1 /*

     2  * Copyright (c) 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 com.sun.tools.javac.jvm;

    27 

    28 import java.util.Map;

    29 import java.util.Map.Entry;

    30 import java.util.WeakHashMap;

    31 

    32 import com.sun.tools.javac.code.Symbol.MethodSymbol;

    33 import com.sun.tools.javac.code.Symbol.VarSymbol;

    34 import com.sun.tools.javac.tree.JCTree;

    35 import com.sun.tools.javac.util.Context;

    36 import com.sun.tools.javac.util.List;

    37 

    38 /** This class contains a one to many relation between a tree and a set of variables.

    39  *  The relation implies that the given tree closes the DA (definite assignment)

    40  *  range for the set of variables.

    41  *

    42  *  <p><b>This is NOT part of any supported API.

    43  *  If you write code that depends on this, you do so at your own risk.

    44  *  This code and its internal interfaces are subject to change or

    45  *  deletion without notice.</b>

    46  */

    47 public class LVTRanges {

    48     /** The context key for the LVT ranges. */

    49     protected static final Context.Key<LVTRanges> lvtRangesKey = new Context.Key<>();

    50 

    51     /** Get the LVTRanges instance for this context. */

    52     public static LVTRanges instance(Context context) {

    53         LVTRanges instance = context.get(lvtRangesKey);

    54         if (instance == null) {

    55             instance = new LVTRanges(context);

    56         }

    57         return instance;

    58     }

    59 

    60     private static final long serialVersionUID = 1812267524140424433L;

    61 

    62     protected Context context;

    63 

    64     protected Map<MethodSymbol, Map<JCTree, List<VarSymbol>>>

    65             aliveRangeClosingTrees = new WeakHashMap<>();

    66 

    67     public LVTRanges(Context context) {

    68         this.context = context;

    69         context.put(lvtRangesKey, this);

    70     }

    71 

    72     public List<VarSymbol> getVars(MethodSymbol method, JCTree tree) {

    73         Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

    74         return (varMap != null) ? varMap.get(tree) : null;

    75     }

    76 

    77     public boolean containsKey(MethodSymbol method, JCTree tree) {

    78         Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

    79         if (varMap == null) {

    80             return false;

    81         }

    82         return varMap.containsKey(tree);

    83     }

    84 

    85     public void setEntry(MethodSymbol method, JCTree tree, List<VarSymbol> vars) {

    86         Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

    87         if (varMap != null) {

    88             varMap.put(tree, vars);

    89         } else {

    90             varMap = new WeakHashMap<>();

    91             varMap.put(tree, vars);

    92             aliveRangeClosingTrees.put(method, varMap);

    93         }

    94     }

    95 

    96     public List<VarSymbol> removeEntry(MethodSymbol method, JCTree tree) {

    97         Map<JCTree, List<VarSymbol>> varMap = aliveRangeClosingTrees.get(method);

    98         if (varMap != null) {

    99             List<VarSymbol> result = varMap.remove(tree);

   100             if (varMap.isEmpty()) {

   101                 aliveRangeClosingTrees.remove(method);

   102             }

   103             return result;

   104         }

   105         return null;

   106     }

   107 

   108     /* This method should be used for debugging LVT related issues.

   109      */

   110     @Override

   111     public String toString() {

   112         String result = "";

   113         for (Entry<MethodSymbol, Map<JCTree, List<VarSymbol>>> mainEntry: aliveRangeClosingTrees.entrySet()) {

   114             result += "Method: \n" + mainEntry.getKey().flatName() + "\n";

   115             int i = 1;

   116             for (Entry<JCTree, List<VarSymbol>> treeEntry: mainEntry.getValue().entrySet()) {

   117                 result += "    Tree " + i + ": \n" + treeEntry.getKey().toString() + "\n";

   118                 result += "        Variables closed:\n";

   119                 for (VarSymbol var: treeEntry.getValue()) {

   120                     result += "            " + var.toString();

   121                 }

   122                 result += "\n";

   123                 i++;

   124             }

   125         }

   126         return result;

   127     }

   128 

   129 }