/*! @file

    @id $Id$
*/
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#ifndef XML_HXX
#define XML_HXX

#include <istream>
#include <string>
#include <vector>
#include <map>
#include <memory>

/*! @page limitations Known Limitations

    - Templates cannot specify number of sub-elements.
    - XML-Comments are not supported.
    - Mixed tags and text is not supported. Tags may either contain
      other tags only (type xml::Node) or text only (type
      xml::String).
    - Unlimited recursion is not possible
      (e.g. &ltp&gt;&ltp&gt;&ltp&gt;&lt/p&gt;&lt/p&gt;&lt/p&gt;)
    - No check yet for optional and mandatory attributes in xml::Factory
    - Exceptions should be optional, best effort otherwise (option "strict") */
namespace xml {

  //============================================================================
    class  Attributes: public std::map<std::string, std::string> {
    public:
      class Value: public value_type {
        public:
          Value(const std::string& name) throw();
          value_type& operator=(const std::string& value) throw();
        private:
          Value(); // not implemented
      };
      Attributes() throw();
      Attributes(const std::string& empty) throw();
      Attributes& operator<<(const value_type& v) throw();
      Attributes& operator<<(const std::string& key) throw();
      Attributes& operator=(const std::string& value) throw();
    private:
      iterator _active;
  };
  typedef Attributes::Value Attr;
  enum NodeType {START, END, EMPTY};
  struct Tag {
      std::string name;
      NodeType type;
      std::string text;
      Attributes attributes;
  };
  const bool mandatory = true;
  const bool optional = false;

  //================================================================= EXCEPTIONS
  class Node;
  class Factory;

  //----------------------------------------------------------------------------
  class exception: public std::exception {
    public:
      exception(std::string reason, const Node& t) throw();
      ~exception() throw();
      const char* what() const throw();
    private:
      std::string _what;
      Node* _node;
  };
  //----------------------------------------------------------------------------
  class no_parent: public exception {
    public:
      no_parent(const Node& t) throw(): exception("node has no parent", t) {}
  };
  //----------------------------------------------------------------------------
  class tag_expected: public exception {
    public:
      tag_expected(const Node& t, const std::string& txt) throw():
          exception("tag ('<') expected, text not allowed\ntext: "+txt, t) {}
  };
  //----------------------------------------------------------------------------
  class access_error: public exception {
    public:
      access_error(const Node& t, const std::string& name) throw();
      ~access_error() throw() {}
      const char* what() const throw();
    private:
      std::string _name;
  };
  //----------------------------------------------------------------------------
  class out_of_range: public exception {
    public:
      out_of_range(const Node& t, size_t pos) throw();
      ~out_of_range() throw() {}
      const char* what() const throw();
    private:
      size_t _pos;
  };
  //----------------------------------------------------------------------------
  class cannot_have_children: public exception {
    public:
      cannot_have_children(const Node& parent, const Node& child) throw();
      ~cannot_have_children() throw();
      const char* what() const throw();
    private:
      Node* _child;
  };
  //----------------------------------------------------------------------------
  class stream_error: public exception {
    public:
      stream_error(const std::string& reason, const Node& t,
                   std::istream& is, Tag tag, char c=0) throw();
      ~stream_error() throw() {}
      const char* what() const throw();
    private:
      std::istream::streampos _pos;
      Tag _tag;
      char _char;
  };
  //----------------------------------------------------------------------------
  class wrong_end_tag: public stream_error {
    public:
      wrong_end_tag(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("mismatching end tag", t, is, tag, c) {
      }
  };
  class missing_end_tag: public stream_error {
    public:
      missing_end_tag(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("missing end tag, end of file reached", t, is, tag, c) {
      }
  };
  class empty_stream: public stream_error {
    public:
      empty_stream(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("no xml tag found, stream is empty", t, is, tag, c) {
      }
  };
  class wrong_start_tag: public stream_error {
    public:
      wrong_start_tag(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("start tag does not match expected tag", t, is, tag, c) {
      }
  };
  class second_slash_in_tag: public stream_error {
    public:
      second_slash_in_tag(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("a tag may have no more than one slash", t, is, tag, c) {
      }
  };
  class character_after_slash: public stream_error {
    public:
      character_after_slash(const Node& t, std::istream& is, Tag tag, char c=0)
          throw():
          stream_error("unexpected character after empty-slash",
                       t, is, tag, c) {
      }
  };
  class attributes_in_end_tag: public stream_error {
    public:
      attributes_in_end_tag(const Node& t, std::istream& is, Tag tag)
          throw():
          stream_error("attributes are not allowed in end tags",t, is, tag) {
      }
  };
  class attribute_value_not_quoted: public stream_error {
    public:
      attribute_value_not_quoted(const Node& t, std::istream& is, Tag tag,
                                 char c, std::string attr) throw():
          stream_error("attribute values must be quoted (\")\nattribute: "+attr,
                       t, is, tag, c) {
      }
  };
  class duplicate_attribute: public stream_error {
    public:
      duplicate_attribute(const Node& t, std::istream& is, Tag tag,
                          std::string attr) throw():
          stream_error("attribute duplicated\nattribute: "+attr,
                       t, is, tag, 0) {
      }
  };

