org.springframework.util.InstanceFilter Maven / Gradle / Ivy
/*
* Copyright 2002-2017 the original author or authors.
*
* 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
*
* https://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.springframework.util;
import java.util.Collection;
import java.util.Collections;
import org.springframework.lang.Nullable;
/**
* A simple instance filter that checks if a given instance match based on
* a collection of includes and excludes element.
*
* Subclasses may want to override {@link #match(Object, Object)} to provide
* a custom matching algorithm.
*
* @author Stephane Nicoll
* @since 4.1
*/
public class InstanceFilter {
private final Collection includes;
private final Collection excludes;
private final boolean matchIfEmpty;
/**
* Create a new instance based on includes/excludes collections.
* A particular element will match if it "matches" the one of the element in the
* includes list and does not match one of the element in the excludes list.
*
Subclasses may redefine what matching means. By default, an element match with
* another if it is equals according to {@link Object#equals(Object)}
*
If both collections are empty, {@code matchIfEmpty} defines if
* an element matches or not.
* @param includes the collection of includes
* @param excludes the collection of excludes
* @param matchIfEmpty the matching result if both the includes and the excludes
* collections are empty
*/
public InstanceFilter(@Nullable Collection includes,
@Nullable Collection excludes, boolean matchIfEmpty) {
this.includes = (includes != null ? includes : Collections.emptyList());
this.excludes = (excludes != null ? excludes : Collections.emptyList());
this.matchIfEmpty = matchIfEmpty;
}
/**
* Determine if the specified {code instance} matches this filter.
*/
public boolean match(T instance) {
Assert.notNull(instance, "Instance to match must not be null");
boolean includesSet = !this.includes.isEmpty();
boolean excludesSet = !this.excludes.isEmpty();
if (!includesSet && !excludesSet) {
return this.matchIfEmpty;
}
boolean matchIncludes = match(instance, this.includes);
boolean matchExcludes = match(instance, this.excludes);
if (!includesSet) {
return !matchExcludes;
}
if (!excludesSet) {
return matchIncludes;
}
return matchIncludes && !matchExcludes;
}
/**
* Determine if the specified {@code instance} is equal to the
* specified {@code candidate}.
* @param instance the instance to handle
* @param candidate a candidate defined by this filter
* @return {@code true} if the instance matches the candidate
*/
protected boolean match(T instance, T candidate) {
return instance.equals(candidate);
}
/**
* Determine if the specified {@code instance} matches one of the candidates.
*
If the candidates collection is {@code null}, returns {@code false}.
* @param instance the instance to check
* @param candidates a list of candidates
* @return {@code true} if the instance match or the candidates collection is null
*/
protected boolean match(T instance, Collection candidates) {
for (T candidate : candidates) {
if (match(instance, candidate)) {
return true;
}
}
return false;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder(getClass().getSimpleName());
sb.append(": includes=").append(this.includes);
sb.append(", excludes=").append(this.excludes);
sb.append(", matchIfEmpty=").append(this.matchIfEmpty);
return sb.toString();
}
}