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  /*
   * Copyright (C) 2008 The Guava Authors
   *
   * 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 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;
 import static java.lang.Double.NEGATIVE_INFINITY;
 import static java.lang.Double.POSITIVE_INFINITY;
 
 
 import java.util.List;
Static utility methods pertaining to double primitives, that are not already found in either java.lang.Double or java.util.Arrays.

See the Guava User Guide article on primitive utilities.

Author(s):
Kevin Bourrillion
Since:
1.0
 
 public final class Doubles {
   private Doubles() {}

  
The number of bytes required to represent a primitive double value.

Since:
10.0
 
   public static final int BYTES = . / .;

  
Returns a hash code for value; equal to the result of invoking ((Double) value).hashCode().

Parameters:
value a primitive double value
Returns:
a hash code for the value
 
   public static int hashCode(double value) {
     return ((Doublevalue).hashCode();
     // TODO(kevinb): do it this way when we can (GWT problem):
     // long bits = Double.doubleToLongBits(value);
     // return (int)(bits ^ (bits >>> 32));
   }

  
Compares the two specified double values. The sign of the value returned is the same as that of ((Double) a).java.lang.Double.compareTo(java.lang.Double)(b). As with that method, NaN is treated as greater than all other values, and 0.0 > -0.0.

Parameters:
a the first double to compare
b the second double to compare
Returns:
a negative value if a is less than b; a positive value if a is greater than b; or zero if they are equal
 
   public static int compare(double adouble b) {
     return Double.compare(ab);
   }

  
Returns true if value represents a real number. This is equivalent to, but not necessarily implemented as, !(Double.isInfinite(value) || Double.isNaN(value)).

Since:
10.0
 
   public static boolean isFinite(double value) {
     return  < value & value < ;
   }

  
Returns true if target is present as an element anywhere in array. Note that this always returns false when target is NaN.

Parameters:
array an array of double values, possibly empty
target a primitive double value
Returns:
true if array[i] == target for some value of i
  public static boolean contains(double[] arraydouble target) {
    for (double value : array) {
      if (value == target) {
        return true;
      }
    }
    return false;
  }

  
Returns the index of the first appearance of the value target in array. Note that this always returns -1 when target is NaN.

Parameters:
array an array of double values, possibly empty
target a primitive double value
Returns:
the least index i for which array[i] == target, or -1 if no such index exists.
  public static int indexOf(double[] arraydouble target) {
    return indexOf(arraytarget, 0, array.length);
  }
  // TODO(kevinb): consider making this public
  private static int indexOf(
      double[] arraydouble targetint startint end) {
    for (int i = starti < endi++) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  
Returns the start position of the first occurrence of the specified target within array, or -1 if there is no such occurrence.

More formally, returns the lowest index i such that java.util.Arrays.copyOfRange(array, i, i + target.length) contains exactly the same elements as target.

Note that this always returns -1 when target contains NaN.

Parameters:
array the array to search for the sequence target
target the array to search for as a sub-sequence of array
  public static int indexOf(double[] arraydouble[] 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.lengthj++) {
        if (array[i + j] != target[j]) {
          continue outer;
        }
      }
      return i;
    }
    return -1;
  }

  
Returns the index of the last appearance of the value target in array. Note that this always returns -1 when target is NaN.

Parameters:
array an array of double values, possibly empty
target a primitive double value
Returns:
the greatest index i for which array[i] == target, or -1 if no such index exists.
  public static int lastIndexOf(double[] arraydouble target) {
    return lastIndexOf(arraytarget, 0, array.length);
  }
  // TODO(kevinb): consider making this public
  private static int lastIndexOf(
      double[] arraydouble targetint startint end) {
    for (int i = end - 1; i >= starti--) {
      if (array[i] == target) {
        return i;
      }
    }
    return -1;
  }

  
Returns the least value present in array, using the same rules of comparison as java.lang.Math.min(double,double).

