    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019
    020package org.apache.bcel.classfile;
    021
    022import java.io.DataInput;
    023import java.io.DataOutputStream;
    024import java.io.IOException;
    025
    026import org.apache.bcel.Const;
    027
    028/**
    029 * This class represents an entry in the requires table of the Module attribute. Each entry describes a module on which
    030 * the parent module depends.
    031 *
    032 * @see Module
    033 * @since 6.4.0
    034 */
    035public final class ModuleRequires implements Cloneable, Node {
    036
    037    private final int requiresIndex; // points to CONSTANT_Module_info
    038    private final int requiresFlags;
    039    private final int requiresVersionIndex; // either 0 or points to CONSTANT_Utf8_info
    040
    041    /**
    042     * Constructs object from file stream.
    043     *
    044     * @param file Input stream.
    045     * @throws IOException if an I/O Exception occurs in readUnsignedShort.
    046     */
    047    ModuleRequires(final DataInput file) throws IOException {
    048        requiresIndex = file.readUnsignedShort();
    049        requiresFlags = file.readUnsignedShort();
    050        requiresVersionIndex = file.readUnsignedShort();
    051    }
    052
    053    /**
    054     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
    055     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
    056     *
    057     * @param v Visitor object.
    058     */
    059    @Override
    060    public void accept(final Visitor v) {
    061        v.visitModuleRequires(this);
    062    }
    063
    064    /**
    065     * @return deep copy of this object.
    066     */
    067    public ModuleRequires copy() {
    068        try {
    069            return (ModuleRequires) clone();
    070        } catch (final CloneNotSupportedException e) {
    071            // TODO should this throw?
    072        }
    073        return null;
    074    }
    075
    076    /**
    077     * Dumps table entry to file stream in binary format.
    078     *
    079     * @param file Output file stream.
    080     * @throws IOException if an I/O Exception occurs in writeShort.
    081     */
    082    public void dump(final DataOutputStream file) throws IOException {
    083        file.writeShort(requiresIndex);
    084        file.writeShort(requiresFlags);
    085        file.writeShort(requiresVersionIndex);
    086    }
    087
    088    /**
    089     * Gets the module name from the constant pool.
    090     *
    091     * @param constantPool Array of constants usually obtained from the ClassFile object.
    092     * @return module name.
    093     * @since 6.10.0
    094     */
    095    public String getModuleName(final ConstantPool constantPool) {
    096        return constantPool.constantToString(requiresIndex, Const.CONSTANT_Module);
    097    }
    098
    099    /**
    100     * Gets the flags for this ModuleRequires.
    101     *
    102     * @return the requiresFlags.
    103     * @since 6.10.0
    104     */
    105    public int getRequiresFlags() {
    106        return requiresFlags;
    107    }
    108
    109    /**
    110     * Gets the required version from the constant pool.
    111     *
    112     * @param constantPool Array of constants usually obtained from the ClassFile object.
    113     * @return required version, "0" if version index is 0.
    114     * @since 6.10.0
    115     */
    116    public String getVersion(final ConstantPool constantPool) {
    117        return requiresVersionIndex == 0 ? "0" : constantPool.getConstantString(requiresVersionIndex, Const.CONSTANT_Utf8);
    118    }
    119
    120    /**
    121     * @return String representation.
    122     */
    123    @Override
    124    public String toString() {
    125        return "requires(" + requiresIndex + ", " + String.format("%04x", requiresFlags) + ", " + requiresVersionIndex + ")";
    126    }
    127
    128    /**
    129     * @return Resolved string representation.
    130     */
    131    public String toString(final ConstantPool constantPool) {
    132        final StringBuilder buf = new StringBuilder();
    133        final String moduleName = getModuleName(constantPool);
    134        buf.append(moduleName);
    135        buf.append(", ").append(String.format("%04x", requiresFlags));
    136        final String version = getVersion(constantPool);
    137        buf.append(", ").append(version);
    138        return buf.toString();
    139    }
    140}