1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * Licensed to the Apache Software Foundation (ASF) under one or more
7 * contributor license agreements.  See the NOTICE file distributed with
8 * this work for additional information regarding copyright ownership.
9 * The ASF licenses this file to You under the Apache License, Version 2.0
10 * (the "License"); you may not use this file except in compliance with
11 * the License.  You may obtain a copy of the License at
12 *
13 *      http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 */
21
22package com.sun.org.apache.bcel.internal.classfile;
23
24import java.io.DataInput;
25import java.io.DataOutputStream;
26import java.io.IOException;
27
28import com.sun.org.apache.bcel.internal.Const;
29
30/**
31 * This class represents the constant pool, i.e., a table of constants, of
32 * a parsed classfile. It may contain null references, due to the JVM
33 * specification that skips an entry after an 8-byte constant (double,
34 * long) entry.  Those interested in generating constant pools
35 * programatically should see <a href="../generic/ConstantPoolGen.html">
36 * ConstantPoolGen</a>.
37
38 * @version $Id: ConstantPool.java 1749603 2016-06-21 20:50:19Z ggregory $
39 * @see     Constant
40 * @see     com.sun.org.apache.bcel.internal.generic.ConstantPoolGen
41 */
42public class ConstantPool implements Cloneable, Node {
43
44    private Constant[] constant_pool;
45
46
47    /**
48     * @param constant_pool Array of constants
49     */
50    public ConstantPool(final Constant[] constant_pool) {
51        this.constant_pool = constant_pool;
52    }
53
54
55    /**
56     * Read constants from given input stream.
57     *
58     * @param input Input stream
59     * @throws IOException
60     * @throws ClassFormatException
61     */
62    public ConstantPool(final DataInput input) throws IOException, ClassFormatException {
63        byte tag;
64        final int constant_pool_count = input.readUnsignedShort();
65        constant_pool = new Constant[constant_pool_count];
66        /* constant_pool[0] is unused by the compiler and may be used freely
67         * by the implementation.
68         */
69        for (int i = 1; i < constant_pool_count; i++) {
70            constant_pool[i] = Constant.readConstant(input);
71            /* Quote from the JVM specification:
72             * "All eight byte constants take up two spots in the constant pool.
73             * If this is the n'th byte in the constant pool, then the next item
74             * will be numbered n+2"
75             *
76             * Thus we have to increment the index counter.
77             */
78            tag = constant_pool[i].getTag();
79            if ((tag == Const.CONSTANT_Double) || (tag == Const.CONSTANT_Long)) {
80                i++;
81            }
82        }
83    }
84
85
86    /**
87     * Called by objects that are traversing the nodes of the tree implicitely
88     * defined by the contents of a Java class. I.e., the hierarchy of methods,
89     * fields, attributes, etc. spawns a tree of objects.
90     *
91     * @param v Visitor object
92     */
93    @Override
94    public void accept( final Visitor v ) {
95        v.visitConstantPool(this);
96    }
97
98
99    /**
100     * Resolve constant to a string representation.
