1 /*
 2  * Copyright (c) 2024, 2025, 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.comp;
27 
28 import java.util.HashMap;
29 import java.util.Map;
30 import java.util.Set;
31 import java.util.WeakHashMap;
32 
33 import com.sun.tools.javac.util.List;
34 
35 import com.sun.tools.javac.code.Symbol.ClassSymbol;
36 import com.sun.tools.javac.code.Symbol.VarSymbol;
37 import com.sun.tools.javac.tree.JCTree;
38 import com.sun.tools.javac.util.Context;
39 
40 /**
41  * A Context class, that can keep useful information about unset fields.
42  * This information will be produced during flow analysis and used during
43  * code generation.
44  *
45  * <p><b>This is NOT part of any supported API.
46  * If you write code that depends on this, you do so at your own risk.
47  * This code and its internal interfaces are subject to change or
48  * deletion without notice.</b>
49  */
50 public class UnsetFieldsInfo {
51     protected static final Context.Key<UnsetFieldsInfo> unsetFieldsInfoKey = new Context.Key<>();
52 
53     public static UnsetFieldsInfo instance(Context context) {
54         UnsetFieldsInfo instance = context.get(unsetFieldsInfoKey);
55         if (instance == null)
56             instance = new UnsetFieldsInfo(context);
57         return instance;
58     }
59 
60     @SuppressWarnings("this-escape")
61     protected UnsetFieldsInfo(Context context) {
62         context.put(unsetFieldsInfoKey, this);
63     }
64 
65     private WeakHashMap<ClassSymbol, Map<JCTree, Set<VarSymbol>>> unsetFieldsMap = new WeakHashMap<>();
66 
67     public void addUnsetFieldsInfo(ClassSymbol csym, JCTree tree, Set<VarSymbol> unsetFields) {
68         Map<JCTree, Set<VarSymbol>> treeToFieldsMap = unsetFieldsMap.get(csym);
69         if (treeToFieldsMap == null) {
70             treeToFieldsMap = new HashMap<>();
71             treeToFieldsMap.put(tree, unsetFields);
72             unsetFieldsMap.put(csym, treeToFieldsMap);
73         } else {
74             if (!treeToFieldsMap.containsKey(tree)) {
75                 // only add if there is no info for the given tree
76                 treeToFieldsMap.put(tree, unsetFields);
77             }
78         }
79     }
80 
81     public Set<VarSymbol> getUnsetFields(ClassSymbol csym, JCTree tree) {
82         Map<JCTree, Set<VarSymbol>> treeToFieldsMap = unsetFieldsMap.get(csym);
83         if (treeToFieldsMap != null) {
84             Set<VarSymbol> result = treeToFieldsMap.get(tree);
85             if (result != null) {
86                 return result;
87             }
88         }
89         return null;
90     }
91 }