From a0f93d9f2e4d6fa64338552aecd349065c8f25ad Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 10:54:03 -0400
Subject: [PATCH 1/8] nitcc: Gram do the state analysis in a 2nd step

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index 0ddb646c73..1d24fc55f5 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -149,7 +149,10 @@ class Gram
 
 			#print state
 			automaton.states.add(state)
-			state.analysis
+			# Extends the core
+			for i in state.items.to_a do
+				state.extends(i)
+			end
 
 			var nexts = new HashMap[Element, LRState]
 			for i in state.items do
@@ -198,6 +201,9 @@ class Gram
 				next.ins.add t
 			end
 		end
+		for state in automaton.states do
+			state.analysis
+		end
 		return automaton
 	end
 
@@ -1020,10 +1026,6 @@ class LRState
 	# Compute guards and conflicts
 	fun analysis
 	do
-		# Extends the core
-		for i in items.to_a do
-			extends(i)
-		end
 
 		# Collect action and conflicts
 		for i in items do

From fa6de054f0b4c56da558756e0d8bc7a02dbe01db Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 10:56:28 -0400
Subject: [PATCH 2/8] nitcc: add Production sample

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 63 +++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index 1d24fc55f5..0b0a48e743 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -43,6 +43,10 @@ class Gram
 				if a == last then res.append(" ;\n") else res.append(" |\n")
 			end
 			if p.is_nullable then res.append "\t// is nullable\n"
+			if p.sample_alternative != null then
+				res.append "\t// sample: {p.sample_to_s}\n"
+			end
+
 			if not p.firsts.is_empty then
 				res.append "\t// firsts:\n"
 				for x in p.firsts do res.append "\t//   {x}\n"
@@ -207,6 +211,37 @@ class Gram
 		return automaton
 	end
 
+	fun compute_sample_length
+	do
+		loop
+			var changed = false
+			for p in prods do
+				for a in p.alts do
+					if a.phony then continue
+					var sample_length = 0
+					for e in a.elems do
+						if e isa Token then
+							sample_length += 1
+						else if e isa Production then
+							var e_len = e.sample_length
+							if e_len == null then continue label alts
+							sample_length += e_len
+						else
+							abort
+						end
+					end
+					var e_len = p.sample_length
+					if e_len == null or e_len > sample_length then
+						p.sample_length = sample_length
+						p.sample_alternative = a
+						changed = true
+					end
+				end label alts
+			end
+			if not changed then break
+		end
+	end
+
 	# Compute `nullables`, `firsts` and `afters` of productions
 	fun analyse
 	do
@@ -237,6 +272,8 @@ class Gram
 			if not changed then break
 		end
 
+		compute_sample_length
+
 		loop
 			var changed = false
 			for p in prods do
@@ -352,6 +389,24 @@ class Production
 	# Is the production nullable
 	var is_nullable = false
 
+	# The lenght (in tokens) of the smallest sample
+	var sample_length: nullable Int = null
+
+	# The allternative used as the smallest sample
+	var sample_alternative: nullable Alternative = null
+
+	redef fun sample_to_s: String
+	do
+		var alt = sample_alternative.as(not null)
+		var res = new Buffer
+		for e in alt.elems do
+			if not res.is_empty then res.add ' '
+			res.append(e.sample_to_s)
+		end
+		return res.to_s
+	end
+
+
 	# The first tokens of the production
 	var firsts = new HashSet[Item]
 
@@ -504,6 +559,9 @@ abstract class Element
 	var name: String
 	redef fun to_s do return name
 
+	# An example of a string
+	fun sample_to_s: String is abstract
+
 	private var acname_cache: nullable String = null
 
 	# The mangled name of the element
@@ -530,6 +588,11 @@ class Token
 	var shifts = new ArraySet[LRState]
 	# States of the LR automaton that reduce on self in the lookahead(1)
 	var reduces = new ArraySet[LRState]
+
+	redef fun sample_to_s
+	do
+		return to_s
+	end
 end
 
 #

From 39eb5b42b336eea1413c7cdcdab2f957151a575c Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 11:12:11 -0400
Subject: [PATCH 3/8] nitcc: LRState remove cname

