ElementValue.java
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.bcel.classfile;
import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.bcel.Const;
/**
* The element_value structure is documented at https://docs.oracle.com/javase/specs/jvms/se11/html/jvms-4.html#jvms-4.7.16.1
*
* <pre>
* element_value {
* u1 tag;
* union {
* u2 const_value_index;
*
* { u2 type_name_index;
* u2 const_name_index;
* } enum_const_value;
*
* u2 class_info_index;
*
* annotation annotation_value;
*
* { u2 num_values;
* element_value values[num_values];
* } array_value;
* } value;
*}
*</pre>
*
* @since 6.0
*/
public abstract class ElementValue {
/** Element value type: string. */
public static final byte STRING = 's';
/** Element value type: enum constant. */
public static final byte ENUM_CONSTANT = 'e';
/** Element value type: class. */
public static final byte CLASS = 'c';
/** Element value type: annotation. */
public static final byte ANNOTATION = '@';
/** Element value type: array. */
public static final byte ARRAY = '[';
/** Element value type: primitive int. */
public static final byte PRIMITIVE_INT = 'I';
/** Element value type: primitive byte. */
public static final byte PRIMITIVE_BYTE = 'B';
/** Element value type: primitive char. */
public static final byte PRIMITIVE_CHAR = 'C';
/** Element value type: primitive double. */
public static final byte PRIMITIVE_DOUBLE = 'D';
/** Element value type: primitive float. */
public static final byte PRIMITIVE_FLOAT = 'F';
/** Element value type: primitive long. */
public static final byte PRIMITIVE_LONG = 'J';
/** Element value type: primitive short. */
public static final byte PRIMITIVE_SHORT = 'S';
/** Element value type: primitive boolean. */
public static final byte PRIMITIVE_BOOLEAN = 'Z';
/** Empty array constant. */
static final ElementValue[] EMPTY_ARRAY = {};
/**
* Reads an {@code element_value} as an {@code ElementValue}.
*
* @param input Raw data input.
* @param cpool Constant pool.
* @return a new ElementValue.
* @throws IOException if an I/O error occurs.
*/
public static ElementValue readElementValue(final DataInput input, final ConstantPool cpool) throws IOException {
return readElementValue(input, cpool, 0);
}
/**
* Reads an {@code element_value} as an {@code ElementValue}.
*
* @param input Raw data input.
* @param cpool Constant pool.
* @param arrayNesting level of current array nesting.
* @return a new ElementValue.
* @throws IOException if an I/O error occurs.
* @since 6.7.0
*/
public static ElementValue readElementValue(final DataInput input, final ConstantPool cpool, int arrayNesting)
throws IOException {
final byte tag = input.readByte();
switch (tag) {
case PRIMITIVE_BYTE:
case PRIMITIVE_CHAR:
case PRIMITIVE_DOUBLE:
case PRIMITIVE_FLOAT:
case PRIMITIVE_INT:
case PRIMITIVE_LONG:
case PRIMITIVE_SHORT:
case PRIMITIVE_BOOLEAN:
case STRING:
return new SimpleElementValue(tag, input.readUnsignedShort(), cpool);
case ENUM_CONSTANT:
return new EnumElementValue(ENUM_CONSTANT, input.readUnsignedShort(), input.readUnsignedShort(), cpool);
case CLASS:
return new ClassElementValue(CLASS, input.readUnsignedShort(), cpool);
case ANNOTATION:
// TODO isRuntimeVisible
return new AnnotationElementValue(ANNOTATION, AnnotationEntry.read(input, cpool, false), cpool);
case ARRAY:
arrayNesting++;
if (arrayNesting > Const.MAX_ARRAY_DIMENSIONS) {
// JVM spec 4.4.1
throw new ClassFormatException(String.format("Arrays are only valid if they represent %,d or fewer dimensions.", Const.MAX_ARRAY_DIMENSIONS));
}
final int numArrayVals = input.readUnsignedShort();
final ElementValue[] evalues = new ElementValue[numArrayVals];
for (int j = 0; j < numArrayVals; j++) {
evalues[j] = readElementValue(input, cpool, arrayNesting);
}
return new ArrayElementValue(ARRAY, evalues, cpool);
default:
throw new ClassFormatException("Unexpected element value tag in annotation: " + tag);
}
}
/**
* @deprecated (since 6.0) will be made private and final; do not access directly, use getter.
*/
@java.lang.Deprecated
protected int type; // TODO should be final
/**
* @deprecated (since 6.0) will be made private and final; do not access directly, use getter.
*/
@java.lang.Deprecated
protected ConstantPool cpool; // TODO should be final
/**
* Constructs an ElementValue.
*
* @param type the element value type.
* @param cpool the constant pool.
*/
protected ElementValue(final int type, final ConstantPool cpool) {
this.type = type;
this.cpool = cpool;
}
/**
* Dumps this element value to a DataOutputStream.
*
* @param dos the output stream.
* @throws IOException if an I/O error occurs.
*/
public abstract void dump(DataOutputStream dos) throws IOException;
/**
* Gets the constant pool.
*
* @return the constant pool.
* @since 6.0
*/
final ConstantPool getConstantPool() {
return cpool;
}
/**
* Gets the element value type.
*
* @return the element value type.
*/
public int getElementValueType() {
return type;
}
/**
* Gets the type.
*
* @return the type.
* @since 6.0
*/
final int getType() {
return type;
}
/**
* Returns a string representation of the element value.
*
* @return a string representation of the element value.
*/
public abstract String stringifyValue();
/**
* Returns a short string representation of the element value.
*
* @return a short string representation of the element value.
*/
public String toShortString() {
return stringifyValue();
}
/**
* Returns a string representation of the element value.
*
* @return a string representation of the element value.
*/
@Override
public String toString() {
return stringifyValue();
}
}