// SPDX-License-Identifier: GPL-2.0-or-later /** @file * @brief Interface for XML nodes * * Authors: * MenTaLguY * Krzysztof Kosiński (documentation) * * Copyright (C) 2018 Authors * Released under GNU GPL v2+, read the file 'COPYING' for more information. */ #ifndef SEEN_INKSCAPE_XML_NODE_H #define SEEN_INKSCAPE_XML_NODE_H #include #include #include #include <2geom/point.h> #include "gc-anchored.h" #include "inkgc/gc-alloc.h" #include "node-iterators.h" #include "util/const_char_ptr.h" #include "svg/svg-length.h" namespace Inkscape { namespace XML { class AttributeRecord; struct Document; class Event; class NodeObserver; using AttributeVector = std::vector>; /** * @brief Enumeration containing all supported node types. */ enum class NodeType { DOCUMENT_NODE, ///< Top-level document node. Do not confuse with the root node. ELEMENT_NODE, ///< Regular element node, e.g. <group />. TEXT_NODE, ///< Text node, e.g. "Some text" in <group>Some text</group> is represented by a text node. COMMENT_NODE, ///< Comment node, e.g. <!-- some comment --> PI_NODE ///< Processing instruction node, e.g. <?xml version="1.0" encoding="utf-8" standalone="no"?> }; // careful; GC::Anchored should only appear once in the inheritance // hierarchy; otherwise there will be leaks /** * @brief Interface for refcounted XML nodes * * This class is an abstract base type for all nodes in an XML document - this includes * everything except attributes. An XML document is also a node itself. This is the main * class used for interfacing with Inkscape's documents. Everything that has to be stored * in the SVG has to go through this class at some point. * * Each node unconditionally has to belong to a document. There are no "documentless" nodes, * and it's not possible to move nodes between documents - they have to be duplicated. * Each node can only refer to the nodes in the same document. Name of the node is immutable, * it cannot be changed after its creation. Same goes for the type of the node. To simplify * the use of this class, you can perform all operations on all nodes, but only some of them * make any sense. For example, only element nodes can have attributes, only element and * document nodes can have children, and all nodes except element and document nodes can * have content. Although you can set content for element nodes, it won't make any difference * in the XML output. * * To create new nodes, use the methods of the Inkscape::XML::Document class. You can obtain * the nodes' document using the document() method. To destroy a node, just unparent it * by calling sp_repr_unparent() or node->parent->removeChild() and release any references * to it. The garbage collector will reclaim the memory in the next pass. * * In addition to regular DOM manipulations, you can register observer objects that will * receive notifications about changes made to the node. See the NodeObserver class. * * @see Inkscape::XML::Document * @see Inkscape::XML::NodeObserver */ class Node : public Inkscape::GC::Anchored { public: Node() = default; ~Node() override = default; /** * @name Retrieve information about the node * @{ */ /** * @brief Get the type of the node * @return NodeType enumeration member corresponding to the type of the node. */ virtual NodeType type() const = 0; /** * @brief Get the name of the element node * * This method only makes sense for element nodes. Names are stored as * GQuarks to accelerate conversions. * * @return Name for element nodes, NULL for others */ virtual char const *name() const = 0; /** * @brief Get the integer code corresponding to the node's name * @return GQuark code corresponding to the name */ virtual int code() const = 0; /** * @brief Get the index of this node in parent's child order * * If this method is used on a node that doesn't have a parent, the method will return 0, * and a warning will be printed on the console. * * @return The node's index, or 0 if the node does not have a parent */ virtual unsigned position() const = 0; /** * @brief Get the number of children of this node * @return The number of children */ virtual unsigned childCount() const = 0; /** * @brief Get the content of a text or comment node * * This method makes no sense for element nodes. To retrieve the element node's name, * use the name() method. * * @return The node's content */ virtual char const *content() const = 0; /** * @brief Get the string representation of a node's attribute * * If there is no attribute with the given name, the method will return NULL. * All strings returned by this method are owned by the node and may not be freed. * The returned pointer will