src/com/google/common/primitives/Doubles.java - platform/external/guava - Git at Google

 /*
  * Copyright (C) 2008 Google Inc.
  *
  * 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 com.google.common.primitives;

 import com.google.common.annotations.GwtCompatible;

 import java.io.Serializable;
 import java.util.AbstractList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;

 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;

 /**
  * Static utility methods pertaining to {@code double} primitives, that are not
  * already found in either {@link Double} or {@link Arrays}.
  *
  * @author Kevin Bourrillion
  * @since 2009.09.15 <b>tentative</b>
  */
 @GwtCompatible
 public final class Doubles {
   private Doubles() {}

   /**
    * Returns a hash code for {@code value}; equal to the result of invoking
    * {@code ((Double) value).hashCode()}.
    *
    * @param value a primitive {@code double} value
    * @return a hash code for the value
    */
   public static int hashCode(double value) {
     return ((Double) value).hashCode();
     // TODO: do it this way when we can (GWT problem):
     // long bits = Double.doubleToLongBits(value);
     // return (int)(bits ^ (bits >>> 32));
   }

   /**
    * Compares the two specified {@code double} values. The sign of the value
    * returned is the same as that of <code>((Double) a).{@linkplain
    * Double#compareTo compareTo}(b)</code>. As with that method, {@code NaN} is
    * treated as greater than all other values, and {@code 0.0 > -0.0}.
    *
    * @param a the first {@code double} to compare
    * @param b the second {@code double} to compare
    * @return a negative value if {@code a} is less than {@code b}; a positive
    *     value if {@code a} is greater than {@code b}; or zero if they are equal
    */
   public static int compare(double a, double b) {
     return Double.compare(a, b);
   }

   /**
    * Returns {@code true} if {@code target} is present as an element anywhere in
    * {@code array}. Note that this always returns {@code false} when {@code
    * target} is {@code NaN}.
    *
    * @param array an array of {@code double} values, possibly empty
    * @param target a primitive {@code double} value
    * @return {@code true} if {@code array[i] == target} for some value of {@code
    *     i}
    */
   public static boolean contains(double[] array, double target) {
     for (double value : array) {
       if (value == target) {
         return true;
       }
     }
     return false;
   }

   /**
    * Returns the index of the first appearance of the value {@code target} in
    * {@code array}. Note that this always returns {@code -1} when {@code target}
    * is {@code NaN}.
    *
    * @param array an array of {@code double} values, possibly empty
    * @param target a primitive {@code double} value
    * @return the least index {@code i} for which {@code array[i] == target}, or
    *     {@code -1} if no such index exists.
    */
   public static int indexOf(double[] array, double target) {
     return indexOf(array, target, 0, array.length);
   }

   // TODO: consider making this public
   private static int indexOf(
       double[] array, double target, int start, int end) {
     for (int i = start; i < end; i++) {
       if (array[i] == target) {
         return i;
       }
     }
     return -1;
   }

   /**
    * Returns the start position of the first occurrence of the specified {@code
    * target} within {@code array}, or {@code -1} if there is no such occurrence.
    *
    * <p>More formally, returns the lowest index {@code i} such that {@code
    * java.util.Arrays.copyOfRange(array, i, i + target.length)} contains exactly
    * the same elements as {@code target}.
    *
    * <p>Note that this always returns {@code -1} when {@code target} contains
    * {@code NaN}.
    *
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
   public static int indexOf(double[] array, double[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
     if (target.length == 0) {
       return 0;
     }

     outer:
     for (int i = 0; i < array.length - target.length + 1; i++) {
       for (int j = 0; j < target.length; j++) {
         if (array[i + j] != target[j]) {
           continue outer;
         }
       }
       return i;
     }
     return -1;
   }

   /**
    * Returns the index of the last appearance of the value {@code target} in
    * {@code array}. Note that this always returns {@code -1} when {@code target}
    * is {@code NaN}.
    *
    * @param array an array of {@code double} values, possibly empty
    * @param target a primitive {@code double} value
    * @return the greatest index {@code i} for which {@code array[i] == target},
    *     or {@code -1} if no such index exists.
    */
   public static int lastIndexOf(double[] array, double target) {
     return lastIndexOf(array, target, 0, array.length);
   }