  //============================================================================

  //----------------------------------------------------------------------------
  class Node {
    private:
      typedef std::vector<Node*> Contents;
    public:
      typedef Contents::size_type size_type;
      Node(std::string name) throw();
      Node(const Node& o) throw();
      Node& operator=(const Node& o) throw();
      virtual ~Node() throw();
      virtual std::auto_ptr<Node> clone() const throw();
      virtual std::ostream& out(std::ostream& o, unsigned int level=0) const
          throw();
      virtual std::string text() const throw();
      virtual Node& text(const std::string& txt) throw(tag_expected);
      virtual Node& append(const Node& o) throw(cannot_have_children);
      virtual Node& set(const Attributes& o) throw();
      Node& clear() throw ();
      std::string name() const throw();
      bool isChild() const throw();
      Node& parent() const throw(no_parent);
      bool hasAttr(const std::string& name) const throw();
      Node& attr(const std::string& name, bool mandatory) throw();
      std::string attr(const std::string& name) const throw();
      std::string& attr(const std::string& name) throw();
      bool operator()(const std::string& child) const throw();
      Node& operator<<(const Node& o) throw(cannot_have_children);
      Node& operator<<(const Attributes& o) throw();
      //! Get the number of children.
      size_type children() const throw();
      //! Get the n-th child.
      const Node& operator[](size_type child) const throw(access_error);
      //! Get the n-th child.
      Node& operator[](size_type child) throw(access_error);
      //! Get the first named child.
      const Node& operator[](const std::string& child) const
          throw(access_error);
      //! Get the first named child.
      Node& operator[](const std::string& child) throw(access_error);
      std::string operator*() const throw();
      Node& operator=(const std::string& contents) throw(tag_expected);
      friend std::ostream& operator<<(std::ostream& o, const Node& t) throw();
    protected:
      Attributes _attributes;
    private:
      Node* find(const std::string& child) const throw();
      virtual std::auto_ptr<Node> clone(Node* p) const throw();
      Node(); // not implemented
      Contents _contents;
      std::string _name;
      Node* _parent;
  };

  //----------------------------------------------------------------------------
  class String: public Node {
    public:
      String(std::string name, const std::string& text = std::string()) throw();
      virtual std::auto_ptr<Node> clone() const throw();
      virtual ~String() throw() {}
      virtual std::string text() const throw();
      virtual String& text(const std::string& txt) throw(tag_expected);
      virtual std::ostream& out(std::ostream& o, unsigned int level=0) const
          throw();
      virtual String& append(const Node& o) throw(cannot_have_children);
      Node& operator=(const std::string& contents) throw();
    private:
      std::string _text;
  };

  //----------------------------------------------------------------------------
  class List: public Node {
  };

  class Factory {
    public:
      Factory(const Node& t) throw();
      const Node& operator*() const throw();
      std::auto_ptr<Node> read(std::istream& is)
          throw(wrong_end_tag, wrong_start_tag, tag_expected,
                second_slash_in_tag, character_after_slash,
                missing_end_tag, attribute_value_not_quoted, access_error,
                empty_stream, duplicate_attribute, attributes_in_end_tag);
    private:
      friend class stream_error;
      Factory(); // not implemented
      Factory(const Factory&); // not implemented
      bool ws(char c) const throw();
      std::auto_ptr<Node> read(std::istream& is, const Node& position)
          throw(wrong_end_tag, wrong_start_tag, tag_expected,
                second_slash_in_tag, character_after_slash,
                missing_end_tag,
                attribute_value_not_quoted, access_error, duplicate_attribute,
                attributes_in_end_tag);
      Tag tag(std::istream& is, const Node& position)
          throw(second_slash_in_tag, character_after_slash,
                missing_end_tag,
                attribute_value_not_quoted, access_error, duplicate_attribute);
      std::auto_ptr<Node> _template;
  };

}
#endif