jaxp/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/generic/InvokeInstruction.java

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * 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.generic;

import com.sun.org.apache.bcel.internal.Constants;
import com.sun.org.apache.bcel.internal.classfile.*;
import java.util.StringTokenizer;

/**
 * Super class for the INVOKExxx family of instructions.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public abstract class InvokeInstruction extends FieldOrMethod
  implements ExceptionThrower, TypedInstruction, StackConsumer, StackProducer {
  /**
   * Empty constructor needed for the Class.newInstance() statement in
   * Instruction.readInstruction(). Not to be used otherwise.
   */
  InvokeInstruction() {}

  /**
   * @param index to constant pool
   */
  protected InvokeInstruction(short opcode, int index) {
    super(opcode, index);
  }

  /**
   * @return mnemonic for instruction with symbolic references resolved
   */
  public String toString(ConstantPool cp) {
    Constant        c   = cp.getConstant(index);
    StringTokenizer tok = new StringTokenizer(cp.constantToString(c));

    return Constants.OPCODE_NAMES[opcode] + " " +
      tok.nextToken().replace('.', '/') + tok.nextToken();
  }

  /**
   * Also works for instructions whose stack effect depends on the
   * constant pool entry they reference.
   * @return Number of words consumed from stack by this instruction
   */
  public int consumeStack(ConstantPoolGen cpg) {
      String signature = getSignature(cpg);
      Type[] args      = Type.getArgumentTypes(signature);
      int    sum;

      if(opcode == Constants.INVOKESTATIC)
        sum = 0;
      else
        sum = 1;  // this reference

      int n = args.length;
      for (int i = 0; i < n; i++)
        sum += args[i].getSize();

      return sum;
   }

  /**
   * Also works for instructions whose stack effect depends on the
   * constant pool entry they reference.
   * @return Number of words produced onto stack by this instruction
   */
  public int produceStack(ConstantPoolGen cpg) {
    return getReturnType(cpg).getSize();
  }

  /** @return return type of referenced method.
   */
  public Type getType(ConstantPoolGen cpg) {
    return getReturnType(cpg);
  }

  /** @return name of referenced method.
   */
  public String getMethodName(ConstantPoolGen cpg) {
    return getName(cpg);
  }

  /** @return return type of referenced method.
   */
  public Type getReturnType(ConstantPoolGen cpg) {
    return Type.getReturnType(getSignature(cpg));
  }

  /** @return argument types of referenced method.
   */
  public Type[] getArgumentTypes(ConstantPoolGen cpg) {
    return Type.getArgumentTypes(getSignature(cpg));
  }
}