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package com.sun.xml.txw2;

/**
 * @author Kohsuke Kawaguchi
 */
abstract class Content {
    private Content next;

    /**
     * Returns null if the next token has not decided yet.
     */
    final Content getNext() {
        return next;
    }

    /**
     *
     * @param doc
     *      A {@link Content} object is so light-weight that
     *      it doesn't even remember what document it belongs to.
     *      So the caller needs to "remind" a {@link Content}
     *      who its owner is.
     */
    final void setNext(Document doc,Content next) {
        assert next!=null;
        assert this.next==null : "next of "+this+" is already set to "+this.next;
        this.next = next;
        doc.run();
    }

    /**
     * Returns true if this content is ready to be committed.
     */
    boolean isReadyToCommit() {
        return true;
    }

    /**
     * Returns true if this {@link Content} can guarantee that
     * no more new namespace decls is necessary for the currently
     * pending start tag.
     */
    abstract boolean concludesPendingStartTag();

    /**
     * Accepts a visitor.
     */
    abstract void accept(ContentVisitor visitor);

    /**
     * Called when this content is written to the output.
     */
    public void written() {
    }
}