become invalid when the attribute changes. If you need * to store the return value, use g_strdup(). To parse the string, use methods * in repr.h * * @param key The name of the node's attribute */ virtual char const *attribute(char const *key) const = 0; /** * @brief Get a list of the node's attributes * * The returned list is a functional programming style list rather than a standard one. * * @return A list of AttributeRecord structures describing the attributes * @todo This method should return std::map * or something similar with a custom allocator */ virtual const AttributeVector & attributeList() const=0; /** * @brief Check whether this node has any attribute that matches a string * * This method checks whether this node has any attributes whose names * have @c partial_name as their substrings. The check is done using * the strstr() function of the C library. I don't know what would require that * functionality, because matchAttributeName("id") matches both "identity" and "hidden". * * @param partial_name The string to match against all attributes * @return true if there is such an attribute, false otherwise */ virtual bool matchAttributeName(char const *partial_name) const = 0; /*@}*/ /** * @name Modify the node * @{ */ /** * @brief Set the position of this node in parent's child order * * To move the node to the end of the parent's child order, pass a negative argument. * * @param pos The new position in parent's child order */ virtual void setPosition(int pos) = 0; /** * @brief Set the content of a text or comment node * * This method doesn't make sense for element nodes. * * @param value The node's new content */ virtual void setContent(char const *value) = 0; //@{ /** * @brief Change an attribute of this node * * The strings passed to this method are copied, so you can free them after use. * * @param key Name of the attribute to change * @param value The new value of the attribute */ void setAttribute(Util::const_char_ptr key, Util::const_char_ptr value); /** * @brief Copy attribute value from another node to this node * * @param key Name of the attribute to change * @param source_node Node from which to take the attribute value * @param remove_if_empty * If true, and the source node has no such attribute, or the source * node's value for the attribute is an empty string, the attribute * will be removed (if present) from this node. * * @return true if the attribute was set, false otherwise. */ bool copyAttribute(Util::const_char_ptr key, Node const *source_node, bool remove_if_empty = false); /** * Parses the boolean value of an attribute "key" in repr and sets val accordingly, or to false if * the attr is not set. * * \return true if the attr was set, false otherwise. */ bool getAttributeBoolean(Util::const_char_ptr key, bool default_value = false) const; int getAttributeInt(Util::const_char_ptr key, int default_value = 0) const; double getAttributeDouble(Util::const_char_ptr key, double default_value = 0.0) const; bool setAttributeBoolean(Util::const_char_ptr key, bool val); bool setAttributeInt(Util::const_char_ptr key, int val); /** * Set a property attribute to \a val [slightly rounded], in the format * required for CSS properties: in particular, it never uses exponent * notation. */ bool setAttributeCssDouble(Util::const_char_ptr key, double val); /** * For attributes where an exponent is allowed. * * Not suitable for property attributes (fill-opacity, font-size etc.). */ bool setAttributeSvgDouble(Util::const_char_ptr key, double val); bool setAttributeSvgNonDefaultDouble(Util::const_char_ptr key, double val, double default_value); bool setAttributeSvgLength(Util::const_char_ptr key, SVGLength const &val); bool setAttributePoint(Util::const_char_ptr key, Geom::Point const &val); Geom::Point getAttributePoint(Util::const_char_ptr key, Geom::Point default_value = {}) const; /** * @brief Change an attribute of this node. Empty string deletes the attribute. * * @param key Name of the attribute to change * @param value The new value of the attribute * */ void setAttributeOrRemoveIfEmpty(Inkscape::Util::const_char_ptr key, Inkscape::Util::const_char_ptr value); /** * @brief Remove an attribute of this node * * @param key Name of the attribute to delete * */ void removeAttribute(Inkscape::Util::const_char_ptr key) { this->setAttributeImpl(key.data(), nullptr); } //@} /** * @brief Set the integer GQuark code for the name of the node. * * Do not use this function unless you really have a good reason. * * @param code The integer value corresponding to the string to be set as * the name of this node */ virtual void setCodeUnsafe(int code) = 