001// Copyright 2009 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
015package org.apache.tapestry5.commons.internal.services;
016
017/**
018 * Creates "interned" strings that are unique for the same content. This is used for common description strings,
019 * particularly those used by {@link org.apache.tapestry5.Binding} instances.  The internal cache of interned strings id
020 * cleared whenever the {@link org.apache.tapestry5.ioc.annotations.ComponentClasses} 
021 * <a href="https://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/InvalidationEventHub.html">InvalidationEventHub</a> is invalidated (i.e., when component class files change).
022 *
023 * @since 5.1.0.0
024 */
025public interface StringInterner
026{
027    /**
028     * Interns a string.
029     *
030     * @param string the string to intern
031     * @return the input string, or another string instance with the same content
032     */
033    String intern(String string);
034
035    /**
036     * Formats a string (using {@link String#format(String, Object[])}) and returns the interned result.
037     *
038     * @param format    string format
039     * @param arguments used inside the format
040     * @return formatted and interned string
041     */
042    String format(String format, Object... arguments);
043}