Package org.eclipse.jface.viewers.deferred

Class LazySortedCollection

java.lang.Object
org.eclipse.jface.viewers.deferred.LazySortedCollection
public class LazySortedCollection extends Object
This object maintains a collection of elements, sorted by a comparator given in the constructor. The collection is lazily sorted, allowing more efficient runtimes for most methods. There are several methods on this object that allow objects to be queried by their position in the sorted collection.

This is a modified binary search tree. Each subtree has a value, a left and right subtree, a count of the number of children, and a set of unsorted children. Insertion happens lazily. When a new node N is inserted into a subtree T, it is initially added to the set of unsorted children for T without actually comparing it with the value for T.

The unsorted children will remain in the unsorted set until some subsequent operation requires us to know the exact set of elements in one of the subtrees. At that time, we partition T by comparing all of its unsorted children with T's value and moving them into the left or right subtrees.

Since:
3.1

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    boolean
    enableDebug
    Disables randomization and enables additional runtime error checking.

  • Constructor Summary

    Constructors
    Constructor
    Description
    LazySortedCollection(Comparator c)
    Creates a new sorted collection using the given comparator to determine sort order.

  • Method Summary

    Modifier and Type
    Method
    Description
    final void
    add(Object toAdd)
    Adds the given object to the collection.
    final void
    addAll(Object[] toAdd)
    Adds all items from the given array to the collection
    final void
    addAll(Collection toAdd)
    Adds all items from the given collection to this collection
    final void
    clear()
    Removes all elements from the collection
    boolean
    contains(Object item)
    Returns true iff this collection contains the given item
    Comparator
    getComparator()
    Returns the comparator that is determining the sort order for this collection
    final int
    getFirst(Object[] result, boolean sorted)
    Fills in an array of size n with the n smallest elements from the collection.
    final Object
    getItem(int index)
    Returns the item at the given index.
    final Object[]
    getItems(boolean sorted)
    Returns the contents of this collection as a sorted or unsorted array.
    final int
    getRange(Object[] result, int rangeStart, boolean sorted)
    Computes the n through n+k items in this collection.
    final boolean
    isEmpty()
    Returns true iff the collection is empty
    final void
    remove(Object toRemove)
    Removes the given object from the collection.
    final void
    removeAll(Object[] toRemove)
    Removes all elements in the given array from this collection.
    final void
    removeRange(int first, int length)
    Removes all elements in the given range from this collection.
    final void
    retainFirst(int n)
    Retains the n smallest items in the collection, removing the rest.
    final void
    setCapacity(int newSize)
    Increases the capacity of this collection, if necessary, so that it can hold the given number of elements.
    int
    size()
    Returns the number of elements in the collection
    void
    testInvariants()
    Tests if this object's internal state is valid.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • enableDebug

      public boolean enableDebug
      Disables randomization and enables additional runtime error checking. Severely degrades performance if set to true. Intended for use in test suites only.

  • Constructor Details

    • LazySortedCollection

      public LazySortedCollection(Comparator c)
      Creates a new sorted collection using the given comparator to determine sort order.
      Parameters:
      c - comparator that determines the sort order

  • Method Details

    • testInvariants

      public void testInvariants()
      Tests if this object's internal state is valid. Throws a runtime exception if the state is invalid, indicating a programming error in this class. This method is intended for use in test suites and should not be called by clients.

    • size

      public int size()
      Returns the number of elements in the collection
      Returns:
      the number of elements in the collection

    • setCapacity

      public final void setCapacity(int newSize)
      Increases the capacity of this collection, if necessary, so that it can hold the given number of elements. This can be used prior to a sequence of additions to avoid memory reallocation. This cannot be used to reduce the amount of memory used by the collection.
      Parameters:
      newSize - capacity for this collection

    • add

      public final void add(Object toAdd)
      Adds the given object to the collection. Runs in O(1) amortized time.
      Parameters:
      toAdd - object to add

    • addAll

      public final void addAll(Collection toAdd)
      Adds all items from the given collection to this collection
      Parameters:
      toAdd - objects to add

    • addAll

      public final void addAll(Object[] toAdd)
      Adds all items from the given array to the collection
      Parameters:
      toAdd - objects to add

    • isEmpty

      public final boolean isEmpty()
      Returns true iff the collection is empty
      Returns:
      true iff the collection contains no elements

    • remove

      public final void remove(Object toRemove)
      Removes the given object from the collection. Has no effect if the element does not exist in this collection.
      Parameters:
      toRemove - element to remove

    • removeAll

      public final void removeAll(Object[] toRemove)
      Removes all elements in the given array from this collection.
      Parameters:
      toRemove - elements to remove

    • retainFirst

      public final void retainFirst(int n)
      Retains the n smallest items in the collection, removing the rest. When this method returns, the size of the collection will be n. Note that this is a no-op if n > the current size of the collection.
      Parameters:
      n - number of items to retain

    • removeRange

      public final void removeRange(int first, int length)
      Removes all elements in the given range from this collection. For example, removeRange(10, 3) would remove the 11th through 13th smallest items from the collection.
      Parameters:
      first - 0-based index of the smallest item to remove
      length - number of items to remove

    • clear

      public final void clear()
      Removes all elements from the collection

    • getComparator

      public Comparator getComparator()
      Returns the comparator that is determining the sort order for this collection
      Returns:
      comparator for this collection

    • getFirst

      public final int getFirst(Object[] result, boolean sorted)
      Fills in an array of size n with the n smallest elements from the collection. Can compute the result in sorted or unsorted order.
      Parameters:
      result - array to be filled
      sorted - if true, the result array will be sorted. If false, the result array may be unsorted. This does not affect which elements appear in the result. It only affects their order. Computing an unsorted result is asymptotically faster.
      Returns:
      the number of items inserted into the result array. This will be equal to the minimum of result.length and container.size()

    • getRange

      public final int getRange(Object[] result, int rangeStart, boolean sorted)
      Computes the n through n+k items in this collection. Computing the result in unsorted order is more efficient. Sorting the result will not change which elements actually show up in the result. That is, even if the result is unsorted, it will still contain the same elements as would have been at that range in a fully sorted collection.
      Parameters:
      result - array containing the result
      rangeStart - index of the first element to be inserted into the result array
      sorted - true iff the result will be computed in sorted order
      Returns:
      the number of items actually inserted into the result array (will be the minimum of result.length and this.size())

    • getItem

      public final Object getItem(int index)
      Returns the item at the given index. Indexes are based on sorted order.
      Parameters:
      index - index to test
      Returns:
      the item at the given index

    • getItems

      public final Object[] getItems(boolean sorted)
      Returns the contents of this collection as a sorted or unsorted array. Computing an unsorted array is more efficient.
      Parameters:
      sorted - if true, the result will be in sorted order. If false, the result may be in unsorted order.
      Returns:
      the contents of this collection as an array.

    • contains

      public boolean contains(Object item)
      Returns true iff this collection contains the given item
      Parameters:
      item - item to test
      Returns:
      true iff this collection contains the given item