xmlconfigfile.h

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/*
    Sheep - A Rigid Body Dynamics Engine
    Copyright (C) 2001-2004 Francois Beaune
    Contact: http://toxicengine.sourceforge.net/

    This file is part of Sheep.

    Sheep 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.

    Sheep 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 Sheep; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifndef SHEEP_MISC_XMLCONFIGFILE_H
#define SHEEP_MISC_XMLCONFIGFILE_H

#include "config.h"
#include "stringutils.h"

#include <xercesc/dom/DOM.hpp>
#include <xercesc/parsers/XercesDOMParser.hpp>
#include <xercesc/sax/ErrorHandler.hpp>

#include <string>

class XPathEvaluator;
class XPathNSResolver;
class XPathResult;

namespace sheep {

    class XMLConfigFile {
    public:
        //! This is the base class for all exceptions thrown by the XMLConfigFile class.
        struct LoadErrorException {
            LoadErrorException(const std::string &message) :
                m_message(message) {}

            std::string m_message;
        };

        //! This exception is thrown if an error occurs when loading the XML document.
        //! It is either an I/O error or, if a schema was provided, a XML document
        //! validation error (the XML document could not be validated against the schema).
        struct ParseErrorException : public LoadErrorException {
            ParseErrorException(const std::string &message) :
                LoadErrorException(message) {}
        };

        //! This exception is thrown if an error occurs when querying the DOM document
        //! corresponding to the XML document. It is likely that the path (given in W3C
        //! XPath 1.0 notation) is badly formatted or could not be found in the document.
        struct QueryErrorException : public LoadErrorException {
            QueryErrorException(const std::string &message) :
                LoadErrorException(message) {}
        };

        XMLConfigFile(
            const std::string &filename,
            xercesc::ErrorHandler *error_handler = 0
        ) throw(ParseErrorException);

        //! Schema file path must be relative to the XML file path.
        XMLConfigFile(
            const std::string &filename,
            const std::string &schema_filename,
            xercesc::ErrorHandler *error_handler = 0
        ) throw(ParseErrorException);

        ~XMLConfigFile();

        //! GetValue<>() methods take a W3C XML Path (XPath) expression as argument.
        //! The W3C Recommendation can be found here: http://www.w3.org/TR/xpath.
        template<typename T>
        T GetValue(const std::string &xpathexpr) const
            throw(QueryErrorException, StringUtils::ConversionErrorException);
        template<>
        bool GetValue<bool>(const std::string &xpathexpr) const
            throw(QueryErrorException, StringUtils::ConversionErrorException);

        //! Returns true if the element designated by the XPath expression
        //! given as argument exists.
        int Count(const std::string &xpathexpr) const
            throw(QueryErrorException);

    private:
        xercesc::XercesDOMParser *m_parser;     //!< The XML DOM parser which owns the DOM document.
        xercesc::DOMElement *m_rootelement;     //!< The root element of the DOM tree.
        XPathEvaluator *m_evaluator;            //!< The XPathEvaluator class is used to create XPathExpression and XPathNSResolver objects.
        XPathNSResolver *m_nsresolver;          //!< The XPathNSResolver class binds XML namespace prefixes to the full namespace string.

        void initialize(
            const std::string &filename,
            const std::string &schema_filename,
            xercesc::ErrorHandler *error_handler
        ) throw(ParseErrorException);

        XPathResult *query(const std::string &xpathexpr) const
            throw(QueryErrorException);

        std::string get_string(const std::string &xpathexpr) const
            throw(QueryErrorException);
    };

#include "xmlconfigfile.inl"

}

#endif  // !SHEEP_MISC_XMLCONFIGFILE_H

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