Path handling

This section explains how to handle XML document 'path' with SASAX.

Path extension

Path primitive

SASAX provides the functionality to know the current hierarchy in the XML document as "path". In SASAX, "path" is the list of the "element", which contains (1)URI, (2)name and (3)attributes.

"Path" and "element" are defined as "Path" and "Path.Element". Path provides utilities to compare itself with another instance: ancestor-ness, descendant-ness, and so on, for example.

Extension for path

Recording current hierarchy in XML document as "path" is not so expensive in performance, but is just overhead if you do not use such information in parsing.

So, SASAX defines such, "path" information handling for example, functionalities as "extension", and provides the toggle to turn each extensions on/off individualy to reduce running cost of parsing. "path extension" is defined as "PathExtension".

At first, you should invoke register() of PathExtension to make SASAX recognize "path extension" as "extension", onece per JVM process. Then, you can enable/disable "path extension" by enable() of PathExtension per parsing (per ElementDrivenHandler, in fact).

PathExtension.register();

ElementDrivenHandler handler = 
    new ElementDrivenHandler(rootElement);

PathExtension.enable(handler);

handler.parse(document);

Define path handling class

For example of path handling, the code to dump current path hierarchy on each "startElement" is shown below. This code is part of PathDemo placed under src/demo/sasax/src in src/bin distribution. This class is included in demo.jar of binary distribution.

public Element startElement(ParseContext context,
                            String uri,
                            String lName,
                            Attributes attrs)
    throws SAXException //
{
    // dump current path hierarchy
    Path path = PathExtension.getPath(context);
    Iterator elements = path.getElements();
    while(elements.hasNext()){
        Path.Element element =
            (Path.Element)(elements.next());
        System.out.print("/");
        System.out.print(element.getLName());
    }
    System.out.println("");

    return this;
}

Parse document

You can parse XML document with path handling by the code shown in "Parse document" as you know.

PathExtension.register();

PathDemo rootElement = new PathDemo(null);

ElementDrivenHandler handler =
    new ElementDrivenHandler(rootElement);

PathExtension.enable(handler);

handler.parse(reader);

Detailed information

Class diagram

Class diagram in this section is shown below:

Class diagram (click for large figure)

Class names

In this tutorial, abbreviated class names are used. Complete names are shown below.