maint-5-2/tapestry-func/src/main/java/org/apache/tapestry5/func/LazyIterate.java

// Copyright 2010 The Apache Software Foundation
//
// 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.apache.tapestry5.func;

/**
 * Continuously re-applies a function, represented as a {@link Mapper}, to a value.
 */
class LazyIterate<T> implements LazyFunction<T>
{
    private final T previousValue;

    private final Mapper<T, T> mapper;

    public LazyIterate(T previousValue, Mapper<T, T> mapper)
    {
        this.previousValue = previousValue;
        this.mapper = mapper;
    }

    public LazyContinuation<T> next()
    {
        T current = mapper.map(previousValue);

        return new LazyContinuation<T>(current, new LazyIterate<T>(current, mapper));
    }
}