| /* |
| * Copyright (c) 2017, 2020, Oracle and/or its affiliates. All rights reserved. |
| */ |
| /* |
| * 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 com.sun.org.apache.bcel.internal.classfile; |
| |
| import java.io.DataInput; |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.util.Objects; |
| |
| import com.sun.org.apache.bcel.internal.Const; |
| import com.sun.org.apache.bcel.internal.util.BCELComparator; |
| |
| /** |
| * 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. |
| * |
| * @LastModified: Jan 2020 |
| */ |
| public abstract class Constant implements Cloneable, Node { |
| |
| private static BCELComparator bcelComparator = new BCELComparator() { |
| |
| @Override |
| public boolean equals( final Object o1, final Object o2 ) { |
| final Constant THIS = (Constant) o1; |
| final Constant THAT = (Constant) o2; |
| return Objects.equals(THIS.toString(), THAT.toString()); |
| } |
| |
| |
| @Override |
| public int hashCode( final Object o ) { |
| final Constant THIS = (Constant) o; |
| return THIS.toString().hashCode(); |
| } |
| }; |
| |
| /* 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. |
| */ |
| private byte tag; |
| |
| Constant(final byte tag) { |
| this.tag = tag; |
| } |
| |
| /** |
| * Called by objects that are traversing the nodes of the tree implicitely |
| * defined by the contents of a Java class. I.e., the hierarchy of methods, |
| * fields, attributes, etc. spawns a tree of objects. |
| * |
| * @param v Visitor object |
| */ |
| @Override |
| public abstract void accept( Visitor v ); |
| |
| public abstract void dump( DataOutputStream file ) throws IOException; |
| |
| /** |
| * @return Tag of constant, i.e., its type. No setTag() method to avoid |
| * confusion. |
| */ |
| public final byte getTag() { |
| return tag; |
| } |
| |
| /** |
| * @return String representation. |
| */ |
| @Override |
| public String toString() { |
| return Const.getConstantName(tag) + "[" + tag + "]"; |
| } |
| |
| /** |
| * @return deep copy of this constant |
| */ |
| public Constant copy() { |
| try { |
| return (Constant) super.clone(); |
| } catch (final CloneNotSupportedException e) { |
| // TODO should this throw? |
| } |
| return null; |
| } |
| |
| @Override |
| public Object clone() { |
| try { |
| return super.clone(); |
| } catch (final CloneNotSupportedException e) { |
| throw new Error("Clone Not Supported"); // never happens |
| } |
| } |
| |
| /** |
| * Reads 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 |
| * @since 6.0 made public |
| */ |
| public static Constant readConstant(final DataInput dataInput) throws IOException, ClassFormatException { |
| final byte b = dataInput.readByte(); // Read tag byte |
| switch (b) { |
| case Const.CONSTANT_Class: |
| return new ConstantClass(dataInput); |
| case Const.CONSTANT_Fieldref: |
| return new ConstantFieldref(dataInput); |
| case Const.CONSTANT_Methodref: |
| return new ConstantMethodref(dataInput); |
| case Const.CONSTANT_InterfaceMethodref: |
| return new ConstantInterfaceMethodref(dataInput); |
| case Const.CONSTANT_String: |
| return new ConstantString(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_NameAndType: |
| return new ConstantNameAndType(dataInput); |
| case Const.CONSTANT_Utf8: |
| return ConstantUtf8.getInstance(dataInput); |
| case Const.CONSTANT_MethodHandle: |
| return new ConstantMethodHandle(dataInput); |
| case Const.CONSTANT_MethodType: |
| return new ConstantMethodType(dataInput); |
| case Const.CONSTANT_Dynamic: |
| return new ConstantDynamic(dataInput); |
| case Const.CONSTANT_InvokeDynamic: |
| return new ConstantInvokeDynamic(dataInput); |
| case Const.CONSTANT_Module: |
| return new ConstantModule(dataInput); |
| case Const.CONSTANT_Package: |
| return new ConstantPackage(dataInput); |
| default: |
| throw new ClassFormatException("Invalid byte tag in constant pool: " + b); |
| } |
| } |
| |
| /** |
| * @return Comparison strategy object |
| */ |
| public static BCELComparator getComparator() { |
| return bcelComparator; |
| } |
| |
| /** |
| * @param comparator Comparison strategy object |
| */ |
| public static void setComparator( final BCELComparator comparator ) { |
| bcelComparator = comparator; |
| } |
| |
| /** |
| * Returns value as defined by given BCELComparator strategy. |
| * By default two Constant objects are said to be equal when |
| * the result of toString() is equal. |
| * |
| * @see java.lang.Object#equals(java.lang.Object) |
| */ |
| @Override |
| public boolean equals( final Object obj ) { |
| return bcelComparator.equals(this, obj); |
| } |
| |
| /** |
| * Returns value as defined by given BCELComparator strategy. |
| * By default return the hashcode of the result of toString(). |
| * |
| * @see java.lang.Object#hashCode() |
| */ |
| @Override |
| public int hashCode() { |
| return bcelComparator.hashCode(this); |
| } |
| } |