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index 0b0a48e743..98683d62c4 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -764,11 +764,11 @@ private class Generator
 
 		add "class Parser_{name}"
 		add "\tsuper Parser"
-		add "\tredef fun start_state do return state_{states.first.cname}"
+		add "\tredef fun start_state do return state_{states.first.number}"
 		add "end"
 		
 		for s in states do
-			add "private fun state_{s.cname}: LRState{s.cname} do return once new LRState{s.cname}"
+			add "private fun state_{s.number}: LRState{s.number} do return once new LRState{s.number}"
 		end
 		for p in gram.prods do
 			add "private fun goto_{p.cname}: Goto_{p.cname} do return once new Goto_{p.cname}"
@@ -784,7 +784,7 @@ private class Generator
 			if not s.need_guard then continue
 			add "\t# guarded action for state {s.name}"
 			add "\t# {s.shifts.length} shift(s) and {s.reduces.length} reduce(s)"
-			add "\tprivate fun action_s{s.cname}(parser: Parser) do"
+			add "\tprivate fun action_s{s.number}(parser: Parser) do"
 			if s.reduces.length != 1 then
 				add "\t\tparser.parse_error"
 			else
@@ -804,14 +804,14 @@ private class Generator
 			add "\tsuper NToken"
 			for s in t.shifts do
 				if not s.need_guard then continue
-				add "\tredef fun action_s{s.cname}(parser) do"
+				add "\tredef fun action_s{s.number}(parser) do"
 				gen_shift_to_nit(s, t)
 				add "\tend"
 			end
 			for s in t.reduces do
 				if not s.need_guard then continue
 				if s.reduces.length <= 1 then continue
-				add "\tredef fun action_s{s.cname}(parser) do"
+				add "\tredef fun action_s{s.number}(parser) do"
 				add "\t\treduce_{s.guarded_reduce[t].first.alt.cname}(parser)"
 				#gen_reduce_to_nit(s.guarded_reduce[t].first.alt)
 				add "\tend"
@@ -823,7 +823,7 @@ private class Generator
 		add "redef class LRGoto"
 		for s in states do
 			if s.gotos.length <= 1 then continue
-			add "\tprivate fun goto_s{s.cname}(parser: Parser) do abort"
+			add "\tprivate fun goto_s{s.number}(parser: Parser) do abort"
 		end
 		add "end"
 
@@ -832,7 +832,7 @@ private class Generator
 			add "\tsuper LRGoto"
 			for s in p.gotos do
 				if s.gotos.length <= 1 then continue
-				add "\tredef fun goto_s{s.cname}(parser) do"
+				add "\tredef fun goto_s{s.number}(parser) do"
 				gen_goto_to_nit(s, p)
 				add "\tend"
 			end
@@ -888,7 +888,7 @@ private class Generator
 
 		for s in states do
 			add "# State {s.name}"
-			add "private class LRState{s.cname}"
+			add "private class LRState{s.number}"
 			add "\tsuper LRState"
 
 			add "\tredef fun to_s do return \"{s.name.escape_to_nit}\""
@@ -907,7 +907,7 @@ private class Generator
 
 			add "\tredef fun action(parser) do"
 			if s.need_guard then
-				add "\t\tparser.peek_token.action_s{s.cname}(parser)"
+				add "\t\tparser.peek_token.action_s{s.number}(parser)"
 			else if s.reduces.length == 1 then
 				add "\t\treduce_{s.reduces.first.cname}(parser)"
 				#gen_reduce_to_nit(s.reduces.first)
@@ -919,7 +919,7 @@ private class Generator
 			if not s.gotos.is_empty then
 				add "\tredef fun goto(parser, goto) do"
 				if s.gotos.length > 1 then
-					add "\t\tgoto.goto_s{s.cname}(parser)"
+					add "\t\tgoto.goto_s{s.number}(parser)"
 				else
 					gen_goto_to_nit(s, s.gotos.first)
 				end
@@ -935,14 +935,14 @@ private class Generator
 	fun gen_shift_to_nit(s: LRState, t: Token)
 	do
 		var dest = s.trans(t)
-		add "\t\tparser.shift(state_{dest.cname})"
+		add "\t\tparser.shift(state_{dest.number})"
 
 	end
 
 	fun gen_goto_to_nit(s: LRState, p: Production)
 	do
 		var dest = s.trans(p)
-		add "\t\tparser.push(state_{dest.cname})"
+		add "\t\tparser.push(state_{dest.number})"
 	end
 
 	fun gen_reduce_to_nit(alt: Alternative)
@@ -1012,8 +1012,6 @@ class LRState
 	# Name of the automaton (short part from the start)
 	var name: String
 
