorderedList:
            newParent = HTMLUListElement::create(document());
            break;
        }
        insertNodeBefore(*newParent, *startListChild);
        appendSiblingNodeRange(startListChild, endListChild, newParent.get());
        m_listElement = WTFMove(newParent);
    }
}

bool IncreaseSelectionListLevelCommand::canIncreaseSelectionListLevel(Document* document)
{
    Node* startListChild;
    Node* endListChild;
    return canIncreaseListLevel(document->frame()->selection().selection(), startListChild, endListChild);
}

RefPtr<Node> IncreaseSelectionListLevelCommand::increaseSelectionListLevel(Document* document, Type type)
{
    ASSERT(document);
    ASSERT(document->frame());
    auto command = create(*document, type);
    command->apply();
    return WTFMove(command->m_listElement);
}

RefPtr<Node> IncreaseSelectionListLevelCommand::increaseSelectionListLevel(Document* document)
{
    return increaseSelectionListLevel(document, Type::InheritedListType);
}

RefPtr<Node> IncreaseSelectionListLevelCommand::increaseSelectionListLevelOrdered(Document* document)
{
    return increaseSelectionListLevel(document, Type::OrderedList);
}

RefPtr<Node> IncreaseSelectionListLevelCommand::increaseSelectionListLevelUnordered(Document* document)
{
    return increaseSelectionListLevel(document, Type::UnorderedList);
}

DecreaseSelectionListLevelCommand::DecreaseSelectionListLevelCommand(Document& document)
    : ModifySelectionListLevelCommand(document)
{
}

// This needs to be static so it can be called by canDecreaseSelectionListLevel
static bool canDecreaseListLevel(const VisibleSelection& selection, Node*& start, Node*& end)
{
    if (!getStartEndListChildren(selection, start, end))
        return false;

    // there must be a destination list to move the items to
    if (!isListHTMLElement(start->parentNode()->parentNode()))
        return false;

    return true;
}

void DecreaseSelectionListLevelCommand::doApply()
{
    Node* startListChild;
    Node* endListChild;
    if (!canDecreaseListLevel(endingSelection(), startListChild, endListChild))
        return;

    Node* previousItem = startListChild->renderer()->previousSibling() ? startListChild->renderer()->previousSibling()->node() : 0;
    Node* nextItem = endListChild->renderer()->nextSibling() ? endListChild->renderer()->nextSibling()->node() : 0;
    Element* listNode = startListChild->parentElement();

    if (!previousItem) {
        // at start of sublist, move the child(ren) to before the sublist
        insertSiblingNodeRangeBefore(startListChild, endListChild, listNode);
        // if that was the whole sublist we moved, remove the sublist node
        if (!nextItem && listNode)
            removeNode(*listNode);
    } else if (!nextItem) {
        // at end of list, move the child(ren) to after the sublist
        insertSiblingNodeRangeAfter(startListChild, endListChild, listNode);    
    } else if (listNode) {
        // in the middle of list, split the list and move the children to the divide
        splitElement(*listNode, *startListChild);
        insertSiblingNodeRangeBefore(startListChild, endListChild, listNode);
    }
}

bool DecreaseSelectionListLevelCommand::canDecreaseSelectionListLevel(Document* document)
{
    Node* startListChild;
    Node* endListChild;
    return canDecreaseListLevel(document->frame()->selection().selection(), startListChild, endListChild);
}

void DecreaseSelectionListLevelCommand::decreaseSelectionListLevel(Document* document)
{
    ASSERT(document);
    ASSERT(document->frame());
    create(*document)->apply();
}

}