Define Syntax for Iterator Definition

[kindlich]

Currently, StdLib's Iterable.zs defines the Iterator-Member like so:

for(item as T) as Iterator<T> => iterate();

However, the parser expects:

for(T) {
    // What to do in here?
}

Defined in ParsedDefinitionMember:

			case K_FOR: {
				tokens.next();

				tokens.required(T_BROPEN, "( expected");

				List<IParsedType> loopVariableTypes = new ArrayList<>();
				if (tokens.optional(T_BRCLOSE) == null) {
					do {
						loopVariableTypes.add(IParsedType.parse(tokens));
					} while (tokens.optional(T_COMMA) != null);
					tokens.required(T_BRCLOSE, ") expected");
				}

				ParsedFunctionBody body = ParsedStatement.parseFunctionBody(tokens);
				return new ParsedIterator(start, modifiers, annotations, loopVariableTypes, body);
			}

We need to define how the iterator members should look like and how it should behave.

Acceptance Criteria:

• The syntax is defined
• The header in stdlibs is adapted to whatever syntax we adopt
• There exist tests that cover the basic iterator functionality
  • Defining an iterator
  • Calling it
  • Overloading iterators with multiple variables
  • Doing that on a generic data type like List