Bug 211839 String grouping unit type needs to support interval range.
Build ID: I20071101-2000 As Chart has supported, the String grouping unit type can be set interval range, the interval range means that the string group will base on row count distinction. For instance, let's say we have a,b,c,d,e,f,g , and set interval range to 2, the grouping result should be a,c,e,g. Now it is a requirement that DtE support the grouping type.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/group/GroupCalculationUtil.java
private int compareTwoValues( Object obj1, Object obj2 )
	{
		if ( obj1 == null || obj2 == null )
		{
			
			if ( obj1 == null && obj2 != null )
				return -1;
			else if ( obj1 != null && obj2 == null )
				return 1;
			else
				return 0;
		}
		if ( obj1 instanceof Boolean )
		{
			if ( obj1.equals( obj2 ) )
				return 0;
			Boolean bool = (Boolean) obj1;
			if ( bool.equals( Boolean.TRUE ) )
				return 1;
			else
				return -1;
		}
		else if ( obj1 instanceof Comparable )
		{
			Comparable comp1 = (Comparable) obj1;
			Comparable comp2 = (Comparable) obj2;
			
			if ( obj1.getClass( ) != obj2.getClass( )
					&& obj1 instanceof Number && obj2 instanceof Number )
			{