   // TODO: consider making this public
   private static int lastIndexOf(
       double[] array, double target, int start, int end) {
     for (int i = end - 1; i >= start; i--) {
       if (array[i] == target) {
         return i;
       }
     }
     return -1;
   }

   /**
    * Returns the least value present in {@code array}, using the same rules of
    * comparison as {@link Math#min(double, double)}.
    *
    * @param array a <i>nonempty</i> array of {@code double} values
    * @return the value present in {@code array} that is less than or equal to
    *     every other value in the array
    * @throws IllegalArgumentException if {@code array} is empty
    */
   public static double min(double... array) {
     checkArgument(array.length > 0);
     double min = array[0];
     for (int i = 1; i < array.length; i++) {
       min = Math.min(min, array[i]);
     }
     return min;
   }

   /**
    * Returns the greatest value present in {@code array}, using the same rules
    * of comparison as {@link Math#max(double, double)}.
    *
    * @param array a <i>nonempty</i> array of {@code double} values
    * @return the value present in {@code array} that is greater than or equal to
    *     every other value in the array
    * @throws IllegalArgumentException if {@code array} is empty
    */
   public static double max(double... array) {
     checkArgument(array.length > 0);
     double max = array[0];
     for (int i = 1; i < array.length; i++) {
       max = Math.max(max, array[i]);
     }
     return max;
   }

   /**
    * Returns the values from each provided array combined into a single array.
    * For example, {@code concat(new double[] {a, b}, new double[] {}, new
    * double[] {c}} returns the array {@code {a, b, c}}.
    *
    * @param arrays zero or more {@code double} arrays
    * @return a single array containing all the values from the source arrays, in
    *     order
    */
   public static double[] concat(double[]... arrays) {
     int length = 0;
     for (double[] array : arrays) {
       length += array.length;
     }
     double[] result = new double[length];
     int pos = 0;
     for (double[] array : arrays) {
       System.arraycopy(array, 0, result, pos, array.length);
       pos += array.length;
     }
     return result;
   }

   /**
    * Returns an array containing the same values as {@code array}, but
    * guaranteed to be of a specified minimum length. If {@code array} already
    * has a length of at least {@code minLength}, it is returned directly.
    * Otherwise, a new array of size {@code minLength + padding} is returned,
    * containing the values of {@code array}, and zeroes in the remaining places.
    *
    * @param array the source array
    * @param minLength the minimum length the returned array must guarantee
    * @param padding an extra amount to "grow" the array by if growth is
    *     necessary
    * @throws IllegalArgumentException if {@code minLength} or {@code padding} is
    *     negative
    * @return an array containing the values of {@code array}, with guaranteed
    *     minimum length {@code minLength}
    */
   public static double[] ensureCapacity(
       double[] array, int minLength, int padding) {
     checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
     checkArgument(padding >= 0, "Invalid padding: %s", padding);
     return (array.length < minLength)
         ? copyOf(array, minLength + padding)
         : array;
   }

   // Arrays.copyOf() requires Java 6
   private static double[] copyOf(double[] original, int length) {
     double[] copy = new double[length];
     System.arraycopy(original, 0, copy, 0, Math.min(original.length, length));
     return copy;
   }

   /**
    * Returns a string containing the supplied {@code double} values, converted
    * to strings as specified by {@link Double#toString(double)}, and separated
    * by {@code separator}. For example, {@code join("-", 1.0, 2.0, 3.0)} returns
    * the string {@code "1.0-2.0-3.0"}.
    *
    * @param separator the text that should appear between consecutive values in
    *     the resulting string (but not at the start or end)
    * @param array an array of {@code double} values, possibly empty
    */
   public static String join(String separator, double... array) {
     checkNotNull(separator);
     if (array.length == 0) {
       return "";
     }

     // For pre-sizing a builder, just get the right order of magnitude
     StringBuilder builder = new StringBuilder(array.length * 12);
     builder.append(array[0]);
     for (int i = 1; i < array.length; i++) {
       builder.append(separator).append(array[i]);
     }
     return builder.toString();
   }

