def from_grammar(cls, grammar):
cidhash = IdentityDict()
goto_cache = {}
add_count = Counter()
C = cls.lr0_items(grammar, add_count, cidhash, goto_cache)
cls.add_lalr_lookaheads(grammar, C, add_count, cidhash, goto_cache)
lr_action = [None] * len(C)
lr_goto = [None] * len(C)
sr_conflicts = []
rr_conflicts = []
for st, I in enumerate(C):
st_action = {}
st_actionp = {}
st_goto = {}
for p in I:
if p.getlength() == p.lr_index + 1:
if p.name == "S'":
# Start symbol. Accept!
st_action["$end"] = 0
st_actionp["$end"] = p
else:
laheads = p.lookaheads[st]
for a in laheads:
if a in st_action:
r = st_action[a]
if r > 0:
sprec, slevel = grammar.productions[st_actionp[a].number].prec
rprec, rlevel = grammar.precedence.get(a, ("right", 0))
if (slevel < rlevel) or (slevel == rlevel and rprec == "left"):
st_action[a] = -p.number
st_actionp[a] = p
if not slevel and not rlevel:
sr_conflicts.append((st, repr(a), "reduce"))
grammar.productions[p.number].reduced += 1
elif not (slevel == rlevel and rprec == "nonassoc"):
if not rlevel:
sr_conflicts.append((st, repr(a), "shift"))
elif r < 0:
oldp = grammar.productions[-r]
pp = grammar.productions[p.number]
if oldp.number > pp.number:
st_action[a] = -p.number
st_actionp[a] = p
chosenp, rejectp = pp, oldp
grammar.productions[p.number].reduced += 1
grammar.productions[oldp.number].reduced -= 1
else:
chosenp, rejectp = oldp, pp
rr_conflicts.append((st, repr(chosenp), repr(rejectp)))
else:
raise ParserGeneratorError("Unknown conflict in state %d" % st)
else:
st_action[a] = -p.number
st_actionp[a] = p
grammar.productions[p.number].reduced += 1
else:
i = p.lr_index
a = p.prod[i + 1]
if a in grammar.terminals:
g = cls.lr0_goto(I, a, add_count, goto_cache)
j = cidhash.get(g, -1)
if j >= 0:
if a in st_action:
r = st_action[a]
if r > 0:
if r != j:
raise ParserGeneratorError("Shift/shift conflict in state %d" % st)
elif r < 0:
rprec, rlevel = grammar.productions[st_actionp[a].number].prec
sprec, slevel = grammar.precedence.get(a, ("right", 0))
if (slevel > rlevel) or (slevel == rlevel and rprec == "right"):
grammar.productions[st_actionp[a].number].reduced -= 1
st_action[a] = j
st_actionp[a] = p
if not rlevel:
sr_conflicts.append((st, repr(a), "shift"))
elif not (slevel == rlevel and rprec == "nonassoc"):
if not slevel and not rlevel:
sr_conflicts.append((st, repr(a), "reduce"))
else:
raise ParserGeneratorError("Unknown conflict in state %d" % st)
else:
st_action[a] = j
st_actionp[a] = p
nkeys = set()
for ii in I:
for s in ii.unique_syms:
if s in grammar.nonterminals:
nkeys.add(s)
for n in nkeys:
g = cls.lr0_goto(I, n, add_count, goto_cache)
j = cidhash.get(g, -1)
if j >= 0:
st_goto[n] = j
lr_action[st] = st_action
lr_goto[st] = st_goto
default_reductions = [0] * len(lr_action)
for state, actions in enumerate(lr_action):
actions = set(itervalues(actions))
if len(actions) == 1 and next(iter(actions)) < 0:
default_reductions[state] = next(iter(actions))
return LRTable(grammar, lr_action, lr_goto, default_reductions, sr_conflicts, rr_conflicts)
def from_grammar(cls, grammar):
cidhash = IdentityDict()
goto_cache = {}
add_count = Counter()
C = cls.lr0_items(grammar, add_count, cidhash, goto_cache)
cls.add_lalr_lookaheads(grammar, C, add_count, cidhash, goto_cache)
lr_action = [None] * len(C)
lr_goto = [None] * len(C)
sr_conflicts = []
rr_conflicts = []
for st, I in enumerate(C):
st_action = {}
st_actionp = {}
st_goto = {}
for p in I:
if p.getlength() == p.lr_index + 1:
if p.name == "S'":
# Start symbol. Accept!
st_action["$end"] = 0
st_actionp["$end"] = p
else:
laheads = p.lookaheads[st]
for a in laheads:
if a in st_action:
r = st_action[a]
if r > 0:
sprec, slevel = grammar.productions[st_actionp[a].number].prec
rprec, rlevel = grammar.precedence.get(a, ("right", 0))
if (slevel < rlevel) or (slevel == rlevel and rprec == "left"):
st_action[a] = -p.number
st_actionp[a] = p
if not slevel and not rlevel:
sr_conflicts.append((st, repr(a), "reduce"))
grammar.productions[p.number].reduced += 1
elif not (slevel == rlevel and rprec == "nonassoc"):
if not rlevel:
sr_conflicts.append((st, repr(a), "shift"))
elif r < 0:
oldp = grammar.productions[-r]
pp = grammar.productions[p.number]
if oldp.number > pp.number:
st_action[a] = -p.number
st_actionp[a] = p
chosenp, rejectp = pp, oldp
grammar.productions[p.number].reduced += 1
grammar.productions[oldp.number].reduced -= 1
else:
chosenp, rejectp = oldp, pp
rr_conflicts.append((st, repr(chosenp), repr(rejectp)))
else:
raise LALRError("Unknown conflict in state %d" % st)
else:
st_action[a] = -p.number
st_actionp[a] = p
grammar.productions[p.number].reduced += 1
else:
i = p.lr_index
a = p.prod[i + 1]
if a in grammar.terminals:
g = cls.lr0_goto(I, a, add_count, goto_cache)
j = cidhash.get(g, -1)
if j >= 0:
if a in st_action:
r = st_action[a]
if r > 0:
if r != j:
raise LALRError("Shift/shift conflict in state %d" % st)
elif r < 0:
rprec, rlevel = grammar.productions[st_actionp[a].number].prec
sprec, slevel = grammar.precedence.get(a, ("right", 0))
if (slevel > rlevel) or (slevel == rlevel and rprec == "right"):
grammar.productions[st_actionp[a].number].reduced -= 1
st_action[a] = j
st_actionp[a] = p
if not rlevel:
sr_conflicts.append((st, repr(a), "shift"))
elif not (slevel == rlevel and rprec == "nonassoc"):
if not slevel and not rlevel:
sr_conflicts.append((st, repr(a), "reduce"))
else:
raise LALRError("Unknown conflict in state %d" % st)
else:
st_action[a] = j
st_actionp[a] = p
nkeys = set()
for ii in I:
for s in ii.unique_syms:
if s in grammar.nonterminals:
nkeys.add(s)
for n in nkeys:
g = cls.lr0_goto(I, n, add_count, goto_cache)
j = cidhash.get(g, -1)
if j >= 0:
st_goto[n] = j
lr_action[st] = st_action
lr_goto[st] = st_goto
default_reductions = [0] * len(lr_action)
for state, actions in enumerate(lr_action):
actions = set(itervalues(actions))
if len(actions) == 1 and next(iter(actions)) < 0:
default_reductions[state] = next(iter(actions))
return LRTable(grammar, lr_action, lr_goto, default_reductions, sr_conflicts, rr_conflicts)