-	# Mangled name
-	var cname: String is lazy do return name.to_cmangle
 
 	# Number
 	var number = -1

From ada17582dfd9806ce6457068d2ed670e913c2e56 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 13:16:32 -0400
Subject: [PATCH 4/8] nitcc: LRState instead of a name, use a real prefix of
 elements

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 43 +++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index 98683d62c4..1dcbc5736f 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -137,7 +137,7 @@ class Gram
 
 		analyse
 
-		var first = new LRState("Start")
+		var first = new LRState
 		first.number = 0
 		for i in start.start_state do first.add(i)
 
@@ -165,13 +165,10 @@ class Gram
 				if nexts.has_key(e) then
 					nexts[e].add(i.avance)
 				else
-					var name
-					if state == automaton.states.first then
-						name = e.to_s
-					else
-						name = "{state.name} {e}"
-					end
-					var next = new LRState(name)
+					var next = new LRState
+					next.prev = state
+					next.prefix.add_all(state.prefix)
+					next.prefix.add(e)
 					nexts[e] = next
 					next.add(i.avance)
 				end
@@ -185,6 +182,10 @@ class Gram
 				var new_state = true
 				for n in seen do
 					if n == next then
+						if next.prefix.length < n.prefix.length then
+							n.prefix = next.prefix
+							n.prev = next.prev
+						end
 						next = n
 						new_state = false
 						break
@@ -611,7 +612,7 @@ class LRAutomaton
 		var res = new Array[String]
 		res.add "* LRAutomaton: {states.length} states\n"
 		for s in states do
-			res.add "s{s.number} {s.name}\n"
+			res.add "STATE {s}\n"
 			res.add "\tCORE\n"
 			for i in s.core do
 				res.add "\t\t{i}\n"
@@ -700,7 +701,7 @@ class LRAutomaton
 		f.write("node[shape=Mrecord,height=0];\n")
 
 		for s in states do
-			f.write "s{s.number} [label=\"{s.number} {s.name.escape_to_dot}|"
+			f.write "s{s.number} [label=\"{s.to_s.escape_to_dot}|"
 			for i in s.core do
 				f.write "{i.to_s.escape_to_dot}\\l"
 			end
@@ -782,7 +783,7 @@ private class Generator
 		add "redef class NToken"
 		for s in states do
 			if not s.need_guard then continue
-			add "\t# guarded action for state {s.name}"
+			add "\t# guarded action for state {s}"
 			add "\t# {s.shifts.length} shift(s) and {s.reduces.length} reduce(s)"
 			add "\tprivate fun action_s{s.number}(parser: Parser) do"
 			if s.reduces.length != 1 then
@@ -887,11 +888,11 @@ private class Generator
 		end
 
 		for s in states do
-			add "# State {s.name}"
+			add "# State {s}"
 			add "private class LRState{s.number}"
 			add "\tsuper LRState"
 
-			add "\tredef fun to_s do return \"{s.name.escape_to_nit}\""
+			add "\tredef fun to_s do return \"{s.to_s.escape_to_nit}\""
 			
 			var err = new Array[String]
 			for t in s.outs do
@@ -1009,9 +1010,13 @@ end
 
 # A state in a LR automaton
 class LRState
-	# Name of the automaton (short part from the start)
-	var name: String
+	# Shortest prefix to go to this state
+	# Is empty for the start state
+	var prefix = new Array[Element]
 
+	# The previous node according to the prefix
+	# Is null for the start state
+	var prev: nullable LRState = null
 
 	# Number
 	var number = -1
@@ -1038,7 +1043,7 @@ class LRState
 	redef fun ==(o) do return o isa LRState and core == o.core
 	redef fun hash do return items.length
 
-	redef fun to_s do return items.join(" ; ")
+	redef fun to_s do return "{number} {prefix.join(" ")}"
 
 	# Add and item in the core
 	fun add(i: Item): Bool
@@ -1120,7 +1125,7 @@ class LRState
 		var removed_reduces = new Array[Token]
 		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}:"
+				print "REDUCE/REDUCE Conflict on state {self} for token {t}:"
 				for i in a do print "\treduce: {i}"
 				conflicting_items.add_all a
 			end
@@ -1153,12 +1158,12 @@ class LRState
 					end
 				end
 				if confs.is_empty then
-					print "Automatic Dangling on state {self.number} {self.name} for token {t}:"
+					print "Automatic Dangling on state {self} for token {t}:"
 					print "\treduce: {ri}"
 					for r in ress do print r
 					removed_reduces.add t
 				else
-					print "SHIFT/REDUCE Conflict on state {self.number} {self.name} for token {t}:"
+					print "SHIFT/REDUCE Conflict on state {self} for token {t}:"
 					print "\treduce: {ri}"
 					for i in guarded_shift[t] do print "\tshift:  {i}"
 					removed_reduces.add t

