RandomSec/src/main/java/com/metaweb/gridlock/expr/functions/Slice.java

package com.metaweb.gridlock.expr.functions;

import java.lang.reflect.Array;
import java.util.Properties;

import com.metaweb.gridlock.expr.Function;

public class Slice implements Function {

	@Override
	public Object call(Properties bindings, Object[] args) {
		if (args.length > 1 && args.length <= 3) {
			Object v = args[0];
			Object from = args[1];
			Object to = args.length == 3 ? args[2] : null;
			
			if (v != null && from != null && from instanceof Number && (to == null || to instanceof Number)) {
				if (v instanceof Array) {
					Object[] a = (Object[]) v;
					int start = ((Number) from).intValue();
					int end = to != null && to instanceof Number ? 
							((Number) to).intValue() : a.length;
								
					if (start < 0) {
						start = a.length - start;
					}
					start = Math.min(a.length, Math.max(0, start));
					
					if (end < 0) {
						end = a.length - end;
					}
					end = Math.min(a.length, Math.max(start, end));
					
					Object[] a2 = new Object[end - start];
					System.arraycopy(a, start, a2, 0, end - start);
					
					return a2;
				} else {
					String s = (v instanceof String ? (String) v : v.toString());
					
					int start = ((Number) from).intValue();
					if (start < 0) {
						start = s.length() - start;
					}
					start = Math.min(s.length(), Math.max(0, start));
					
					if (to != null && to instanceof Number) {
						int end = ((Number) to).intValue();
						if (end < 0) {
							end = s.length() - end;
						}
						end = Math.min(s.length(), Math.max(start, end));
						
						return s.substring(start, end);
					} else {
						return s.substring(start);
					}
				}
			}
		}
		return null;
	}

}