nashorn/src/jdk/nashorn/internal/ir/BreakNode.java
author lagergren
Tue, 07 May 2013 14:43:17 +0200
changeset 17524 703643aeb0d6
parent 17523 cb4a7c901e0d
child 17769 14ea7feaf658
permissions -rw-r--r--
8013914: Removed explicit LineNumberNodes that were too brittle when code moves around, and also introduced unnecessary footprint. Introduced the Statement node and fixed dead code elimination issues that were discovered by the absense of labels for LineNumberNodes. Reviewed-by: jlaskey, attila

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.ir;

import jdk.nashorn.internal.ir.annotations.Immutable;
import jdk.nashorn.internal.ir.visitor.NodeVisitor;

/**
 * IR representation for {@code break} statements.
 */
@Immutable
public final class BreakNode extends Statement {

    private final IdentNode label;

    /**
     * Constructor
     *
     * @param lineNumber line number
     * @param token      token
     * @param finish     finish
     * @param label      label for break or null if none
     */
    public BreakNode(final int lineNumber, final long token, final int finish, final IdentNode label) {
        super(lineNumber, token, finish);
        this.label = label;
    }

    @Override
    public boolean hasGoto() {
        return true;
    }

    /**
     * Assist in IR navigation.
     * @param visitor IR navigating visitor.
     */
    @Override
    public Node accept(final NodeVisitor visitor) {
        if (visitor.enterBreakNode(this)) {
            return visitor.leaveBreakNode(this);
        }

        return this;
    }

    /**
     * Get the label for this break node
     * @return label, or null if none
     */
    public IdentNode getLabel() {
        return label;
    }

    @Override
    public void toString(final StringBuilder sb) {
        sb.append("break");

        if (label != null) {
            sb.append(' ');
            label.toString(sb);
        }
    }
}