325N/A/*
325N/A * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
325N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
325N/A *
325N/A * This code is free software; you can redistribute it and/or modify it
325N/A * under the terms of the GNU General Public License version 2 only, as
325N/A * published by the Free Software Foundation. Oracle designates this
325N/A * particular file as subject to the "Classpath" exception as provided
325N/A * by Oracle in the LICENSE file that accompanied this code.
325N/A *
325N/A * This code is distributed in the hope that it will be useful, but WITHOUT
325N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
325N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
325N/A * version 2 for more details (a copy is included in the LICENSE file that
325N/A * accompanied this code).
325N/A *
325N/A * You should have received a copy of the GNU General Public License version
325N/A * 2 along with this work; if not, write to the Free Software Foundation,
325N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
325N/A *
325N/A * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
325N/A * or visit www.oracle.com if you need additional information or have any
325N/A * questions.
325N/A */
325N/A
325N/Apackage com.sun.tools.internal.xjc.reader.gbind;
325N/A
325N/A/**
325N/A * {@link Expression} that represents a concatanation of two expressions
325N/A * "A,B".
325N/A *
325N/A * @author Kohsuke Kawaguchi
325N/A */
325N/Apublic final class Sequence extends Expression {
325N/A /**
325N/A * 'A' of 'A,B'
325N/A */
325N/A private final Expression lhs;
325N/A /**
325N/A * 'B' of 'A,B'
325N/A */
325N/A private final Expression rhs;
325N/A /**
325N/A * Compute this value eagerly for better performance
325N/A */
325N/A private final boolean isNullable;
325N/A
325N/A /**
325N/A * Cached value of {@link #lastSet()} for better performance.
325N/A * Sequence tends to be where the recursive lastSet computation occurs.
325N/A */
325N/A private ElementSet lastSet;
325N/A
325N/A public Sequence(Expression lhs, Expression rhs) {
325N/A this.lhs = lhs;
325N/A this.rhs = rhs;
325N/A isNullable = lhs.isNullable() && rhs.isNullable();
325N/A }
325N/A
325N/A ElementSet lastSet() {
325N/A if(lastSet==null) {
325N/A if(rhs.isNullable())
325N/A lastSet = ElementSets.union(lhs.lastSet(),rhs.lastSet());
325N/A else
325N/A lastSet = rhs.lastSet();
325N/A }
325N/A return lastSet;
325N/A }
325N/A
325N/A boolean isNullable() {
325N/A return isNullable;
325N/A }
325N/A
325N/A void buildDAG(ElementSet incoming) {
325N/A lhs.buildDAG(incoming);
325N/A if(lhs.isNullable())
325N/A rhs.buildDAG(ElementSets.union(incoming,lhs.lastSet()));
325N/A else
325N/A rhs.buildDAG(lhs.lastSet());
325N/A }
325N/A
325N/A public String toString() {
325N/A return '('+lhs.toString()+','+rhs.toString()+')';
325N/A }
325N/A}