   /**
    * Returns a comparator that compares two {@code double} arrays
    * lexicographically. That is, it compares, using {@link
    * #compare(double, double)}), the first pair of values that follow any
    * common prefix, or when one array is a prefix of the other, treats the
    * shorter array as the lesser. For example,
    * {@code [] < [1.0] < [1.0, 2.0] < [2.0]}.
    *
    * <p>The returned comparator is inconsistent with {@link
    * Object#equals(Object)} (since arrays support only identity equality), but
    * it is consistent with {@link Arrays#equals(double[], double[])}.
    *
    * @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order">
    *     Lexicographical order</a> article at Wikipedia
    * @since 2010.01.04 <b>tentative</b>
    */
   public static Comparator<double[]> lexicographicalComparator() {
     return LexicographicalComparator.INSTANCE;
   }

   private enum LexicographicalComparator implements Comparator<double[]> {
     INSTANCE;

     public int compare(double[] left, double[] right) {
       int minLength = Math.min(left.length, right.length);
       for (int i = 0; i < minLength; i++) {
         int result = Doubles.compare(left[i], right[i]);
         if (result != 0) {
           return result;
         }
       }
       return left.length - right.length;
     }
   }

   /**
    * Copies a collection of {@code Double} instances into a new array of
    * primitive {@code double} values.
    *
    * <p>Elements are copied from the argument collection as if by {@code
    * collection.toArray()}.  Calling this method is as thread-safe as calling
    * that method.
    *
    * @param collection a collection of {@code Double} objects
    * @return an array containing the same values as {@code collection}, in the
    *     same order, converted to primitives
    * @throws NullPointerException if {@code collection} or any of its elements
    *     is null
    */
   public static double[] toArray(Collection<Double> collection) {
     if (collection instanceof DoubleArrayAsList) {
       return ((DoubleArrayAsList) collection).toDoubleArray();
     }

     Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
     double[] array = new double[len];
     for (int i = 0; i < len; i++) {
       array[i] = (Double) boxedArray[i];
     }
     return array;
   }

   /**
    * Returns a fixed-size list backed by the specified array, similar to {@link
    * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)},
    * but any attempt to set a value to {@code null} will result in a {@link
    * NullPointerException}.
    *
    * <p>The returned list maintains the values, but not the identities, of
    * {@code Double} objects written to or read from it.  For example, whether
    * {@code list.get(0) == list.get(0)} is true for the returned list is
    * unspecified.
    *
    * <p>The returned list may have unexpected behavior if it contains {@code
    * NaN}, or if {@code NaN} is used as a parameter to any of its methods.
    *
    * @param backingArray the array to back the list
    * @return a list view of the array
    */
   public static List<Double> asList(double... backingArray) {
     if (backingArray.length == 0) {
       return Collections.emptyList();
     }
     return new DoubleArrayAsList(backingArray);
   }

   @GwtCompatible
   private static class DoubleArrayAsList extends AbstractList<Double>
       implements RandomAccess, Serializable {
     final double[] array;
     final int start;
     final int end;

     DoubleArrayAsList(double[] array) {
       this(array, 0, array.length);
     }

     DoubleArrayAsList(double[] array, int start, int end) {
       this.array = array;
       this.start = start;
       this.end = end;
     }

     @Override public int size() {
       return end - start;
     }

     @Override public boolean isEmpty() {
       return false;
     }

     @Override public Double get(int index) {
       checkElementIndex(index, size());
       return array[start + index];
     }

     @Override public boolean contains(Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Double)
           && Doubles.indexOf(array, (Double) target, start, end) != -1;
     }

     @Override public int indexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.indexOf(array, (Double) target, start, end);
         if (i >= 0) {
           return i - start;
         }
       }
       return -1;
     }

     @Override public int lastIndexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.lastIndexOf(array, (Double) target, start, end);
         if (i >= 0) {
           return i - start;
         }
       }
       return -1;
     }

     @Override public Double set(int index, Double element) {
       checkElementIndex(index, size());
       double oldValue = array[start + index];
       array[start + index] = element;
       return oldValue;
     }

