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 opens table of the Module attribute. Each entry describes a package which the
030 * parent module opens.
031 *
032 * @see Module
033 * @since 6.4.0
034 */
035public final class ModuleOpens implements Cloneable, Node {
036
037    private static String getToModuleNameAtIndex(final ConstantPool constantPool, final int index) {
038        return constantPool.getConstantString(index, Const.CONSTANT_Module);
039    }
040    private final int opensIndex; // points to CONSTANT_Package_info
041    private final int opensFlags;
042    private final int opensToCount;
043
044    private final int[] opensToIndex; // points to CONSTANT_Module_info
045
046    /**
047     * Constructs object from file stream.
048     *
049     * @param dataInput Input stream.
050     * @throws IOException if an I/O Exception occurs in readUnsignedShort.
051     */
052    ModuleOpens(final DataInput dataInput) throws IOException {
053        opensIndex = dataInput.readUnsignedShort();
054        opensFlags = dataInput.readUnsignedShort();
055        opensToIndex = ClassParser.readU2U2Table(dataInput);
056        opensToCount = opensToIndex.length;
057    }
058
059    /**
060     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
061     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
062     *
063     * @param v Visitor object.
064     */
065    @Override
066    public void accept(final Visitor v) {
067        v.visitModuleOpens(this);
068    }
069
070    /**
071     * @return deep copy of this object.
072     */
073    public ModuleOpens copy() {
074        try {
075            return (ModuleOpens) clone();
076        } catch (final CloneNotSupportedException e) {
077            // TODO should this throw?
078        }
079        return null;
080    }
081
082    /**
083     * Dumps table entry to file stream in binary format.
084     *
085     * @param file Output file stream.
086     * @throws IOException if an I/O Exception occurs in writeShort.
087     */
088    public void dump(final DataOutputStream file) throws IOException {
089        file.writeShort(opensIndex);
090        file.writeShort(opensFlags);
091        file.writeShort(opensToCount);
092        for (final int entry : opensToIndex) {
093            file.writeShort(entry);
094        }
095    }
096
097    /**
098     * Gets the flags for this ModuleOpens.
099     *
100     * @return the opensFlags.
101     * @since 6.10.0
102     */
103    public int getOpensFlags() {
104        return opensFlags;
105    }
106
107    /**
108     * Gets the opened package name.
109     *
110     * @param constantPool the constant pool from the ClassFile.
111     * @return the opened package name.
112     * @since 6.10.0
113     */
114    public String getPackageName(final ConstantPool constantPool) {
115        return constantPool.constantToString(opensIndex, Const.CONSTANT_Package);
116    }
117
118    /**
119     * Gets an array of module names for this ModuleOpens.
120     *
121     * @param constantPool Array of constants usually obtained from the ClassFile object.
122     * @return array of module names following 'opens to'.
123     * @since 6.10.0
124     */
125    public String[] getToModuleNames(final ConstantPool constantPool) {
126        final String[] toModuleNames = new String[opensToCount];
127        for (int i = 0; i < opensToCount; i++) {
128            toModuleNames[i] = getToModuleNameAtIndex(constantPool, opensToIndex[i]);
129        }
130        return toModuleNames;
131    }
132
133    /**
134     * @return String representation.
135     */
136    @Override
137    public String toString() {
138        return "opens(" + opensIndex + ", " + opensFlags + ", " + opensToCount + ", ...)";
139    }
140
141    /**
142     * @return Resolved string representation.
143     */
144    public String toString(final ConstantPool constantPool) {
145        final StringBuilder buf = new StringBuilder();
146        final String packageName = getPackageName(constantPool);
147        buf.append(packageName);
148        buf.append(", ").append(String.format("%04x", opensFlags));
149        buf.append(", to(").append(opensToCount).append("):\n");
150        for (final int index : opensToIndex) {
151            final String moduleName = getToModuleNameAtIndex(constantPool, index);
152            buf.append("      ").append(moduleName).append("\n");
153        }
154        return buf.substring(0, buf.length() - 1); // remove the last newline
155    }
156}