    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;
    023
    024import org.apache.bcel.Const;
    025
    026/**
    027 * This class represents an entry in the requires table of the Module attribute. Each entry describes a module on which
    028 * the parent module depends.
    029 *
    030 * @see Module
    031 * @since 6.4.0
    032 */
    033public final class ModuleRequires implements Cloneable, Node {
    034
    035    private final int requiresIndex; // points to CONSTANT_Module_info
    036    private final int requiresFlags;
    037    private final int requiresVersionIndex; // either 0 or points to CONSTANT_Utf8_info
    038
    039    /**
    040     * Constructs object from file stream.
    041     *
    042     * @param file Input stream
    043     * @throws IOException if an I/O Exception occurs in readUnsignedShort
    044     */
    045    ModuleRequires(final DataInput file) throws IOException {
    046        requiresIndex = file.readUnsignedShort();
    047        requiresFlags = file.readUnsignedShort();
    048        requiresVersionIndex = file.readUnsignedShort();
    049    }
    050
    051    /**
    052     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    053     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    054     *
    055     * @param v Visitor object
    056     */
    057    @Override
    058    public void accept(final Visitor v) {
    059        v.visitModuleRequires(this);
    060    }
    061
    062    /**
    063     * @return deep copy of this object
    064     */
    065    public ModuleRequires copy() {
    066        try {
    067            return (ModuleRequires) clone();
    068        } catch (final CloneNotSupportedException e) {
    069            // TODO should this throw?
    070        }
    071        return null;
    072    }
    073
    074    /**
    075     * Dump table entry to file stream in binary format.
    076     *
    077     * @param file Output file stream
    078     * @throws IOException if an I/O Exception occurs in writeShort
    079     */
    080    public void dump(final DataOutputStream file) throws IOException {
    081        file.writeShort(requiresIndex);
    082        file.writeShort(requiresFlags);
    083        file.writeShort(requiresVersionIndex);
    084    }
    085
    086    /**
    087     * Gets the module name from the constant pool.
    088     * @param constantPool Array of constants usually obtained from the ClassFile object
    089     * @return module name
    090     * @since 6.10.0
    091     */
    092    public String getModuleName(final ConstantPool constantPool) {
    093        return constantPool.constantToString(requiresIndex, Const.CONSTANT_Module);
    094    }
    095
    096    /**
    097     * Gets the flags for this ModuleRequires.
    098     * @return the requiresFlags
    099     * @since 6.10.0
    100     */
    101    public int getRequiresFlags() {
    102        return requiresFlags;
    103    }
    104
    105    /**
    106     * Gets the required version from the constant pool.
    107     * @param constantPool Array of constants usually obtained from the ClassFile object
    108     * @return required version, "0" if version index is 0.
    109     * @since 6.10.0
    110     */
    111    public String getVersion(final ConstantPool constantPool) {
    112        return requiresVersionIndex == 0 ? "0" : constantPool.getConstantString(requiresVersionIndex, Const.CONSTANT_Utf8);
    113    }
    114
    115    /**
    116     * @return String representation
    117     */
    118    @Override
    119    public String toString() {
    120        return "requires(" + requiresIndex + ", " + String.format("%04x", requiresFlags) + ", " + requiresVersionIndex + ")";
    121    }
    122
    123    /**
    124     * @return Resolved string representation
    125     */
    126    public String toString(final ConstantPool constantPool) {
    127        final StringBuilder buf = new StringBuilder();
    128        final String moduleName = getModuleName(constantPool);
    129        buf.append(moduleName);
    130        buf.append(", ").append(String.format("%04x", requiresFlags));
    131        final String version = getVersion(constantPool);
    132        buf.append(", ").append(version);
    133        return buf.toString();
    134    }
    135}