1/***
2 * ASM: a very small and fast Java bytecode manipulation framework
3 * Copyright (c) 2000-2007 INRIA, France Telecom
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the copyright holders nor the names of its
15 *    contributors may be used to endorse or promote products derived from
16 *    this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
28 * THE POSSIBILITY OF SUCH DAMAGE.
29 */
30package org.mockito.asm;
31
32/**
33 * A non standard class, field, method or code attribute.
34 *
35 * @author Eric Bruneton
36 * @author Eugene Kuleshov
37 */
38public class Attribute {
39
40    /**
41     * The type of this attribute.
42     */
43    public final String type;
44
45    /**
46     * The raw value of this attribute, used only for unknown attributes.
47     */
48    byte[] value;
49
50    /**
51     * The next attribute in this attribute list. May be <tt>null</tt>.
52     */
53    Attribute next;
54
55    /**
56     * Constructs a new empty attribute.
57     *
58     * @param type the type of the attribute.
59     */
60    protected Attribute(final String type) {
61        this.type = type;
62    }
63
64    /**
65     * Returns <tt>true</tt> if this type of attribute is unknown. The default
66     * implementation of this method always returns <tt>true</tt>.
67     *
68     * @return <tt>true</tt> if this type of attribute is unknown.
69     */
70    public boolean isUnknown() {
71        return true;
72    }
73
74    /**
75     * Returns <tt>true</tt> if this type of attribute is a code attribute.
76     *
77     * @return <tt>true</tt> if this type of attribute is a code attribute.
78     */
79    public boolean isCodeAttribute() {
80        return false;
81    }
82
83    /**
84     * Returns the labels corresponding to this attribute.
85     *
86     * @return the labels corresponding to this attribute, or <tt>null</tt> if
87     *         this attribute is not a code attribute that contains labels.
88     */
89    protected Label[] getLabels() {
90        return null;
91    }
92
93    /**
94     * Reads a {@link #type type} attribute. This method must return a <i>new</i>
95     * {@link Attribute} object, of type {@link #type type}, corresponding to
96     * the <tt>len</tt> bytes starting at the given offset, in the given class
97     * reader.
98     *
99     * @param cr the class that contains the attribute to be read.
100     * @param off index of the first byte of the attribute's content in {@link
101     *        ClassReader#b cr.b}. The 6 attribute header bytes, containing the
102     *        type and the length of the attribute, are not taken into account
103     *        here.
104     * @param len the length of the attribute's content.
105     * @param buf buffer to be used to call
106     *        {@link ClassReader#readUTF8 readUTF8},
107     *        {@link ClassReader#readClass(int,char[]) readClass} or
108     *        {@link ClassReader#readConst readConst}.
109     * @param codeOff index of the first byte of code's attribute content in
110     *        {@link ClassReader#b cr.b}, or -1 if the attribute to be read is
111     *        not a code attribute. The 6 attribute header bytes, containing the
112     *        type and the length of the attribute, are not taken into account
113     *        here.
114     * @param labels the labels of the method's code, or <tt>null</tt> if the
115     *        attribute to be read is not a code attribute.
116     * @return a <i>new</i> {@link Attribute} object corresponding to the given
117     *         bytes.
118     */
119    protected Attribute read(
120        final ClassReader cr,
121        final int off,
122        final int len,
123        final char[] buf,
124        final int codeOff,
125        final Label[] labels)
126    {
127        Attribute attr = new Attribute(type);
128        attr.value = new byte[len];
129        System.arraycopy(cr.b, off, attr.value, 0, len);
130        return attr;
131    }
132
133    /**
134     * Returns the byte array form of this attribute.
135     *
136     * @param cw the class to which this attribute must be added. This parameter
137     *        can be used to add to the constant pool of this class the items
138     *        that corresponds to this attribute.
139     * @param code the bytecode of the method corresponding to this code
140     *        attribute, or <tt>null</tt> if this attribute is not a code
141     *        attributes.
