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}