109 lines
3.9 KiB
Java
109 lines
3.9 KiB
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
|
|
*
|
|
* http://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.tomcat.util.bcel.classfile;
|
|
|
|
import java.io.DataInput;
|
|
import java.io.IOException;
|
|
|
|
import org.apache.tomcat.util.bcel.Const;
|
|
|
|
/**
|
|
* Abstract superclass for classes to represent the different constant types
|
|
* in the constant pool of a class file. The classes keep closely to
|
|
* the JVM specification.
|
|
*
|
|
* @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A>
|
|
*/
|
|
public abstract class Constant {
|
|
|
|
/* In fact this tag is redundant since we can distinguish different
|
|
* `Constant' objects by their type, i.e., via `instanceof'. In some
|
|
* places we will use the tag for switch()es anyway.
|
|
*
|
|
* First, we want match the specification as closely as possible. Second we
|
|
* need the tag as an index to select the corresponding class name from the
|
|
* `CONSTANT_NAMES' array.
|
|
*/
|
|
protected final byte tag;
|
|
|
|
Constant(final byte tag) {
|
|
this.tag = tag;
|
|
}
|
|
|
|
/**
|
|
* @return Tag of constant, i.e., its type. No setTag() method to avoid
|
|
* confusion.
|
|
*/
|
|
public final byte getTag() {
|
|
return tag;
|
|
}
|
|
|
|
/**
|
|
* Read one constant from the given input, the type depends on a tag byte.
|
|
*
|
|
* @param dataInput Input stream
|
|
* @return Constant object
|
|
* @throws IOException if an I/O error occurs reading from the given {@code dataInput}.
|
|
* @throws ClassFormatException if the next byte is not recognized
|
|
*/
|
|
static Constant readConstant(final DataInput dataInput) throws IOException, ClassFormatException {
|
|
final byte b = dataInput.readByte(); // Read tag byte
|
|
int skipSize;
|
|
switch (b) {
|
|
case Const.CONSTANT_Class:
|
|
return new ConstantClass(dataInput);
|
|
case Const.CONSTANT_Integer:
|
|
return new ConstantInteger(dataInput);
|
|
case Const.CONSTANT_Float:
|
|
return new ConstantFloat(dataInput);
|
|
case Const.CONSTANT_Long:
|
|
return new ConstantLong(dataInput);
|
|
case Const.CONSTANT_Double:
|
|
return new ConstantDouble(dataInput);
|
|
case Const.CONSTANT_Utf8:
|
|
return ConstantUtf8.getInstance(dataInput);
|
|
case Const.CONSTANT_String:
|
|
case Const.CONSTANT_MethodType:
|
|
case Const.CONSTANT_Module:
|
|
case Const.CONSTANT_Package:
|
|
skipSize = 2; // unsigned short
|
|
break;
|
|
case Const.CONSTANT_MethodHandle:
|
|
skipSize = 3; // unsigned byte, unsigned short
|
|
break;
|
|
case Const.CONSTANT_Fieldref:
|
|
case Const.CONSTANT_Methodref:
|
|
case Const.CONSTANT_InterfaceMethodref:
|
|
case Const.CONSTANT_NameAndType:
|
|
case Const.CONSTANT_Dynamic:
|
|
case Const.CONSTANT_InvokeDynamic:
|
|
skipSize = 4; // unsigned short, unsigned short
|
|
break;
|
|
default:
|
|
throw new ClassFormatException("Invalid byte tag in constant pool: " + b);
|
|
}
|
|
Utility.skipFully(dataInput, skipSize);
|
|
return null;
|
|
}
|
|
|
|
@Override
|
|
public String toString() {
|
|
return "[" + tag + "]";
|
|
}
|
|
}
|