Parameters:
array a nonempty array of double values
Returns:
the value present in array that is less than or equal to every other value in the array
Throws:
java.lang.IllegalArgumentException if array is empty
  public static double min(double... array) {
    checkArgument(array.length > 0);
    double min = array[0];
    for (int i = 1; i < array.lengthi++) {
      min = Math.min(minarray[i]);
    }
    return min;
  }

  
Returns the greatest value present in array, using the same rules of comparison as java.lang.Math.max(double,double).

Parameters:
array a nonempty array of double values
Returns:
the value present in array that is greater than or equal to every other value in the array
Throws:
java.lang.IllegalArgumentException if array is empty
  public static double max(double... array) {
    checkArgument(array.length > 0);
    double max = array[0];
    for (int i = 1; i < array.lengthi++) {
      max = Math.max(maxarray[i]);
    }
    return max;
  }

  
Returns the values from each provided array combined into a single array. For example, concat(new double[] {a, b, new double[] {}, new double[] {c}} returns the array {a, b, c}.

Parameters:
arrays zero or more double arrays
Returns:
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, resultposarray.length);
      pos += array.length;
    }
    return result;
  }

  
Returns an array containing the same values as array, but guaranteed to be of a specified minimum length. If array already has a length of at least minLength, it is returned directly. Otherwise, a new array of size minLength + padding is returned, containing the values of array, and zeroes in the remaining places.

Parameters:
array the source array
minLength the minimum length the returned array must guarantee
padding an extra amount to "grow" the array by if growth is necessary
Returns:
an array containing the values of array, with guaranteed minimum length minLength
Throws:
java.lang.IllegalArgumentException if minLength or padding is negative
  public static double[] ensureCapacity(
      double[] arrayint minLengthint padding) {
    checkArgument(minLength >= 0, "Invalid minLength: %s"minLength);
    checkArgument(padding >= 0, "Invalid padding: %s"padding);
    return (array.length < minLength)
        ? copyOf(arrayminLength + padding)
        : array;
  }
  // Arrays.copyOf() requires Java 6
  private static double[] copyOf(double[] originalint length) {
    double[] copy = new double[length];
    System.arraycopy(original, 0, copy, 0, Math.min(original.lengthlength));
    return copy;
  }

  
Returns a string containing the supplied double values, converted to strings as specified by java.lang.Double.toString(double), and separated by separator. For example, join("-", 1.0, 2.0, 3.0) returns the string "1.0-2.0-3.0".

Note that java.lang.Double.toString(double) formats double differently in GWT sometimes. In the previous example, it returns the string "1-2-3".

Parameters:
separator the text that should appear between consecutive values in the resulting string (but not at the start or end)
array an array of double values, possibly empty
  public static String join(String separatordouble... 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.lengthi++) {
      builder.append(separator).append(array[i]);
    }
    return builder.toString();
  }

  
Returns a comparator that compares two double arrays lexicographically. That is, it compares, using 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, [] < [1.0] < [1.0, 2.0] < [2.0].

The returned comparator is inconsistent with java.lang.Object.equals(java.lang.Object) (since arrays support only identity equality), but it is consistent with java.util.Arrays.equals(double[],double[]).

Since:
2.0
See also:
Lexicographical order article at Wikipedia
  public static Comparator<double[]> lexicographicalComparator() {
  }
  private enum LexicographicalComparator implements Comparator<double[]> {
    INSTANCE;
    @Override
    public int compare(double[] leftdouble[] right) {
      int minLength = Math.min(left.lengthright.length);
      for (int i = 0; i < minLengthi++) {
        int result = Doubles.compare(left[i], right[i]);
        if (result != 0) {
          return result;
        }
      }
      return left.length - right.length;
    }
  }

  
Returns an array containing each value of collection, converted to a double value in the manner of java.lang.Number.doubleValue().

Elements are copied from the argument collection as if by collection.toArray(). Calling this method is as thread-safe as calling that method.

