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elinks/src/dom/node.h
2022-01-28 13:47:42 +01:00

487 lines
16 KiB
C

/** DOM node module
*
* @file dom/node.h
*
* This module defines the various node and node list data structures
* and functionality to modify and access them, such as adding a node as
* a child to a given node and getting the text string of a node as
* defined by the DOM specification.
*
* @par Node hierarchy
*
* DOM documents are represented as a collection of nodes arranged in a
* hierarchic structure. At the root is either a #DOM_NODE_DOCUMENT or
* #DOM_NODE_DOCUMENT_FRAGMENT node, each of which may have multiple
* child nodes. There is a well-defined order that dictates which child
* nodes may be descendants of a given type of node. For example, text
* and attribute nodes can have no children, while elements node may
* have both attribute and element nodes as children but with each type
* in different node lists. The hierarchy is somewhat encoded in the
* type specific node data, however, certain node types also define
* "custom" node lists for conveniently storing additional "embedded"
* data, such as processing instruction nodes having an attribute node
* list for conveniently accessing variable-value pairs given for
* XML-specific processing instructions:
*
* @verbatim <?xml version="1.0"?> @endverbatim
*
* @par Node lists
*
* There are two types of list: unordered (the default) and
* alphabetically ordered (also called "maps"). Both types of list
* stores all contained nodes in the index-oriented #dom_node_list data
* structure.
*
* When inserting a node into a list, first use either
* #get_dom_node_list_index or #get_dom_node_map_index (depending on
* whether the list is unordered or ordered respectively) to calculate
* the index at which to insert the new node. Then use
* #add_to_dom_node_list to insert the node in the list at the given
* position. Alternatively (and mostly preferred), simply use
* #add_dom_node to have all of the above done automatically plus some
* additional checks.
*
* A variety of node list accessors are defined. The node structure does
* not define any "next" or "previous" members to get siblings due to
* reduce memory usage (this might have to change --jonas). Instead, use
* #get_dom_node_next and #get_dom_node_next to access siblings. To
* lookup the existence of a node in a sorted node list (map) use
* #get_dom_node_map_entry. If a specific and unique node subtype should
* be found use #get_dom_node_child that given a parent node will find a
* child node based on a specific child node type and subtype. Finally,
* list can be iterated in forward and reverse order using
* #foreach_dom_node and #foreachback_dom_node.
*/
#ifndef EL_DOM_NODE_H
#define EL_DOM_NODE_H
#include "dom/string.h"
#ifdef __cplusplus
extern "C" {
#endif
struct dom_node_list;
struct dom_document;
/** DOM node types */
enum dom_node_type {
DOM_NODE_UNKNOWN = 0, /**< Node type used internally. */
DOM_NODE_ELEMENT = 1, /**< Element node */
DOM_NODE_ATTRIBUTE = 2, /**< Attribute node */
DOM_NODE_TEXT = 3, /**< Text node */
DOM_NODE_CDATA_SECTION = 4, /**< CData section node */
DOM_NODE_ENTITY_REFERENCE = 5, /**< Entity reference node */
DOM_NODE_ENTITY = 6, /**< Entity node */
DOM_NODE_PROCESSING_INSTRUCTION = 7, /**< Processing instruction node */
DOM_NODE_COMMENT = 8, /**< Comment node */
DOM_NODE_DOCUMENT = 9, /**< Document root node */
DOM_NODE_DOCUMENT_TYPE = 10, /**< Document type (DTD) node */
DOM_NODE_DOCUMENT_FRAGMENT = 11, /**< Document fragment node */
DOM_NODE_NOTATION = 12, /**< Notation node */
DOM_NODES /**< The number of DOM nodes */
};
/* Following is the node specific data structures. They may contain no
* more than 4 pointers or something equivalent. */
/* The document URI is stored in the string / length members. */
struct dom_document_node {
/* The document. */
struct dom_document *document;
/* The child nodes. May be NULL. Ordered like they where inserted. */
/* FIXME: Should be just one element (root) node reference. */
struct dom_node_list *children;
};
struct dom_id {
struct dom_string public_id;
struct dom_string system_id;
};
struct dom_doctype_subset_info {
struct dom_string internal;
struct dom_id external;
};
struct dom_document_type_node {
/* These are really maps and should be sorted alphabetically. */
struct dom_node_list *entities;
struct dom_node_list *notations;
/* The string/length members of dom_node hold the name of the document
* type "<!DOCTYPE {name} ...>". This holds the ids for the external
* subset and the string of the internal subset. */
struct dom_doctype_subset_infot *subset;
};
/* Element nodes are indexed nodes stored in node lists of either
* other child nodes or the root node. */
struct dom_element_node {
/* The child nodes. May be NULL. Ordered like they where inserted. */
struct dom_node_list *children;
/* Only element nodes can have attributes and element nodes can only be
* child nodes so the map is put here.
