How to print a YACC grammar graph starting from a specific node?

I have a vast YACC grammar for processing a family of related standards. I want to print its graph with bison --graph command, but the generated .dot file has over 40 thousand lines.

The graph is so big, xdot and dot tools are unable to render it. I finally managed to generate an output with sfdp, but the resulting image has over 50MB and is simply unintelligible.

Resulting grammar graph

I am only interested in visualizing a part of the grammar, preferably a subset starting from a specific grammar rule. Is there a way to add such constraints to the graph generation or rendering?

Solution

You can restrict a grammar to the subset starting at a nonterminal by adding

%start the_nonterminal

You'll get lots of useless production and useless non-terminal warnings, but you'll still get the graph.

If you want to restrict it to a single production of a non-terminal, you could temporarily introduce a new start non-terminal for only that production (assuming that the grammar for the original non-terminal is not recursive).