0; /*@}*/ /** * @name Traverse the XML tree * @{ */ //@{ /** * @brief Get the node's associated document * @return The document to which the node belongs. Never NULL. */ virtual Document *document() = 0; virtual Document const *document() const = 0; //@} //@{ /** * @brief Get the root node of this node's document * * This method works on any node that is part of an XML document, and returns * the root node of the document in which it resides. For detached node hierarchies * (i.e. nodes that are not descendants of a document node) this method * returns the highest-level element node. For detached non-element nodes this method * returns NULL. * * @return A pointer to the root element node, or NULL if the node is detached */ virtual Node *root() = 0; virtual Node const *root() const = 0; //@} //@{ /** * @brief Get the parent of this node * * This method will return NULL for detached nodes. * * @return Pointer to the parent, or NULL */ virtual Node *parent() = 0; virtual Node const *parent() const = 0; //@} //@{ /** * @brief Get the next sibling of this node * * This method will return NULL if the node is the last sibling element of the parent. * The nodes form a singly-linked list, so there is no "prev()" method. Use the provided * external function for that. * * @return Pointer to the next sibling, or NULL * @see Inkscape::XML::previous_node() */ virtual Node *next() = 0; virtual Node const *next() const = 0; virtual Node *prev() = 0; virtual Node const *prev() const = 0; //@} //@{ /** * @brief Get the first child of this node * * For nodes without any children, this method returns NULL. * * @return Pointer to the first child, or NULL */ virtual Node *firstChild() = 0; virtual Node const *firstChild() const = 0; //@} //@{ /** * @brief Get the last child of this node * * For nodes without any children, this method returns NULL. * * @return Pointer to the last child, or NULL */ virtual Node *lastChild() = 0; virtual Node const *lastChild() const = 0; //@} //@{ /** * @brief Get the child of this node with a given index * * If there is no child with the specified index number, this method will return NULL. * * @param index The zero-based index of the child to retrieve * @return Pointer to the appropriate child, or NULL */ virtual Node *nthChild(unsigned index) = 0; virtual Node const *nthChild(unsigned index) const = 0; //@} /*@}*/ /** * @name Manipulate the XML tree * @{ */ /** * @brief Create a duplicate of this node * * The newly created node has no parent, and a refcount equal 1. * You need to manually insert it into the document, using e.g. appendChild(). * Afterwards, call Inkscape::GC::release on it, so that it will be * automatically collected when the parent is collected. * * @param doc The document in which the duplicate should be created * @return A pointer to the duplicated node */ virtual Node *duplicate(Document *doc) const = 0; /** * @brief Insert another node as a child of this node * * When @c after is NULL, the inserted node will be placed as the first child * of this node. @c after must be a child of this node. * * @param child The node to insert * @param after The node after which the inserted node should be placed, or NULL */ virtual void addChild(Node *child, Node *after) = 0; /** * @brief Insert another node as a child of this node * * This is more efficient than appendChild() + setPosition(). * * @param child The node to insert * @param pos The position in parent's child order */ void addChildAtPos(Node *child, unsigned pos) { Node *after = (pos == 0) ? nullptr : nthChild(pos - 1); addChild(child, after); } /** * @brief Append a node as the last child of this node * @param child The node to append */ virtual void appendChild(Node *child) = 0; /** * @brief Remove a child of this node * * Once the pointer to the removed node disappears from the stack, the removed node * will be collected in the next GC pass, but only as long as its refcount is zero. * You should keep a refcount of zero for all nodes in the document except for * the document node itself, because they will be held in memory by the parent. * * @param child The child to remove */ virtual void removeChild(Node *child) = 0; /** * @brief Move a given node in this node's child order * * Both @c child and @c after must be children of this node for the method to work. * * @param child The node to move in the order * @param after The sibling node after which the moved node should be placed */ virtual void changeOrder(Node *child, Node *after) = 0; /** * @brief Remove all elements that not in src node * @param src The node to check for elements into this node * @param