*
* The @map may be NULL if there are none. The @map nodes are sorted
* alphabetically according to the attributes name so it has fast
* lookup. */
struct dom_node_list *map;
/* For <xsl:stylesheet ...> elements this holds the offset of
* 'stylesheet' */
uint16_t namespace_offset;
/* Special implementation dependent type specifier for example
* containing an enum value representing the element to reduce string
* comparing and only do one fast find mapping. */
uint16_t type;
};
/* Attribute nodes are named nodes stored in a node map of an element node. */
struct dom_attribute_node {
/* The string that hold the attribute value. The @string / @length
* members of {struct dom_node} holds the name that identifies the node
* in the map. */
struct dom_string value;
/* For xml:lang="en" attributes this holds the offset of 'lang' */
uint16_t namespace_offset;
/* Special implementation dependent type specifier. For HTML it (will)
* contain an enum value representing the attribute HTML_CLASS, HTML_ID etc.
* to reduce string comparing and only do one fast find mapping. */
uint16_t type;
/* The attribute value is delimited by quotes. Can be NUL, ' or ". */
unsigned char quoted;
/* Was the attribute specified in the DTD as a default attribute or was
* it added from the document source. */
unsigned int specified:1;
/* Has the node->string been converted to internal charset. */
unsigned int converted:1;
/* Is the attribute a unique identifier. */
unsigned int id:1;
/* The attribute value references some other resource */
unsigned int reference:1;
};
struct dom_text_node {
/* The number of newlines the text string contains */
unsigned int newlines;
/* We will need to add text nodes even if they contain only whitespace.
* In order to quickly identify such nodes this member is used. */
unsigned int only_space:1;
/* Has the node->string been converted to internal charset. */
unsigned int converted:1;
};
enum dom_proc_instruction_type {
DOM_PROC_INSTRUCTION,
/* Keep this group sorted */
DOM_PROC_INSTRUCTION_XML, /* XML header */
DOM_PROC_INSTRUCTION_XML_STYLESHEET, /* XML stylesheet link */
DOM_PROC_INSTRUCTION_TYPES
};
struct dom_proc_instruction_node {
/* The target of the processing instruction (xml for '<?xml ... ?>')
* is in the @string / @length members. */
/* This holds the value to be processed */
struct dom_string instruction;
/* For fast checking of the target type */
uint16_t type; /* enum dom_proc_instruction_type */
/* For some processing instructions like xml the instructions contain
* attributes and those attribute can be collected in this @map. */
struct dom_node_list *map;
};
union dom_node_data {
struct dom_document_node document;
struct dom_document_type_node document_type;
struct dom_element_node element;
struct dom_attribute_node attribute;
struct dom_text_node text;
struct dom_id notation;
/* For entities string/length hold the notation name */
struct dom_id entity;
struct dom_proc_instruction_node proc_instruction;
/* Node types without a union member yet (mostly because it hasn't
* been necessary):
*
* DOM_NODE_CDATA_SECTION: Use dom_text_node?
