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Interval.java
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Interval.java
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/*
* Copyright 2013 Gordon Burgett and individual contributors
*
* 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.xflatdb.xflat.query;
import java.util.Comparator;
import java.util.Objects;
/**
* Represents one interval within an interval set. The interval
* is represented by two values, the begin and the end,
* which can be inclusive or exclusive.
* @param T The type of values representing the interval.
*/
public class Interval<T> {
final T begin;
final T end;
boolean endInclusive;
boolean beginInclusive;
/**
* Gets the begin value of this interval. A null value means negative infinity.
*/
public T getBegin() {
return begin;
}
/**
* Gets the end value of this interval. A null value means positive infinity.
*/
public T getEnd() {
return end;
}
/**
* Gets whether the interval is inclusive of the beginning.
* True means inclusive, false means exclusive.
*/
public boolean getBeginInclusive() {
//Too late I realized it would have been better to do this having the booleans mean inclusive.
//Unfortunately too much work to undo it now, fortunately I hadn't written any public facing
//stuff based on that paradigm yet.
return this.beginInclusive;
}
/**
* Gets whether the interval is inclusive of the end.
* True means inclusive, false means exclusive.
*/
public boolean getEndInclusive() {
return this.endInclusive;
}
public Interval(T begin, boolean beginInclusive, T end, boolean endInclusive) {
this.begin = begin;
this.end = end;
this.beginInclusive = beginInclusive;
this.endInclusive = endInclusive;
}
/**
* Returns true iff the given value is contained by this Interval, according
* to the given comparator.
* @param value The value to test.
* @param comparator The comparator used to compare values.
* @return true if the value is contained by the Interval, false otherwise.
*/
public boolean contains(T value, Comparator<T> comparator) {
int lower = comparator.compare(value, begin);
if (lower < 0) {
return false;
}
if (lower == 0) {
return this.beginInclusive;
}
int upper = comparator.compare(value, end);
if (upper > 0) {
return false;
}
if (upper == 0) {
return this.endInclusive;
}
return true;
}
static <U> int compareBegin(Interval<U> val1, Interval<U> val2, Comparator<U> itemComparer){
if(val1.begin == null){
if(val2.begin == null){
//val1 == val2;
return compareExclusivity(val1.beginInclusive, val2.beginInclusive);
}
//if val2 != null, then val1 < val2 cause we're comparing beginning
return -1;
}
if(val2.begin == null){
//val1 is not null, so val1 is > val2
return 1;
}
int ret = itemComparer.compare(val1.begin, val2.begin);
if(ret == 0){
return compareExclusivity(val1.beginInclusive, val2.beginInclusive);
}
return ret;
}
static <U> int compareEnd(Interval<U> val1, Interval<U> val2, Comparator<U> itemComparer){
if(val1.end == null){
if(val2.end == null){
//val1 == val2;
return -1 * compareExclusivity(val1.beginInclusive, val2.beginInclusive);
}
//if val2 != null, then val1 > val2 cause we're comparing ends
return 1;
}
if(val2.end == null){
//val1 is not null, so val1 is < val2
return -1;
}
int ret = itemComparer.compare(val1.end, val2.end);
if(ret == 0){
return -1 * compareExclusivity(val1.endInclusive, val2.endInclusive);
}
return ret;
}
static <U> int compareEndBegin(Interval<U> val1, Interval<U> val2, Comparator<U> itemComparer){
if(val1.end == null){
//val2 begin cannot be +∞, so val1 end > val2 begin
return 1;
}
if(val2.begin == null){
//val1 end cannot be -∞, so val1 end > val2 begin
return 1;
}
int ret = itemComparer.compare(val1.end, val2.begin);
if(ret == 0){
if(val1.endInclusive && val2.beginInclusive){
return 0;
}
//else val1 is lower than val2
return -1;
}
return ret;
}
private static int compareExclusivity(boolean val1Inclusive, boolean val2Inclusive){
if(val1Inclusive){
//if val2 is exclusive of beginning, val 1 is less
return val2Inclusive ? 0 : -1;
}
//val1 is exclusive of begin, val2 is less if inclusive
return val2Inclusive ? 1 : 0;
}
/**
* Returns true iff the given interval intersects this interval, according
* to the given comparator.
* @param other The other interval to test against this interval.
* @param comparator The comparator used to compare values.
* @return true if the other interval intersects this one, false otherwise.
*/
public boolean intersects(Interval<T> other, Comparator<T> comparator){
int compare = compareBegin(this, other, comparator);
if(compare <= 0){
compare = compareEndBegin(this, other, comparator);
if(compare < 0){
return false;
}
else{
return true;
}
}
else {
compare = compareEndBegin(other, this, comparator);
if(compare < 0){
return false;
}
else{
return true;
}
}
}
@Override
public int hashCode() {
int hash = 3;
hash = 67 * hash + Objects.hashCode(this.begin);
hash = 67 * hash + Objects.hashCode(this.end);
hash = 67 * hash + (this.beginInclusive ? 1 : 0);
hash = 67 * hash + (this.endInclusive ? 1 : 0);
return hash;
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Interval<T> other = (Interval<T>) obj;
if (!Objects.equals(this.begin, other.begin)) {
return false;
}
if (!Objects.equals(this.end, other.end)) {
return false;
}
if (this.beginInclusive != other.beginInclusive) {
return false;
}
if (this.endInclusive != other.endInclusive) {
return false;
}
return true;
}
/**
* Represents this object as a string, appended to the given StringBuilder.
* @param sb The StringBuilder to which this object's string representation
* should be appended.
*/
public void toString(StringBuilder sb) {
if (beginInclusive) {
sb.append('[');
} else {
sb.append('(');
}
if (begin != null) {
sb.append(begin);
} else {
sb.append("-∞");
}
sb.append(", ");
if (end != null) {
sb.append(end);
} else {
sb.append("∞");
}
if (endInclusive) {
sb.append(']');
} else {
sb.append(')');
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
toString(sb);
return sb.toString();
}
}