001    // Copyright 2007, 2008, 2010 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.services;
016    
017    import org.apache.tapestry5.Translator;
018    import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
019    import org.apache.tapestry5.ioc.util.StrategyRegistry;
020    
021    /**
022     * A source for {@link org.apache.tapestry5.Translator}s, either by name or by property type. The source knows
023     * about two sets of translators: the <em>standard</em> translators contributed directly to the service
024     * and the <em>alternate</em> translators, contributed to the {@link TranslatorAlternatesSource} service.
025     * <p/>
026     * Each contributed translator must have a unique {@linkplain org.apache.tapestry5.Translator#getName() name}.
027     * <p>
028     * Generally, Translators are matched by type (i.e., the type matching a particular property that will be read or
029     * updated). Contributions to this service use a {@link StrategyRegistry} to match by type. Translators can also be
030     * selected by name. The {@link TranslatorAlternatesSource} service configuration is often used for this purpose.
031     * <p>
032     * The contribution key must match the {@linkplain Translator#getType() translator type}.
033     */
034    @UsesMappedConfiguration(key=Class.class, value=Translator.class)
035    @SuppressWarnings("unchecked")
036    public interface TranslatorSource
037    {
038        /**
039         * Returns the translator with the given name (either a standard translator, or an alternate).
040         * 
041         * @param name
042         *            name of translator (as configured, but case is ignored)
043         * @return the shared translator instance
044         * @throws RuntimeException
045         *             if no translator is configured for the provided name
046         */
047        Translator get(String name);
048    
049        /**
050         * Finds a {@link Translator} that is appropriate to the given type, which is usually obtained via
051         * {@link org.apache.tapestry5.Binding#getBindingType()}. Performs an inheritance-based search for the best match,
052         * among the <em>standard</em> translator (not alternates).
053         * 
054         * @param valueType
055         *            the type of value for which a default translator is needed
056         * @return the matching translator, or null if no match can be found
057         */
058        Translator findByType(Class valueType);
059    
060        /**
061         * Finds a {@link Translator} that is appropriate to the given type, which is usually obtained via
062         * {@link org.apache.tapestry5.Binding#getBindingType()}. Performs an inheritance-based search for the best match,
063         * among the <em>standard</em> translators (not alternates).
064         * 
065         * @param valueType
066         *            the type of value for which a default translator is needed
067         * @return the matching translator
068         * @throws IllegalArgumentException
069         *             if no standard validator matches the provided type
070         */
071        Translator getByType(Class valueType);
072    }