/*
* Copyright (C) 2014 The Android Open Source Project
*
* 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 android.util;
import static com.android.internal.util.Preconditions.*;
import android.hardware.camera2.utils.HashCodeHelpers;
/**
* Immutable class for describing the range of two numeric values.
* <p>
* A range (or "interval") defines the inclusive boundaries around a contiguous span of
* values of some {@link Comparable} type; for example,
* "integers from 1 to 100 inclusive."
* </p>
* <p>
* All ranges are bounded, and the left side of the range is always {@code >=}
* the right side of the range.
* </p>
*
* <p>Although the implementation itself is immutable, there is no restriction that objects
* stored must also be immutable. If mutable objects are stored here, then the range
* effectively becomes mutable. </p>
*/
public final class Range<T extends Comparable<? super T>> {
/**
* Create a new immutable range.
*
* <p>
* The endpoints are {@code [lower, upper]}; that
* is the range is bounded. {@code lower} must be {@link Comparable#compareTo lesser or equal}
* to {@code upper}.
* </p>
*
* @param lower The lower endpoint (inclusive)
* @param upper The upper endpoint (inclusive)
*
* @throws NullPointerException if {@code lower} or {@code upper} is {@code null}
*/
public Range(final T lower, final T upper) {
mLower = checkNotNull(lower, "lower must not be null");
mUpper = checkNotNull(upper, "upper must not be null");
if (lower.compareTo(upper) > 0) {
throw new IllegalArgumentException("lower must be less than or equal to upper");
}
}
/**
* Create a new immutable range, with the argument types inferred.
*
* <p>
* The endpoints are {@code [lower, upper]}; that
* is the range is bounded. {@code lower} must be {@link Comparable#compareTo lesser or equal}
* to {@code upper}.
* </p>
*
* @param lower The lower endpoint (inclusive)
* @param upper The upper endpoint (inclusive)
*
* @throws NullPointerException if {@code lower} or {@code upper} is {@code null}
*/
public static <T extends Comparable<? super T>> Range<T> create(final T lower, final T upper) {
return new Range<T>(lower, upper);
}
/**
* Get the lower endpoint.
*
* @return a non-{@code null} {@code T} reference
*/
public T getLower() {
return mLower;
}
/**
* Get the upper endpoint.
*
* @return a non-{@code null} {@code T} reference
*/
public T getUpper() {
return mUpper;
}
/**
* Checks if the {@code value} is within the bounds of this range.
*
* <p>A value is considered to be within this range if it's {@code >=}
* the lower endpoint <i>and</i> {@code <=} the upper endpoint (using the {@link Comparable}
* interface.)</p>
*
* @param value a non-{@code null} {@code T} reference
* @return {@code true} if the value is within this inclusive range, {@code false} otherwise
*
* @throws NullPointerException if {@code value} was {@code null}
*/
public boolean contains(T value) {
checkNotNull(value, "value must not be null");
boolean gteLower = value.compareTo(mLower) >= 0;
boolean lteUpper = value.compareTo(mUpper) <= 0;
return gteLower && lteUpper;
}
/**
* Checks if another {@code range} is within the bounds of this range.
*
* <p>A range is considered to be within this range if both of its endpoints
* are within this range.</p>
*
* @param range a non-{@code null} {@code T} reference
* @return {@code true} if the range is within this inclusive range, {@code false} otherwise
*
* @throws NullPointerException if {@code range} was {@code null}
*/
public boolean contains(Range<T> range) {
checkNotNull(range, "value must not be null");
boolean gteLower = range.mLower.compareTo(mLower) >= 0;
boolean lteUpper = range.mUpper.compareTo(mUpper) <= 0;
return gteLower && lteUpper;
}
/**
* Compare two ranges for equality.
*
* <p>A range is considered equal if and only if both the lower and upper endpoints
* are also equal.</p>
*
* @return {@code true} if the ranges are equal, {@code false} otherwise
*/
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
} else if (this == obj) {
return true;
} else if (obj instanceof Range) {
@SuppressWarnings("rawtypes")
Range other = (Range) obj;
return mLower.equals(other.mLower) && mUpper.equals(other.mUpper);
}
return false;
}
/**
* Clamps {@code value} to this range.
*
* <p>If the value is within this range, it is returned. Otherwise, if it
* is {@code <} than the lower endpoint, the lower endpoint is returned,
* else the upper endpoint is returned. Comparisons are performed using the
* {@link Comparable} interface.</p>
*
* @param value a non-{@code null} {@code T} reference
* @return {@code value} clamped to this range.
*/
public T clamp(T value) {
checkNotNull(value, "value must not be null");
if (value.compareTo(mLower) < 0) {
return mLower;
} else if (value.compareTo(mUpper) > 0) {
return mUpper;
} else {
return value;
}
}
/**
* Returns the intersection of this range and another {@code range}.
* <p>
* E.g. if a {@code <} b {@code <} c {@code <} d, the
* intersection of [a, c] and [b, d] ranges is [b, c].
