Class SuballocatedIntVector


  • public class SuballocatedIntVector
    extends java.lang.Object
    A very simple table that stores a list of int. Very similar API to our IntVector class (same API); different internal storage.

    This version uses an array-of-arrays solution. Read/write access is thus a bit slower than the simple IntVector, and basic storage is a trifle higher due to the top-level array -- but appending is O(1) fast rather than O(N**2) slow, which will swamp those costs in situations where long vectors are being built up.

    Known issues:

    Some methods are private because they haven't yet been tested properly.

    Retrieval performance is critical, since this is used at the core of the DTM model. (Append performance is almost as important.) That's pushing me toward just letting reads from unset indices throw exceptions or return stale data; safer behavior would have performance costs.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected int m_blocksize
      Size of blocks to allocate
      protected int[] m_buildCache
      "Shortcut" handle to most recently added row of m_map.
      protected int m_buildCacheStartIndex  
      protected int m_firstFree
      Number of ints in array
      protected int[][] m_map
      Array of arrays of ints
      protected int[] m_map0
      "Shortcut" handle to m_map[0].
      protected int m_MASK  
      protected int m_numblocks
      The number of blocks to (over)allocate by
      protected int m_SHIFT
      Bitwise addressing (much faster than div/remainder
      protected static int NUMBLOCKS_DEFAULT
      The default number of blocks to (over)allocate by
    • Constructor Summary

      Constructors 
      Constructor Description
      SuballocatedIntVector​(int blocksize)
      Construct a IntVector, using the given block size and the default number of blocks (32).
      SuballocatedIntVector​(int blocksize, int numblocks)
      Construct a IntVector, using the given block size and number of blocks.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addElement​(int value)
      Append a int onto the vector.
      int elementAt​(int i)
      Get the nth element.
      int indexOf​(int elem)
      Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
      int indexOf​(int elem, int index)
      Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
      void setElementAt​(int value, int at)
      Sets the component at the specified index of this vector to be the specified object.
      int size()
      Get the length of the list.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • m_blocksize

        protected final int m_blocksize
        Size of blocks to allocate
      • m_SHIFT

        protected int m_SHIFT
        Bitwise addressing (much faster than div/remainder
      • m_MASK

        protected final int m_MASK
      • NUMBLOCKS_DEFAULT

        protected static final int NUMBLOCKS_DEFAULT
        The default number of blocks to (over)allocate by
        See Also:
        Constant Field Values
      • m_numblocks

        protected final int m_numblocks
        The number of blocks to (over)allocate by
      • m_map

        protected int[][] m_map
        Array of arrays of ints
      • m_firstFree

        protected int m_firstFree
        Number of ints in array
      • m_map0

        protected final int[] m_map0
        "Shortcut" handle to m_map[0]. Surprisingly helpful for short vectors.
      • m_buildCache

        protected int[] m_buildCache
        "Shortcut" handle to most recently added row of m_map. Very helpful during construction.
      • m_buildCacheStartIndex

        protected int m_buildCacheStartIndex
    • Constructor Detail

      • SuballocatedIntVector

        public SuballocatedIntVector​(int blocksize,
                                     int numblocks)
        Construct a IntVector, using the given block size and number of blocks. For efficiency, we will round the requested size off to a power of two.
        Parameters:
        blocksize - Size of block to allocate
        numblocks - Number of blocks to allocate
      • SuballocatedIntVector

        public SuballocatedIntVector​(int blocksize)
        Construct a IntVector, using the given block size and the default number of blocks (32).
        Parameters:
        blocksize - Size of block to allocate
    • Method Detail

      • size

        public int size()
        Get the length of the list.
        Returns:
        length of the list
      • addElement

        public void addElement​(int value)
        Append a int onto the vector.
        Parameters:
        value - Int to add to the list
      • setElementAt

        public void setElementAt​(int value,
                                 int at)
        Sets the component at the specified index of this vector to be the specified object. The previous component at that position is discarded.

        The index must be a value greater than or equal to 0 and less than the current size of the vector.

        Parameters:
        value - object to set
        at - Index of where to set the object
      • elementAt

        public int elementAt​(int i)
        Get the nth element. This is often at the innermost loop of an application, so performance is critical.
        Parameters:
        i - index of value to get
        Returns:
        value at given index. If that value wasn't previously set, the result is undefined for performance reasons. It may throw an exception (see below), may return zero, or (if setSize has previously been used) may return stale data.
        Throws:
        java.lang.ArrayIndexOutOfBoundsException - if the index was _clearly_ unreasonable (negative, or past the highest block).
        java.lang.NullPointerException - if the index points to a block that could have existed (based on the highest index used) but has never had anything set into it. %REVIEW% Could add a catch to create the block in that case, or return 0. Try/Catch is _supposed_ to be nearly free when not thrown to. Do we believe that? Should we have a separate safeElementAt?
      • indexOf

        public int indexOf​(int elem,
                           int index)
        Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
        Parameters:
        elem - object to look for
        index - Index of where to begin search
        Returns:
        the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.
      • indexOf

        public int indexOf​(int elem)
        Searches for the first occurence of the given argument, beginning the search at index, and testing for equality using the equals method.
        Parameters:
        elem - object to look for
        Returns:
        the index of the first occurrence of the object argument in this vector at position index or later in the vector; returns -1 if the object is not found.