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 * Copyright (C) 2004-2011

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package com.sun.xml.internal.rngom.binary.visitor;

import com.sun.xml.internal.rngom.binary.Pattern;

import com.sun.xml.internal.rngom.nc.NameClass;

import java.util.HashSet;

import java.util.Set;

/**

 * Visits a pattern and creates a list of possible child elements.

 *

 * <p>

 * One can use a similar technique to introspect a pattern.

 *

 * @author Kohsuke Kawaguchi (kk@kohsuke.org)

 */

public class ChildElementFinder extends PatternWalker {

    private final Set children = new HashSet();

    /**

     * Represents a child element.

     */

    public static class Element {

        public final NameClass nc;

        public final Pattern content;

        public Element(NameClass nc, Pattern content) {

            this.nc = nc;

            this.content = content;

        }

        public boolean equals(Object o) {

            if (this == o) return true;

            if (!(o instanceof Element)) return false;

            final Element element = (Element) o;

            if (content != null ? !content.equals(element.content) : element.content != null) return false;

            if (nc != null ? !nc.equals(element.nc) : element.nc != null) return false;

            return true;

        }

        public int hashCode() {

            int result;

            result = (nc != null ? nc.hashCode() : 0);

            result = 29 * result + (content != null ? content.hashCode() : 0);

            return result;

        }

    }

    /**

     * Returns a set of {@link Element}.

     */

    public Set getChildren() {

        return children;

    }

    public void visitElement(NameClass nc, Pattern content) {

        children.add(new Element(nc,content));

    }

    public void visitAttribute(NameClass ns, Pattern value) {

        // there will be no element inside attribute,

        // so don't go in there.

    }

    public void visitList(Pattern p) {

        // there will be no element inside a list,

        // so don't go in there.

    }

}