001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 *  Unless required by applicable law or agreed to in writing, software
012 *  distributed under the License is distributed on an "AS IS" BASIS,
013 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 *  See the License for the specific language governing permissions and
015 *  limitations under the License.
016 */
017
018package org.apache.bcel.classfile;
019
020import java.io.DataInput;
021import java.io.DataOutputStream;
022import java.io.IOException;
023import java.util.Arrays;
024
025import org.apache.bcel.Const;
026
027/**
028 * This class represents a bootstrap method attribute, i.e., the bootstrap
029 * method ref, the number of bootstrap arguments and an array of the
030 * bootstrap arguments.
031 *
032 * @see <a href="http://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.23">
033 * The class File Format : The BootstrapMethods Attribute</a>
034 * @since 6.0
035 */
036public class BootstrapMethod implements Cloneable {
037
038    /** Index of the CONSTANT_MethodHandle_info structure in the constant_pool table */
039    private int bootstrap_method_ref;
040
041    /** Array of references to the constant_pool table */
042    private int[] bootstrap_arguments;
043
044
045    /**
046     * Initialize from another object.
047     */
048    public BootstrapMethod(final BootstrapMethod c) {
049        this(c.getBootstrapMethodRef(), c.getBootstrapArguments());
050    }
051
052    /**
053     * Construct object from input stream.
054     *
055     * @param input Input stream
056     * @throws IOException
057     */
058    BootstrapMethod(final DataInput input) throws IOException {
059        this(input.readUnsignedShort(), input.readUnsignedShort());
060
061        for (int i = 0; i < bootstrap_arguments.length; i++) {
062            bootstrap_arguments[i] = input.readUnsignedShort();
063        }
064    }
065
066    // helper method
067    private BootstrapMethod(final int bootstrap_method_ref, final int num_bootstrap_arguments) {
068        this(bootstrap_method_ref, new int[num_bootstrap_arguments]);
069    }
070
071    /**
072     * @param bootstrap_method_ref int index into constant_pool of CONSTANT_MethodHandle
073     * @param bootstrap_arguments int[] indices into constant_pool of CONSTANT_[type]_info
074     */
075    public BootstrapMethod(final int bootstrap_method_ref, final int[] bootstrap_arguments) {
076        this.bootstrap_method_ref = bootstrap_method_ref;
077        this.bootstrap_arguments = bootstrap_arguments;
078    }
079
080    /**
081     * @return index into constant_pool of bootstrap_method
082     */
083    public int getBootstrapMethodRef() {
084        return bootstrap_method_ref;
085    }
086
087    /**
088     * @param bootstrap_method_ref int index into constant_pool of CONSTANT_MethodHandle
089     */
090    public void setBootstrapMethodRef(final int bootstrap_method_ref) {
091        this.bootstrap_method_ref = bootstrap_method_ref;
092    }
093
094    /**
095     * @return int[] of bootstrap_method indices into constant_pool of CONSTANT_[type]_info
096     */
097    public int[] getBootstrapArguments() {
098        return bootstrap_arguments;
099    }
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, false));
133        final int num_bootstrap_arguments = bootstrap_arguments.length;
134        if (num_bootstrap_arguments > 0) {
135            buf.append("\nMethod 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}