pop.java

JGAP（发音"jay-gap"）是一款用Java编写的遗传算法包。提供了基本的遗传算法.你可以使用它来解决一些适用于遗传算法解决的问题.

/*
 * This file is part of JGAP.
 *
 * JGAP offers a dual license model containing the LGPL as well as the MPL.
 *
 * For licencing information please see the file license.txt included with JGAP
 * or have a look at the top of class org.jgap.Chromosome which representatively
 * includes the JGAP license policy applicable for any file delivered with JGAP.
 */
package org.jgap.gp.function;

import org.jgap.*;
import org.jgap.gp.*;
import org.jgap.gp.impl.*;

/**
 * Pops a value from the stack after it has been pushed onto it (PushCommand)
 *
 * @author Klaus Meffert
 * @since 3.0
 */
public class Pop
    extends MathCommand {
  /** String containing the CVS revision. Read out via reflection!*/
  private final static String CVS_REVISION = "$Revision: 1.3 $";

  public Pop(final GPConfiguration a_conf, Class type)
      throws InvalidConfigurationException {
    super(a_conf, 0, type);
  }

  protected CommandGene newGeneInternal() {
    try {
      CommandGene gene = new Pop(getGPConfiguration(), getReturnType());
      return gene;
    }
    catch (InvalidConfigurationException iex) {
      throw new IllegalStateException(iex.getMessage());
    }
  }

  public String toString() {
    return "pop &1";
  }

  public int execute_int(ProgramChromosome c, int n, Object[] args) {
    check(c);
    // Pop from stack.
    // ---------------
    if ( getGPConfiguration().stackSize() < 1) {
      throw new IllegalStateException("pop without push");
    }
    return ( (Integer) getGPConfiguration().popFromStack()).
        intValue();
  }

  public long execute_long(ProgramChromosome c, int n, Object[] args) {
    check(c);
    if ( getGPConfiguration().stackSize() < 1) {
      throw new IllegalStateException("pop without push");
    }
    return ( (Long) getGPConfiguration().popFromStack()).longValue();
  }

  public double execute_double(ProgramChromosome c, int n, Object[] args) {
    check(c);
    if ( getGPConfiguration().stackSize() < 1) {
      throw new IllegalStateException("pop without push");
    }
    return ( (Double) getGPConfiguration().popFromStack()).doubleValue();
  }

  public float execute_float(ProgramChromosome c, int n, Object[] args) {
    check(c);
    if ( getGPConfiguration().stackSize() < 1) {
      throw new IllegalStateException("pop without push");
    }
    return ( (Float) getGPConfiguration().popFromStack()).floatValue();
  }

  public Object execute_object(ProgramChromosome c, int n, Object[] args) {
    check(c);
    if ( getGPConfiguration().stackSize() < 1) {
      throw new IllegalStateException("pop without push");
    }
    return getGPConfiguration().popFromStack();
  }

  public static interface Compatible {
    public Object execute_pop(Object o);
  }
  public boolean isValid(ProgramChromosome a_program) {
    return a_program.getCommandOfClass(0,Push.class) >= 0;
  }
}