| /******************************************************************************* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.sling.scripting.sightly.impl.filter; |
| |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.Set; |
| |
| import org.apache.sling.scripting.sightly.compiler.expression.Expression; |
| |
| /** |
| * A filter is a transformation which performs modifications on expressions. Unlike plugins, filters are always applied on an expression. |
| * Whether the filter transformation is actually necessary is decided by the filter. The application order of filters is given by filter |
| * priority. |
| */ |
| public interface Filter extends Comparable<Filter> { |
| |
| /** |
| * Transform the given expression |
| * |
| * @param expression the original expression |
| * @param expressionContext the expression's context |
| * @return a transformed expression. If the filter is not applicable |
| * to the given expression, then the original expression shall be returned |
| */ |
| Expression apply(Expression expression, ExpressionContext expressionContext); |
| |
| /** |
| * The priority with which filters are applied. This establishes order between filters. Filters with |
| * lower priority are applied first. |
| * |
| * @return an integer representing the filter's priority |
| */ |
| int priority(); |
| |
| /** |
| * Provides the option names this {@code Filter} will process. |
| * |
| * @return a set of option names |
| */ |
| default Set<String> getOptions() { |
| return Collections.emptySet(); |
| } |
| |
| /** |
| * Provides the option names that will trigger a filter's execution. |
| * |
| * @return the required options from an expression in order to trigger the filter |
| */ |
| default Set<String> getRequiredOptions() { |
| return Collections.emptySet(); |
| } |
| |
| /** |
| * Provides the applicable contexts for this filter. |
| * |
| * @return the applicable contexts for this filter |
| */ |
| default Set<ExpressionContext> getApplicableContexts() { |
| return new HashSet<>(Arrays.asList(ExpressionContext.values())); |
| } |
| |
| } |