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.commons.services;
014
015import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
016import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
017
018/**
019 * Used by {@link org.apache.tapestry5.beanmodel.services.BeanModelSource} to identify the type of data associated with a particular property (represented as a
020 * {@link PropertyAdapter}). The data type is a string used to determine what kind of interface to use for displaying
021 * the value of the property, or what kind of interface to use for editing the value of the property. Common property
022 * types are "text", "enum", "checkbox", but the list is extensible.
023 *
024 * Different strategies for identifying the data type are encapsulated in the DataTypeAnalyzer service, forming a
025 * chain of command.
026 *
027 * The DefaultDataTypeAnalyzer service maps property types to data type names.
028 *
029 * The DataTypeAnalyzer service is an extensible {@linkplain org.apache.tapestry5.ioc.services.ChainBuilder chain of
030 * command}), that (by default) includes {@link org.apache.tapestry5.commons.internal.services.AnnotationDataTypeAnalyzer} and
031 * the {@link org.apache.tapestry5.commons.internal.services.DefaultDataTypeAnalyzer} service (ordered last).   It uses an ordered configuration.
032 *
033 * @see org.apache.tapestry5.corelib.components.Grid
034 * @see org.apache.tapestry5.corelib.components.BeanEditForm
035 * @see org.apache.tapestry5.services.BeanBlockSource
036 */
037@UsesOrderedConfiguration(DataTypeAnalyzer.class)
038@UsesMappedConfiguration(key = Class.class, value = String.class)
039public interface DataTypeAnalyzer
040{
041    /**
042     * Identifies the data type, if known, or returns null if not known.
043     */
044    String identifyDataType(PropertyAdapter adapter);
045}