101     *
102     * @param  c Constant to be printed
103     * @return String representation
104     */
105    public String constantToString( Constant c ) throws ClassFormatException {
106        String str;
107        int i;
108        final byte tag = c.getTag();
109        switch (tag) {
110            case Const.CONSTANT_Class:
111                i = ((ConstantClass) c).getNameIndex();
112                c = getConstant(i, Const.CONSTANT_Utf8);
113                str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
114                break;
115            case Const.CONSTANT_String:
116                i = ((ConstantString) c).getStringIndex();
117                c = getConstant(i, Const.CONSTANT_Utf8);
118                str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
119                break;
120            case Const.CONSTANT_Utf8:
121                str = ((ConstantUtf8) c).getBytes();
122                break;
123            case Const.CONSTANT_Double:
124                str = String.valueOf(((ConstantDouble) c).getBytes());
125                break;
126            case Const.CONSTANT_Float:
127                str = String.valueOf(((ConstantFloat) c).getBytes());
128                break;
129            case Const.CONSTANT_Long:
130                str = String.valueOf(((ConstantLong) c).getBytes());
131                break;
132            case Const.CONSTANT_Integer:
133                str = String.valueOf(((ConstantInteger) c).getBytes());
134                break;
135            case Const.CONSTANT_NameAndType:
136                str = constantToString(((ConstantNameAndType) c).getNameIndex(),
137                        Const.CONSTANT_Utf8)
138                        + ":" + constantToString(((ConstantNameAndType) c).getSignatureIndex(),
139                        Const.CONSTANT_Utf8);
140                break;
141            case Const.CONSTANT_InterfaceMethodref:
142            case Const.CONSTANT_Methodref:
143            case Const.CONSTANT_Fieldref:
144                str = constantToString(((ConstantCP) c).getClassIndex(), Const.CONSTANT_Class)
145                        + "." + constantToString(((ConstantCP) c).getNameAndTypeIndex(),
146                        Const.CONSTANT_NameAndType);
147                break;
148            case Const.CONSTANT_MethodHandle:
149                // Note that the ReferenceIndex may point to a Fieldref, Methodref or
150                // InterfaceMethodref - so we need to peek ahead to get the actual type.
151                final ConstantMethodHandle cmh = (ConstantMethodHandle) c;
152                str = Const.getMethodHandleName(cmh.getReferenceKind())
153                        + " " + constantToString(cmh.getReferenceIndex(),
154                        getConstant(cmh.getReferenceIndex()).getTag());
155                break;
156            case Const.CONSTANT_MethodType:
157                final ConstantMethodType cmt = (ConstantMethodType) c;
158                str = constantToString(cmt.getDescriptorIndex(), Const.CONSTANT_Utf8);
159                break;
160            case Const.CONSTANT_InvokeDynamic:
161                final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) c;
162                str = cid.getBootstrapMethodAttrIndex()
163                        + ":" + constantToString(cid.getNameAndTypeIndex(),
164                        Const.CONSTANT_NameAndType);
165                break;
166            default: // Never reached
167                throw new RuntimeException("Unknown constant type " + tag);
168        }
169        return str;
170    }
171
172
173    private static String escape( final String str ) {
174        final int len = str.length();
175        final StringBuilder buf = new StringBuilder(len + 5);
176        final char[] ch = str.toCharArray();
177        for (int i = 0; i < len; i++) {
178            switch (ch[i]) {
179                case '\n':
180                    buf.append("\\n");
181                    break;
182                case '\r':
183                    buf.append("\\r");
184                    break;
185                case '\t':
186                    buf.append("\\t");
187                    break;
188                case '\b':
189                    buf.append("\\b");
190                    break;
191                case '"':
192                    buf.append("\\\"");
193                    break;
194                default:
195                    buf.append(ch[i]);
196            }
197        }
198        return buf.toString();
199    }
200
201
202    /**
203     * Retrieve constant at `index' from constant pool and resolve it to
204     * a string representation.
205     *
206     * @param  index of constant in constant pool
207     * @param  tag expected type
208     * @return String representation
209     */
210    public String constantToString( final int index, final byte tag ) throws ClassFormatException {
211        final Constant c = getConstant(index, tag);
212        return constantToString(c);
213    }
214
215
216    /**
217     * Dump constant pool to file stream in binary format.
218     *
219     * @param file Output file stream
220     * @throws IOException
221     */
222    public void dump( final DataOutputStream file ) throws IOException {
223        file.writeShort(constant_pool.length);
224        for (int i = 1; i < constant_pool.length; i++) {
225            if (constant_pool[i] != null) {
226                constant_pool[i].dump(file);
227            }
228        }
229    }
230
231
232    /**
233     * Get constant from constant pool.
