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

class LazyRange implements LazyFunction<Integer>
{
    private final int lower, upper, delta;

    public LazyRange(int lower, int upper, int delta)
    {
        this.lower = lower;
        this.upper = upper;
        this.delta = delta;
    }

    public LazyContinuation<Integer> next()
    {
        if (delta < 0 && lower + delta < upper)
            return null;

        if (delta > 0 && lower + delta > upper)
            return null;

        return new LazyContinuation<Integer>(lower, new LazyRange(lower + delta, upper, delta));
    }

}