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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#ifndef INCLUDED_ORCUS_SAX_NS_PARSER_HPP
#define INCLUDED_ORCUS_SAX_NS_PARSER_HPP
#include "sax_parser.hpp"
#include "xml_namespace.hpp"
#include <unordered_set>
#include <vector>
#include <algorithm>
namespace orcus {
struct sax_ns_parser_element
{
/** Element namespace identifier. */
xmlns_id_t ns;
/** Element namespace alias. */
std::string_view ns_alias;
/** Element name. */
std::string_view name;
/** Position of the opening brace '<'. */
std::ptrdiff_t begin_pos;
/** Position immediately after the closing brace '>'. */
std::ptrdiff_t end_pos;
};
struct sax_ns_parser_attribute
{
/** Attribute namespace identifier. */
xmlns_id_t ns;
/** Attribute namespace alias. */
std::string_view ns_alias;
/** Attribute name. */
std::string_view name;
/** Attribute value. */
std::string_view value;
/** Whether or not the attribute value is transient. */
bool transient;
};
namespace sax { namespace detail {
struct entity_name
{
std::string_view ns;
std::string_view name;
entity_name(std::string_view _ns, std::string_view _name) :
ns(_ns), name(_name) {}
bool operator== (const entity_name& other) const
{
return other.ns == ns && other.name == name;
}
struct hash
{
size_t operator() (const entity_name& v) const
{
std::hash<std::string_view> hasher;
return hasher(v.ns) + hasher(v.name);
}
};
};
typedef std::unordered_set<std::string_view> ns_keys_type;
typedef std::unordered_set<entity_name, entity_name::hash> entity_names_type;
struct elem_scope
{
xmlns_id_t ns;
std::string_view name;
ns_keys_type ns_keys;
elem_scope() {}
elem_scope(const elem_scope&) = delete;
elem_scope(elem_scope&& other) = default;
};
using elem_scopes_type = std::vector<elem_scope>;
}} // namespace sax::detail
class sax_ns_handler
{
public:
/**
* Called when a doctype declaration <!DOCTYPE ... > is encountered.
*
* @param dtd struct containing doctype declaration data.
*/
void doctype(const orcus::sax::doctype_declaration& dtd)
{
(void)dtd;
}
/**
* Called when <?... is encountered, where the '...' may be an
* arbitraray dentifier. One common declaration is <?xml which is
* typically given at the start of an XML stream.
*
* @param decl name of the identifier.
*/
void start_declaration(std::string_view decl)
{
(void)decl;
}
/**
* Called when the closing tag (>) of a <?... ?> is encountered.
*
* @param decl name of the identifier.
*/
void end_declaration(std::string_view decl)
{
(void)decl;
}
/**
* Called at the start of each element.
*
* @param elem information of the element being parsed.
*/
void start_element(const orcus::sax_ns_parser_element& elem)
{
(void)elem;
}
/**
* Called at the end of each element.
*
* @param elem information of the element being parsed.
*/
void end_element(const orcus::sax_ns_parser_element& elem)
{
(void)elem;
}
/**
* Called when a segment of a text content is parsed. Each text content
* is a direct child of an element, which may have multiple child contents
* when the element also has a child element that are direct sibling to
* the text contents or the text contents are splitted by a comment.
*
* @param val value of the text content.
* @param transient when true, the text content has been converted and is
* stored in a temporary buffer due to presence of one or
* more encoded characters, in which case <em>the passed
* text value needs to be either immediately converted to
* a non-text value or be interned within the scope of
* the callback</em>.
*/
void characters(std::string_view val, bool transient)
{
(void)val;
(void)transient;
}
/**
* Called upon parsing of an attribute of a declaration. The value of an
* attribute is assumed to be transient thus should be consumed within the
* scope of this callback.
*
* @param name name of an attribute.
* @param val value of an attribute.
*
* @todo Perhaps we should pass the transient flag here as well like all the
* other places.
*/
void attribute(std::string_view name, std::string_view val)
{
(void)name;
(void)val;
}
/**
* Called upon parsing of an attribute of an element. Note that <em>when
* the attribute's transient flag is set, the attribute value is stored in
* a temporary buffer due to a presence of encoded characters, and must be
* processed within the scope of the callback</em>.
*
* @param attr struct containing attribute information.
*/
void attribute(const orcus::sax_ns_parser_attribute& attr)
{
(void)attr;
}
};
/**
* SAX based XML parser with extra namespace handling.
*
* It uses an instance of xmlns_context passed by the caller to validate and
* convert namespace values into identifiers. The namespace identifier of
* each encountered element is always given even if one is not explicitly
* given.
