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.ast.AstNodeTypeEnum;

import org.momut.ooas.ast.IAst;

import org.momut.ooas.ast.identifiers.Identifier;

import org.momut.ooas.ast.identifiers.IdentifierKind;

import org.momut.ooas.ast.identifiers.MethodIdentifier;

import org.momut.ooas.ast.identifiers.NamedActionIdentifier;

import org.momut.ooas.ast.statements.Block;

import org.momut.ooas.ast.statements.GuardedCommand;

import org.momut.ooas.ast.statements.NondetBlock;

import org.momut.ooas.ast.statements.Statement;

import org.momut.ooas.ast.statements.StatementKind;

import org.momut.ooas.ast.types.OoActionSystemType;

import org.momut.ooas.ast.types.Type;

import org.momut.ooas.parser.ParserState;

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

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

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

import org.momut.ooas.visitors.OoaCompleteAstTraversalVisitor;

/**

 * 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 (((Type)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;

        }

}