/*

 * Copyright 2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.tools.javac.model;

import java.util.AbstractList;

import java.util.Iterator;

import java.util.NoSuchElementException;

import com.sun.tools.javac.code.Scope;

import com.sun.tools.javac.code.Symbol;

import static com.sun.tools.javac.code.Flags.*;

/**

 * Utility to construct a view of a symbol's members,

 * filtering out unwanted elements such as synthetic ones.

 * This view is most efficiently accessed through its iterator() method.

 *

 * <p><b>This is NOT part of any API supported by Sun Microsystems.  If

 * you write code that depends on this, you do so at your own risk.

 * This code and its internal interfaces are subject to change or

 * deletion without notice.</b>

 */

public class FilteredMemberList extends AbstractList<Symbol> {

    private final Scope scope;

    public FilteredMemberList(Scope scope) {

        this.scope = scope;

    }

    public int size() {

        int cnt = 0;

        for (Scope.Entry e = scope.elems; e != null; e = e.sibling) {

            if (!unwanted(e.sym))

                cnt++;

        }

        return cnt;

    }

    public Symbol get(int index) {

        for (Scope.Entry e = scope.elems; e != null; e = e.sibling) {

            if (!unwanted(e.sym) && (index-- == 0))

                return e.sym;

        }

        throw new IndexOutOfBoundsException();

    }

    // A more efficient implementation than AbstractList's.

    public Iterator<Symbol> iterator() {

        return new Iterator<Symbol>() {

            /** The next entry to examine, or null if none. */

            private Scope.Entry nextEntry = scope.elems;

            private boolean hasNextForSure = false;

            public boolean hasNext() {

                if (hasNextForSure) {

                    return true;

                }

                while (nextEntry != null && unwanted(nextEntry.sym)) {

                    nextEntry = nextEntry.sibling;

                }

                hasNextForSure = (nextEntry != null);

                return hasNextForSure;

            }

            public Symbol next() {

                if (hasNext()) {

                    Symbol result = nextEntry.sym;

                    nextEntry = nextEntry.sibling;

                    hasNextForSure = false;

                    return result;

                } else {

                    throw new NoSuchElementException();

                }

            }

            public void remove() {

                throw new UnsupportedOperationException();

            }

        };

    }

    /**

     * Tests whether this is a symbol that should never be seen by

     * clients, such as a synthetic class.  Returns true for null.

     */

    private static boolean unwanted(Symbol s) {

        return s == null  ||  (s.flags() & SYNTHETIC) != 0;

    }

}