def prune_cfg(self, cfg, lex):
""" Given a grammar (gp), prune the unreachable rules.
The cfg is directly manipulated.
"""
unreachable = MiniUtils.unreachable_rules(cfg)
if len(unreachable) > 0:
print "=> unreachable: ", unreachable
_rules = []
for rule in cfg.rules:
if rule.name not in unreachable:
_rules.append(rule)
return CFG.CFG(lex, cfg.sym_tokens, _rules)
return cfg
