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 opens table of the Module attribute. Each entry describes a package which the
028 * parent module opens.
029 *
030 * @see Module
031 * @since 6.4.0
032 */
033public final class ModuleOpens implements Cloneable, Node {
034
035    private static String getToModuleNameAtIndex(final ConstantPool constantPool, final int index) {
036        return constantPool.getConstantString(index, Const.CONSTANT_Module);
037    }
038    private final int opensIndex; // points to CONSTANT_Package_info
039    private final int opensFlags;
040    private final int opensToCount;
041
042    private final int[] opensToIndex; // points to CONSTANT_Module_info
043
044    /**
045     * Constructs object from file stream.
046     *
047     * @param file Input stream
048     * @throws IOException if an I/O Exception occurs in readUnsignedShort
049     */
050    ModuleOpens(final DataInput file) throws IOException {
051        opensIndex = file.readUnsignedShort();
052        opensFlags = file.readUnsignedShort();
053        opensToCount = file.readUnsignedShort();
054        opensToIndex = new int[opensToCount];
055        for (int i = 0; i < opensToCount; i++) {
056            opensToIndex[i] = file.readUnsignedShort();
057        }
058    }
059
060    /**
061     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class.
062     * I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
063     *
064     * @param v Visitor object
065     */
066    @Override
067    public void accept(final Visitor v) {
068        v.visitModuleOpens(this);
069    }
070
071    /**
072     * @return deep copy of this object
073     */
074    public ModuleOpens copy() {
075        try {
076            return (ModuleOpens) clone();
077        } catch (final CloneNotSupportedException e) {
078            // TODO should this throw?
079        }
080        return null;
081    }
082
083    /**
084     * Dump table entry to file stream in binary format.
085     *
086     * @param file Output file stream
087     * @throws IOException if an I/O Exception occurs in writeShort
088     */
089    public void dump(final DataOutputStream file) throws IOException {
090        file.writeShort(opensIndex);
091        file.writeShort(opensFlags);
092        file.writeShort(opensToCount);
093        for (final int entry : opensToIndex) {
094            file.writeShort(entry);
095        }
096    }
097
098    /**
099     * Gets the flags for this ModuleOpens.
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     * @param constantPool the constant pool from the ClassFile
110     * @return the opened package name
111     * @since 6.10.0
112     */
113    public String getPackageName(final ConstantPool constantPool) {
114        return constantPool.constantToString(opensIndex, Const.CONSTANT_Package);
115    }
116
117    /**
118     * Gets an array of module names for this ModuleOpens.
119     * @param constantPool Array of constants usually obtained from the ClassFile object
120     * @return array of module names following 'opens to'
121     * @since 6.10.0
122     */
123    public String[] getToModuleNames(final ConstantPool constantPool) {
124        final String[] toModuleNames = new String[opensToCount];
125        for (int i = 0; i < opensToCount; i++) {
126            toModuleNames[i] = getToModuleNameAtIndex(constantPool, opensToIndex[i]);
127        }
128        return toModuleNames;
129    }
130
131    /**
132     * @return String representation
133     */
134    @Override
135    public String toString() {
136        return "opens(" + opensIndex + ", " + opensFlags + ", " + opensToCount + ", ...)";
137    }
138
139    /**
140     * @return Resolved string representation
141     */
142    public String toString(final ConstantPool constantPool) {
143        final StringBuilder buf = new StringBuilder();
144        final String packageName = getPackageName(constantPool);
145        buf.append(packageName);
146        buf.append(", ").append(String.format("%04x", opensFlags));
147        buf.append(", to(").append(opensToCount).append("):\n");
148        for (final int index : opensToIndex) {
149            final String moduleName = getToModuleNameAtIndex(constantPool, index);
150            buf.append("      ").append(moduleName).append("\n");
151        }
152        return buf.substring(0, buf.length() - 1); // remove the last newline
153    }
154}