* DOM_NODE_DOCUMENT_FRAGMENT: struct dom_node_list children;
* DOM_NODE_ENTITY_REFERENCE: unicode_val_T
* DOM_NODE_COMMENT
*/
};
/** DOM node
*
* The node data structure is an abstract container that can be used to
* represent the hierarchic structure of a document, such as relation
* between elements, attributes, etc.
*
* @note This structure is size critical so keep ordering to make
* it easier to pack and avoid unneeded members.
*/
struct dom_node {
/** The type of the node. Holds a #dom_node_type enum value. */
uint16_t type; /* -> enum dom_node_type */
/** Was the node string allocated? */
unsigned int allocated:1;
/** Type specific node string. Can contain either stuff like
* element name or for attributes the attribute name. */
struct dom_string string;
/** The parent node. The parent node is NULL for the root node. */
struct dom_node *parent;
/** Type specific node data. */
union dom_node_data data;
};
/** DOM node list
*
* A node list can be used for storing indexed nodes. If a node list
* should be sorted alphabetically use the #get_dom_node_map_index
* function to find the index of new nodes before inserting them. */
struct dom_node_list {
size_t size;
struct dom_node *entries[1];
};
#define foreach_dom_node(list, node, i) \
for ((i) = 0; (i) < (list)->size; (i)++) \
if (((node) = (list)->entries[(i)]))
#define foreachback_dom_node(list, node, i) \
for ((i) = (list)->size - 1; (i) > 0; (i)--) \
if (((node) = (list)->entries[(i)]))
#define is_dom_node_list_member(list, member) \
((list) && 0 <= (member) && (member) < (list)->size)
/* Adds @node to the list pointed to by @list_ptr at the given @position. If
* @position is -1 the node is added at the end. */
struct dom_node_list *
add_to_dom_node_list(struct dom_node_list **list_ptr,
struct dom_node *node, int position);
void done_dom_node_list(struct dom_node_list *list);
/* Returns the position or index where the @node has been inserted into the
* 'default' list of the @parent node. (Default means use get_dom_node_list()
* to acquire the list to search in. Returns -1, if the node is not found. */
int get_dom_node_list_index(struct dom_node *parent, struct dom_node *node);
/* Returns the position or index where the @node should be inserted into the
* node @list in order to the list to be alphabetically sorted. Assumes that
* @list is already sorted properly. */
int get_dom_node_map_index(struct dom_node_list *list, struct dom_node *node);
/* Returns the previous sibling to the node. */
struct dom_node *get_dom_node_prev(struct dom_node *node);
/* Returns the next sibling to the node. */
struct dom_node *get_dom_node_next(struct dom_node *node);
/* Returns first text node of the element or NULL. */
struct dom_node *
get_dom_node_child(struct dom_node *node, /*enum dom_node_type*/ uint16_t child_type,
int16_t child_subtype);
/* Looks up the @node_map for a node matching the requested type and name.
* The @subtype maybe be 0 indication unknown subtype and only name should be
* tested else it will indicate either the element or attribute private
* subtype. */
struct dom_node *
get_dom_node_map_entry(struct dom_node_list *node_map,
/*enum dom_node_type*/ uint16_t type, uint16_t subtype,
struct dom_string *name);
/* Removes the node and all its children and free()s itself.
* A dom_stack_callback_T must not use this to free the node
* it gets as a parameter. */
void done_dom_node(struct dom_node *node);
#ifndef DEBUG_MEMLEAK
/* The allocated argument is used as the value of node->allocated if >= 0.
