org.snmp4j.agent.MOScopeComparator Maven / Gradle / Ivy
/*_############################################################################
_##
_## SNMP4J-Agent 3 - MOScopeComparator.java
_##
_## Copyright (C) 2005-2018 Frank Fock (SNMP4J.org)
_##
_## 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.snmp4j.agent;
import java.util.Comparator;
import org.snmp4j.smi.OctetString;
/**
* The {@code MOScopeComparator} compares two scopes with each other.
*
* Two scopes are compared by their context (if both are {@link MOContextScope}
* instances) first and then by their lower bound.
*
* A scope is compared with a query by comparing the scope with the queries
* scope and then if both are deemed to be equal, the upper bound of the scope
* is checked. If it is unbounded (upper bound is {@code null}, then
* the scoped is deemed to be greater than the query. Otherwise, the upper bound
* of the scope is compared with the lower bound of the query. Scope and query
* are deemed to be equal if both bounds are equal and both are included.
* Otherwise the scope is deemed to be less than the query.
*
* @author Frank Fock
* @version 1.0
*/
public class MOScopeComparator implements Comparator {
public MOScopeComparator() {
}
/**
* Compares a scope with another scope or query. See also the class
* description how comparison is done.
* @param o1
* a MOScope instance.
* @param o2
* a MOScope instance.
* @return
* an integer less than zero if {@code o1} is less than {@code o2}
* and zero if both values are deemed to be equal and a value greater than
* zero if {@code o1} is greater than {@code o2}.
*/
public int compare(MOScope o1, MOScope o2) {
if (o1 == o2) {
return 0; // ensure identity is equal
}
int result = 0;
if (o2 instanceof MOQuery) {
result = compareQueryWithScope(o1, (MOQuery)o2);
}
else if (o1 instanceof MOQuery) {
result = -compareQueryWithScope(o2, (MOQuery)o1);
}
else {
if (o2 instanceof MOContextScope) {
result = compareContextScope(o1, (MOContextScope) o2);
}
else if (o1 instanceof MOContextScope) {
result = -compareContextScope(o2, (MOContextScope) o1);
}
else {
result = compareScope(o1, o2);
}
}
return result;
}
private static int compareContextScope(MOScope scope, MOContextScope scope2) {
if (scope == scope2) {
return 0;
}
int result = compareScope(scope, scope2);
if ((result == 0) && (scope instanceof MOContextScope)) {
OctetString c1 = ((MOContextScope)scope).getContext();
OctetString c2 = scope2.getContext();
if ((c1 != null) && (c2 != null)) {
result = c1.compareTo(c2);
}
}
return result;
}
private static int compareScope(MOScope scope, MOScope scope2) {
if ((scope == scope2) || scope.equals(scope2)) {
return 0;
}
int result = 0;
if (scope.getUpperBound() == null) {
result = 1;
if (scope2.getUpperBound() == null) {
result = scope.getLowerBound().compareTo(scope2.getLowerBound());
if (result == 0) {
result += (scope.isLowerIncluded() ? -1 : 0);
result += (scope2.isLowerIncluded() ? 1 : 0);
}
}
}
else {
result = scope.getUpperBound().compareTo(scope2.getUpperBound());
if (result == 0) {
result += (scope.isUpperIncluded() ? -1 : 0);
result += (scope2.isUpperIncluded() ? 1 : 0);
if (result == 0) {
result = scope.getUpperBound().compareTo(scope2.getLowerBound());
if (result == 0) {
if ((!scope.isUpperIncluded()) ||
(!scope2.isLowerIncluded())) {
return -1;
}
}
}
}
}
return result;
}
private static int compareQueryWithScope(MOScope scope, MOQuery scope2) {
int result = 0;
if (scope.getUpperBound() == null) {
return 1;
}
else {
result = scope.getUpperBound().compareTo(scope2.getLowerBound());
if (result == 0) {
if ((!scope.isUpperIncluded()) ||
(!scope2.isLowerIncluded())) {
return -1;
}
}
}
if (result == 0) {
if (scope instanceof MOContextScope) {
OctetString c1 = ((MOContextScope)scope).getContext();
OctetString c2 = scope2.getContext();
if ((c1 != null) && (c2 != null)) {
result = c1.compareTo(c2);
}
}
}
return result;
}
/**
* Indicates whether the given query's context matches the context of the given
* scope.
* @param a
* a MOQuery instance.
* @param b
* another MOScope instance.
* @return
* {@code true} if the query's context is {@code null} or if both contexts
* match or if the context of {@code scope} is the empty string.
* @since 2.0.2
*/
public static boolean isQueryContextMatching(MOQuery a, MOScope b) {
OctetString ca = a.getContext();
if (ca == null) {
return true;
}
if (b instanceof MOContextScope) {
OctetString cb = ((MOContextScope)b).getContext();
if (!ca.equals(cb)) {
return false;
}
}
return true;
}
public boolean equals(Object obj) {
if (obj instanceof MOScopeComparator) {
return (this == obj);
}
return false;
}
public int hashCode() {
return super.hashCode();
}
}