key The attribute to use as the identity attribute */ virtual void cleanOriginal(Node *src, gchar const *key) = 0; /** * @brief Compare 2 nodes equality * @param other The other node to compare * @param recursive Recursive mode check */ virtual bool equal(Node const *other, bool recursive, bool skip_ids = false) = 0; /** * @brief Merge all children of another node with the current * * This method merges two node hierarchies, where @c src takes precedence. * @c key is the name of the attribute that determines whether two nodes are * corresponding (it must be the same for both, and all of their ancestors). If there is * a corresponding node in @c src hierarchy, their attributes and content override the ones * already present in this node's hierarchy. If there is no corresponding node, * it is copied from @c src to this node. This method is used when merging the user's * preferences file with the defaults, and has little use beyond that. * * @param src The node to merge into this node * @param key The attribute to use as the identity attribute * @param noid If true process noid items * @param key If clean callback to cleanOriginal */ virtual void mergeFrom(Node const *src, char const *key, bool extension = false, bool clean = false) = 0; /*@}*/ /** * @name Notify observers about operations on the node * @{ */ /** * @brief Add an object that will be notified of the changes to this node * * @c observer must be an object deriving from the NodeObserver class. * The virtual methods of this object will be called when a corresponding change * happens to this node. You can also notify the observer of the node's current state * using synthesizeEvents(NodeObserver &). * * @param observer The observer object */ virtual void addObserver(NodeObserver &observer) = 0; /** * @brief Remove an object from the list of observers * @param observer The object to be removed */ virtual void removeObserver(NodeObserver &observer) = 0; /** * @brief Generate a sequence of events corresponding to the state of this node * * This function notifies the specified observer of all the events that would * recreate the current state of this node; e.g. the observer is notified of * all the attributes, children and content like they were just created. * This function can greatly simplify observer logic. * * @param observer The node observer to notify of the events */ virtual void synthesizeEvents(NodeObserver &observer) = 0; /** * @brief Add an object that will be notified of the changes to this node and its descendants * * The difference between adding a regular observer and a subtree observer is that * the subtree observer will also be notified if a change occurs to any of the node's * descendants, while a regular observer will only be notified of changes to the node * it was assigned to. * * @param observer The observer object */ virtual void addSubtreeObserver(NodeObserver &observer) = 0; /** * @brief Remove an object from the subtree observers list * @param observer The object to be removed */ virtual void removeSubtreeObserver(NodeObserver &observer) = 0; virtual void recursivePrintTree(unsigned level) = 0; /*@}*/ using iterator = Inkscape::XML::NodeSiblingIterator; /** @brief Iterator over children */ iterator begin() { return iterator(this->firstChild()); } /** @brief Helper to use the standard lib container functions */ iterator end() { return iterator(nullptr); } /** @brief Compare a node by looking at its name to a string */ bool operator==(const std::string &name) const { return this->name() == name; } /** @brief depth first search to find a node * * This function takes any list structure you want and uses that * to compare Node's down the child tree. It will do depth first * searching into the tree. The key part is that since it is a template * you have flexibility on the container, and the comparison that is * being used. Typically it will be used with something like a * std::list which will compare against the node's name * but more complex searches could be imagined. */ template Node *findChildPath(T list) { return findChildPath(list.cbegin(), list.cend()); } /** @brief template reshuffling to make the more useful findChildPath cleaner */ template Node *findChildPath(iterT itr, iterT end) { if (itr == end) { return this; } for (auto &child : *this) { if (child == *itr) { auto found = child.findChildPath(std::next(itr), end); if (found != nullptr) { return found; } } } return nullptr; } protected: Node(Node const &) : Anchored() {} virtual void setAttributeImpl(char const *key, char const *value) = 0; }; } // 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 :