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.generic;
019
020import org.apache.bcel.Const;
021import org.apache.bcel.classfile.ConstantCP;
022import org.apache.bcel.classfile.ConstantNameAndType;
023import org.apache.bcel.classfile.ConstantPool;
024import org.apache.bcel.classfile.ConstantUtf8;
025
026/**
027 * Super class for InvokeInstruction and FieldInstruction, since they have
028 * some methods in common!
029 *
030 */
031public abstract class FieldOrMethod extends CPInstruction implements LoadClass {
032
033    /**
034     * Empty constructor needed for Instruction.readInstruction.
035     * Not to be used otherwise.
036     */
037    FieldOrMethod() {
038        // no init
039    }
040
041
042    /**
043     * @param index to constant pool
044     */
045    protected FieldOrMethod(final short opcode, final int index) {
046        super(opcode, index);
047    }
048
049
050    /** @return signature of referenced method/field.
051     */
052    public String getSignature(final ConstantPoolGen cpg) {
053        final ConstantPool cp = cpg.getConstantPool();
054        final ConstantCP cmr = (ConstantCP) cp.getConstant(super.getIndex());
055        final ConstantNameAndType cnat = (ConstantNameAndType) cp.getConstant(cmr.getNameAndTypeIndex());
056        return ((ConstantUtf8) cp.getConstant(cnat.getSignatureIndex())).getBytes();
057    }
058
059
060    /** @return name of referenced method/field.
061     */
062    public String getName(final ConstantPoolGen cpg) {
063        final ConstantPool cp = cpg.getConstantPool();
064        final ConstantCP cmr = (ConstantCP) cp.getConstant(super.getIndex());
065        final ConstantNameAndType cnat = (ConstantNameAndType) cp.getConstant(cmr.getNameAndTypeIndex());
066        return ((ConstantUtf8) cp.getConstant(cnat.getNameIndex())).getBytes();
067    }
068
069
070    /**
071     * @return name of the referenced class/interface
072     * @deprecated If the instruction references an array class,
073     *    this method will return "java.lang.Object".
074     *    For code generated by Java 1.5, this answer is
075     *    sometimes wrong (e.g., if the "clone()" method is
076     *    called on an array).  A better idea is to use
077     *    the {@link #getReferenceType(ConstantPoolGen)} method, which correctly distinguishes
078     *    between class types and array types.
079     *
080     */
081    @Deprecated
082    public String getClassName(final ConstantPoolGen cpg) {
083        final ConstantPool cp = cpg.getConstantPool();
084        final ConstantCP cmr = (ConstantCP) cp.getConstant(super.getIndex());
085        final String className = cp.getConstantString(cmr.getClassIndex(), Const.CONSTANT_Class);
086        if (className.startsWith("[")) {
087            // Turn array classes into java.lang.Object.
088            return "java.lang.Object";
089        }
090        return className.replace('/', '.');
091    }
092
093
094    /** @return type of the referenced class/interface
095     * @deprecated If the instruction references an array class,
096     *    the ObjectType returned will be invalid.  Use
097     *    getReferenceType() instead.
098     */
099    @Deprecated
100    public ObjectType getClassType(final ConstantPoolGen cpg) {
101        return ObjectType.getInstance(getClassName(cpg));
102    }
103
104
105    /**
106     * Gets the reference type representing the class, interface,
107     * or array class referenced by the instruction.
108     * @param cpg the ConstantPoolGen used to create the instruction
109     * @return an ObjectType (if the referenced class type is a class
110     *   or interface), or an ArrayType (if the referenced class
111     *   type is an array class)
112     */
113    public ReferenceType getReferenceType(final ConstantPoolGen cpg) {
114        final ConstantPool cp = cpg.getConstantPool();
115        final ConstantCP cmr = (ConstantCP) cp.getConstant(super.getIndex());
116        String className = cp.getConstantString(cmr.getClassIndex(), Const.CONSTANT_Class);
117        if (className.startsWith("[")) {
118            return (ArrayType) Type.getType(className);
119        }
120        className = className.replace('/', '.');
121        return ObjectType.getInstance(className);
122    }
123
124
125    /**
126     * Gets the ObjectType of the method return or field.
127     *
128     * @return type of the referenced class/interface
129     * @throws ClassGenException when the field is (or method returns) an array,
130     */
131    @Override
132    public ObjectType getLoadClassType(final ConstantPoolGen cpg) {
133        final ReferenceType rt = getReferenceType(cpg);
134        if (rt instanceof ObjectType) {
135            return (ObjectType) rt;
136        }
137        throw new ClassGenException(
138            rt.getClass().getCanonicalName() + " " + rt.getSignature() + " does not represent an ObjectType");
139    }
140}