xml_graph.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
 
# ifndef XML_GRAPH_H
# define XML_GRAPH_H
 
# include <tpl_dynArray.H>
# include <tpl_graph.H>
# include <ah-graph-concepts.H>
# include <tpl_dynMapTree.H>
# include <ah-errors.H>
# include <optional>
# include <type_traits>
# include <utility>
 
# include <libxml++/libxml++.h>
# include <libxml++/parsers/textreader.h>
# include <libxml++/nodes/node.h>
# include <libxml++/document.h>
 
using namespace Aleph;
 
namespace Aleph
{
  struct Attr
  {
    std::string name;
    std::string value;
  };
 
  template <class GT>
  struct Dft_Node_Reader
  {
    void operator () (GT &, typename GT::Node *, DynArray <Attr> &)
    {
      // Empty
    }
  };
 
  template <class GT>
  struct Dft_Node_Writer
  {
    void operator () (GT &, typename GT::Node *, DynArray <Attr> &)
    {
      // Empty
    }
  };
 
  template <class GT>
  struct Dft_Arc_Reader
  {
    void operator () (GT &, typename GT::Arc *, DynArray <Attr> &)
    {
      // Empty
    }
  };
 
  template <class GT>
  struct Dft_Arc_Writer
  {
    void operator () (GT &, typename GT::Arc *, DynArray <Attr> &)
    {
      // Empty
    }
  };
 
  /* TODO: still owe an explanation of the details of each of the
     reader and writer classes
  */
 
  template <AlephGraph GT,
            class Node_Reader = Dft_Node_Reader<GT>,
            class Arc_Reader = Dft_Arc_Reader<GT>,
            class Node_Writer = Dft_Node_Writer<GT>,
            class Arc_Writer = Dft_Arc_Writer<GT>
           >
  class Xml_Graph
  {
    std::string graph_name;
 
    std::string node_name;
 
    std::string arc_name;
 
    // Functors received as rvalues (including the defaults) are owned here, so
    // the references below never outlive them. Functors received as lvalues
    // are not copied: the references share them with the caller.
    std::optional<Node_Reader> own_node_reader;
    std::optional<Arc_Reader> own_arc_reader;
    std::optional<Node_Writer> own_node_writer;
    std::optional<Arc_Writer> own_arc_writer;
 
    Node_Reader & node_reader;
 
    Arc_Reader & arc_reader;
 
    Node_Writer & node_writer;
 
    Arc_Writer & arc_writer;
 
    GT read_graph(xmlpp::TextReader & reader)
    {
      GT g;
      DynMapTreap <size_t, typename GT::Node *> map;
 
      size_t num_nodes = 0;
 
      while(reader.read())
        {
          if (reader.get_name() == node_name)
            {
              typename GT::Node * p = g.insert_node();
              map.insert(num_nodes++, p);
 
              if (not reader.has_attributes())
                continue;
 
              reader.move_to_first_attribute();
 
              DynArray <Attr> attrs;
 
              do 
                {
                  Attr & attr = attrs.append();
                  attr.name = reader.get_name();
                  attr.value = reader.get_value();
                }
              while (reader.move_to_next_attribute());
 
              node_reader(g, p, attrs);
 
              reader.move_to_element();
           }
 
          else if (reader.get_name() == arc_name)
            {
              assert(reader.has_attributes());
              reader.move_to_first_attribute();
              size_t src = std::atol(reader.get_value().c_str());
              bool test = reader.move_to_next_attribute();
              assert(test);
              size_t tgt = std::atol(reader.get_value().c_str());
              test = reader.move_to_next_attribute();
 
              typename GT::Arc * a = g.insert_arc(map.find(src), map.find(tgt));
 
              if (not test)
                {
                  reader.move_to_element();
                  continue;
                }
 
              DynArray <Attr> attrs;
 
              do 
                {
                  Attr & attr = attrs.append();
                  attr.name = reader.get_name();
                  attr.value = reader.get_value();
                }
              while (reader.move_to_next_attribute());
 
              arc_reader(g, a, attrs);
 
              reader.move_to_element();
            }
        }
      return g;
    }
 
    GT read(const std::string & file_name)
    {
      xmlpp::TextReader reader(file_name);
      return read_graph(reader);
    }
 
    void write_graph(GT & g, xmlpp::Document & doc)
    {
      xmlpp::Element * element = doc.create_root_node(graph_name);
 
      xmlpp::Element * nodes = element->add_child("nodes");
 