From 5f295b4342f96d6ec490daa1daa43052ffdc4fe5 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 14:59:34 -0400
Subject: [PATCH 5/8] nitcc: add LREngine to simulate an LR automaton and build
 CST

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 132 ++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index 1dcbc5736f..f6027eff42 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -1204,6 +1204,138 @@ class LRState
 	end
 end
 
+# Execution engine simulator on a LR automaton.
+# It has a stack of LR states and AST nodes.
+class LREngine
+	# The stack of stale, starts with start state
+	var state_stack = new Array[nullable LRState]
+
+	# A stack of AST node, reduced production and shifted token are pushed onto
+	var node_stack = new Array[CSTNode]
+
+	# The sequence of elements shifted for the first state
+	var past = new Array[Element]
+
+	# The sequence of elements shifted since the first state
+	var future = new Array[Element]
+
+	# The current state (top of the stack)
+	fun state: nullable LRState do return state_stack.last
+
+	# Initialize the engine on a given `state`.
+	# A consistent `past` is created to reach `state`.
+	# Subsequent shifts will be added to the `future`.
+	fun start(state: LRState)
+	do
+		var start = state
+		loop
+			var prev = start.prev
+			if prev == null then break
+			start = prev
+		end
+		state_stack.add(start)
+		for e in state.prefix do shift(e)
+		assert self.state == state
+
+		var tmp = future
+		future = past
+		past = tmp
+	end
+
+	# Perform a shift on `e` for the current `state` and add it to `future`.
+	# Both tokens and productions can be shifted.
+	# If the shift is impossible, the current state become null,
+	fun shift(e: Element)
+	do
+		state_stack.add state.trans(e)
+		future.add(e)
+		node_stack.add(new CSTNode(e))
+	end
+
+	# Perform a reduction on an alternative `a` on the current state.
+	fun reduce(a: Alternative)
+	do
+		assert can_reduce(a)
+		var len = a.elems.length
+		for i in [0..len[ do state_stack.pop
+		var node = new CSTNode(a.prod)
+		for i in [0..len[ do node.children.unshift(node_stack.pop)
+		node_stack.add(node)
+
+		# TODO something smart when accepting
+		if a.prod.accept then
+			state_stack.add null
+			return
+		end
+
+		state_stack.add state.trans(a.prod)
+	end
+
+	# Return true if the elements in the stack are compatible with the reduction.
+	fun can_reduce(alternative: Alternative): Bool
+	do
+		var idx = node_stack.length - alternative.elems.length
+		if idx < 0 then return false
+		for i in [0..alternative.elems.length[ do
+			if alternative.elems[i] != node_stack[idx+i].element then return false
+		end
+		return true
+	end
+
+	# Try to shift on the current state.
+	# If not doable, try to reduce something, then shift.
+	# Return true is a shift was done.
+	fun try_shift(e: Element): Bool
+	do
+		var s = state.trans(e)
+		if s == null then
+			if not try_reduce then
+				return false
+			end
+			return try_shift(e)
+		end
+		shift(e)
+		return true
+	end
+
+	# Try to reduce something on the current state.
+	fun try_reduce: Bool
+	do
+		for i in state.core do
+			# Filter out items that are not reduction
+			if i.next != null then continue
+			if can_reduce(i.alt) then
+				reduce(i.alt)
+				return true
+			end
+		end
+		return false
+	end
+
+	fun tree: CSTNode do return node_stack.last
+end
+
+# A CST node of the LREngine
+class CSTNode
+	var element: Element
+	var children = new Array[CSTNode]
+
+	fun dump(prefix: nullable String): String
+	do
+		if prefix == null then prefix = ""
+		var res = element.to_s + "\n"
+		if children.length == 0 then return res
+		var p2 = prefix + "│ "
+		for c in [0..children.length-1[ do
+			res += prefix + "├╴"
+			res += children[c].dump(p2)
+		end
+		res += prefix + "└╴"
+		res += children.last.dump(prefix + "  ")
+		return res
+	end
+end
+
 # A transition in a LR automaton
 class LRTransition
 	# The origin state

