[mkgmap-dev] if-then-else in style and style options

Fri Mar 17 13:02:55 GMT 2017

Hi Gerd,

you seem to evaluate scenarios, that I didn't think of. You probably 
want to unwind a rule with double types into 2 rules with single type. 
My idea was different, based on my guess, how mkgmap works. I have 
looked at code now, and I can explain more precisely.

First there is class ActionRule, which contains a trio:
  private Op expression;
  private final List<Action> actions;
  private final GType type;

Here I would suggest to add 4-th element:
  private final GType type2;

And then support it in all methods, like add creator with 2 types:

public ActionRule(Op expression, List<Action> actions, GType type, GType 
type2)

Or support for 2 types in resolveType:

if (type != null && finalizeRule != null) {
	....
	if (type2 != null) {
		...
	}
}

And similarly in RuleFileReader:

GType type = null;
GType type2 = null;
if (scanner.checkToken("[")) {
	type = typeReader.readType(...);
	if (scanner.checkToken("[") {
		type2 = typeReader.readType(...);
	}
}
else ...
saveRule(scanner, expr, actionList, type, type2);

I hope my theoretical implementation answers your questions. When 2 type 
elements are present, there is no need to evaluate "continue" or 
"continue with_actions" in first element, it is hardcoded as "continue 
with_actions". And "continue" in last element will result in further 
processing of OSM object.

There is no limitation for content of action part, rule with 2 types 
behaves exactly like a rule with single type.

I'm sure that my understanding of your code is incomplete but I hope the 
general idea is feasible. I think type element could be even a list, 
like actions.

-- 
Best regards,
Andrzej