     /** In GWT, List and AbstractList do not have the subList method. */
     /*@Override*/ public List<Double> subList(int fromIndex, int toIndex) {
       int size = size();
       checkPositionIndexes(fromIndex, toIndex, size);
       if (fromIndex == toIndex) {
         return Collections.emptyList();
       }
       return new DoubleArrayAsList(array, start + fromIndex, start + toIndex);
     }

     @Override public boolean equals(Object object) {
       if (object == this) {
         return true;
       }
       if (object instanceof DoubleArrayAsList) {
         DoubleArrayAsList that = (DoubleArrayAsList) object;
         int size = size();
         if (that.size() != size) {
           return false;
         }
         for (int i = 0; i < size; i++) {
           if (array[start + i] != that.array[that.start + i]) {
             return false;
           }
         }
         return true;
       }
       return super.equals(object);
     }

     @Override public int hashCode() {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Doubles.hashCode(array[i]);
       }
       return result;
     }

     @Override public String toString() {
       StringBuilder builder = new StringBuilder(size() * 12);
       builder.append('[').append(array[start]);
       for (int i = start + 1; i < end; i++) {
         builder.append(", ").append(array[i]);
       }
       return builder.append(']').toString();
     }

     double[] toDoubleArray() {
       // Arrays.copyOfRange() requires Java 6
       int size = size();
       double[] result = new double[size];
       System.arraycopy(array, start, result, 0, size);
       return result;
     }

     private static final long serialVersionUID = 0;
   }
 }
	/*
	* Copyright (C) 2008 Google Inc.
	*
	* 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 com.google.common.primitives;

	import com.google.common.annotations.GwtCompatible;

	import java.io.Serializable;
	import java.util.AbstractList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Comparator;
	import java.util.List;
	import java.util.RandomAccess;

	import static com.google.common.base.Preconditions.checkArgument;
	import static com.google.common.base.Preconditions.checkElementIndex;
	import static com.google.common.base.Preconditions.checkNotNull;
	import static com.google.common.base.Preconditions.checkPositionIndexes;

	/**
	* Static utility methods pertaining to {@code double} primitives, that are not
	* already found in either {@link Double} or {@link Arrays}.
	*
	* @author Kevin Bourrillion
	* @since 2009.09.15 <b>tentative</b>
	*/
	@GwtCompatible
	public final class Doubles {
	private Doubles() {}

	/**
	* Returns a hash code for {@code value}; equal to the result of invoking
	* {@code ((Double) value).hashCode()}.
	*
	* @param value a primitive {@code double} value
	* @return a hash code for the value
	*/
	public static int hashCode(double value) {
	return ((Double) value).hashCode();
	// TODO: do it this way when we can (GWT problem):
	// long bits = Double.doubleToLongBits(value);
	// return (int)(bits ^ (bits >>> 32));
	}

	/**
	* Compares the two specified {@code double} values. The sign of the value
	* returned is the same as that of <code>((Double) a).{@linkplain
	* Double#compareTo compareTo}(b)</code>. As with that method, {@code NaN} is
	* treated as greater than all other values, and {@code 0.0 > -0.0}.
	*
	* @param a the first {@code double} to compare
	* @param b the second {@code double} to compare
	* @return a negative value if {@code a} is less than {@code b}; a positive
	* value if {@code a} is greater than {@code b}; or zero if they are equal
	*/
	public static int compare(double a, double b) {
	return Double.compare(a, b);
	}

	/**
	* Returns {@code true} if {@code target} is present as an element anywhere in
	* {@code array}. Note that this always returns {@code false} when {@code
	* target} is {@code NaN}.
	*
	* @param array an array of {@code double} values, possibly empty
	* @param target a primitive {@code double} value
	* @return {@code true} if {@code array[i] == target} for some value of {@code
	* i}
	*/
	public static boolean contains(double[] array, double target) {
	for (double value : array) {
	if (value == target) {
	return true;
	}
	}
	return false;
	}

