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Lookup optimisation

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avoid a couple of dynamic lookup in the core of the parsing loop.
Performance improvement will be minimal, but adding a little many time
can be consequent.
This commit is contained in:
Matthias Bussonnier
2017-03-13 19:32:29 -07:00
committed by Dave Halter
parent bb8fe0b24c
commit 9a851165ad
1 changed files with 11 additions and 6 deletions
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17
jedi/parser/pgen2/parse.py
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@@ -135,22 +135,27 @@ class PgenParser(object):
ilabel = token_to_ilabel(self.grammar, type_, value)
# Loop until the token is shifted; may raise exceptions
_gram = self.grammar
_labels = _gram.labels
_push = self.push
_pop = self.pop
_shift = self.shift
while True:
dfa, state, node = self.stack[-1]
states, first = dfa
arcs = states[state]
# Look for a state with this label
for i, newstate in arcs:
t, v = self.grammar.labels[i]
t, v = _labels[i]
if ilabel == i:
# Look it up in the list of labels
assert t < 256
# Shift a token; we're done with it
self.shift(type_, value, newstate, prefix, start_pos)
_shift(type_, value, newstate, prefix, start_pos)
# Pop while we are in an accept-only state
state = newstate
while states[state] == [(0, state)]:
self.pop()
_pop()
if not self.stack:
# Done parsing!
return True
@@ -160,16 +165,16 @@ class PgenParser(object):
return False
elif t >= 256:
# See if it's a symbol and if we're in its first set
itsdfa = self.grammar.dfas[t]
itsdfa = _gram.dfas[t]
itsstates, itsfirst = itsdfa
if ilabel in itsfirst:
# Push a symbol
self.push(t, itsdfa, newstate)
_push(t, itsdfa, newstate)
break # To continue the outer while loop
else:
if (0, state) in arcs:
# An accepting state, pop it and try something else
self.pop()
_pop()
if not self.stack:
# Done parsing, but another token is input
raise InternalParseError("too much input", type_, value, start_pos)