    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 * The element_value structure is documented at https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-4.html#jvms-4.7.16.1
    028 *
    029 * <pre>
    030 * element_value {
    031 *    u1 tag;
    032 *    union {
    033 *        u2 const_value_index;
    034 *
    035 *        {   u2 type_name_index;
    036 *            u2 const_name_index;
    037 *        } enum_const_value;
    038 *
    039 *        u2 class_info_index;
    040 *
    041 *        annotation annotation_value;
    042 *
    043 *        {   u2            num_values;
    044 *            element_value values[num_values];
    045 *        } array_value;
    046 *    } value;
    047 *}
    048 *</pre>
    049 * @since 6.0
    050 */
    051public abstract class ElementValue {
    052
    053    public static final byte STRING = 's';
    054    public static final byte ENUM_CONSTANT = 'e';
    055    public static final byte CLASS = 'c';
    056    public static final byte ANNOTATION = '@';
    057    public static final byte ARRAY = '[';
    058    public static final byte PRIMITIVE_INT = 'I';
    059    public static final byte PRIMITIVE_BYTE = 'B';
    060    public static final byte PRIMITIVE_CHAR = 'C';
    061    public static final byte PRIMITIVE_DOUBLE = 'D';
    062    public static final byte PRIMITIVE_FLOAT = 'F';
    063    public static final byte PRIMITIVE_LONG = 'J';
    064    public static final byte PRIMITIVE_SHORT = 'S';
    065    public static final byte PRIMITIVE_BOOLEAN = 'Z';
    066    static final ElementValue[] EMPTY_ARRAY = {};
    067
    068    /**
    069     * Reads an {@code element_value} as an {@code ElementValue}.
    070     *
    071     * @param input Raw data input.
    072     * @param cpool Constant pool.
    073     * @return a new ElementValue.
    074     * @throws IOException if an I/O error occurs.
    075     */
    076    public static ElementValue readElementValue(final DataInput input, final ConstantPool cpool) throws IOException {
    077        return readElementValue(input, cpool, 0);
    078    }
    079
    080    /**
    081     * Reads an {@code element_value} as an {@code ElementValue}.
    082     *
    083     * @param input Raw data input.
    084     * @param cpool Constant pool.
    085     * @param arrayNesting level of current array nesting.
    086     * @return a new ElementValue.
    087     * @throws IOException if an I/O error occurs.
    088     * @since 6.7.0
    089     */
    090    public static ElementValue readElementValue(final DataInput input, final ConstantPool cpool, int arrayNesting)
    091            throws IOException {
    092        final byte tag = input.readByte();
    093        switch (tag) {
    094        case PRIMITIVE_BYTE:
    095        case PRIMITIVE_CHAR:
    096        case PRIMITIVE_DOUBLE:
    097        case PRIMITIVE_FLOAT:
    098        case PRIMITIVE_INT:
    099        case PRIMITIVE_LONG:
    100        case PRIMITIVE_SHORT:
    101        case PRIMITIVE_BOOLEAN:
    102        case STRING:
    103            return new SimpleElementValue(tag, input.readUnsignedShort(), cpool);
    104
    105        case ENUM_CONSTANT:
    106            return new EnumElementValue(ENUM_CONSTANT, input.readUnsignedShort(), input.readUnsignedShort(), cpool);
    107
    108        case CLASS:
    109            return new ClassElementValue(CLASS, input.readUnsignedShort(), cpool);
    110
    111        case ANNOTATION:
    112            // TODO isRuntimeVisible
    113            return new AnnotationElementValue(ANNOTATION, AnnotationEntry.read(input, cpool, false), cpool);
    114
    115        case ARRAY:
    116            arrayNesting++;
    117            if (arrayNesting > Const.MAX_ARRAY_DIMENSIONS) {
    118                // JVM spec 4.4.1
    119                throw new ClassFormatException(String.format("Arrays are only valid if they represent %,d or fewer dimensions.", Const.MAX_ARRAY_DIMENSIONS));
    120            }
    121            final int numArrayVals = input.readUnsignedShort();
    122            final ElementValue[] evalues = new ElementValue[numArrayVals];
    123            for (int j = 0; j < numArrayVals; j++) {
    124                evalues[j] = readElementValue(input, cpool, arrayNesting);
    125            }
    126            return new ArrayElementValue(ARRAY, evalues, cpool);
    127
    128        default:
    129            throw new ClassFormatException("Unexpected element value tag in annotation: " + tag);
    130        }
    131    }
    132
    133    /**
    134     * @deprecated (since 6.0) will be made private and final; do not access directly, use getter
    135     */
    136    @java.lang.Deprecated
    137    protected int type; // TODO should be final
    138    /**
    139     * @deprecated (since 6.0) will be made private and final; do not access directly, use getter
    140     */
    141    @java.lang.Deprecated
    142    protected ConstantPool cpool; // TODO should be final
    143
    144    protected ElementValue(final int type, final ConstantPool cpool) {
    145        this.type = type;
    146        this.cpool = cpool;
    147    }
    148
    149    public abstract void dump(DataOutputStream dos) throws IOException;
    150
    151    /** @since 6.0 */
    152    final ConstantPool getConstantPool() {
    153        return cpool;
    154    }
    155
    156    public int getElementValueType() {
    157        return type;
    158    }
    159
    160    /** @since 6.0 */
    161    final int getType() {
    162        return type;
    163    }
    164
    165    public abstract String stringifyValue();
    166
    167    public String toShortString() {
    168        return stringifyValue();
    169    }
    170
    171    @Override
    172    public String toString() {
    173        return stringifyValue();
    174    }
    175}