	/**
	* Returns the index of the first appearance of the value {@code target} in
	* {@code array}. Note that this always returns {@code -1} when {@code target}
	* is {@code NaN}.
	*
	* @param array an array of {@code double} values, possibly empty
	* @param target a primitive {@code double} value
	* @return the least index {@code i} for which {@code array[i] == target}, or
	* {@code -1} if no such index exists.
	*/
	public static int indexOf(double[] array, double target) {
	return indexOf(array, target, 0, array.length);
	}

	// TODO: consider making this public
	private static int indexOf(
	double[] array, double target, int start, int end) {
	for (int i = start; i < end; i++) {
	if (array[i] == target) {
	return i;
	}
	}
	return -1;
	}

	/**
	* Returns the start position of the first occurrence of the specified {@code
	* target} within {@code array}, or {@code -1} if there is no such occurrence.
	*
	* <p>More formally, returns the lowest index {@code i} such that {@code
	* java.util.Arrays.copyOfRange(array, i, i + target.length)} contains exactly
	* the same elements as {@code target}.
	*
	* <p>Note that this always returns {@code -1} when {@code target} contains
	* {@code NaN}.
	*
	* @param array the array to search for the sequence {@code target}
	* @param target the array to search for as a sub-sequence of {@code array}
	*/
	public static int indexOf(double[] array, double[] target) {
	checkNotNull(array, "array");
	checkNotNull(target, "target");
	if (target.length == 0) {
	return 0;
	}

	outer:
	for (int i = 0; i < array.length - target.length + 1; i++) {
	for (int j = 0; j < target.length; j++) {
	if (array[i + j] != target[j]) {
	continue outer;
	}
	}
	return i;
	}
	return -1;
	}

	/**
	* Returns the index of the last appearance of the value {@code target} in
	* {@code array}. Note that this always returns {@code -1} when {@code target}
	* is {@code NaN}.
	*
	* @param array an array of {@code double} values, possibly empty
	* @param target a primitive {@code double} value
	* @return the greatest index {@code i} for which {@code array[i] == target},
	* or {@code -1} if no such index exists.
	*/
	public static int lastIndexOf(double[] array, double target) {
	return lastIndexOf(array, target, 0, array.length);
	}

	// TODO: consider making this public
	private static int lastIndexOf(
	double[] array, double target, int start, int end) {
	for (int i = end - 1; i >= start; i--) {
	if (array[i] == target) {
	return i;
	}
	}
	return -1;
	}

	/**
	* Returns the least value present in {@code array}, using the same rules of
	* comparison as {@link Math#min(double, double)}.
	*
	* @param array a <i>nonempty</i> array of {@code double} values
	* @return the value present in {@code array} that is less than or equal to
	* every other value in the array
	* @throws IllegalArgumentException if {@code array} is empty
	*/
	public static double min(double... array) {
	checkArgument(array.length > 0);
	double min = array[0];
	for (int i = 1; i < array.length; i++) {
	min = Math.min(min, array[i]);
	}
	return min;
	}

	/**
	* Returns the greatest value present in {@code array}, using the same rules
	* of comparison as {@link Math#max(double, double)}.
	*
	* @param array a <i>nonempty</i> array of {@code double} values
	* @return the value present in {@code array} that is greater than or equal to
	* every other value in the array
	* @throws IllegalArgumentException if {@code array} is empty
	*/
	public static double max(double... array) {
	checkArgument(array.length > 0);
	double max = array[0];
	for (int i = 1; i < array.length; i++) {
	max = Math.max(max, array[i]);
	}
	return max;
	}

	/**
	* Returns the values from each provided array combined into a single array.
	* For example, {@code concat(new double[] {a, b}, new double[] {}, new
	* double[] {c}} returns the array {@code {a, b, c}}.
	*
	* @param arrays zero or more {@code double} arrays
	* @return a single array containing all the values from the source arrays, in
	* order
	*/
	public static double[] concat(double[]... arrays) {
	int length = 0;
	for (double[] array : arrays) {
	length += array.length;
	}
	double[] result = new double[length];
	int pos = 0;
	for (double[] array : arrays) {
	System.arraycopy(array, 0, result, pos, array.length);
	pos += array.length;
	}
	return result;
	}

