/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
*
* Copyright (c) 2013 Edugility LLC.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* The original copy of this license is available at
* http://www.opensource.org/license/mit-license.html.
*/
package com.edugility.objexj.engine;
import java.io.Serializable; // for javadoc only
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* An {@link Instruction} that {@linkplain
* InstructionContext#advanceProgramCounter() advances the program
* counter} if and only if an {@link InstructionContext} is
* {@linkplain InstructionContext#atStart() at the beginning of the
* input}.
*
* @param <T> the type of {@link Object} that {@link
* InstructionContext} instances passed to the {@link
* #execute(InstructionContext)} method can work with
*
* @author <a href="http://about.me/lairdnelson"
* target="_parent">Laird Nelson</a>
*/
public class BeginInput<T> extends Instruction<T> {
/**
* The version of this class for {@linkplain Serializable
* serialization purposes}.
*/
private static final long serialVersionUID = 1L;
/**
* Creates a new {@link BeginInput} instruction.
*/
public BeginInput() {
super();
}
/**
* {@linkplain InstructionContext#advanceProgramCounter() Advances
* the program counter} if and only if the supplied {@link
* InstructionContext} is {@linkplain InstructionContext#atStart()
* at the beginning of the input}. {@linkplain
* InstructionContext#die() Kills the
* <code>InstructionContext</code} otherwise.
*
* @param context the {@link InstructionContext} to operate on; must
* not be {@code null}
*
* @exception IllegalArgumentException if {@code context} is {@code
* null}
*/
@Override
public final void execute(final InstructionContext<? extends T> context) {
final Logger logger = this.getLogger();
final boolean finer = logger != null && logger.isLoggable(Level.FINER);
final String className = this.getClass().getName();
if (finer) {
logger.entering(className, "execute", context);
}
if (context == null) {
throw new IllegalArgumentException("context");
}
if (context.atStart()) {
context.advanceProgramCounter();
} else {
context.die();
}
if (finer) {
logger.exiting(className, "execute");
}
}
}