      DynMapTreap <typename GT::Node *, size_t> map;
 
      size_t i = 0;
 
      for (typename GT::Node_Iterator it(g); it.has_curr(); it.next_ne(), ++i)
        {
          typename GT::Node * p = it.get_curr();
 
          map.insert(p, i);
 
          xmlpp::Element * node = nodes->add_child(node_name);
 
          DynArray <Attr> attrs;
 
          node_writer(g, p, attrs);
 
          for (size_t i = 0; i < attrs.size(); ++i)
            {
              Attr & attr = attrs.access(i);
             node->set_attribute(attr.name, attr.value);
            }
        }
 
      xmlpp::Element * arcs = element->add_child("arcs");
 
      for (typename GT::Arc_Iterator it(g); it.has_curr(); it.next_ne(), ++i)
        {
          typename GT::Arc * a = it.get_curr();
        
          xmlpp::Element * arc = arcs->add_child(arc_name);
 
          const size_t & src = map.find(g.get_src_node(a));
          arc->set_attribute("src", std::to_string(src));
 
          const size_t & tgt = map.find(g.get_tgt_node(a));
          arc->set_attribute("tgt", std::to_string(tgt));
 
          DynArray <Attr> attrs;
 
          arc_writer(g, a, attrs);
 
          for (size_t i = 0; i < attrs.size(); ++i)
            {
              Attr & attr = attrs.access(i);
              arc->set_attribute(attr.name, attr.value);
            }
        }
    }
 
    void write(GT & g, const std::string & file_name)
    {
      xmlpp::Document doc;
      write_graph(g, doc);
      doc.write_to_file_formatted(file_name, "UTF-8");
    }
 
  public:
    Xml_Graph(Node_Reader & _node_reader, Arc_Reader & _arc_reader,
              Node_Writer & _node_writer, Arc_Writer & _arc_writer)
      : graph_name("graph"), node_name("node"), arc_name("arc"),
        node_reader(_node_reader), arc_reader(_arc_reader),
        node_writer(_node_writer), arc_writer(_arc_writer)
    {
      // Empty
    }
 
    Xml_Graph(Node_Reader && _node_reader = Node_Reader(),
              Arc_Reader && _arc_reader = Arc_Reader(),
              Node_Writer && _node_writer = Node_Writer(),
              Arc_Writer && _arc_writer = Arc_Writer())
      : graph_name("graph"), node_name("node"), arc_name("arc"),
        own_node_reader(std::move(_node_reader)),
        own_arc_reader(std::move(_arc_reader)),
        own_node_writer(std::move(_node_writer)),
        own_arc_writer(std::move(_arc_writer)),
        node_reader(*own_node_reader), arc_reader(*own_arc_reader),
        node_writer(*own_node_writer), arc_writer(*own_arc_writer)
    {
      // Empty
    }
 
    template <class F>
    static std::optional<F> copy_own(const std::optional<F> & src)
    {
      if constexpr (std::is_copy_constructible_v<F>)
        return src;
      else
        {
          ah_runtime_error_if(src.has_value())
            << "Xml_Graph: cannot copy a reader/writer that owns a "
               "non-copy-constructible functor; share it instead "
               "(construct from an lvalue)";
          return std::nullopt;
        }
    }
 
    Xml_Graph(const Xml_Graph & other)
      : graph_name(other.graph_name), node_name(other.node_name),
        arc_name(other.arc_name),
        own_node_reader(copy_own(other.own_node_reader)),
        own_arc_reader(copy_own(other.own_arc_reader)),
        own_node_writer(copy_own(other.own_node_writer)),
        own_arc_writer(copy_own(other.own_arc_writer)),
        node_reader(own_node_reader ? *own_node_reader : other.node_reader),
        arc_reader(own_arc_reader ? *own_arc_reader : other.arc_reader),
        node_writer(own_node_writer ? *own_node_writer : other.node_writer),
        arc_writer(own_arc_writer ? *own_arc_writer : other.arc_writer)
    {
      // Empty
    }
 
    const std::string & get_graph_name() const
    {
      return graph_name;
    }
 
    void set_graph_name(const std::string & _graph_name)
    {
      graph_name = _graph_name;
    }
      
    const std::string & get_node_name() const
    {
      return node_name;
    }
 
    void set_node_name(const std::string & _node_name)
    {
      node_name = _node_name;
    }
 
    const std::string & get_arc_name() const
    {
      return arc_name;
    }
 
    void set_arc_name(const std::string & _arc_name)
    {
      arc_name = _arc_name;
    }
 
    GT operator () (const std::string & file_name)
    {
      return read(file_name);
    }
 
    void operator () (GT & g, const std::string & file_name)
    {
      write(g, file_name);
    }
  };
} // End namespace Aleph
 
# endif // XML_GRAPH_H