1 /*
   2  * reserved comment block
   3  * DO NOT REMOVE OR ALTER!
   4  */
   5 /*
   6  * Copyright 2001-2004 The Apache Software Foundation.
   7  *
   8  * Licensed under the Apache License, Version 2.0 (the "License");
   9  * you may not use this file except in compliance with the License.
  10  * You may obtain a copy of the License at
  11  *
  12  *     http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  * Unless required by applicable law or agreed to in writing, software
  15  * distributed under the License is distributed on an "AS IS" BASIS,
  16  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  17  * See the License for the specific language governing permissions and
  18  * limitations under the License.
  19  */
  20 /*
  21  * $Id: FlowList.java,v 1.2.4.1 2005/09/01 15:21:43 pvedula Exp $
  22  */
  23 
  24 package com.sun.org.apache.xalan.internal.xsltc.compiler;
  25 
  26 import java.util.Iterator;
  27 import java.util.Vector;
  28 
  29 import com.sun.org.apache.bcel.internal.generic.BranchHandle;
  30 import com.sun.org.apache.bcel.internal.generic.InstructionHandle;
  31 import com.sun.org.apache.bcel.internal.generic.InstructionList;
  32 
  33 /**
  34  * @author Jacek Ambroziak
  35  * @author Santiago Pericas-Geertsen
  36  */
  37 public final class FlowList {
  38     private Vector _elements;
  39 
  40     public FlowList() {
  41         _elements = null;
  42     }
  43 
  44     public FlowList(InstructionHandle bh) {
  45         _elements = new Vector();
  46         _elements.addElement(bh);
  47     }
  48 
  49     public FlowList(FlowList list) {
  50         _elements = list._elements;
  51     }
  52 
  53     public FlowList add(InstructionHandle bh) {
  54         if (_elements == null) {
  55             _elements = new Vector();
  56         }
  57         _elements.addElement(bh);
  58         return this;
  59     }
  60 
  61     public FlowList append(FlowList right) {
  62         if (_elements == null) {
  63             _elements = right._elements;
  64         }
  65         else {
  66             final Vector temp = right._elements;
  67             if (temp != null) {
  68                 final int n = temp.size();
  69                 for (int i = 0; i < n; i++) {
  70                     _elements.addElement(temp.elementAt(i));
  71                 }
  72             }
  73         }
  74         return this;
  75     }
  76 
  77     /**
  78      * Back patch a flow list. All instruction handles must be branch handles.
  79      */
  80     public void backPatch(InstructionHandle target) {
  81         if (_elements != null) {
  82             final int n = _elements.size();
  83             for (int i = 0; i < n; i++) {
  84                 BranchHandle bh = (BranchHandle)_elements.elementAt(i);
  85                 bh.setTarget(target);
  86             }
  87             _elements.clear();          // avoid backpatching more than once
  88         }
  89     }
  90 
  91     /**
  92      * Redirect the handles from oldList to newList. "This" flow list
  93      * is assumed to be relative to oldList.
  94      */
  95     public FlowList copyAndRedirect(InstructionList oldList,
  96         InstructionList newList)
  97     {
  98         final FlowList result = new FlowList();
  99         if (_elements == null) {
 100             return result;
 101         }
 102 
 103         final int n = _elements.size();
 104         final Iterator oldIter = oldList.iterator();
 105         final Iterator newIter = newList.iterator();
 106 
 107         while (oldIter.hasNext()) {
 108             final InstructionHandle oldIh = (InstructionHandle) oldIter.next();
 109             final InstructionHandle newIh = (InstructionHandle) newIter.next();
 110 
 111             for (int i = 0; i < n; i++) {
 112                 if (_elements.elementAt(i) == oldIh) {
 113                     result.add(newIh);
 114                 }
 115             }
 116         }
 117         return result;
 118     }
 119 }