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    
015    package org.apache.tapestry5.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.services.ComponentClasses} {@link
021     * org.apache.tapestry5.services.InvalidationEventHub} is invalidated (i.e., when component class files change).
022     *
023     * @since 5.1.0.0
024     */
025    public 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    }