* As the endpoints are object references, there is no guarantee
* which specific endpoint reference is used from the input ranges:</p>
* <p>
* E.g. if a {@code ==} a' {@code <} b {@code <} c, the
* intersection of [a, b] and [a', c] ranges could be either
* [a, b] or ['a, b], where [a, b] could be either the exact
* input range, or a newly created range with the same endpoints.</p>
*
* @param range a non-{@code null} {@code Range<T>} reference
* @return the intersection of this range and the other range.
*
* @throws NullPointerException if {@code range} was {@code null}
* @throws IllegalArgumentException if the ranges are disjoint.
*/
public Range<T> intersect(Range<T> range) {
checkNotNull(range, "range must not be null");
int cmpLower = range.mLower.compareTo(mLower);
int cmpUpper = range.mUpper.compareTo(mUpper);
if (cmpLower <= 0 && cmpUpper >= 0) {
// range includes this
return this;
} else if (cmpLower >= 0 && cmpUpper <= 0) {
// this inludes range
return range;
} else {
return Range.create(
cmpLower <= 0 ? mLower : range.mLower,
cmpUpper >= 0 ? mUpper : range.mUpper);
}
}
/**
* Returns the intersection of this range and the inclusive range
* specified by {@code [lower, upper]}.
* <p>
* See {@link #intersect(Range)} for more details.</p>
*
* @param lower a non-{@code null} {@code T} reference
* @param upper a non-{@code null} {@code T} reference
* @return the intersection of this range and the other range
*
* @throws NullPointerException if {@code lower} or {@code upper} was {@code null}
* @throws IllegalArgumentException if the ranges are disjoint.
*/
public Range<T> intersect(T lower, T upper) {
checkNotNull(lower, "lower must not be null");
checkNotNull(upper, "upper must not be null");
int cmpLower = lower.compareTo(mLower);
int cmpUpper = upper.compareTo(mUpper);
if (cmpLower <= 0 && cmpUpper >= 0) {
// [lower, upper] includes this
return this;
} else {
return Range.create(
cmpLower <= 0 ? mLower : lower,
cmpUpper >= 0 ? mUpper : upper);
}
}
/**
* Returns the smallest range that includes this range and
* another {@code range}.
* <p>
* E.g. if a {@code <} b {@code <} c {@code <} d, the
* extension of [a, c] and [b, d] ranges is [a, d].
* As the endpoints are object references, there is no guarantee
* which specific endpoint reference is used from the input ranges:</p>
* <p>
* E.g. if a {@code ==} a' {@code <} b {@code <} c, the
* extension of [a, b] and [a', c] ranges could be either
* [a, c] or ['a, c], where ['a, c] could be either the exact
* input range, or a newly created range with the same endpoints.</p>
*
* @param range a non-{@code null} {@code Range<T>} reference
* @return the extension of this range and the other range.
*
* @throws NullPointerException if {@code range} was {@code null}
*/
public Range<T> extend(Range<T> range) {
checkNotNull(range, "range must not be null");
int cmpLower = range.mLower.compareTo(mLower);
int cmpUpper = range.mUpper.compareTo(mUpper);
if (cmpLower <= 0 && cmpUpper >= 0) {
// other includes this
return range;
} else if (cmpLower >= 0 && cmpUpper <= 0) {
// this inludes other
return this;
} else {
return Range.create(
cmpLower >= 0 ? mLower : range.mLower,
cmpUpper <= 0 ? mUpper : range.mUpper);
}
}
/**
* Returns the smallest range that includes this range and
* the inclusive range specified by {@code [lower, upper]}.
* <p>
* See {@link #extend(Range)} for more details.</p>
*
* @param lower a non-{@code null} {@code T} reference
* @param upper a non-{@code null} {@code T} reference
* @return the extension of this range and the other range.
*
* @throws NullPointerException if {@code lower} or {@code
* upper} was {@code null}
*/
public Range<T> extend(T lower, T upper) {
checkNotNull(lower, "lower must not be null");
checkNotNull(upper, "upper must not be null");
int cmpLower = lower.compareTo(mLower);
int cmpUpper = upper.compareTo(mUpper);
if (cmpLower >= 0 && cmpUpper <= 0) {
// this inludes other
return this;
} else {
return Range.create(
cmpLower >= 0 ? mLower : lower,
cmpUpper <= 0 ? mUpper : upper);
}
}
/**
* Returns the smallest range that includes this range and
* the {@code value}.
* <p>
* See {@link #extend(Range)} for more details, as this method is
* equivalent to {@code extend(Range.create(value, value))}.</p>
*
* @param value a non-{@code null} {@code T} reference
* @return the extension of this range and the value.
*
* @throws NullPointerException if {@code value} was {@code null}
*/
public Range<T> extend(T value) {
checkNotNull(value, "value must not be null");
return extend(value, value);
}
/**
* Return the range as a string representation {@code "[lower, upper]"}.
*
* @return string representation of the range
*/
@Override
public String toString() {
return String.format("[%s, %s]", mLower, mUpper);
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
return HashCodeHelpers.hashCode(mLower, mUpper);
}
private final T mLower;
private final T mUpper;
};
