net.sf.farrago.catalog
Class FarragoColumnHistogram.HistogramRange

java.lang.Object
  net.sf.farrago.catalog.FarragoColumnHistogram.HistogramRange

Enclosing class:

FarragoColumnHistogram

private class FarragoColumnHistogram.HistogramRange
extends Object

Histogram range represents a set of bars in a histogram

Field Summary

private List<FemColumnHistogramBar>	bars
private boolean	empty
private int	firstBar
private SargInterval	interval
private int	lastBar
private int	minBar

Constructor Summary

protected

FarragoColumnHistogram.HistogramRange(List<FemColumnHistogramBar> bars, SargInterval interval, int minBar) Initializes a range of histogram bars spanning a search interval

Method Summary

protected void	evaluate() Searches through the histogram to find the first and last bars the interval may cover in the histogram.
private int	findEndBar(int min, SargEndpoint point) Finds the first histogram bar which does not contain the specified point.
private int	findStartBar(int min, SargEndpoint point) Finds the first histogram bar which may contain the specified starting search point, or points greater than the search point.
protected int	getFirstBar() Returns the zero based index of the first bar in the range, or -1 if the range is empty.
protected int	getLastBar() Returns the zero based index of the last bar in the range, or -1 if the range is empty.
protected boolean	isEmpty() Returns whether the range is empty

Methods inherited from class java.lang.Object

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

Field Detail

bars

private List<FemColumnHistogramBar> bars

interval

private SargInterval interval

minBar

private int minBar

empty

private boolean empty

firstBar

private int firstBar

lastBar

private int lastBar

Constructor Detail

FarragoColumnHistogram.HistogramRange

protected FarragoColumnHistogram.HistogramRange(List<FemColumnHistogramBar> bars,
                                                SargInterval interval,
                                                int minBar)

Initializes a range of histogram bars spanning a search interval

Parameters:

bars - histogram bars to search

interval - the search interval

minBar - the first bar to search

Method Detail

evaluate

protected void evaluate()

Searches through the histogram to find the first and last bars the interval may cover in the histogram. This range may be empty.

isEmpty

protected boolean isEmpty()

Returns whether the range is empty

getFirstBar

protected int getFirstBar()

Returns the zero based index of the first bar in the range, or -1 if the range is empty.

getLastBar

protected int getLastBar()

Returns the zero based index of the last bar in the range, or -1 if the range is empty.

findStartBar

private int findStartBar(int min,
                         SargEndpoint point)

Finds the first histogram bar which may contain the specified starting search point, or points greater than the search point. We can rule out histogram bars which end before the search point. However, we can never rule out the last histogram bar, because it has no definite end.

Parameters:

min - index of first histogram bar to search

point - start point to search for

Returns:

index of first bar not containing point

findEndBar

private int findEndBar(int min,
                       SargEndpoint point)

Finds the first histogram bar which does not contain the specified point. A bar which does not contain the end point will have a starting value greater than the point.

If all bars may contain the search point, returns the index of the last bar + 1.

Parameters:

min - index of first histogram bar to search

point - point to search for

Returns:

index of first bar not containing point