234     *
235     * @param  index Index in constant pool
236     * @return Constant value
237     * @see    Constant
238     */
239    public Constant getConstant( final int index ) {
240        if (index >= constant_pool.length || index < 0) {
241            throw new ClassFormatException("Invalid constant pool reference: " + index
242                    + ". Constant pool size is: " + constant_pool.length);
243        }
244        return constant_pool[index];
245    }
246
247
248    /**
249     * Get constant from constant pool and check whether it has the
250     * expected type.
251     *
252     * @param  index Index in constant pool
253     * @param  tag Tag of expected constant, i.e., its type
254     * @return Constant value
255     * @see    Constant
256     * @throws  ClassFormatException
257     */
258    public Constant getConstant( final int index, final byte tag ) throws ClassFormatException {
259        Constant c;
260        c = getConstant(index);
261        if (c == null) {
262            throw new ClassFormatException("Constant pool at index " + index + " is null.");
263        }
264        if (c.getTag() != tag) {
265            throw new ClassFormatException("Expected class `" + Const.getConstantName(tag)
266                    + "' at index " + index + " and got " + c);
267        }
268        return c;
269    }
270
271
272    /**
273     * @return Array of constants.
274     * @see    Constant
275     */
276    public Constant[] getConstantPool() {
277        return constant_pool;
278    }
279
280
281    /**
282     * Get string from constant pool and bypass the indirection of
283     * `ConstantClass' and `ConstantString' objects. I.e. these classes have
284     * an index field that points to another entry of the constant pool of
285     * type `ConstantUtf8' which contains the real data.
286     *
287     * @param  index Index in constant pool
288     * @param  tag Tag of expected constant, either ConstantClass or ConstantString
289     * @return Contents of string reference
290     * @see    ConstantClass
291     * @see    ConstantString
292     * @throws  ClassFormatException
293     */
294    public String getConstantString( final int index, final byte tag ) throws ClassFormatException {
295        Constant c;
296        int i;
297        c = getConstant(index, tag);
298        /* This switch() is not that elegant, since the two classes have the
299         * same contents, they just differ in the name of the index
300         * field variable.
301         * But we want to stick to the JVM naming conventions closely though
302         * we could have solved these more elegantly by using the same
303         * variable name or by subclassing.
304         */
305        switch (tag) {
306            case Const.CONSTANT_Class:
307                i = ((ConstantClass) c).getNameIndex();
308                break;
309            case Const.CONSTANT_String:
310                i = ((ConstantString) c).getStringIndex();
311                break;
312            default:
313                throw new RuntimeException("getConstantString called with illegal tag " + tag);
314        }
315        // Finally get the string from the constant pool
316        c = getConstant(i, Const.CONSTANT_Utf8);
317        return ((ConstantUtf8) c).getBytes();
318    }
319
320
321    /**
322     * @return Length of constant pool.
323     */
324    public int getLength() {
325        return constant_pool == null ? 0 : constant_pool.length;
326    }
327
328
329    /**
330     * @param constant Constant to set
331     */
332    public void setConstant( final int index, final Constant constant ) {
333        constant_pool[index] = constant;
334    }
335
336
337    /**
338     * @param constant_pool
339     */
340    public void setConstantPool( final Constant[] constant_pool ) {
341        this.constant_pool = constant_pool;
342    }
343
344
345    /**
346     * @return String representation.
347     */
348    @Override
349    public String toString() {
350        final StringBuilder buf = new StringBuilder();
351        for (int i = 1; i < constant_pool.length; i++) {
352            buf.append(i).append(")").append(constant_pool[i]).append("\n");
353        }
354        return buf.toString();
355    }
356
357
358    /**
359     * @return deep copy of this constant pool
360     */
361    public ConstantPool copy() {
362        ConstantPool c = null;
363        try {
364            c = (ConstantPool) clone();
365            c.constant_pool = new Constant[constant_pool.length];
366            for (int i = 1; i < constant_pool.length; i++) {
367                if (constant_pool[i] != null) {
368                    c.constant_pool[i] = constant_pool[i].copy();
369                }
370            }
371        } catch (final CloneNotSupportedException e) {
372            // TODO should this throw?
373        }
374        return c;
375    }
376}
377