From b0243a0c4375346afe32ac80c5e82140fa4a3eab Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 15:04:48 -0400
Subject: [PATCH 6/8] nitcc: show example of S/R R/R conflict (and possible
 ambiguities)

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 100 ++++++++++++++++++++++++++++++++--
 1 file changed, 96 insertions(+), 4 deletions(-)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index f6027eff42..fc9e13280a 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -630,6 +630,9 @@ class LRAutomaton
 					res.add "\t\t\t{i2}\n"
 				end
 			end
+			var engine = new LREngine
+			engine.start(s)
+			res.add "\tPOSSIBLE EXIT {engine.find_exit}\n"
 			res.add "\tTRANSITIONS {s.outs.length}\n"
 			for t in s.outs do
 				res.add "\t\t{t.elem} |-> s{t.to.number}\n"
@@ -1089,10 +1092,25 @@ class LRState
 	# Is the state LR0?
 	fun is_lr0: Bool do return reduces.length <= 1 and shifts.is_empty or reduces.is_empty
 
+	# The item that reduces the most
+	# Is used by `find_exit`
+	fun exit_item: Item
+	do
+		var exit_candidate = core.first
+		for i in core do
+			if i.alt.prod.accept then return i
+			if i.pos > exit_candidate.pos then
+				exit_candidate = i
+			else if i.pos == exit_candidate.pos and i.alt.elems.length < exit_candidate.alt.elems.length then
+				exit_candidate = i
+			end
+		end
+		return exit_candidate
+	end
+
 	# Compute guards and conflicts
 	fun analysis
 	do
-
 		# Collect action and conflicts
 		for i in items do
 			var n = i.next
@@ -1125,9 +1143,35 @@ class LRState
 		var removed_reduces = new Array[Token]
 		for t, a in guarded_reduce do
 			if a.length > 1 then
+				print "---"
 				print "REDUCE/REDUCE Conflict on state {self} for token {t}:"
-				for i in a do print "\treduce: {i}"
+				print "A possible past: {prefix}"
 				conflicting_items.add_all a
+				var worst_exit = null
+				for i in a do
+					var engine = new LREngine
+					engine.start(self)
+					engine.reduce(i.alt)
+					var exit = engine.find_exit
+					if worst_exit == null or exit.length > worst_exit.length then worst_exit = exit
+				end
+				var amb = 0
+				for i in a do
+					var engine = new LREngine
+					engine.start(self)
+					engine.reduce(i.alt)
+					for e in worst_exit.as(not null) do
+						if not engine.try_shift(e) then break
+					end
+					print "REDUCE on item: {i}"
+					var exit = engine.find_exit
+					print "A possible future: {exit}"
+					print engine.tree.dump
+					if exit == worst_exit then amb += 1
+				end
+				if amb > 1 then
+					print "AMBIGUITY detected: same elements, different trees"
+				end
 			end
 			if guarded_shift.has_key(t) then
 				var ri = a.first
@@ -1158,17 +1202,46 @@ class LRState
 					end
 				end
 				if confs.is_empty then
+					print "---"
 					print "Automatic Dangling on state {self} for token {t}:"
 					print "\treduce: {ri}"
 					for r in ress do print r
 					removed_reduces.add t
 				else
+					print "---"
 					print "SHIFT/REDUCE Conflict on state {self} for token {t}:"
-					print "\treduce: {ri}"
-					for i in guarded_shift[t] do print "\tshift:  {i}"
+					print "A possible past: {prefix}"
 					removed_reduces.add t
 					conflicting_items.add_all a
 					conflicting_items.add_all guarded_shift[t]
+
+					var worst_exit = null
+					for i in guarded_shift[t] do
+						print "SHIFT on item: {i}"
+						var engine = new LREngine
+						engine.start(self)
+						for e in i.future do engine.shift(e)
+						var exit = engine.find_exit
+						print "A possible future: {exit}"
+						print engine.tree.dump
+						if worst_exit == null or exit.length < worst_exit.length then
+							worst_exit = exit
+						end
+					end
+					var engine = new LREngine
+					engine.start(self)
+					engine.reduce(ri.alt)
+					for e in worst_exit.as(not null) do
+						if not engine.try_shift(e) then break
+					end
+					var reduce_exit = engine.find_exit
+					print "REDUCE on item: {ri}"
+					var exit = engine.find_exit
+					print "A possible future: {exit}"
+					print engine.tree.dump
+					if exit == worst_exit then
+						print "AMBIGUITY detected: same elements, different trees"
+					end
 				end
 			end
 		end
@@ -1313,6 +1386,16 @@ class LREngine
 	end
 
