* Introduce a new subclass for chained contextual (sub and pos)
* Rename .substitutions to .rules in subst builders to allow for code reuse
* Make format of subtable break marker tuple common between sub/pos
Note that prior to this patch, add_subtable_break in a Subst builder adds:
(self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_)
while add_subtable_break in a Pos builder adds:
(self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, [self.SUBTABLE_BREAK_])
This is messy. If we read the first element from the tuple instead of the last one to test if a rule is a subtable break, we can make the marker tuple the same.
* And now the subtable break code can be hoisted into superclass
* These helper methods will make the build routine common
* Hoist common build method to superclass
The diff doesn’t show it very clearly because it’s being too clever, but all I’ve done is moved one method. Everything works apart from the error message, which comes next.
* Fix the error message
6364d36633