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 exports table of the Module attribute. Each entry describes a package which may
030 * open the parent module.
031 *
032 * @see Module
033 * @since 6.4.0
034 */
035public final class ModuleExports 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 exportsIndex; // points to CONSTANT_Package_info
041    private final int exportsFlags;
042    private final int exportsToCount;
043
044    private final int[] exportsToIndex; // points to CONSTANT_Module_info
045
046    /**
047     * Constructs object from file stream.
048     *
049     * @param dataInput Input stream.
050     * @throws IOException Thrown if an I/O Exception occurs in readUnsignedShort.
051     */
052    ModuleExports(final DataInput dataInput) throws IOException {
053        exportsIndex = dataInput.readUnsignedShort();
054        exportsFlags = dataInput.readUnsignedShort();
055        exportsToIndex = ClassParser.readU2U2Table(dataInput);
056        exportsToCount = exportsToIndex.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.visitModuleExports(this);
068    }
069
070    /**
071     * Creates a deep copy of this object.
072     *
073     * @return deep copy of this object.
074     */
075    public ModuleExports copy() {
076        try {
077            return (ModuleExports) clone();
078        } catch (final CloneNotSupportedException e) {
079            // TODO should this throw?
080        }
081        return null;
082    }
083
084    /**
085     * Dumps table entry to file stream in binary format.
086     *
087     * @param file Output file stream.
088     * @throws IOException Thrown if an I/O Exception occurs in writeShort.
089     */
090    public void dump(final DataOutputStream file) throws IOException {
091        file.writeShort(exportsIndex);
092        file.writeShort(exportsFlags);
093        file.writeShort(exportsToCount);
094        for (final int entry : exportsToIndex) {
095            file.writeShort(entry);
096        }
097    }
098
099    /**
100     * Gets the flags for this ModuleExports.
101     *
102     * @return The exportsFlags.
103     * @since 6.10.0
104     */
105    public int getExportsFlags() {
106        return exportsFlags;
107    }
108
109    /**
110     * Gets the exported package name.
111     *
112     * @param constantPool The constant pool from the ClassFile.
113     * @return The exported package name.
114     * @since 6.10.0
115     */
116    public String getPackageName(final ConstantPool constantPool) {
117        return constantPool.constantToString(exportsIndex, Const.CONSTANT_Package);
118    }
119
120    /**
121     * Gets an array of module names for this ModuleExports.
122     *
123     * @param constantPool Array of constants usually obtained from the ClassFile object.
124     * @return array of module names following 'exports to'.
125     * @since 6.10.0
126     */
127    public String[] getToModuleNames(final ConstantPool constantPool) {
128        final String[] toModuleNames = new String[exportsToCount];
129        for (int i = 0; i < exportsToCount; i++) {
130            toModuleNames[i] = getToModuleNameAtIndex(constantPool, exportsToIndex[i]);
131        }
132        return toModuleNames;
133    }
134
135    /**
136     * @return String representation.
137     */
138    @Override
139    public String toString() {
140        return "exports(" + exportsIndex + ", " + exportsFlags + ", " + exportsToCount + ", ...)";
141    }
142
143    /**
144     * Gets the resolved string representation.
145     *
146     * @param constantPool The constant pool.
147     * @return Resolved string representation.
148     */
149    public String toString(final ConstantPool constantPool) {
150        final StringBuilder buf = new StringBuilder();
151        final String packageName = getPackageName(constantPool);
152        buf.append(packageName);
153        buf.append(", ").append(String.format("%04x", exportsFlags));
154        buf.append(", to(").append(exportsToCount).append("):\n");
155        for (final int index : exportsToIndex) {
156            final String moduleName = getToModuleNameAtIndex(constantPool, index);
157            buf.append("      ").append(moduleName).append("\n");
158        }
159        return buf.substring(0, buf.length() - 1); // remove the last newline
160    }
161}