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 method ref, the number of bootstrap arguments
029 * and an array of the bootstrap arguments.
030 *
031 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.23"> The class File Format :
032 *      The BootstrapMethods Attribute</a>
033 * @since 6.0
034 */
035public class BootstrapMethod implements Cloneable {
036
037    /** Index of the CONSTANT_MethodHandle_info structure in the constant_pool table */
038    private int bootstrapMethodRef;
039
040    /** Array of references to the constant_pool table */
041    private int[] bootstrapArguments;
042
043    /**
044     * Initialize from another object.
045     *
046     * @param c Source to copy.
047     */
048    public BootstrapMethod(final BootstrapMethod c) {
049        this(c.getBootstrapMethodRef(), c.getBootstrapArguments());
050    }
051
052    /**
053     * Constructs object from input stream.
054     *
055     * @param input Input stream
056     * @throws IOException if an I/O error occurs.
057     */
058    BootstrapMethod(final DataInput input) throws IOException {
059        this(input.readUnsignedShort(), input.readUnsignedShort());
060
061        for (int i = 0; i < bootstrapArguments.length; i++) {
062            bootstrapArguments[i] = input.readUnsignedShort();
063        }
064    }
065
066    // helper method
067    private BootstrapMethod(final int bootstrapMethodRef, final int numBootstrapArguments) {
068        this(bootstrapMethodRef, new int[numBootstrapArguments]);
069    }
070
071    /**
072     * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle
073     * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info
074     */
075    public BootstrapMethod(final int bootstrapMethodRef, final int[] bootstrapArguments) {
076        this.bootstrapMethodRef = bootstrapMethodRef;
077        this.bootstrapArguments = bootstrapArguments;
078    }
079
080    /**
081     * @return deep copy of this object
082     */
083    public BootstrapMethod copy() {
084        try {
085            return (BootstrapMethod) clone();
086        } catch (final CloneNotSupportedException e) {
087            // TODO should this throw?
088        }
089        return null;
090    }
091
092    /**
093     * Dump object to file stream in binary format.
094     *
095     * @param file Output file stream
096     * @throws IOException if an I/O error occurs.
097     */
098    public final void dump(final DataOutputStream file) throws IOException {
099        file.writeShort(bootstrapMethodRef);
100        file.writeShort(bootstrapArguments.length);
101        for (final int bootstrapArgument : bootstrapArguments) {
102            file.writeShort(bootstrapArgument);
103        }
104    }
105
106    /**
107     * @return int[] of bootstrap_method indices into constant_pool of CONSTANT_[type]_info
108     */
109    public int[] getBootstrapArguments() {
110        return bootstrapArguments;
111    }
112
113    /**
114     * @return index into constant_pool of bootstrap_method
115     */
116    public int getBootstrapMethodRef() {
117        return bootstrapMethodRef;
118    }
119
120    /**
121     * @return count of number of boostrap arguments
122     */
123    public int getNumBootstrapArguments() {
124        return bootstrapArguments.length;
125    }
126
127    /**
128     * @param bootstrapArguments int[] indices into constant_pool of CONSTANT_[type]_info
129     */
130    public void setBootstrapArguments(final int[] bootstrapArguments) {
131        this.bootstrapArguments = bootstrapArguments;
132    }
133
134    /**
135     * @param bootstrapMethodRef int index into constant_pool of CONSTANT_MethodHandle
136     */
137    public void setBootstrapMethodRef(final int bootstrapMethodRef) {
138        this.bootstrapMethodRef = bootstrapMethodRef;
139    }
140
141    /**
142     * @return String representation.
143     */
144    @Override
145    public final String toString() {
146        return "BootstrapMethod(" + bootstrapMethodRef + ", " + bootstrapArguments.length + ", " + Arrays.toString(bootstrapArguments) + ")";
147    }
148
149    /**
150     * @return Resolved string representation
151     */
152    public final String toString(final ConstantPool constantPool) {
153        final StringBuilder buf = new StringBuilder();
154        final String bootstrapMethodName = constantPool.constantToString(bootstrapMethodRef, Const.CONSTANT_MethodHandle);
155        buf.append(Utility.compactClassName(bootstrapMethodName, false));
156        final int bootstrapArgumentsLen = bootstrapArguments.length;
157        if (bootstrapArgumentsLen > 0) {
158            buf.append("\nMethod Arguments:");
159            for (int i = 0; i < bootstrapArgumentsLen; i++) {
160                buf.append("\n  ").append(i).append(": ");
161                buf.append(constantPool.constantToString(constantPool.getConstant(bootstrapArguments[i])));
162            }
163        }
164        return buf.toString();
165    }
166}