LibXmlDomDocumentHandler.hxx

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/*
 * Copyright (c) 2001-2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#ifndef _LibXmlDomDocumentHandler_hxx_
#define _LibXmlDomDocumentHandler_hxx_

#include "LibXmlDomReadingContext.hxx"
#include "LibXmlDomWritingContext.hxx"
#include "LibXmlDomReader.hxx"
#include "LibXmlDomWriter.hxx"


#include <libxml++/libxml++.h>

namespace CLAM 
{
class LibXmlDomReadingContext;
class LibXmlDomWritingContext;
class LibXmlDomDocumentHandler
{
public:
        typedef LibXmlDomWritingContext WritingContext;
        typedef LibXmlDomReadingContext ReadingContext;
        ReadingContext * GetReadingContext()
        {
                return _currentReadContext;
        }
        void SetReadingContext(ReadingContext * context)
        {
                _currentReadContext = context;
        }
        WritingContext * GetWritingContext()
        {
                return _currentWriteContext;
        }
        void SetWritingContext(WritingContext * context)
        {
                _currentWriteContext = context;
        }
private:
        ReadingContext * _currentReadContext;
        WritingContext * _currentWriteContext;
        xmlpp::Document * _document;
        xmlpp::Element * _selection;
        xmlpp::DomParser * _parser;
public:
        LibXmlDomDocumentHandler()
        {
                _document = 0;
                _selection = 0;
                _parser = 0;
        }
        ~LibXmlDomDocumentHandler()
        {
                releaseIfAnyDocument();
        }
        void setDocument(xmlpp::Document * document)
        {
                _document = document;
                _selection = _document->get_root_node();
        }
        void selectPath(const char * path)
        {
                if (path[0]!='/') 
                        _selection = recursiveSelection(_selection, path, 0);
                else
                        _selection = absoluteSelection(path);
                return;
        }
        xmlpp::Element * getSelection()
        {
                return _selection;
        }
        void create(const char * rootName)
        {
                releaseIfAnyDocument();
                
                xmlpp::Document * domDoc = new xmlpp::Document;
                domDoc->create_root_node(rootName);
                setDocument(domDoc);
        }
        void read(std::istream & stream)
        {
                LibXmlDomReader reader;
                xmlpp::Document * domDoc;
                domDoc = reader.read(stream);
                setDocument(domDoc);
                _parser = reader.adoptParser();
        }
        void writeDocument(std::ostream & os, bool useIndentation=false)
        {
                LibXmlDomWriter writer;
                writer.DoIndentedFormat(useIndentation);
                writer.write(os,_document);
        }
        void writeSelection(std::ostream & os, bool useIndentation=false)
        {
                LibXmlDomWriter writer;
                writer.DoIndentedFormat(useIndentation);
                writer.write(os,_selection);
        }
private:
        void releaseIfAnyDocument()
        {
                if (!_document) return;

                if (_parser)
                        delete _parser;
                else
                        delete _document;
                _parser=0;
                _document=0;
        }
        xmlpp::Element * absoluteSelection(const std::string & path)
        {
                xmlpp::Element * root = _document->get_root_node();
                unsigned int nextSlash = std::string(path).find('/',1);
                std::string rootStep = std::string(path).substr(1,nextSlash-1);
                std::string rootName = root->get_name();
                if (rootStep=="") return root;

                if (rootName== rootStep)
                        return recursiveSelection(root, path, nextSlash+1);

                throw XmlStorageErr("Wrong root name, expected '"+rootStep+"' but found '"+rootName+"'");
        }
        xmlpp::Element * recursiveSelection(xmlpp::Element * current, const std::string & path, unsigned int pos)
        {
                if (pos >= path.length()) return current;
                unsigned int slashPosition = path.find('/', pos);
                unsigned int stepSize = 
                        slashPosition == std::string::npos ? 
                                std::string::npos : slashPosition-pos;
                std::string step = path.substr(pos, stepSize);
                xmlpp::Element::NodeList children = current->get_children();
                for (
                        xmlpp::Element::NodeList::iterator child = children.begin();
                        child!=children.end();
                        child++)
                {
                        xmlpp::Element * element = dynamic_cast<xmlpp::Element*>(*child);
                        if (!element) continue;
                        std::string nodeName= element->get_name();
                        if (nodeName != step) continue;
                        if (slashPosition==std::string::npos) return element;
                        return recursiveSelection(element, path, slashPosition+1);
                }
                std::string msg = "Wrong path step '" + step + "'";
                throw XmlStorageErr(msg);
        }
};


}

#endif//_LibXmlDomDocumentHandler_hxx_