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// $Id: Dimension.java 64 2006-07-12 22:30:50Z edavis $
/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
* supporting documentation. Further, UCAR requests that the user credit
* UCAR/Unidata in any publications that result from the use of this
* software or in any product that includes this software. The names UCAR
* and/or Unidata, however, may not be used in any advertising or publicity
* to endorse or promote any products or commercial entity unless specific
* written permission is obtained from UCAR/Unidata. The user also
* understands that UCAR/Unidata is not obligated to provide the user with
* any support, consulting, training or assistance of any kind with regard
* to the use, operation and performance of this software nor to provide
* the user with any updates, revisions, new versions or "bug fixes."
*
* THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
* INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package ucar.units;
/**
* Provides support for the concept of "dimension": pairs of base entities and
* exponents.
*
* @author Steven R. Emmerson
* @version $Id: Dimension.java 64 2006-07-12 22:30:50Z edavis $
*/
public abstract class Dimension {
/**
* The individual elements of this dimension.
*
* @serial
*/
protected final Factor[] _factors;
private transient volatile int hashCode;
/**
* Constructs a dimensionless dimension from nothing.
*/
public Dimension() {
this(new Factor[0]);
}
/**
* Constructs from a single Factor.
*
* @param factor
* The single Factor that defines the dimension.
*/
protected Dimension(final Factor factor) {
this(new Factor[] { factor });
}
/**
* Constructs from an array of Factor-s. This is a trusted constructor for
* use by subclasses only.
*
* @param factors
* The factors that define the dimension.
*/
protected Dimension(final Factor[] factors) {
_factors = factors;
}
/**
* Returns the rank of this dimension. The rank is the number of base entity
* and exponent pairs (i.e. the number of Factor-s constituting this
* dimension).
*
* @return The rank of this dimension.
*/
public final int getRank() {
return _factors.length;
}
/**
* Returns the array of Factor-s constituting this dimension.
*
* @return The array of Factor-s constituting this dimension.
*/
public final Factor[] getFactors() {
final Factor[] factors = new Factor[_factors.length];
System.arraycopy(_factors, 0, factors, 0, factors.length);
return factors;
}
/**
* Multiplies this dimension by another dimension.
*
* @param that
* The other dimension.
* @return The product of the Factor-s of this dimension and the Factor-s of
* the other dimension.
*/
protected Factor[] mult(final Dimension that) {
// relys on _factors always sorted
final Factor[] factors1 = _factors;
final Factor[] factors2 = that._factors;
int i1 = 0;
int i2 = 0;
int k = 0;
Factor[] newFactors = new Factor[factors1.length + factors2.length];
for (;;) {
if (i1 == factors1.length) {
final int n = factors2.length - i2;
System.arraycopy(factors2, i2, newFactors, k, n);
k += n;
break;
}
if (i2 == factors2.length) {
final int n = factors1.length - i1;
System.arraycopy(factors1, i1, newFactors, k, n);
k += n;
break;
}
final Factor f1 = factors1[i1];
final Factor f2 = factors2[i2];
final int comp = f1.getID().compareTo(f2.getID());
if (comp < 0) {
newFactors[k++] = f1;
i1++;
}
else if (comp == 0) {
final int exponent = f1.getExponent() + f2.getExponent();
if (exponent != 0) {
newFactors[k++] = new Factor(f1, exponent);
}
i1++;
i2++;
}
else {
newFactors[k++] = f2;
i2++;
}
}
if (k < newFactors.length) {
final Factor[] tmp = new Factor[k];
System.arraycopy(newFactors, 0, tmp, 0, k);
newFactors = tmp;
}
return newFactors;
}
/**
* Raises this dimension to a power.
*
* @param power
* The power to raise this dimension by.
* @return The Factor-s of this dimension raised to the power
* power.
*/
protected Factor[] pow(final int power) {
Factor[] factors;
if (power == 0) {
factors = new Factor[0];
}
else {
factors = getFactors();
if (power != 1) {
for (int i = factors.length; --i >= 0;) {
factors[i] = factors[i].pow(power);
}
}
}
return factors;
}
/**
* Indicates if this Dimension is the reciprocal of another dimension.
*
* @param that
* The other dimension.
* @return true if and only if this dimension is the reciprocal
* of the other dimension.
*/
public final boolean isReciprocalOf(final Dimension that) {
final Factor[] theseFactors = _factors;
final Factor[] thoseFactors = that._factors;
boolean isReciprocalOf;
if (theseFactors.length != thoseFactors.length) {
isReciprocalOf = false;
}
else {
int i;
for (i = theseFactors.length; --i >= 0;) {
if (!theseFactors[i].isReciprocalOf(thoseFactors[i])) {
break;
}
}
isReciprocalOf = i < 0;
}
return isReciprocalOf;
}
/**
* Indicates if this dimension is semantically identical to an object.
*
* @param object
* The object.
* @return true if and only if this dimension is semantically
* identical to object.
*/
@Override
public final boolean equals(final Object object) {
boolean equals;
if (this == object) {
equals = true;
}
else if (!(object instanceof Dimension)) {
equals = false;
}
else {
final Factor[] thatFactors = ((Dimension) object)._factors;
if (_factors.length != thatFactors.length) {
equals = false;
}
else {
int i = _factors.length;
while (--i >= 0) {
if (!_factors[i].equals(thatFactors[i])) {
break;
}
}
equals = i < 0;
}
}
return equals;
}
/**
* Returns the hash code of this instance.
*
* @return The hash code of this instance.
*/
@Override
public int hashCode() {
if (hashCode == 0) {
int hash = 0;
for (int i = 0; i < _factors.length; i++) {
hash ^= _factors[i].hashCode();
}
hashCode = hash;
}
return hashCode;
}
/**
* Indicates if this dimension is dimensionless. A dimension is
* dimensionless if it has no Factor-s or if all Factor-s are, themselves,
* dimensionless.
*
* @return true if and only if this dimension is dimensionless.
*/
public final boolean isDimensionless() {
for (int i = _factors.length; --i >= 0;) {
if (!_factors[i].isDimensionless()) {
return false;
}
}
return true;
}
/**
* Returns the string representation of this dimension.
*
* @return The string representation of this dimension.
*/
@Override
public String toString() {
final StringBuffer buf = new StringBuffer(40);
for (int i = 0; i < _factors.length; i++) {
buf.append(_factors[i]).append('.');
}
if (buf.length() != 0) {
buf.setLength(buf.length() - 1);
}
return buf.toString();
}
}
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