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Trying to reduce the amount of variables used in first sets

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Dave Halter
2018-06-26 01:04:22 +02:00
parent e9fde82512
commit 5d46c3e18b
1 changed files with 1 additions and 5 deletions
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parso/pgen2/grammar.py
+1 -5
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@@ -71,10 +71,8 @@ class Grammar(object):
# We only need to check the first dfa. All the following ones are not # We only need to check the first dfa. All the following ones are not
# interesting to find first terminals. # interesting to find first terminals.
state = dfas[0] state = dfas[0]
totalset = set()
for transition, next_ in state.ilabel_to_plan.items(): for transition, next_ in state.ilabel_to_plan.items():
# It's a string. We have finally found a possible first token. # It's a string. We have finally found a possible first token.
totalset.add(transition)
first_plans[transition] = [next_.next_dfa] first_plans[transition] = [next_.next_dfa]
for nonterminal2, next_ in state.nonterminal_arcs.items(): for nonterminal2, next_ in state.nonterminal_arcs.items():
@@ -84,11 +82,9 @@ class Grammar(object):
fset = self._first_terminals[nonterminal2] fset = self._first_terminals[nonterminal2]
except KeyError: except KeyError:
self._calculate_first_terminals(nonterminal2) self._calculate_first_terminals(nonterminal2)
fset = self._first_terminals[nonterminal2]
else: else:
if fset is None: if fset is None:
raise ValueError("left recursion for rule %r" % nonterminal) raise ValueError("left recursion for rule %r" % nonterminal)
totalset.update(fset)
for t, pushes in self._first_plans[nonterminal2].items(): for t, pushes in self._first_plans[nonterminal2].items():
check = first_plans.get(t) check = first_plans.get(t)
@@ -100,4 +96,4 @@ class Grammar(object):
) )
first_plans[t] = [next_] + pushes first_plans[t] = [next_] + pushes
self._first_terminals[nonterminal] = totalset self._first_terminals[nonterminal] = 1