	/**
	* Returns an array containing the same values as {@code array}, but
	* guaranteed to be of a specified minimum length. If {@code array} already
	* has a length of at least {@code minLength}, it is returned directly.
	* Otherwise, a new array of size {@code minLength + padding} is returned,
	* containing the values of {@code array}, and zeroes in the remaining places.
	*
	* @param array the source array
	* @param minLength the minimum length the returned array must guarantee
	* @param padding an extra amount to "grow" the array by if growth is
	* necessary
	* @throws IllegalArgumentException if {@code minLength} or {@code padding} is
	* negative
	* @return an array containing the values of {@code array}, with guaranteed
	* minimum length {@code minLength}
	*/
	public static double[] ensureCapacity(
	double[] array, int minLength, int padding) {
	checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
	checkArgument(padding >= 0, "Invalid padding: %s", padding);
	return (array.length < minLength)
	? copyOf(array, minLength + padding)
	: array;
	}

	// Arrays.copyOf() requires Java 6
	private static double[] copyOf(double[] original, int length) {
	double[] copy = new double[length];
	System.arraycopy(original, 0, copy, 0, Math.min(original.length, length));
	return copy;
	}

	/**
	* Returns a string containing the supplied {@code double} values, converted
	* to strings as specified by {@link Double#toString(double)}, and separated
	* by {@code separator}. For example, {@code join("-", 1.0, 2.0, 3.0)} returns
	* the string {@code "1.0-2.0-3.0"}.
	*
	* @param separator the text that should appear between consecutive values in
	* the resulting string (but not at the start or end)
	* @param array an array of {@code double} values, possibly empty
	*/
	public static String join(String separator, double... array) {
	checkNotNull(separator);
	if (array.length == 0) {
	return "";
	}

	// For pre-sizing a builder, just get the right order of magnitude
	StringBuilder builder = new StringBuilder(array.length * 12);
	builder.append(array[0]);
	for (int i = 1; i < array.length; i++) {
	builder.append(separator).append(array[i]);
	}
	return builder.toString();
	}

	/**
	* Returns a comparator that compares two {@code double} arrays
	* lexicographically. That is, it compares, using {@link
	* #compare(double, double)}), the first pair of values that follow any
	* common prefix, or when one array is a prefix of the other, treats the
	* shorter array as the lesser. For example,
	* {@code [] < [1.0] < [1.0, 2.0] < [2.0]}.
	*
	* <p>The returned comparator is inconsistent with {@link
	* Object#equals(Object)} (since arrays support only identity equality), but
	* it is consistent with {@link Arrays#equals(double[], double[])}.
	*
	* @see <a href="http://en.wikipedia.org/wiki/Lexicographical_order">
	* Lexicographical order</a> article at Wikipedia
	* @since 2010.01.04 <b>tentative</b>
	*/
	public static Comparator<double[]> lexicographicalComparator() {
	return LexicographicalComparator.INSTANCE;
	}

	private enum LexicographicalComparator implements Comparator<double[]> {
	INSTANCE;

	public int compare(double[] left, double[] right) {
	int minLength = Math.min(left.length, right.length);
	for (int i = 0; i < minLength; i++) {
	int result = Doubles.compare(left[i], right[i]);
	if (result != 0) {
	return result;
	}
	}
	return left.length - right.length;
	}
	}

	/**
	* Copies a collection of {@code Double} instances into a new array of
	* primitive {@code double} values.
	*
	* <p>Elements are copied from the argument collection as if by {@code
	* collection.toArray()}. Calling this method is as thread-safe as calling
	* that method.
	*
	* @param collection a collection of {@code Double} objects
	* @return an array containing the same values as {@code collection}, in the
	* same order, converted to primitives
	* @throws NullPointerException if {@code collection} or any of its elements
	* is null
	*/
	public static double[] toArray(Collection<Double> collection) {
	if (collection instanceof DoubleArrayAsList) {
	return ((DoubleArrayAsList) collection).toDoubleArray();
	}

