LocalVariableTableWriter.java revision 2942:08092deced3f 
1/*
2 * Copyright (c) 2009, 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
26package com.sun.tools.javap;
27
28import com.sun.tools.classfile.Attribute;
29import com.sun.tools.classfile.Code_attribute;
30import com.sun.tools.classfile.ConstantPool;
31import com.sun.tools.classfile.ConstantPoolException;
32import com.sun.tools.classfile.Descriptor;
33import com.sun.tools.classfile.Descriptor.InvalidDescriptor;
34import com.sun.tools.classfile.Instruction;
35import com.sun.tools.classfile.LocalVariableTable_attribute;
36import java.util.ArrayList;
37import java.util.HashMap;
38import java.util.List;
39import java.util.ListIterator;
40import java.util.Map;
41
42/**
43 * Annotate instructions with details about local variables.
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 */
50public class LocalVariableTableWriter extends  InstructionDetailWriter {
51    public enum NoteKind {
52        START("start") {
53            public boolean match(LocalVariableTable_attribute.Entry entry, int pc) {
54                return (pc == entry.start_pc);
55            }
56        },
57        END("end") {
58            public boolean match(LocalVariableTable_attribute.Entry entry, int pc) {
59                return (pc == entry.start_pc + entry.length);
60            }
61        };
62        NoteKind(String text) {
63            this.text = text;
64        }
65        public abstract boolean match(LocalVariableTable_attribute.Entry entry, int pc);
66        public final String text;
67    }
68
69    static LocalVariableTableWriter instance(Context context) {
70        LocalVariableTableWriter instance = context.get(LocalVariableTableWriter.class);
71        if (instance == null)
72            instance = new LocalVariableTableWriter(context);
73        return instance;
74    }
75
76    protected LocalVariableTableWriter(Context context) {
77        super(context);
78        context.put(LocalVariableTableWriter.class, this);
79        classWriter = ClassWriter.instance(context);
80    }
81
82    public void reset(Code_attribute attr) {
83        codeAttr = attr;
84        pcMap = new HashMap<>();
85        LocalVariableTable_attribute lvt =
86                (LocalVariableTable_attribute) (attr.attributes.get(Attribute.LocalVariableTable));
87        if (lvt == null)
88            return;
89
90        for (int i = 0; i < lvt.local_variable_table.length; i++) {
91            LocalVariableTable_attribute.Entry entry = lvt.local_variable_table[i];
92            put(entry.start_pc, entry);
93            put(entry.start_pc + entry.length, entry);
94        }
95    }
96
97    public void writeDetails(Instruction instr) {
98        int pc = instr.getPC();
99        writeLocalVariables(pc, NoteKind.END);
100        writeLocalVariables(pc, NoteKind.START);
101    }
102
103    @Override
104    public void flush() {
105        int pc = codeAttr.code_length;
106        writeLocalVariables(pc, NoteKind.END);
107    }
108
109    public void writeLocalVariables(int pc, NoteKind kind) {
110        ConstantPool constant_pool = classWriter.getClassFile().constant_pool;
111        String indent = space(2); // get from Options?
112        List<LocalVariableTable_attribute.Entry> entries = pcMap.get(pc);
113        if (entries != null) {
114            for (ListIterator<LocalVariableTable_attribute.Entry> iter =
115                    entries.listIterator(kind == NoteKind.END ? entries.size() : 0);
116                    kind == NoteKind.END ? iter.hasPrevious() : iter.hasNext() ; ) {
117                LocalVariableTable_attribute.Entry entry =
118                        kind == NoteKind.END ? iter.previous() : iter.next();
119                if (kind.match(entry, pc)) {
120                    print(indent);
121                    print(kind.text);
122                    print(" local ");
123                    print(entry.index);
124                    print(" // ");
125                    Descriptor d = new Descriptor(entry.descriptor_index);
126                    try {
127                        print(d.getFieldType(constant_pool));
128                    } catch (InvalidDescriptor e) {
129                        print(report(e));
130                    } catch (ConstantPoolException e) {
131                        print(report(e));
132                    }
133                    print(" ");
134                    try {
135                        print(constant_pool.getUTF8Value(entry.name_index));
136                    } catch (ConstantPoolException e) {
137                        print(report(e));
138                    }
139                    println();
140                }
141            }
142        }
143    }
144
145    private void put(int pc, LocalVariableTable_attribute.Entry entry) {
146        List<LocalVariableTable_attribute.Entry> list = pcMap.get(pc);
147        if (list == null) {
148            list = new ArrayList<>();
149            pcMap.put(pc, list);
150        }
151        if (!list.contains(entry))
152            list.add(entry);
153    }
154
155    private ClassWriter classWriter;
156    private Code_attribute codeAttr;
157    private Map<Integer, List<LocalVariableTable_attribute.Entry>> pcMap;
158}
159