# ValueConstraintsInstance.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.lang.annotation.Annotation;
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.List;
    import org.qi4j.api.common.Optional;
    import org.qi4j.api.constraint.ConstraintViolation;

    /**
     * JAVADOC
     */
    public final class ValueConstraintsInstance
    {
        private static final Optional OPTIONAL;

        static
        {
            OPTIONAL = new OptionalDummy();
        }

        @SuppressWarnings( "raw" )
        private final List<ConstraintInstance> constraints;
        private String name;
        private boolean optional;

        public ValueConstraintsInstance( List<AbstractConstraintModel> constraintModels, String name, boolean optional )
        {
            this.name = name;
            this.optional = optional;
            constraints = new ArrayList<>();
            for( AbstractConstraintModel constraintModel : constraintModels )
            {
                constraints.add( constraintModel.newInstance() );
            }
        }

        @SuppressWarnings( {"raw", "unchecked"} )
        public List<ConstraintViolation> checkConstraints( Object value )
        {
            List<ConstraintViolation> violations = null;

            // Check optional first - this avoids NPE's in constraints
            if( optional )
            {
                if( value == null )
                {
                    violations = Collections.emptyList();
                }
            }
            else
            {
                if( value == null )
                {
                    violations = new ArrayList<>();
                    violations.add( new ConstraintViolation( name, OPTIONAL, null ) );
                }
            }

            if( violations == null && value != null )
            {
                for( ConstraintInstance constraint : constraints )
                {
                    boolean valid;
                    try
                    {
                        valid = constraint.isValid( value );
                    }
                    catch( NullPointerException e )
                    {
                        // A NPE is the same as a failing constraint
                        valid = false;
                    }

                    if( !valid )
                    {
                        if( violations == null )
                        {
                            violations = new ArrayList<>();
                        }
                        ConstraintViolation violation = new ConstraintViolation( name, constraint.annotation(), value );
                        violations.add( violation );
                    }
                }
            }

            if( violations == null )
            {
                violations = Collections.emptyList();
            }

            return violations;
        }

        @SuppressWarnings( "AnnotationAsSuperInterface" )
        private static class OptionalDummy
            implements Optional
        {
            @Override
            public Class<? extends Annotation> annotationType()
            {
                return Optional.class;
            }

            @Override
            public String toString()
            {
                return "not optional";
            }
        }
    }