com.spun.util.parser.SteppingIterator Maven / Gradle / Ivy
package com.spun.util.parser;
import java.util.Arrays;
public class SteppingIterator
{
public static final int[] DEFAULT_STEPPING = {1};
private int offset = 0;
private int[] stepping = DEFAULT_STEPPING;
private int actualSize = 0;
public SteppingIterator(int offset, int[] stepping, int actualSize)
{
this.offset = offset;
this.stepping = stepping;
this.actualSize = actualSize;
assertSteppingValid(stepping);
}
private void assertSteppingValid(int[] stepping)
{
if (stepping == null || stepping.length == 0 || stepping[0] == 0)
{ throw new NullPointerException("Stepping cannot be null or zero in " + Arrays.toString(stepping)); }
for (int i = stepping.length - 1; i > 0; i--)
{
if (stepping[i - 1] % stepping[i] != 0)
{
String string = String.format("Invalid stepping parameters - %s is not divisible by %s in parameters %s",
stepping[i - 1], stepping[i], Arrays.toString(stepping));
throw new Error(string);
}
}
}
public boolean isLast(int currentPlace, int forSteppingLevel)
{
if (forSteppingLevel == -1 || stepping[forSteppingLevel] == 1)
{
return (currentPlace + 1) == getSize(true, true);
}
else
{
return (((currentPlace + 1) % stepping[forSteppingLevel]) == 0);
}
}
public boolean isFirst(int index, int forSteppingLevel)
{
return (getStepPositionForRound(forSteppingLevel, 0, index) == 0);
}
public int getSize(boolean includeOffset, boolean includeStepping)
{
int size = actualSize;
size += includeOffset ? offset : 0;
if (includeStepping && (size % stepping[0]) != 0)
{
size += (stepping[0] - (size % stepping[0]));
}
return size;
}
/**
* @return the index of the current Step.
**/
public static int getStepCountForRound(int forSteppingLevel, int onIndex, int[] stepping, int indexBase)
{
if (forSteppingLevel == -1 || stepping[forSteppingLevel] == 1)
{
return indexBase;
}
else
{
return ((onIndex / stepping[forSteppingLevel]) + indexBase);
}
}
public int getStepCountForRound(int forSteppingLevel, int currentPlace, int indexBase)
{
return getStepCountForRound(forSteppingLevel, currentPlace, this.stepping, indexBase);
}
public int getTotalStepCountForRound(int forSteppingLevel, int indexBase)
{
return getStepCountForRound(forSteppingLevel, getSize(true, true) - 1, stepping, indexBase);
}
public int getStepPositionForRound(int forSteppingLevel, int indexBase, int currentIndex)
{
if (forSteppingLevel == -1 || stepping[forSteppingLevel] == 1)
{
return currentIndex + indexBase;
}
else
{
return ((currentIndex % stepping[forSteppingLevel]) + indexBase);
}
}
public int getActualPosition(int position)
{
position = position - this.offset;
return (position < 0 || this.actualSize <= position) ? -1 : position;
}
}