mapnik/src/rapidxml_loader.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#ifdef HAVE_LIBXML2
#error HAVE_LIBXML2 defined but compiling rapidxml_loader.cpp!
#endif

// mapnik
#include <mapnik/config_error.hpp>
#include <mapnik/util/fs.hpp>
#include <mapnik/xml_loader.hpp>
#include <mapnik/xml_node.hpp>
#include <mapnik/util/trim.hpp>
#include <mapnik/util/noncopyable.hpp>
#include <mapnik/util/utf_conv_win.hpp>

#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <boost/property_tree/detail/xml_parser_read_rapidxml.hpp>
MAPNIK_DISABLE_WARNING_POP

// stl
#include <iostream>
#include <fstream>

namespace rapidxml = boost::property_tree::detail::rapidxml;

namespace mapnik {
class rapidxml_loader : util::noncopyable
{
  public:
    rapidxml_loader()
        : filename_()
    {}

    ~rapidxml_loader() {}

    void load(std::string const& filename, xml_node& node)
    {
        if (!mapnik::util::exists(filename))
        {
            throw config_error(std::string("Could not load map file: File does not exist"), 0, filename);
        }
        filename_ = filename;
#ifdef _WIN32
        std::basic_ifstream<char> stream(mapnik::utf8_to_utf16(filename));
#else
        std::basic_ifstream<char> stream(filename.c_str());
#endif
        if (!stream)
        {
            throw config_error("Could not load map file", 0, filename);
        }
        stream.unsetf(std::ios::skipws);
        std::vector<char> v(std::istreambuf_iterator<char>(stream.rdbuf()), std::istreambuf_iterator<char>());
        if (!stream.good())
        {
            throw config_error("Could not load map file", 0, filename_);
        }
        v.push_back(0); // zero-terminate
        load_array(v, node);
    }

    template<typename T>
    void load_array(T&& array, xml_node& node)
    {
        try
        {
            // Parse using appropriate flags
            // https://github.com/mapnik/mapnik/issues/1856
            // const int f_tws = rapidxml::parse_normalize_whitespace;
            const int f_tws = rapidxml::parse_trim_whitespace | rapidxml::parse_validate_closing_tags;
            rapidxml::xml_document<> doc;
            doc.parse<f_tws>(&array.front());

            for (rapidxml::xml_node<char>* child = doc.first_node(); child; child = child->next_sibling())
            {
                populate_tree(child, node);
            }
        } catch (rapidxml::parse_error const& e)
        {
            long line = static_cast<long>(std::count(&array.front(), e.where<char>(), '\n') + 1);
            throw config_error(e.what(), line, filename_);
        }
    }

    void load_string(std::string const& buffer, xml_node& node, std::string const&)
    {
        // Note: base_path ignored because its not relevant - only needed for xml2 to load entities (see
        // libxml2_loader.cpp)
        load_array(std::string(buffer), node);
    }

  private:
    void populate_tree(rapidxml::xml_node<char>* cur_node, xml_node& node)
    {
        switch (cur_node->type())
        {
            case rapidxml::node_element: {
                xml_node& new_node = node.add_child(cur_node->name(), 0, false);
                // Copy attributes
                for (rapidxml::xml_attribute<char>* attr = cur_node->first_attribute(); attr;
                     attr = attr->next_attribute())
                {
                    new_node.add_attribute(attr->name(), attr->value());
                }

                // Copy children
                for (rapidxml::xml_node<char>* child = cur_node->first_node(); child; child = child->next_sibling())
                {
                    populate_tree(child, new_node);
                }
            }
            break;

            // Data nodes
            case rapidxml::node_data:
            case rapidxml::node_cdata: {
                if (cur_node->value_size() > 0) // Don't add empty text nodes
                {
                    // parsed text values should have leading and trailing
                    // whitespace trimmed.
                    std::string trimmed = cur_node->value();
                    mapnik::util::trim(trimmed);
                    node.add_child(trimmed.c_str(), 0, true);
                }
            }
            break;
            default:
                break;
        }
    }

  private:
    std::string filename_;
};

void read_xml(std::string const& filename, xml_node& node)
{
    rapidxml_loader loader;
    loader.load(filename, node);
}
void read_xml_string(std::string const& str, xml_node& node, std::string const& base_path)
{
    rapidxml_loader loader;
    loader.load_string(str, node, base_path);
}

} // end of namespace mapnik