BindingSet


1   /*
2    * Bytecode Analysis Framework
3    * Copyright (C) 2003,2004 University of Maryland
4    * 
5    * This library is free software; you can redistribute it and/or
6    * modify it under the terms of the GNU Lesser General Public
7    * License as published by the Free Software Foundation; either
8    * version 2.1 of the License, or (at your option) any later version.
9    * 
10   * This library is distributed in the hope that it will be useful,
11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   * Lesser General Public License for more details.
14   * 
15   * You should have received a copy of the GNU Lesser General Public
16   * License along with this library; if not, write to the Free Software
17   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
18   */
19  
20  package edu.umd.cs.findbugs.ba.bcp;
21  
22  /**
23   * A set of Bindings, which are definitions of variables occuring
24   * in a ByteCodePattern.  BindingSets are immutable; to add a binding,
25   * a new cell is allocated.  (Are we CONSING yet?)
26   *
27   * @author David Hovemeyer
28   * @see Binding
29   */
30  public class BindingSet {
31      private final Binding binding;
32      private final BindingSet parent;
33  
34      /**
35       * Constructor; creates a new BindingSet as an extension of an existing one.
36       *
37       * @param binding a variable binding
38       * @param parent  the parent BindingSet, containing other bindings
39       */
40      public BindingSet(Binding binding, BindingSet parent) {
41          this.binding = binding;
42          this.parent = parent;
43      }
44  
45      /**
46       * Look for a Binding for given variable.
47       *
48       * @param varName name of the variable
49       * @return the Binding, or null if no such Binding is present in the set
50       */
51      public Binding lookup(String   varName) {
52          if (varName.equals(binding.getVarName()))
53              return binding;
54          return parent != null ? parent.lookup(varName) : null;
55      }
56  
57      @Override  
58           public String   toString() {
59          StringBuffer   buf = new StringBuffer  ();
60          BindingSet cur = this;
61          buf.append('[');
62          while (cur != null) {
63              if (cur != this)
64                  buf.append(", ");
65              buf.append(cur.binding.toString());
66              cur = cur.parent;
67          }
68          buf.append(']');
69          return buf.toString();
70      }
71  }
72  
73  // vim:ts=4
74
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