/*
* Copyright 2011 Google Inc.
*
* 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 com.google.ipc.invalidation.util;
import com.google.common.base.Receiver;
/**
* Utilities to enable creation of lazy strings, where the instantiation of the string is delayed
* so that, e.g., log messages that aren't printed have reduced overhead.
*/
public class LazyString {
/**
* Given an {@code element} to be logged lazily, returns null if the object is null. Otherwise,
* return an object that would convert it to a string using {@code builderFunction}. I.e., this
* method will call {@code builderFunction} with a new {@link TextBuilder} return the string
* created with it.
*/
public static <T> Object toLazyCompactString(final T element,
final Receiver<TextBuilder> builderFunction) {
if (element == null) {
return null;
}
return new Object() {
@Override
public String toString() {
TextBuilder builder = new TextBuilder();
builderFunction.accept(builder);
return builder.toString();
}
};
}
private LazyString() { // To prevent instantiation.
}
}