Class IndexSupport

java.lang.Object
org.apache.commons.numbers.arrays.IndexSupport
final class IndexSupport extends Object
Support for creating UpdatingInterval implementations and validating indices.
Since:
1.2

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private static final int
    INSERTION_SORT_SIZE
    The upper threshold to use a modified insertion sort to find unique indices.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    IndexSupport()
    No instances.

  • Method Summary

    Modifier and Type
    Method
    Description
    private static int
    ceilLog2(int x)
    Compute ceil(log2(x)).
    (package private) static void
    checkFromToIndex(int fromIndex, int toIndex, int length)
    Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).
    (package private) static void
    checkIndex(int fromIndex, int toIndex, int index)
    Checks if the index is within the half-open interval [fromIndex, toIndex).
    (package private) static void
    checkIndices(int fromIndex, int toIndex, int[] k)
    Checks if the index is within the half-open interval [fromIndex, toIndex).
    private static int
    compressDuplicates(int[] data, int n)
    Compress duplicates in the ascending data.
    (package private) static int
    countIndices(UpdatingInterval keys, int n)
    Count the number of indices.
    (package private) static UpdatingInterval
    createUpdatingInterval(int left, int right, int[] k, int n)
    Returns an interval that covers the specified indices k.
    private static boolean
    isAscending(int[] data, int n)
    Test the data is in ascending order: data[i] <= data[i+1] for all i.
    private static String
    msgIndexOutOfBounds(int fromIndex, int toIndex, int index)
    Format a message when index is not within range [from, to).
    private static String
    msgRangeOutOfBounds(int fromIndex, int toIndex, int length)
    Format a message when range [from, to) is not entirely within the length.
    private static UpdatingInterval
    newUpdatingInterval(int[] k, int n)
    Returns an interval that covers the specified indices k.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • INSERTION_SORT_SIZE

      private static final int INSERTION_SORT_SIZE
      The upper threshold to use a modified insertion sort to find unique indices.
      See Also:

  • Constructor Details

    • IndexSupport

      private IndexSupport()
      No instances.

  • Method Details

    • createUpdatingInterval

      static UpdatingInterval createUpdatingInterval(int left, int right, int[] k, int n)
      Returns an interval that covers the specified indices k.
      Parameters:
      left - Lower bound of data (inclusive).
      right - Upper bound of data (inclusive).
      k - Indices.
      n - Count of indices (must be strictly positive).
      Returns:
      the interval
      Throws:
      IndexOutOfBoundsException - if any index k is not within the sub-range [left, right]

    • isAscending

      private static boolean isAscending(int[] data, int n)
      Test the data is in ascending order: data[i] <= data[i+1] for all i. Data is assumed to be at least length 1.
      Parameters:
      data - Data.
      n - Length of data.
      Returns:
      true if ascending

    • compressDuplicates

      private static int compressDuplicates(int[] data, int n)
      Compress duplicates in the ascending data.

      Warning: Requires n > 0.

      Parameters:
      data - Indices.
      n - Number of indices.
      Returns:
      the number of unique indices

    • ceilLog2

      private static int ceilLog2(int x)
      Compute ceil(log2(x)). This is valid for all strictly positive x.

      Returns -1 for x = 0 in place of -infinity.

      Parameters:
      x - Value.
      Returns:
      ceil(log2(x))

    • newUpdatingInterval

      private static UpdatingInterval newUpdatingInterval(int[] k, int n)
      Returns an interval that covers the specified indices k. The indices must be sorted.
      Parameters:
      k - Indices.
      n - Count of indices (must be strictly positive).
      Returns:
      the interval
      Throws:
      IndexOutOfBoundsException - if any index k is not within the sub-range [left, right]

    • countIndices

      static int countIndices(UpdatingInterval keys, int n)
      Count the number of indices. Returns a negative value if the indices are sorted.
      Parameters:
      keys - Keys.
      n - Count of indices.
      Returns:
      the count of (sorted) indices

    • checkFromToIndex

      static void checkFromToIndex(int fromIndex, int toIndex, int length)
      Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).

      This function provides the functionality of java.utils.Objects.checkFromToIndex introduced in JDK 9. The Objects javadoc has been reproduced for reference. The return value has been changed to void.

      The sub-range is defined to be out of bounds if any of the following inequalities is true:

      • fromIndex < 0
      • fromIndex > toIndex
      • toIndex > length
      • length < 0, which is implied from the former inequalities
      Parameters:
      fromIndex - Lower-bound (inclusive) of the sub-range.
      toIndex - Upper-bound (exclusive) of the sub-range.
      length - Upper-bound (exclusive) of the range.
      Throws:
      IndexOutOfBoundsException - if the sub-range is out of bounds

    • checkIndices

      static void checkIndices(int fromIndex, int toIndex, int[] k)
      Checks if the index is within the half-open interval [fromIndex, toIndex).
      Parameters:
      fromIndex - Lower-bound (inclusive) of the sub-range.
      toIndex - Upper-bound (exclusive) of the sub-range.
      k - Indices.
      Throws:
      IndexOutOfBoundsException - if any index is out of bounds

    • checkIndex

      static void checkIndex(int fromIndex, int toIndex, int index)
      Checks if the index is within the half-open interval [fromIndex, toIndex).
      Parameters:
      fromIndex - Lower-bound (inclusive) of the sub-range.
      toIndex - Upper-bound (exclusive) of the sub-range.
      index - Index.
      Throws:
      IndexOutOfBoundsException - if the index is out of bounds

    • msgRangeOutOfBounds

      private static String msgRangeOutOfBounds(int fromIndex, int toIndex, int length)
      Format a message when range [from, to) is not entirely within the length.
      Parameters:
      fromIndex - Lower-bound (inclusive) of the sub-range.
      toIndex - Upper-bound (exclusive) of the sub-range.
      length - Upper-bound (exclusive) of the range.
      Returns:
      the message

    • msgIndexOutOfBounds

      private static String msgIndexOutOfBounds(int fromIndex, int toIndex, int index)
      Format a message when index is not within range [from, to).
      Parameters:
      fromIndex - Lower-bound (inclusive) of the sub-range.
      toIndex - Upper-bound (exclusive) of the sub-range.
      index - Index.
      Returns:
      the message