    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 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     * @return deep copy of this object.
    072     */
    073    public ModuleExports copy() {
    074        try {
    075            return (ModuleExports) 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(exportsIndex);
    090        file.writeShort(exportsFlags);
    091        file.writeShort(exportsToCount);
    092        for (final int entry : exportsToIndex) {
    093            file.writeShort(entry);
    094        }
    095    }
    096
    097    /**
    098     * Gets the flags for this ModuleExports.
    099     *
    100     * @return the exportsFlags.
    101     * @since 6.10.0
    102     */
    103    public int getExportsFlags() {
    104        return exportsFlags;
    105    }
    106
    107    /**
    108     * Gets the exported package name.
    109     *
    110     * @param constantPool the constant pool from the ClassFile.
    111     * @return the exported package name.
    112     * @since 6.10.0
    113     */
    114    public String getPackageName(final ConstantPool constantPool) {
    115        return constantPool.constantToString(exportsIndex, Const.CONSTANT_Package);
    116    }
    117
    118    /**
    119     * Gets an array of module names for this ModuleExports.
    120     *
    121     * @param constantPool Array of constants usually obtained from the ClassFile object.
    122     * @return array of module names following 'exports to'.
    123     * @since 6.10.0
    124     */
    125    public String[] getToModuleNames(final ConstantPool constantPool) {
    126        final String[] toModuleNames = new String[exportsToCount];
    127        for (int i = 0; i < exportsToCount; i++) {
    128            toModuleNames[i] = getToModuleNameAtIndex(constantPool, exportsToIndex[i]);
    129        }
    130        return toModuleNames;
    131    }
    132
    133    /**
    134     * @return String representation.
    135     */
    136    @Override
    137    public String toString() {
    138        return "exports(" + exportsIndex + ", " + exportsFlags + ", " + exportsToCount + ", ...)";
    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", exportsFlags));
    149        buf.append(", to(").append(exportsToCount).append("):\n");
    150        for (final int index : exportsToIndex) {
    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}