* Use -1 to default node->allocated to the value of parent->allocated. */
struct dom_node *
init_dom_node_at(struct dom_node *parent, /*enum dom_node_type*/ uint16_t type,
struct dom_string *string, int allocated);
#define init_dom_node(type, string, allocated) \
init_dom_node_at(NULL, type, string, allocated)
#define add_dom_node(parent, type, string) \
init_dom_node_at(parent, type, string, -1)
#else
struct dom_node *
init_dom_node_at(char *file, int line,
struct dom_node *parent, /*enum dom_node_type*/ uint16_t type,
struct dom_string *string, int allocated);
#define init_dom_node(type, string, allocated) \
init_dom_node_at(__FILE__, __LINE__, NULL, type, string, allocated)
#define add_dom_node(parent, type, string) \
init_dom_node_at(__FILE__, __LINE__, parent, type, string, -1)
#endif /* DEBUG_MEMLEAK */
#define add_dom_element(parent, string) \
add_dom_node(parent, DOM_NODE_ELEMENT, string)
static inline struct dom_node *
add_dom_attribute(struct dom_node *parent, struct dom_string *name,
struct dom_string *value)
{
struct dom_node *node = add_dom_node(parent, DOM_NODE_ATTRIBUTE, name);
if (node && value) {
struct dom_string *str = &node->data.attribute.value;
if (node->allocated) {
if (!init_dom_string(str, value->string, value->length)) {
done_dom_node(node);
return NULL;
}
} else {
copy_dom_string(str, value);
}
}
return node;
}
static inline struct dom_node *
add_dom_proc_instruction(struct dom_node *parent, struct dom_string *string,
struct dom_string *instruction)
{
struct dom_node *node = add_dom_node(parent, DOM_NODE_PROCESSING_INSTRUCTION, string);
if (node && instruction) {
struct dom_string *str = &node->data.proc_instruction.instruction;
if (node->allocated) {
if (!init_dom_string(str, instruction->string, instruction->length)) {
done_dom_node(node);
return NULL;
}
} else {
copy_dom_string(str, instruction);
}
}
return node;
}
/* Compare two nodes returning non-zero if they differ. */
int dom_node_casecmp(struct dom_node *node1, struct dom_node *node2);
/* Returns the name of the node in an allocated string. */
struct dom_string *get_dom_node_name(struct dom_node *node);
/* Returns the value of the node or NULL if no value is defined for the node
* type. */
struct dom_string *get_dom_node_value(struct dom_node *node);
/* Returns the name used for identifying the node type. */
struct dom_string *get_dom_node_type_name(/*enum dom_node_type*/ uint16_t type);
/** Based on the type of the @a parent and the node @a type return a
* proper list or NULL. This is useful when adding a node to a parent
* node.
*
* With a <code>struct dom_node_list **list</code> returned by this
* function, there are four possibilities:
*
* - <code>list == NULL</code>. This means @a parent does not support
* child nodes of the given @a type.
*
* - <code>*list == NULL</code>. This means @a parent does not yet
* have any child nodes of the given @a type and so no list has been
* allocated for them. Callers should treat the lack of a list in
* the same way as an empty list.
*
* - <code>(*list)->size == 0</code>. This is an empty list. It is
* unspecified whether the DOM code keeps such lists; it could
* instead change them back to NULL.
*
* - <code>(*list)->size != 0</code>. This is a nonempty list.
* However, the nodes in it might not actually be of the given
* @a type because some lists are used for multiple types. */
static inline struct dom_node_list **
get_dom_node_list_by_type(struct dom_node *parent, /*enum dom_node_type*/ uint16_t type)
{
switch (parent->type) {
case DOM_NODE_DOCUMENT:
return &parent->data.document.children;
case DOM_NODE_ELEMENT:
switch (type) {
case DOM_NODE_ATTRIBUTE:
return &parent->data.element.map;
default:
return &parent->data.element.children;
}
case DOM_NODE_DOCUMENT_TYPE:
switch (type) {
case DOM_NODE_ENTITY:
return &parent->data.document_type.entities;
case DOM_NODE_NOTATION:
return &parent->data.document_type.notations;
default:
return NULL;
}
case DOM_NODE_PROCESSING_INSTRUCTION:
switch (type) {
case DOM_NODE_ATTRIBUTE:
return &parent->data.proc_instruction.map;
default:
return NULL;
}
default:
return NULL;
}
}
#define get_dom_node_list(parent, node) \
get_dom_node_list_by_type(parent, (node)->type)
#ifdef __cplusplus
}
#endif
#endif