    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.services;
    014
    015import org.apache.tapestry5.Translator;
    016import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
    017import org.apache.tapestry5.ioc.util.StrategyRegistry;
    018
    019/**
    020 * A source for {@link org.apache.tapestry5.Translator}s, either by name or by property type. The source knows
    021 * about two sets of translators: the <em>standard</em> translators contributed directly to the service
    022 * and the <em>alternate</em> translators, contributed to the {@link TranslatorAlternatesSource} service.
    023 *
    024 * Each contributed translator must have a unique {@linkplain org.apache.tapestry5.Translator#getName() name}.
    025 *
    026 * Generally, Translators are matched by type (i.e., the type matching a particular property that will be read or
    027 * updated). Contributions to this service use a {@link StrategyRegistry} to match by type. Translators can also be
    028 * selected by name. The {@link TranslatorAlternatesSource} service configuration is often used for this purpose.
    029 *
    030 * The contribution key must match the {@linkplain Translator#getType() translator type}.
    031 */
    032@UsesMappedConfiguration(key=Class.class, value=Translator.class)
    033@SuppressWarnings("unchecked")
    034public interface TranslatorSource
    035{
    036    /**
    037     * Returns the translator with the given name (either a standard translator, or an alternate).
    038     *
    039     * @param name
    040     *            name of translator (as configured, but case is ignored)
    041     * @return the shared translator instance
    042     * @throws RuntimeException
    043     *             if no translator is configured for the provided name
    044     */
    045    Translator get(String name);
    046
    047    /**
    048     * Finds a {@link Translator} that is appropriate to the given type, which is usually obtained via
    049     * {@link org.apache.tapestry5.Binding#getBindingType()}. Performs an inheritance-based search for the best match,
    050     * among the <em>standard</em> translator (not alternates).
    051     *
    052     * @param valueType
    053     *            the type of value for which a default translator is needed
    054     * @return the matching translator, or null if no match can be found
    055     */
    056    Translator findByType(Class valueType);
    057
    058    /**
    059     * Finds a {@link Translator} that is appropriate to the given type, which is usually obtained via
    060     * {@link org.apache.tapestry5.Binding#getBindingType()}. Performs an inheritance-based search for the best match,
    061     * among the <em>standard</em> translators (not alternates).
    062     *
    063     * @param valueType
    064     *            the type of value for which a default translator is needed
    065     * @return the matching translator
    066     * @throws IllegalArgumentException
    067     *             if no standard validator matches the provided type
    068     */
    069    Translator getByType(Class valueType);
    070}