nashorn/src/jdk/nashorn/internal/codegen/Namespace.java

/*
 * 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.codegen;

import static jdk.nashorn.internal.codegen.MethodEmitter.LARGE_STRING_THRESHOLD;

import java.util.HashMap;

/**
 * A name space hierarchy, where each level holds a name directory with
 * names that may be unique for each level.
 */

public class Namespace {
    /** Parent namespace. */
    private final Namespace parent;

    /** Name directory - version count for each name */
    private final HashMap<String, Integer> directory;

    /**
     * Constructor
     */
    public Namespace() {
        this(null);
    }

    /**
     * Constructor
     *
     * @param parent parent name space
     */
    public Namespace(final Namespace parent) {
        this.parent    = parent;
        this.directory = new HashMap<>();
    }

    /**
     * Return the parent Namespace of this space.
     *
     * @return parent name space
     */
    public Namespace getParent() {
        return parent;
    }

    /**
     * Create a uniqueName name in the namespace in the form base$n where n varies.
     * Also truncates very long names that would otherwise break ASM.
     *
     * @param base Base of name.  Base will be returned if uniqueName.
     * @return Generated uniqueName name.
     */
    public String uniqueName(final String base) {
        final String truncatedBase = base.length() > LARGE_STRING_THRESHOLD ? base.substring(0, LARGE_STRING_THRESHOLD) : base;
        for (Namespace namespace = this; namespace != null; namespace = namespace.getParent()) {
            final HashMap<String, Integer> namespaceDirectory = namespace.directory;
            final Integer                  counter            = namespaceDirectory.get(truncatedBase);

            if (counter != null) {
                final int count = counter + 1;
                namespaceDirectory.put(truncatedBase, count);
                return truncatedBase + '-' + count;
            }
        }

        directory.put(truncatedBase, 0);

        return truncatedBase;
    }

    @Override
    public String toString() {
        return directory.toString();
    }
}