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1   /*
2    * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package jdk.nashorn.internal.codegen;
27  
28  import java.util.HashMap;
29  
30  /**
31   * A name space hierarchy, where each level holds a name directory with
32   * names that may be unique for each level.
33   */
34  
35  public class Namespace {
36      /** Parent namespace. */
37      private final Namespace parent;
38  
39      /** Name directory - version count for each name */
40      private final HashMap<String, Integer> directory;
41  
42      /**
43       * Constructor
44       */
45      public Namespace() {
46          this(null);
47      }
48  
49      /**
50       * Constructor
51       *
52       * @param parent parent name space
53       */
54      public Namespace(final Namespace parent) {
55          this.parent    = parent;
56          this.directory = new HashMap<>();
57      }
58  
59      /**
60       * Return the parent Namespace of this space.
61       *
62       * @return parent name space
63       */
64      public Namespace getParent() {
65          return parent;
66      }
67  
68      /**
69       * Create a uniqueName name in the namespace in the form base$n where n varies
70       * .
71       * @param base Base of name.  Base will be returned if uniqueName.
72       *
73       * @return Generated uniqueName name.
74       */
75      public String uniqueName(final String base) {
76          for (Namespace namespace = this; namespace != null; namespace = namespace.getParent()) {
77              final HashMap<String, Integer> namespaceDirectory = namespace.directory;
78              final Integer                  counter            = namespaceDirectory.get(base);
79  
80              if (counter != null) {
81                  final int count = counter + 1;
82                  namespaceDirectory.put(base, count);
83  
84                  return base + '-' + count;
85              }
86          }
87  
88          directory.put(base, 0);
89  
90          return base;
91      }
92  
93      @Override
94      public String toString() {
95          return directory.toString();
96      }
97  }