	Object[] boxedArray = collection.toArray();
	int len = boxedArray.length;
	double[] array = new double[len];
	for (int i = 0; i < len; i++) {
	array[i] = (Double) boxedArray[i];
	}
	return array;
	}

	/**
	* Returns a fixed-size list backed by the specified array, similar to {@link
	* Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)},
	* but any attempt to set a value to {@code null} will result in a {@link
	* NullPointerException}.
	*
	* <p>The returned list maintains the values, but not the identities, of
	* {@code Double} objects written to or read from it. For example, whether
	* {@code list.get(0) == list.get(0)} is true for the returned list is
	* unspecified.
	*
	* <p>The returned list may have unexpected behavior if it contains {@code
	* NaN}, or if {@code NaN} is used as a parameter to any of its methods.
	*
	* @param backingArray the array to back the list
	* @return a list view of the array
	*/
	public static List<Double> asList(double... backingArray) {
	if (backingArray.length == 0) {
	return Collections.emptyList();
	}
	return new DoubleArrayAsList(backingArray);
	}

	@GwtCompatible
	private static class DoubleArrayAsList extends AbstractList<Double>
	implements RandomAccess, Serializable {
	final double[] array;
	final int start;
	final int end;

	DoubleArrayAsList(double[] array) {
	this(array, 0, array.length);
	}

	DoubleArrayAsList(double[] array, int start, int end) {
	this.array = array;
	this.start = start;
	this.end = end;
	}

	@Override public int size() {
	return end - start;
	}

	@Override public boolean isEmpty() {
	return false;
	}

	@Override public Double get(int index) {
	checkElementIndex(index, size());
	return array[start + index];
	}

	@Override public boolean contains(Object target) {
	// Overridden to prevent a ton of boxing
	return (target instanceof Double)
	&& Doubles.indexOf(array, (Double) target, start, end) != -1;
	}

	@Override public int indexOf(Object target) {
	// Overridden to prevent a ton of boxing
	if (target instanceof Double) {
	int i = Doubles.indexOf(array, (Double) target, start, end);
	if (i >= 0) {
	return i - start;
	}
	}
	return -1;
	}

	@Override public int lastIndexOf(Object target) {
	// Overridden to prevent a ton of boxing
	if (target instanceof Double) {
	int i = Doubles.lastIndexOf(array, (Double) target, start, end);
	if (i >= 0) {
	return i - start;
	}
	}
	return -1;
	}

	@Override public Double set(int index, Double element) {
	checkElementIndex(index, size());
	double oldValue = array[start + index];
	array[start + index] = element;
	return oldValue;
	}

	/** In GWT, List and AbstractList do not have the subList method. */
	/@Override/ public List<Double> subList(int fromIndex, int toIndex) {
	int size = size();
	checkPositionIndexes(fromIndex, toIndex, size);
	if (fromIndex == toIndex) {
	return Collections.emptyList();
	}
	return new DoubleArrayAsList(array, start + fromIndex, start + toIndex);
	}

	@Override public boolean equals(Object object) {
	if (object == this) {
	return true;
	}
	if (object instanceof DoubleArrayAsList) {
	DoubleArrayAsList that = (DoubleArrayAsList) object;
	int size = size();
	if (that.size() != size) {
	return false;
	}
	for (int i = 0; i < size; i++) {
	if (array[start + i] != that.array[that.start + i]) {
	return false;
	}
	}
	return true;
	}
	return super.equals(object);
	}

	@Override public int hashCode() {
	int result = 1;
	for (int i = start; i < end; i++) {
	result = 31 * result + Doubles.hashCode(array[i]);
	}
	return result;
	}

	@Override public String toString() {
	StringBuilder builder = new StringBuilder(size() * 12);
	builder.append('[').append(array[start]);
	for (int i = start + 1; i < end; i++) {
	builder.append(", ").append(array[i]);
	}
	return builder.append(']').toString();
	}

	double[] toDoubleArray() {
	// Arrays.copyOfRange() requires Java 6
	int size = size();
	double[] result = new double[size];
	System.arraycopy(array, start, result, 0, size);
	return result;
	}

	private static final long serialVersionUID = 0;
	}
	}