org.jdom2.output.support.Walker Maven / Gradle / Ivy
/*--
Copyright (C) 2012 Jason Hunter & Brett McLaughlin.
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* Implementations of this class restructure the content to a particular format
* and expose the restructured content in this 'Walker' which is a loose
* equivalent to an iterator.
*
* The next() method will return a Content instance (perhaps null) if there
* is more content. If the returned content is null, then there will be some
* formatted characters available in the text() method. These characters may
* need to be represented as CDATA (check the isCDATA() method).
*
* Not all CDATA and Text nodes need to be reformatted, and as a result they
* may be returned as their original CDATA or Text instances instead of using
* the formatted text() / isCDATA() mechanism.
*
* The 'Rules' for the walkers are that no padding is done before the
* first content step, and no padding is done after the last content step (but
* the first/last content items may be trimmed to the correct format).
* Any required padding will be done in plain text (not CDATA) content.
* Consecutive CDATA sections may be separated by whitespace text for example.
*
* @author Rolf Lear
*
*/
public interface Walker {
/**
* If all the content in this walker is empty, or if whatever content
* is available is Text-like.
*
* Text-like content is considered to be {@link Text}, {@link CDATA},
* {@link EntityRef}, or any (potentially mixed) sequence of these types,
* but no other types.
*
* @return true if there is no content, or all content is Text
*/
public abstract boolean isAllText();
/**
* If all the content is Text-like ({@link #isAllText()} returns true), and
* additionally that any content is either Text or CDATA, and that the
* values of these Text/CDATA members are all XML Whitespace.
* @return true
*/
public abstract boolean isAllWhitespace();
/**
* Behaves similarly to to a regular Iterator
*
* @return true if there is more content to be processed
*/
public abstract boolean hasNext();
/**
* Similar to an Iterator, but null return values need special treatment.
*
* @return the next content to be processed, perhaps null if the next
* content is re-formatted text of some sort (Text / CDATA).
* @throws NoSuchElementException if there is no further content.
*/
public abstract Content next();
/**
* If the previous call to next() returned null, then this will return the
* required text to be processed. Check to see whether this text is CDATA
* by calling the isCDATA() method.
* @return The current text value (null if the previous invocation of next()
* returned a non-null value).
* @throws IllegalStateException if there was not previous call to next()
*/
public abstract String text();
/**
* If the previous next() method returned null, then this will indicate
* whether the current text() value is CDATA or regular Text.
* @return true if the current text() is valid, and is CDATA.
* @throws IllegalStateException if there was not previous call to next()
*/
public abstract boolean isCDATA();
}