# ConstraintsModel.java

    /*
     * Copyright (c) 2008, Rickard Öberg. All Rights Reserved.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     *
     */

    package org.qi4j.runtime.composite;

    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.List;
    import org.qi4j.api.constraint.ConstraintsDescriptor;
    import org.qi4j.functional.HierarchicalVisitor;
    import org.qi4j.functional.VisitableHierarchy;

    /**
     * JAVADOC
     */
    public final class ConstraintsModel
        implements ConstraintsDescriptor, VisitableHierarchy<Object, Object>
    {
        private List<ValueConstraintsModel> parameterConstraintModels;

        private static ConstraintsInstance EMPTY_CONSTRAINTS = new ConstraintsInstance( Collections.<ValueConstraintsInstance>emptyList() );

        public ConstraintsModel( List<ValueConstraintsModel> parameterConstraintModels )
        {
            this.parameterConstraintModels = parameterConstraintModels;
        }

        public ConstraintsInstance newInstance()
        {
            if( parameterConstraintModels.isEmpty() )
            {
                return EMPTY_CONSTRAINTS;
            }
            else
            {
                List<ValueConstraintsInstance> parameterConstraintsInstances = new ArrayList<ValueConstraintsInstance>( parameterConstraintModels
                                                                                                                            .size() );
                for( ValueConstraintsModel parameterConstraintModel : parameterConstraintModels )
                {
                    parameterConstraintsInstances.add( parameterConstraintModel.newInstance() );
                }
                return new ConstraintsInstance( parameterConstraintsInstances );
            }
        }

        @Override
        public <ThrowableType extends Throwable> boolean accept( HierarchicalVisitor<? super Object, ? super Object, ThrowableType> modelVisitor )
            throws ThrowableType
        {
            if( modelVisitor.visitEnter( this ) )
            {
                if( parameterConstraintModels != null )
                {
                    for( ValueConstraintsModel parameterConstraintModel : parameterConstraintModels )
                    {
                        if( !parameterConstraintModel.accept( modelVisitor ) )
                        {
                            break;
                        }
                    }
                }
            }
            return modelVisitor.visitLeave( this );
        }
    }