/*
* Copyright 2014 Attila Szegedi, Daniel Dekany, Jonathan Revusky
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package freemarker.core;
import java.util.Locale;
import freemarker.template.Configuration;
/**
* Factory for a certain type of number formatting ({@link TemplateNumberFormat}). Usually a singleton (one-per-VM or
* one-per-{@link Configuration}), and so must be thread-safe.
*
* @since 2.3.24
*/
public abstract class TemplateNumberFormatFactory {
/**
* Returns a formatter for the given parameters.
*
* <p>
* The returned formatter can be a new instance or a reused (cached) instance. Note that {@link Environment} itself
* caches the returned instances, though that cache is lost with the {@link Environment} (i.e., when the top-level
* template execution ends), also it might flushes lot of entries if the locale or time zone is changed during
* template execution. So caching on the factory level is still useful, unless creating the formatters is
* sufficiently cheap.
*
* @param params
* The string that further describes how the format should look. For example, when the
* {@link Configurable#getNumberFormat() numberFormat} is {@code "@fooBar 1, 2"}, then it will be
* {@code "1, 2"} (and {@code "@fooBar"} selects the factory). The format of this string is up to the
* {@link TemplateNumberFormatFactory} implementation. Not {@code null}, often an empty string.
* @param locale
* The locale to format for. Not {@code null}. The resulting format should be bound to this locale
* forever (i.e. locale changes in the {@link Environment} shouldn't be followed).
* @param env
* The runtime environment from which the formatting was called. This is mostly meant to be used for
* {@link Environment#setCustomState(Object, Object)}/{@link Environment#getCustomState(Object)}.
*/
public abstract TemplateNumberFormat get(String params, Locale locale, Environment env)
throws InvalidFormatParametersException;
}