/*
* Copyright 2002-2016 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
*
* 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.springframework.util;
import java.util.
Collection;
import java.util.
Collections;
/**
* A simple instance filter that checks if a given instance match based on
* a collection of includes and excludes element.
*
* <p>Subclasses may want to override {@link #match(Object, Object)} to provide
* a custom matching algorithm.
*
* @author Stephane Nicoll
* @since 4.1
*/
public class
InstanceFilter<T> {
private final
Collection<? extends T>
includes;
private final
Collection<? extends T>
excludes;
private final boolean
matchIfEmpty;
/**
* Create a new instance based on includes/excludes collections.
* <p>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.
* <p>Subclasses may redefine what matching means. By default, an element match with
* another if it is equals according to {@link Object#equals(Object)}
* <p>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(
Collection<? extends T>
includes,
Collection<? extends T>
excludes, boolean
matchIfEmpty) {
this.
includes = (
includes != null ?
includes :
Collections.<T>
emptyList());
this.
excludes = (
excludes != null ?
excludes :
Collections.<T>
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.
* <p>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<? extends T>
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();
}
}