Java example source code file (InvokeInstruction.java)

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Java - Java tags/keywords

constant, exceptionthrower, fieldormethod, invokeinstruction, stackconsumer, stackproducer, string, stringtokenizer, type, typedinstruction, util

The InvokeInstruction.java Java example source code

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package com.sun.org.apache.bcel.internal.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 * 5. Products derived from this software may not be called "Apache",
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
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
 */
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));
  }
}