1 /*
   2  * Copyright (c) 2016, 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.graalvm.compiler.lir.phases;
  24 
  25 import java.util.ArrayList;
  26 import java.util.ListIterator;
  27 
  28 /**
  29  * Allows storing of arbitrary data.
  30  */
  31 public class GenericContext {
  32 
  33     private ArrayList<Object> context;
  34 
  35     public GenericContext() {
  36         context = null;
  37     }
  38 
  39     public <T> void contextAdd(T obj) {
  40         if (context == null) {
  41             context = new ArrayList<>();
  42         }
  43         context.add(obj);
  44     }
  45 
  46     @SuppressWarnings("unchecked")
  47     public <T> T contextLookup(Class<T> clazz) {
  48         if (context != null) {
  49             for (Object e : context) {
  50                 if (clazz.isInstance(e)) {
  51                     return (T) e;
  52                 }
  53             }
  54         }
  55         return null;
  56     }
  57 
  58     @SuppressWarnings("unchecked")
  59     public <T> T contextRemove(Class<T> clazz) {
  60         if (context != null) {
  61             ListIterator<Object> it = context.listIterator();
  62             while (it.hasNext()) {
  63                 Object e = it.next();
  64                 if (clazz.isInstance(e)) {
  65                     // remove entry
  66                     it.remove();
  67                     if (context.isEmpty()) {
  68                         context = null;
  69                     }
  70                     return (T) e;
  71                 }
  72             }
  73         }
  74         return null;
  75     }
  76 }