*
* This parser keeps track of element scopes and detects non-matching element
* pairs.
*
* @tparam HandlerT Handler type with member functions for event callbacks.
* Refer to @ref sax_ns_handler.
*/
template<typename HandlerT>
class sax_ns_parser
{
public:
typedef HandlerT handler_type;
sax_ns_parser(std::string_view content, xmlns_context& ns_cxt, handler_type& handler);
~sax_ns_parser() = default;
/**
* Start parsing the document.
*
* @exception orcus::malformed_xml_error when it encounters a
* non-matching closing element.
*/
void parse();
private:
/**
* Re-route callbacks from the internal sax_parser into sax_ns_parser
* callbacks.
*/
class handler_wrapper
{
sax::detail::elem_scopes_type m_scopes;
sax::detail::ns_keys_type m_ns_keys;
sax::detail::entity_names_type m_attrs;
sax_ns_parser_element m_elem;
sax_ns_parser_attribute m_attr;
xmlns_context& m_ns_cxt;
handler_type& m_handler;
bool m_declaration;
public:
handler_wrapper(xmlns_context& ns_cxt, handler_type& handler) : m_ns_cxt(ns_cxt), m_handler(handler), m_declaration(false) {}
void doctype(const sax::doctype_declaration& dtd)
{
m_handler.doctype(dtd);
}
void start_declaration(std::string_view name)
{
m_declaration = true;
m_handler.start_declaration(name);
}
void end_declaration(std::string_view name)
{
m_declaration = false;
m_handler.end_declaration(name);
}
void start_element(const sax::parser_element& elem)
{
m_scopes.emplace_back();
sax::detail::elem_scope& scope = m_scopes.back();
scope.ns = m_ns_cxt.get(elem.ns);
scope.name = elem.name;
scope.ns_keys.swap(m_ns_keys);
m_elem.ns = scope.ns;
m_elem.ns_alias = elem.ns;
m_elem.name = scope.name;
m_elem.begin_pos = elem.begin_pos;
m_elem.end_pos = elem.end_pos;
m_handler.start_element(m_elem);
m_attrs.clear();
}
void end_element(const sax::parser_element& elem)
{
sax::detail::elem_scope& scope = m_scopes.back();
if (scope.ns != m_ns_cxt.get(elem.ns) || scope.name != elem.name)
throw malformed_xml_error("mis-matching closing element.", -1);
m_elem.ns = scope.ns;
m_elem.ns_alias = elem.ns;
m_elem.name = scope.name;
m_elem.begin_pos = elem.begin_pos;
m_elem.end_pos = elem.end_pos;
m_handler.end_element(m_elem);
// Pop all namespaces declared in this scope.
for (const std::string_view& key : scope.ns_keys)
m_ns_cxt.pop(key);
m_scopes.pop_back();
}
void characters(std::string_view val, bool transient)
{
m_handler.characters(val, transient);
}
void attribute(const sax::parser_attribute& attr)
{
if (m_declaration)
{
// XML declaration attribute. Pass it through to the handler without namespace.
m_handler.attribute(attr.name, attr.value);
return;
}
if (m_attrs.count(sax::detail::entity_name(attr.ns, attr.name)) > 0)
throw malformed_xml_error(
"You can't define two attributes of the same name in the same element.", -1);
m_attrs.insert(sax::detail::entity_name(attr.ns, attr.name));
if (attr.ns.empty() && attr.name == "xmlns")
{
// Default namespace
m_ns_cxt.push(std::string_view{}, attr.value);
m_ns_keys.insert(std::string_view{});
return;
}
if (attr.ns == "xmlns")
{
// Namespace alias
if (!attr.name.empty())
{
m_ns_cxt.push(attr.name, attr.value);
m_ns_keys.insert(attr.name);
}
return;
}
m_attr.ns = attr.ns.empty() ? XMLNS_UNKNOWN_ID : m_ns_cxt.get(attr.ns);
m_attr.ns_alias = attr.ns;
m_attr.name = attr.name;
m_attr.value = attr.value;
m_attr.transient = attr.transient;
m_handler.attribute(m_attr);
}
};
private:
handler_wrapper m_wrapper;
sax_parser<handler_wrapper> m_parser;
};
template<typename HandlerT>
sax_ns_parser<HandlerT>::sax_ns_parser(
std::string_view content, xmlns_context& ns_cxt, handler_type& handler) :
m_wrapper(ns_cxt, handler), m_parser(content, m_wrapper)
{
}
template<typename HandlerT>
void sax_ns_parser<HandlerT>::parse()
{
m_parser.parse();
}
}
#endif
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