def _max_expansion_coverage(self, symbol, max_depth):
if max_depth <= 0:
return set()
self._symbols_seen.add(symbol)
expansions = set()
for expansion in self.grammar[symbol]:
expansions.add(expansion_key(symbol, expansion))
for nonterminal in nonterminals(expansion):
if nonterminal not in self._symbols_seen:
expansions |= self._max_expansion_coverage(
nonterminal, max_depth - 1)
return expansions
def _max_symbol_expansion_coverage(
self, symbol, max_depth, cov, symbols_seen):
"""Return set of all expansions in a grammar starting with `symbol`"""
if max_depth <= 0:
return (cov, symbols_seen)
symbols_seen.add(symbol)
for expansion in self.grammar[symbol]:
key = self.expansion_key(symbol, expansion)
if key in cov:
continue
cov.add(key)
for s in nonterminals(expansion):
if s in symbols_seen:
continue
new_cov, new_symbols_seen = (
self._max_symbol_expansion_coverage(s, max_depth - 1, cov, symbols_seen))
cov |= new_cov
symbols_seen |= new_symbols_seen
return (cov, symbols_seen)
