# TransientBuilderInstance.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 org.qi4j.api.common.ConstructionException;
    import org.qi4j.api.composite.CompositeInstance;
    import org.qi4j.api.composite.TransientBuilder;
    import org.qi4j.api.property.PropertyDescriptor;
    import org.qi4j.runtime.property.PropertyInfo;
    import org.qi4j.runtime.property.PropertyInstance;
    import org.qi4j.spi.module.ModelModule;

    /**
     * JAVADOC
     */
    public final class TransientBuilderInstance<T>
        implements TransientBuilder<T>
    {
        private ModelModule<TransientModel> model;

        // lazy initialized in accessor
        private UsesInstance uses = UsesInstance.EMPTY_USES;

        // lazy initialized in accessor
        private CompositeInstance prototypeInstance;

        private TransientStateInstance state;

        public TransientBuilderInstance( ModelModule<TransientModel> model,
                                         TransientStateInstance state,
                                         UsesInstance uses
        )
        {
            this.model = model;
            this.state = state;
            this.uses = uses;
        }

        @Override
        public TransientBuilder<T> use( Object... usedObjects )
        {
            uses = uses.use( usedObjects );
            return this;
        }

        @Override
        public T prototype()
        {
            // Instantiate given value type
            if( prototypeInstance == null )
            {
                prototypeInstance = model.model().newInstance( model.module(), uses, state );
            }

            return prototypeInstance.<T>proxy();
        }

        @Override
        public <K> K prototypeFor( Class<K> mixinType )
        {
            // Instantiate given value type
            if( prototypeInstance == null )
            {
                prototypeInstance = model.model().newInstance( model.module(), uses, state );
            }

            return prototypeInstance.newProxy( mixinType );
        }

        @Override
        public T newInstance()
            throws ConstructionException
        {
            // Set correct info's (immutable) on the state
            for( PropertyDescriptor propertyDescriptor : model.model().state().properties() )
            {
                ( (PropertyInstance<Object>) state.propertyFor( propertyDescriptor.accessor() ) ).setPropertyInfo( (PropertyInfo) propertyDescriptor );
            }

            model.model().checkConstraints( state );

            CompositeInstance compositeInstance =
                model.model().newInstance( model.module(), uses, state );
            return compositeInstance.<T>proxy();
        }
    }