Class State

  • All Implemented Interfaces:
    ContentHandler
    Direct Known Subclasses:
    IgnoreState, NamespaceState, SimpleState

    public abstract class State
    extends Object
    implements ContentHandler
    base interface of 'parsing state'. parsing of XML representation of a grammar is done by using various states.

    Each State-derived class is responsible for a particular type of declaration of the grammar. For example, SequenceState is responsible for parsing <sequence> element of RELAX module.

    State objects interact each other. There are two ways of interaction.

    • from parent to child
    • from child to parent
    The first type of communication occurs only when a child state object is created. The last type of communication occurs usually (but not limited to) when a child state sees its end tag.

    In this level of inheritance, contract is somewhat abstract.

    1. When a State object is created, its init method is called and various information is set. Particularly, start tag information (if any) and the parent state is set. This process should only be initiated by GrammarReader.
    2. After that, startSelf method is called. Usually, this is the place to do something useful.
    3. State object is registered as a ContentHandler, and therefore will receive SAX events from now on.
    4. Derived classes are expected to do something useful by receiving SAX events.
    5. When a State object finishes its own part, it should call GrammarReader.popState method. It will remove the current State object and registers the parent state as a ContentHandler again.
    Of course some derived classes introduce more restricted contract. See SimpleState.

    this class also provides:

    • access to the parent state
    • default implementations for all ContentHandler callbacks except startElement and endElement
    Author:
    Kohsuke KAWAGUCHI