 	fun tree: CSTNode do return node_stack.last
+
+	fun find_exit: Array[Element]
+	do
+		while state != null do
+			var item = state.exit_item
+			for e in item.future do shift(e)
+			reduce(item.alt)
+		end
+		return future
+	end
 end
 
 # A CST node of the LREngine
@@ -1401,4 +1484,13 @@ class Item
 		var res = new Item(alt, pos+1)
 		return res
 	end
+
+	fun future: Array[Element]
+	do
+		var res = new Array[Element]
+		for i in [pos .. alt.elems.length[ do
+			res.add alt.elems[i]
+		end
+		return res
+	end
 end

From b1dddbf08f0cf27ac33674e9bbe87f34b6ff8aed Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Thu, 18 Jul 2024 15:40:43 -0400
Subject: [PATCH 7/8] nitcc: add new tests of grammars (some with conflicts)

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/tests/amb.input           |  1 +
 contrib/nitcc/tests/amb.sablecc         |  4 ++++
 contrib/nitcc/tests/amb2.input          |  1 +
 contrib/nitcc/tests/amb2.sablecc        |  6 +++++
 contrib/nitcc/tests/amb3.input          |  1 +
 contrib/nitcc/tests/amb3.sablecc        |  5 ++++
 contrib/nitcc/tests/calc0.input         |  1 +
 contrib/nitcc/tests/calc0.sablecc       | 11 +++++++++
 contrib/nitcc/tests/eq.input            |  1 +
 contrib/nitcc/tests/eq.sablecc          |  9 +++++++
 contrib/nitcc/tests/eq2.input           |  1 +
 contrib/nitcc/tests/eq2.sablecc         | 10 ++++++++
 contrib/nitcc/tests/eq3.input           |  1 +
 contrib/nitcc/tests/eq3.sablecc         | 10 ++++++++
 contrib/nitcc/tests/geom.input          |  1 +
 contrib/nitcc/tests/geom.sablecc        |  8 +++++++
 contrib/nitcc/tests/lg.input            |  1 +
 contrib/nitcc/tests/lg.input2           |  1 +
 contrib/nitcc/tests/lg.sablecc          |  6 +++++
 contrib/nitcc/tests/lg2.input           |  1 +
 contrib/nitcc/tests/lg2.input2          |  1 +
 contrib/nitcc/tests/lg2.sablecc         |  5 ++++
 contrib/nitcc/tests/sav/amb.input.res   |  4 ++++
 contrib/nitcc/tests/sav/amb.res         |  1 +
 contrib/nitcc/tests/sav/amb2.input.res  | 10 ++++++++
 contrib/nitcc/tests/sav/amb2.res        |  1 +
 contrib/nitcc/tests/sav/amb3.input.res  |  6 +++++
 contrib/nitcc/tests/sav/amb3.res        |  1 +
 contrib/nitcc/tests/sav/calc0.input.res | 23 ++++++++++++++++++
 contrib/nitcc/tests/sav/eq.input.res    | 13 ++++++++++
 contrib/nitcc/tests/sav/eq.res          |  1 +
 contrib/nitcc/tests/sav/eq2.input.res   | 13 ++++++++++
 contrib/nitcc/tests/sav/eq2.res         |  1 +
 contrib/nitcc/tests/sav/eq3.input.res   | 13 ++++++++++
 contrib/nitcc/tests/sav/eq3.res         |  1 +
 contrib/nitcc/tests/sav/geom.input.res  | 32 +++++++++++++++++++++++++
 contrib/nitcc/tests/sav/lg.input.res    | 19 +++++++++++++++
 contrib/nitcc/tests/sav/lg.input2.res   | 19 +++++++++++++++
 contrib/nitcc/tests/sav/lg.res          |  1 +
 contrib/nitcc/tests/sav/lg2.input.res   | 15 ++++++++++++
 contrib/nitcc/tests/sav/lg2.input2.res  | 17 +++++++++++++
 contrib/nitcc/tests/sav/lg2.res         |  1 +
 42 files changed, 278 insertions(+)
 create mode 100644 contrib/nitcc/tests/amb.input
 create mode 100644 contrib/nitcc/tests/amb.sablecc
 create mode 100644 contrib/nitcc/tests/amb2.input
 create mode 100644 contrib/nitcc/tests/amb2.sablecc
 create mode 100644 contrib/nitcc/tests/amb3.input
 create mode 100644 contrib/nitcc/tests/amb3.sablecc
 create mode 100644 contrib/nitcc/tests/calc0.input
 create mode 100644 contrib/nitcc/tests/calc0.sablecc
 create mode 100644 contrib/nitcc/tests/eq.input
 create mode 100644 contrib/nitcc/tests/eq.sablecc
 create mode 100644 contrib/nitcc/tests/eq2.input
 create mode 100644 contrib/nitcc/tests/eq2.sablecc
 create mode 100644 contrib/nitcc/tests/eq3.input
 create mode 100644 contrib/nitcc/tests/eq3.sablecc
 create mode 100644 contrib/nitcc/tests/geom.input
 create mode 100644 contrib/nitcc/tests/geom.sablecc
 create mode 100644 contrib/nitcc/tests/lg.input
 create mode 100644 contrib/nitcc/tests/lg.input2
 create mode 100644 contrib/nitcc/tests/lg.sablecc
 create mode 100644 contrib/nitcc/tests/lg2.input
 create mode 100644 contrib/nitcc/tests/lg2.input2
 create mode 100644 contrib/nitcc/tests/lg2.sablecc
 create mode 100644 contrib/nitcc/tests/sav/amb.input.res
 create mode 100644 contrib/nitcc/tests/sav/amb.res
 create mode 100644 contrib/nitcc/tests/sav/amb2.input.res
 create mode 100644 contrib/nitcc/tests/sav/amb2.res
 create mode 100644 contrib/nitcc/tests/sav/amb3.input.res
 create mode 100644 contrib/nitcc/tests/sav/amb3.res
 create mode 100644 contrib/nitcc/tests/sav/calc0.input.res
 create mode 100644 contrib/nitcc/tests/sav/eq.input.res
 create mode 100644 contrib/nitcc/tests/sav/eq.res
 create mode 100644 contrib/nitcc/tests/sav/eq2.input.res
 create mode 100644 contrib/nitcc/tests/sav/eq2.res
 create mode 100644 contrib/nitcc/tests/sav/eq3.input.res
 create mode 100644 contrib/nitcc/tests/sav/eq3.res
 create mode 100644 contrib/nitcc/tests/sav/geom.input.res
 create mode 100644 contrib/nitcc/tests/sav/lg.input.res
 create mode 100644 contrib/nitcc/tests/sav/lg.input2.res
 create mode 100644 contrib/nitcc/tests/sav/lg.res
 create mode 100644 contrib/nitcc/tests/sav/lg2.input.res
 create mode 100644 contrib/nitcc/tests/sav/lg2.input2.res
 create mode 100644 contrib/nitcc/tests/sav/lg2.res

