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// SPDX-License-Identifier: GPL-2.0-or-later
/** @file
* @brief Interface for XML node observers
*//*
* Authors:
* MenTaLguY <mental@rydia.net>
* Krzysztof Kosiński <tweenk.pl@gmail.com> (documentation)
*
* Copyright (C) 2018 Authors
* Released under GNU GPL v2+, read the file 'COPYING' for more information.
*/
/** @file
*/
#ifndef SEEN_INKSCAPE_XML_NODE_OBSERVER_H
#define SEEN_INKSCAPE_XML_NODE_OBSERVER_H
#include "util/share.h"
typedef unsigned int GQuark;
#ifndef INK_UNUSED
#define INK_UNUSED(x) ((void)(x))
#endif // INK_UNUSED
namespace Inkscape {
namespace XML {
class Node;
/**
* @brief Interface for XML node observers
*
* This class defines an interface for objects that can receive
* XML node state change notifications. The observer has to be registered using
* the Node::addObserver() method to be notified of changes of this node only,
* or using Node::addSubtreeObserver() to also receive notifications about its
* descendants. All observer methods are called when the operations in question have
* been completed, just before returning from the modifying methods.
*
* Be careful when e.g. changing an attribute of @c node in notifyAttributeChanged().
* The method will be called again due to the XML modification performed in it. If you
* don't take special precautions to ignore the second call, it will result in infinite
* recursion.
*
* The virtual methods of this class do nothing by default, so you don't need to provide
* stubs for things you don't use. A good idea is to make the observer register itself
* on construction and unregister itself on destruction. This will ensure there are
* no dangling references.
*/
class NodeObserver {
protected:
/* the constructor is protected to prevent instantiation */
NodeObserver() = default;
public:
virtual ~NodeObserver() = default;
// FIXME: somebody needs to learn what "pure virtual" means
/**
* @brief Child addition callback
*
* This method is called whenever a child is added to the observed node. The @c prev
* parameter is NULL when the newly added child is first in the sibling order.
*
* @param node The changed XML node
* @param child The newly added child node
* @param prev The node after which the new child was inserted into the sibling order, or NULL
*/
virtual void notifyChildAdded(Node &node, Node &child, Node *prev) {
INK_UNUSED(node);
INK_UNUSED(child);
INK_UNUSED(prev);
}
/**
* @brief Child removal callback
*
* This method is called whenever a child is removed from the observed node. The @c prev
* parameter is NULL when the removed child was first in the sibling order.
*
* @param node The changed XML node
* @param child The removed child node
* @param prev The node that was before the removed node in sibling order, or NULL
*/
virtual void notifyChildRemoved(Node &node, Node &child, Node *prev) {
INK_UNUSED(node);
INK_UNUSED(child);
INK_UNUSED(prev);
}
/**
* @brief Child order change callback
*
* This method is called whenever the order of a node's children is changed using
* Node::changeOrder(). The @c old_prev parameter is NULL if the relocated node
* was first in the sibling order before the order change, and @c new_prev is NULL
* if it was moved to the first position by this operation.
*
* @param node The changed XML node
* @param child The child node that was relocated in the sibling order
* @param old_prev The node that was before @c child prior to the order change
* @param new_prev The node that is before @c child after the order change
*/
virtual void notifyChildOrderChanged(Node &node, Node &child,
Node *old_prev, Node *new_prev) {
INK_UNUSED(node);
INK_UNUSED(child);
INK_UNUSED(old_prev);
INK_UNUSED(new_prev);
}
/**
* @brief Content change callback
*
* This method is called whenever a node's content is changed using Node::setContent(),
* e.g. for text or comment nodes.
*
* @param node The changed XML node
* @param old_content Old content of @c node
* @param new_content New content of @c node
*/
virtual void notifyContentChanged(Node &node,
Util::ptr_shared old_content,
Util::ptr_shared new_content) {
INK_UNUSED(node);
INK_UNUSED(old_content);
INK_UNUSED(new_content);
}
/**
* @brief Attribute change callback
*
* This method is called whenever one of a node's attributes is changed.
*
* @param node The changed XML node
* @param name GQuark corresponding to the attribute's name
* @param old_value Old value of the modified attribute
* @param new_value New value of the modified attribute
*/
virtual void notifyAttributeChanged(Node &node, GQuark name,
Util::ptr_shared old_value,
Util::ptr_shared new_value) {
INK_UNUSED(node);
INK_UNUSED(name);
INK_UNUSED(old_value);
INK_UNUSED(new_value);
}
/**
* @brief Element name change callback.
*
* This method is called whenever an element node's name is changed.
*
* @param node The changed XML node.
* @param old_name GQuark corresponding to the old element name.
* @param new_name GQuark corresponding to the new element name.
*/
virtual void notifyElementNameChanged(Node& node, GQuark old_name, GQuark new_name) {
INK_UNUSED(node);
INK_UNUSED(old_name);
INK_UNUSED(new_name);
}
};
} // namespace XML
} // namespace Inkscape
#endif
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
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