C++ XML Class Library

This is a C++ class for reading and writing XML structures.

• Specify your XML schema in C++ using common C++ syntax, such as shift, dereference, etc.
• Verify the schema of XML files while they are read from a stream.
• Map and store your own C++ classes to XML and restore them back.

Rationale

The initial idea was to map C++ data structures to XML files for configuration files that can easily be edited by hand.

This library does not need any kind of C++ code parser or special pre compiler. You can specify a schema entirly in native C++. The schema is verified when XML is read and exceptions are thrown when the XML to be parse is invalid. Exceptions specify exactly the location and reason of the problem, so that the editor of the XML file can easily find and correct the problem.

C++ classes can inherit xml::Serialize and become serializable this way. All you need to do is to overwrite one single method, where you declare XML tag names for the class name and for all members.

More rationale: See also Related Pages in the doxygen project documentation.

Basics

Include file:

#include <xml-cxx/xml.hxx>

Link option:

-lxml-cxx

Factory with Schema Declaration

Small example on how to declare an XML schema, you may then use template.read(is) to read XML from a stream:

// start with root element: <root id="">
xml::Factory template(xml::Node("root").attr("id", xml::optional)
                      // <root> contains any number of <child>
                      <<xml::String("child")
                      // must contain exactly one <other>
                      <<(xml::Node("other").limits(1, 1)
                         // <other> contains min 2 max 4 <text>
                         <<xml::String("text").limits(2, 4)));

Using Macros Instead of Literal Text

If you prefere using constants instead of literal texts, you can declare the node names before you use them:

XML_NODE(root);
XML_STRING(child);
[...]

xml::Factory template(xml::node::root.clone()->attr("id", xml::optional)
                      <<*xml::string::child.clone()
                      [...]

Serialize Classes, Join Classes with XML

When inheriting from xml::Serialize, your class inherits the methods xml::Serialize::loadXml and xml::Serialize::saveXml. Simply overwrite xml::Serialize::initXmlMembers to make your class serializable:

class MyClass: public xml::Serialize {
  [...]
  protected:
    void initXmlMembers() {
      className("MyClass");
      persist(i, "i");
      persist(s, "s");
      persist(l, "l");
    }
  private:
    int i;
    std::string s;
    xml::List<std::string> l; // same behaviour as std::list
};

Known Limitations

• XML-Comments are only ignored, not read, not stored.
• Mixed tags and text is not supported. Tags may either contain other tags only (type xml::Node) or text only (type xml::String). -> This is intended behaviour!
• Unlimited recursion is not possible (e.g. <p><p><p></p></p></p>;)
• Exceptions should be optional, best effort otherwise (option "strict")

Limitations of Serialization

• Only the following types are intended to be serialized:
  (It is possible to use other techniques, but that's not recommended)
  • basic C++ types (except pointer)
  • std::string
  • classes derieved from xml::Serialize
  • most standard containers, but in their xml-form, e.g. xml::List instead of std::list (xml::List inherits std::list)
  • Optional values are supported through xml::Optional
  • std::bitset, std::priority_queue, std::queue and std::stack are not implemented
  • Polymorfic serialisation is not yet implemented