[erlang-questions] Debugging yecc grammars: what techniques are available?
Sun Feb 5 11:18:39 CET 2017
Hugo Mills writes:
> I'm in the process of writing a domain-specific language, using a
> custom lexer and a yecc parser. In the process of attempting to add a
> new feature to the grammar, I've managed to break what appears to me
> to be a completely unrelated piece of the grammar: I'm adding a
> structure similar to a list comprehension, and suddenly the integer
> comparison operators have stopped working in one group of cases.
> What approaches are there for debugging this kind of problem? The
> best I can some up with is inspection of the .yrl source in detail,
> but that's not helping. How else can I work out what the issue is?
> Obviously, I could post the grammar here for inspection by more
> experienced minds than mine, but I'd prefer to find better tooling and
> techniques rather than mere appeal to higher authority...
Caveat: while I have experience with various parsing techniques, including
LALR(1), I have none with the yecc tool.
Does yecc issue any warnings about shift/reduce or reduce/reduce conflicts?
If it does, you need to investigate those and resolve them. With yacc and
bison it's possible to manually inspect the LALR(1) automaton for debugging.
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