001    // Copyright 2010 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.func;
016    
017    /**
018     * The result of the evaluation of a {@link LazyFunction}.
019     * 
020     * @since 5.2.0
021     */
022    public class LazyContinuation<T>
023    {
024        private final LazyValue<T> nextValue;
025    
026        private final LazyFunction<T> nextFunction;
027    
028        public LazyContinuation(T nextValue, LazyFunction<T> nextFunction)
029        {
030            this(new StaticValue<T>(nextValue), nextFunction);
031        }
032    
033        public LazyContinuation(LazyValue<T> nextValue, LazyFunction<T> nextFunction)
034        {
035            assert nextValue != null;
036            assert nextFunction != null;
037    
038            this.nextValue = nextValue;
039            this.nextFunction = nextFunction;
040        }
041    
042        /**
043         * Returns, indirectly, the next value computed by the lazy function. The LazyValue represents
044         * a deferred computation.
045         */
046        public LazyValue<T> nextValue()
047        {
048            return nextValue;
049        }
050    
051        /** Returns a new lazy function that will return the next continuation. */
052        public LazyFunction<T> nextFunction()
053        {
054            return nextFunction;
055        }
056    
057    }