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.IScope;

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

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

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

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

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

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

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

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

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;

/**

 * Removes Seq blocks that only have one element...

 * @author KrennW

 */

public final class OoaRemoveTrivialSequentialCompositionVisitor extends OoaCompleteAstTraversalVisitor {

        private void setNewParent(Statement s, final IScope oldScope,final IScope newParentScope) {

                class ParentScopeVis extends OoaCompleteAstTraversalVisitor {

                        @Override

                        protected void VisitAstElement(IAst element, IAst parent) {

                                if (element instanceof IScope) {

                                        final IScope scope = (IScope) element;

                                        if (scope.GetParentScope() == oldScope)

                                                scope.SetParentScope(newParentScope);

                                }

                                super.VisitAstElement(element, parent);

                        }

                        public ParentScopeVis() {

                                super(null);

                        }

                }

                if (s instanceof IScope)

                        ((IScope)s).SetParentScope(newParentScope);

                final ParentScopeVis visitor = new ParentScopeVis();

                s.Accept(visitor);

        }

        /// <summary>

        /// replaces the seqBlock by its child

        /// </summary>

        private IAst ConvertNondetBlock(SeqBlock seqBlock, IAst parent)

        {

                if (seqBlock.statements().size() <= 1 &&            // max one statement in block

                    seqBlock.isSimpleBlock() &&                     // block must not have local vars etc.

                    parent.nodeType() !=  AstNodeTypeEnum.type)     // we cannot simplify if block is owned by an OoActionSystem since dood always is a block

                {

                        final Statement stmt = seqBlock.statements().peekFirst();

                        setNewParent(stmt, seqBlock, seqBlock.GetParentScope()); // change AST and correct all parentscope pointers to this seqblock

                        switch (parent.nodeType())

                        {

                        case statement:

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

                                {

                                case SeqBlock:

                                case NondetBlock:

                                case PrioBlock:

                                        final Block aBlock = (Block)parent;

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

                                        if (idx == -1)

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

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

                                        break;

                                case GuardedCommand:

                                        final GuardedCommand gc = (GuardedCommand)parent;

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

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

                                        gc.SetBody(stmt);

                                        break;

                                default:

                                        throw new NotImplementedException();

                                }

                                break;

                        case identifier:

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

                                {

                                case NamedActionIdentifier:

                                case MethodIdentifier:

                                        final FunctionIdentifier method = (FunctionIdentifier)parent;

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

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

                                        method.SetBody(stmt);

                                        break;

                                default:

                                        throw new NotImplementedException();

                                }

                                break;

                        default:

                                throw new NotImplementedException();

                        }

                        m_changes = true;

                        return stmt;

                }

                else

                        return seqBlock;

        }

        @Override

        protected void VisitAstElement(IAst element, IAst parent)

        {

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

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

                      // 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((SeqBlock)element, parent);

                        super.VisitAstElement(newchild, parent);

                }

                else

                        super.VisitAstElement(element, parent);

        }

        private boolean m_changes = false;

        public OoaRemoveTrivialSequentialCompositionVisitor(ParserState aState)

        {

                super (aState);

        }

        public boolean changedAst() {

                return m_changes;

        }

}