int getFirstActiveFactoryIndex(BigInteger index, FieldFactory[] factories) {
		for (int i = 0; i < factories.length; i++) {
			if (factories[i].isActive(index)) {
				return i;
			}
		}
		return -1;
	}
Returns the index of the first factory that is active for a given index
@param index the line index
@param factories the list of factories that generate values on a line
@return the index of the first active factory on that line. This will be 0 except for
the first line of a block which may start part way in the line.
Ghidra/Features/ByteViewer/src/main/java/ghidra/app/plugin/core/byteviewer/IndexMap.java