142     * @param len the length of the bytecode of the method corresponding to this
143     *        code attribute, or <tt>null</tt> if this attribute is not a code
144     *        attribute.
145     * @param maxStack the maximum stack size of the method corresponding to
146     *        this code attribute, or -1 if this attribute is not a code
147     *        attribute.
148     * @param maxLocals the maximum number of local variables of the method
149     *        corresponding to this code attribute, or -1 if this attribute is
150     *        not a code attribute.
151     * @return the byte array form of this attribute.
152     */
153    protected ByteVector write(
154        final ClassWriter cw,
155        final byte[] code,
156        final int len,
157        final int maxStack,
158        final int maxLocals)
159    {
160        ByteVector v = new ByteVector();
161        v.data = value;
162        v.length = value.length;
163        return v;
164    }
165
166    /**
167     * Returns the length of the attribute list that begins with this attribute.
168     *
169     * @return the length of the attribute list that begins with this attribute.
170     */
171    final int getCount() {
172        int count = 0;
173        Attribute attr = this;
174        while (attr != null) {
175            count += 1;
176            attr = attr.next;
177        }
178        return count;
179    }
180
181    /**
182     * Returns the size of all the attributes in this attribute list.
183     *
184     * @param cw the class writer to be used to convert the attributes into byte
185     *        arrays, with the {@link #write write} method.
186     * @param code the bytecode of the method corresponding to these code
187     *        attributes, or <tt>null</tt> if these attributes are not code
188     *        attributes.
189     * @param len the length of the bytecode of the method corresponding to
190     *        these code attributes, or <tt>null</tt> if these attributes are
191     *        not code attributes.
192     * @param maxStack the maximum stack size of the method corresponding to
193     *        these code attributes, or -1 if these attributes are not code
194     *        attributes.
195     * @param maxLocals the maximum number of local variables of the method
196     *        corresponding to these code attributes, or -1 if these attributes
197     *        are not code attributes.
198     * @return the size of all the attributes in this attribute list. This size
199     *         includes the size of the attribute headers.
200     */
201    final int getSize(
202        final ClassWriter cw,
203        final byte[] code,
204        final int len,
205        final int maxStack,
206        final int maxLocals)
207    {
208        Attribute attr = this;
209        int size = 0;
210        while (attr != null) {
211            cw.newUTF8(attr.type);
212            size += attr.write(cw, code, len, maxStack, maxLocals).length + 6;
213            attr = attr.next;
214        }
215        return size;
216    }
217
218    /**
219     * Writes all the attributes of this attribute list in the given byte
220     * vector.
221     *
222     * @param cw the class writer to be used to convert the attributes into byte
223     *        arrays, with the {@link #write write} method.
224     * @param code the bytecode of the method corresponding to these code
225     *        attributes, or <tt>null</tt> if these attributes are not code
226     *        attributes.
227     * @param len the length of the bytecode of the method corresponding to
228     *        these code attributes, or <tt>null</tt> if these attributes are
229     *        not code attributes.
230     * @param maxStack the maximum stack size of the method corresponding to
231     *        these code attributes, or -1 if these attributes are not code
232     *        attributes.
233     * @param maxLocals the maximum number of local variables of the method
234     *        corresponding to these code attributes, or -1 if these attributes
235     *        are not code attributes.
236     * @param out where the attributes must be written.
237     */
238    final void put(
239        final ClassWriter cw,
240        final byte[] code,
241        final int len,
242        final int maxStack,
243        final int maxLocals,
244        final ByteVector out)
245    {
246        Attribute attr = this;
247        while (attr != null) {
248            ByteVector b = attr.write(cw, code, len, maxStack, maxLocals);
249            out.putShort(cw.newUTF8(attr.type)).putInt(b.length);
250            out.putByteArray(b.data, 0, b.length);
251            attr = attr.next;
252        }
253    }
254}
255