for t, a in guarded_reduce do
if a.length > 1 then
print "REDUCE/REDUCE Conflict on state {self.number} {self.name} for token {t}:"
- for i in a do print "\t{i}"
+ for i in a do print "\treduce: {i}"
else if guarded_shift.has_key(t) then
- print "SHIFT/REDUCE Conflict on state {self.number} {self.name} for token {t}:"
- for i in a do print "\t{i}"
- for i in guarded_shift[t] do print "\t{i}"
+ for ri in a.to_a do for si in guarded_shift[t] do
+ if lookahead(ri).has(si) then
+ var p = ri.alt.prod
+ var csi: nullable Item = null
+ for bsi in back_expand(si) do
+ if bsi.alt.prod == p then
+ csi = bsi
+ break
+ end
+ end
+ if csi == null then continue
+ print "Automatic Dangling on state {self.number} {self.name} for token {t}:"
+ print "\treduce: {ri}"
+ print "\tshift: {si}"
+ if si != csi then
+ print "\tcore shift: {csi}"
+ end
+ a.remove(ri)
+ end
+ end
+ if a.is_empty then
+ guarded_reduce.keys.remove(t)
+ else
+ print "SHIFT/REDUCE Conflict on state {self.number} {self.name} for token {t}:"
+ for i in a do print "\treduce: {i}"
+ for i in guarded_shift[t] do print "\tshift: {i}"
+ end
end
end
end
+
+ # Return `i` and all other items of the state that expands, directly or undirectly, to `i`
+ fun back_expand(i: Item): Set[Item]
+ do
+ var res = new ArraySet[Item]
+ var todo = [i]
+ res.add(i)
+ while not todo.is_empty do
+ var x = todo.pop
+ if x.pos > 0 then continue
+ var p = x.alt.prod
+ for y in items do
+ if y.next != p then continue
+ if res.has(y) then continue
+ res.add(y)
+ todo.add(y)
+ end
+ end
+ return res
+ end
end
# A transition in a LR automaton
nitlanguage / nit.git / commitdiff