/*
* 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.tamaya.core.internal;
import org.apache.tamaya.spi.ConfigurationContext;
import org.apache.tamaya.spi.FilterContext;
import org.apache.tamaya.spi.PropertyFilter;
import org.apache.tamaya.spi.PropertySource;
import org.apache.tamaya.spi.PropertyValue;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Implementation of the Configuration API. This class uses the current {@link ConfigurationContext} to evaluate the
* chain of {@link PropertySource} and {@link PropertyFilter}
* instance to evaluate the current Configuration.
*/
public final class PropertyFiltering{
/**
* The logger.
*/
private static final Logger LOG = Logger.getLogger(PropertyFiltering.class.getName());
/**
* The maximal number of filter cycles performed before aborting.
*/
private static final int MAX_FILTER_LOOPS = 10;
/**
* Private singleton constructor.
*/
private PropertyFiltering(){}
/**
* Filters a single value.
* @param value the raw value, not {@code null}.
* @param context the context
* @return the filtered value, including {@code null}.
*/
public static PropertyValue applyFilter(PropertyValue value, ConfigurationContext context) {
FilterContext filterContext = new FilterContext(value, context);
return filterValue(filterContext);
}
/**
* Filters all properties.
* @param rawProperties the unfiltered properties, not {@code null}.
* @param context the context
* @return the filtered value, inclusing null.
*/
public static Map<String, PropertyValue> applyFilters(Map<String, PropertyValue> rawProperties, ConfigurationContext context) {
Map<String, PropertyValue> result = new HashMap<>();
// Apply filters to values, prevent values filtered to null!
for (Map.Entry<String, PropertyValue> entry : rawProperties.entrySet()) {
FilterContext filterContext = new FilterContext(entry.getValue(), rawProperties, context);
PropertyValue filtered = filterValue(filterContext);
if(filtered!=null){
result.put(filtered.getKey(), filtered);
}
}
return result;
}
/**
* Basic filter logic.
* @param context the filter context, not {@code null}.
* @return the filtered value.
*/
private static PropertyValue filterValue(FilterContext context) {
PropertyValue inputValue = context.getProperty();
PropertyValue filteredValue = inputValue;
for (int i = 0; i < MAX_FILTER_LOOPS; i++) {
int changes = 0;
for (PropertyFilter filter : context.getContext().getPropertyFilters()) {
filteredValue = filter.filterProperty(inputValue, context);
if (filteredValue != null && !filteredValue.equals(inputValue)) {
changes++;
LOG.finest("Filter - " + inputValue + " -> " + filteredValue + " by " + filter);
}
if(filteredValue==null){
LOG.finest("Filter removed entry - " + inputValue + ": " + filter);
break;
}else{
inputValue = filteredValue;
}
}
if (changes == 0) {
LOG.finest("Finishing filter loop, no changes detected.");
break;
} else if (filteredValue == null) {
break;
} else {
if (i == (MAX_FILTER_LOOPS - 1)) {
if (LOG.isLoggable(Level.WARNING)) {
LOG.warning("Maximal filter loop count reached, aborting filter evaluation after cycles: " + i);
}
} else {
LOG.finest("Repeating filter loop, changes detected: " + changes);
}
}
}
return filteredValue;
}
}