Parameters:
collection a collection of Number instances
Returns:
an array containing the same values as collection, in the same order, converted to primitives
Throws:
java.lang.NullPointerException if collection or any of its elements is null
Since:
1.0 (parameter was Collection<Double> before 12.0)
  public static double[] toArray(Collection<? extends Numbercollection) {
    if (collection instanceof DoubleArrayAsList) {
      return ((DoubleArrayAsListcollection).toDoubleArray();
    }
    Object[] boxedArray = collection.toArray();
    int len = boxedArray.length;
    double[] array = new double[len];
    for (int i = 0; i < leni++) {
      // checkNotNull for GWT (do not optimize)
      array[i] = ((NumbercheckNotNull(boxedArray[i])).doubleValue();
    }
    return array;
  }

  
Returns a fixed-size list backed by the specified array, similar to java.util.Arrays.asList(java.lang.Object[]). The list supports java.util.List.set(int,java.lang.Object), but any attempt to set a value to null will result in a java.lang.NullPointerException.

The returned list maintains the values, but not the identities, of Double objects written to or read from it. For example, whether list.get(0) == list.get(0) is true for the returned list is unspecified.

The returned list may have unexpected behavior if it contains NaN, or if NaN is used as a parameter to any of its methods.

Parameters:
backingArray the array to back the list
Returns:
a list view of the array
  public static List<DoubleasList(double... backingArray) {
    if (backingArray.length == 0) {
      return Collections.emptyList();
    }
    return new DoubleArrayAsList(backingArray);
  }
  private static class DoubleArrayAsList extends AbstractList<Double>
      implements RandomAccessSerializable {
    final double[] array;
    final int start;
    final int end;
    DoubleArrayAsList(double[] array) {
      this(array, 0, array.length);
    }
    DoubleArrayAsList(double[] arrayint startint end) {
      this. = array;
      this. = start;
      this. = end;
    }
    @Override public int size() {
      return  - ;
    }
    @Override public boolean isEmpty() {
      return false;
    }
    @Override public Double get(int index) {
      checkElementIndex(indexsize());
      return [ + index];
    }
    @Override public boolean contains(Object target) {
      // Overridden to prevent a ton of boxing
      return (target instanceof Double)
          && Doubles.indexOf(, (Doubletarget) != -1;
    }
    @Override public int indexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Double) {
        int i = Doubles.indexOf(, (Doubletarget);
        if (i >= 0) {
          return i - ;
        }
      }
      return -1;
    }
    @Override public int lastIndexOf(Object target) {
      // Overridden to prevent a ton of boxing
      if (target instanceof Double) {
        int i = Doubles.lastIndexOf(, (Doubletarget);
        if (i >= 0) {
          return i - ;
        }
      }
      return -1;
    }
    @Override public Double set(int indexDouble element) {
      checkElementIndex(indexsize());
      double oldValue = [ + index];
      // checkNotNull for GWT (do not optimize)
      [ + index] = checkNotNull(element);
      return oldValue;
    }
    @Override public List<DoublesubList(int fromIndexint toIndex) {
      int size = size();
      checkPositionIndexes(fromIndextoIndexsize);
      if (fromIndex == toIndex) {
        return Collections.emptyList();
      }
      return new DoubleArrayAsList( + fromIndex + toIndex);
    }
    @Override public boolean equals(Object object) {
      if (object == this) {
        return true;
      }
      if (object instanceof DoubleArrayAsList) {
        DoubleArrayAsList that = (DoubleArrayAsListobject;
        int size = size();
        if (that.size() != size) {
          return false;
        }
        for (int i = 0; i < sizei++) {
          if ([ + i] != that.array[that.start + i]) {
            return false;
          }
        }
        return true;
      }
      return super.equals(object);
    }
    @Override public int hashCode() {
      int result = 1;
      for (int i = i < i++) {
        result = 31 * result + Doubles.hashCode([i]);
      }
      return result;
    }
    @Override public String toString() {
      StringBuilder builder = new StringBuilder(size() * 12);
      builder.append('[').append([]);
      for (int i =  + 1; i < i++) {
        builder.append(", ").append([i]);
      }
      return builder.append(']').toString();
    }
    double[] toDoubleArray() {
      // Arrays.copyOfRange() is not available under GWT
      int size = size();
      double[] result = new double[size];
      System.arraycopy(result, 0, size);
      return result;
    }
    private static final long serialVersionUID = 0;
  }
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