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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   *  Unless required by applicable law or agreed to in writing, software
12   *  distributed under the License is distributed on an "AS IS" BASIS,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   */
17  
18  package org.apache.bcel.classfile;
19  
20  import java.io.DataInput;
21  import java.io.DataOutputStream;
22  import java.io.IOException;
23  import java.util.Arrays;
24  
25  import org.apache.bcel.Const;
26  
27  /**
28   * This class represents a bootstrap method attribute, i.e., the bootstrap
29   * method ref, the number of bootstrap arguments and an array of the
30   * bootstrap arguments.
31   *
32   * @see <a href="http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.23">
33   * The class File Format : The BootstrapMethods Attribute</a>
34   * @since 6.0
35   */
36  public class BootstrapMethod implements Cloneable {
37  
38      /** Index of the CONSTANT_MethodHandle_info structure in the constant_pool table */
39      private int bootstrap_method_ref;
40  
41      /** Array of references to the constant_pool table */
42      private int[] bootstrap_arguments;
43  
44  
45      /**
46       * Initialize from another object.
47       */
48      public BootstrapMethod(final BootstrapMethod c) {
49          this(c.getBootstrapMethodRef(), c.getBootstrapArguments());
50      }
51  
52      /**
53       * Construct object from input stream.
54       *
55       * @param input Input stream
56       * @throws IOException
57       */
58      BootstrapMethod(final DataInput input) throws IOException {
59          this(input.readUnsignedShort(), input.readUnsignedShort());
60  
61          for (int i = 0; i < bootstrap_arguments.length; i++) {
62              bootstrap_arguments[i] = input.readUnsignedShort();
63          }
64      }
65  
66      // helper method
67      private BootstrapMethod(final int bootstrap_method_ref, final int num_bootstrap_arguments) {
68          this(bootstrap_method_ref, new int[num_bootstrap_arguments]);
69      }
70  
71      /**
72       * @param bootstrap_method_ref int index into constant_pool of CONSTANT_MethodHandle
73       * @param bootstrap_arguments int[] indices into constant_pool of CONSTANT_<type>_info
74       */
75      public BootstrapMethod(final int bootstrap_method_ref, final int[] bootstrap_arguments) {
76          this.bootstrap_method_ref = bootstrap_method_ref;
77          this.bootstrap_arguments = bootstrap_arguments;
78      }
79  
80      /**
81       * @return index into constant_pool of bootstrap_method
82       */
83      public int getBootstrapMethodRef() {
84          return bootstrap_method_ref;
85      }
86  
87      /**
88       * @param bootstrap_method_ref int index into constant_pool of CONSTANT_MethodHandle
89       */
90      public void setBootstrapMethodRef(final int bootstrap_method_ref) {
91          this.bootstrap_method_ref = bootstrap_method_ref;
92      }
93  
94      /**
95       * @return int[] of bootstrap_method indices into constant_pool of CONSTANT_<type>_info
96       */
97      public int[] getBootstrapArguments() {
98          return bootstrap_arguments;
99      }
100 
101     /**
102      * @return count of number of boostrap arguments
103      */
104     public int getNumBootstrapArguments() {
105         return bootstrap_arguments.length;
106     }
107 
108     /**
109      * @param bootstrap_arguments int[] indices into constant_pool of CONSTANT_<type>_info
110      */
111     public void setBootstrapArguments(final int[] bootstrap_arguments) {
112         this.bootstrap_arguments = bootstrap_arguments;
113     }
114 
115     /**
116      * @return String representation.
117      */
118     @Override
119     public final String toString() {
120         return "BootstrapMethod(" + bootstrap_method_ref + ", " + bootstrap_arguments.length + ", "
121                + Arrays.toString(bootstrap_arguments) + ")";
122     }
123 
124     /**
125      * @return Resolved string representation
126      */
127     public final String toString( final ConstantPool constant_pool ) {
128         final StringBuilder buf = new StringBuilder();
129         String bootstrap_method_name;
130         bootstrap_method_name = constant_pool.constantToString(bootstrap_method_ref,
131                 Const.CONSTANT_MethodHandle);
132         buf.append(Utility.compactClassName(bootstrap_method_name));
133         final int num_bootstrap_arguments = bootstrap_arguments.length;
134         if (num_bootstrap_arguments > 0) {
135             buf.append("\n     Method Arguments:");
136             for (int i = 0; i < num_bootstrap_arguments; i++) {
137                 buf.append("\n     ").append(i).append(": ");
138                 buf.append(constant_pool.constantToString(constant_pool.getConstant(bootstrap_arguments[i])));
139             }
140         }
141         return buf.toString();
142     }
143 
144     /**
145      * Dump object to file stream in binary format.
146      *
147      * @param file Output file stream
148      * @throws IOException
149      */
150     public final void dump(final DataOutputStream file) throws IOException {
151         file.writeShort(bootstrap_method_ref);
152         file.writeShort(bootstrap_arguments.length);
153         for (final int bootstrap_argument : bootstrap_arguments) {
154             file.writeShort(bootstrap_argument);
155         }
156     }
157 
158     /**
159      * @return deep copy of this object
160      */
161     public BootstrapMethod copy() {
162         try {
163             return (BootstrapMethod) clone();
164         } catch (final CloneNotSupportedException e) {
165             // TODO should this throw?
166         }
167         return null;
168     }
169 }