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 static jdk.nashorn.internal.codegen.MethodEmitter.LARGE_STRING_THRESHOLD;
  29 
  30 import java.util.HashMap;
  31 
  32 /**
  33  * A name space hierarchy, where each level holds a name directory with
  34  * names that may be unique for each level.
  35  */
  36 
  37 public class Namespace {
  38     /** Parent namespace. */
  39     private final Namespace parent;
  40 
  41     /** Name directory - version count for each name */
  42     private final HashMap<String, Integer> directory;
  43 
  44     /**
  45      * Constructor
  46      */
  47     public Namespace() {
  48         this(null);
  49     }
  50 
  51     /**
  52      * Constructor
  53      *
  54      * @param parent parent name space
  55      */
  56     public Namespace(final Namespace parent) {
  57         this.parent    = parent;
  58         this.directory = new HashMap<>();
  59     }
  60 
  61     /**
  62      * Return the parent Namespace of this space.
  63      *
  64      * @return parent name space
  65      */
  66     public Namespace getParent() {
  67         return parent;
  68     }
  69 
  70     /**
  71      * Create a uniqueName name in the namespace in the form base$n where n varies.
  72      * Also truncates very long names that would otherwise break ASM.

  73      *
  74      * @param base Base of name.  Base will be returned if uniqueName.
  75      * @return Generated uniqueName name.
  76      */
  77     public String uniqueName(final String base) {
  78         final String truncatedBase = base.length() > LARGE_STRING_THRESHOLD ? base.substring(0, LARGE_STRING_THRESHOLD) : base;
  79         for (Namespace namespace = this; namespace != null; namespace = namespace.getParent()) {
  80             final HashMap<String, Integer> namespaceDirectory = namespace.directory;
  81             final Integer                  counter            = namespaceDirectory.get(truncatedBase);
  82 
  83             if (counter != null) {
  84                 final int count = counter + 1;
  85                 namespaceDirectory.put(truncatedBase, count);
  86                 return truncatedBase + '-' + count;
  87             }
  88         }
  89 
  90         directory.put(truncatedBase, 0);
  91 
  92         return truncatedBase;
  93     }
  94 
  95     @Override
  96     public String toString() {
  97         return directory.toString();
  98     }
  99 }
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