OoasTools

/**

  *

  *                      OOAS Compiler

  *

  *       Copyright 2015, AIT Austrian Institute of Technology.

  * This code is based on the C# Version of the OOAS Compiler, which is

  * copyright 2015 by the Institute of Software Technology, Graz University

  * of Technology with portions copyright by the AIT Austrian Institute of

  * Technology. All rights reserved.

  *

  * SEE THE "LICENSE" FILE FOR THE TERMS UNDER WHICH THIS FILE IS PROVIDED.

  *

  * If you modify the file please update the list of contributors below to in-

  * clude your name. Please also stick to the coding convention of using TABs

  * to do the basic (block-level) indentation and spaces for anything after

  * that. (Enable the display of special chars and it should be pretty obvious

  * what this means.) Also, remove all trailing whitespace.

  *

  * Contributors:

  *               Willibald Krenn (AIT)

  *               Stephan Zimmerer (AIT)

  *               Markus Demetz (AIT)

  *               Christoph Czurda (AIT)

  *

  */

package org.momut.ooas.visitors.optimisation;

import org.momut.ooas.utils.exceptions.InternalCompilerException;

/**

 * Similar (and should be run after) the RemoveTrivialPrioritizedCompositionVisitor.

 * Removes Nondet-Choice blocks that only have one choice...

 * @author KrennW

 *

 */

public final class OoaRemoveTrivialNondetChoiceCompositionVisitor extends OoaCompleteAstTraversalVisitor {

	/// <summary>

	/// replaces the nondetBlock by its child

	/// </summary>

	private IAst ConvertNondetBlock(NondetBlock nondetBlock, IAst parent)

	{

		if (nondetBlock.statements().size() <= 1 && nondetBlock.isSimpleBlock())

		{

			final Block newBlock = (Block)nondetBlock.statements().peekFirst();

			newBlock.SetParentScope(nondetBlock.GetParentScope());

			switch (parent.nodeType())

			{

			case type:

				switch (((UlyssesType)parent).kind())

				{

				case OoActionSystemType:

					final OoActionSystemType atype = (OoActionSystemType)parent;

					final Block ablock = atype.doOdBlock();

					if (ablock != nondetBlock) // ref equ.

						throw new InternalCompilerException("Internal Error: Cannot replace doOdBlock.");

					atype.SetDoOdBlock(newBlock);

					break;

				default:

					throw new NotImplementedException();

				}

				break;

			case statement:

				switch (((Statement)parent).kind())

				{

				case SeqBlock:

				case PrioBlock:

					final Block aBlock = (Block)parent;

					final int idx = aBlock.statements().indexOf(nondetBlock);

					if (idx == -1)

						throw new OoasCompilerRuntimeException(); // must not happen?!

					aBlock.statements().set(idx, newBlock);

					break;

				case GuardedCommand:

					final GuardedCommand gc = (GuardedCommand)parent;

					if(gc.body() != nondetBlock) // ref equ.

						throw new InternalCompilerException("Internal Error: Cannot replace guarded command body.");

					gc.SetBody(newBlock);

					break;

				default:

					throw new NotImplementedException();

				}

				break;

			case identifier:

				switch (((Identifier)parent).kind())

				{

				case NamedActionIdentifier:

					final NamedActionIdentifier action = (NamedActionIdentifier)parent;

					if (action.body() != nondetBlock) // ref equ.

						throw new InternalCompilerException("Internal Error: Cannot replace action body.");

					action.SetBody(newBlock);

					break;

				case MethodIdentifier:

					final MethodIdentifier method = (MethodIdentifier)parent;

					if (method.body() != nondetBlock) // ref equ.

						throw new InternalCompilerException("Internal Error: Cannot replace method body.");

					method.SetBody(newBlock);

					break;

				default:

					throw new NotImplementedException();

				}

				break;

			default:

				throw new NotImplementedException();

			}

			m_changes = true;

			return newBlock;

		}

		else

			return nondetBlock;

	}

	@Override

	protected void VisitAstElement(IAst element, IAst parent)

	{

		if ( (element.nodeType() == AstNodeTypeEnum.statement) &&

		     (((Statement)element).kind() == StatementKind.NondetBlock) &&

		      // we're only interested in actionblock and actionbody composition, not in type composition

		     !(parent.nodeType() == AstNodeTypeEnum.identifier &&

		       ((Identifier)parent).kind() == IdentifierKind.List))

		{

			final IAst newchild = ConvertNondetBlock((NondetBlock)element, parent);

			super.VisitAstElement(newchild, parent);

		}

		else

			super.VisitAstElement(element, parent);

	}

	private boolean m_changes = false;

	public OoaRemoveTrivialNondetChoiceCompositionVisitor(ParserState aState)

	{

		super (aState);

	}

	public boolean changedAst() {

		return m_changes;

	}

}