diff --git a/contrib/nitcc/tests/amb.input b/contrib/nitcc/tests/amb.input
new file mode 100644
index 0000000000..074d1eeb40
--- /dev/null
+++ b/contrib/nitcc/tests/amb.input
@@ -0,0 +1 @@
+id
diff --git a/contrib/nitcc/tests/amb.sablecc b/contrib/nitcc/tests/amb.sablecc
new file mode 100644
index 0000000000..bbe895fe49
--- /dev/null
+++ b/contrib/nitcc/tests/amb.sablecc
@@ -0,0 +1,4 @@
+Grammar amb;
+Parser
+Ignored #10, #32;
+e = 'id' | e | e;
diff --git a/contrib/nitcc/tests/amb2.input b/contrib/nitcc/tests/amb2.input
new file mode 100644
index 0000000000..7d5c7b2b5e
--- /dev/null
+++ b/contrib/nitcc/tests/amb2.input
@@ -0,0 +1 @@
+-0+
diff --git a/contrib/nitcc/tests/amb2.sablecc b/contrib/nitcc/tests/amb2.sablecc
new file mode 100644
index 0000000000..ad1d48f5a9
--- /dev/null
+++ b/contrib/nitcc/tests/amb2.sablecc
@@ -0,0 +1,6 @@
+Grammar amb;
+Parser
+Ignored #10, #32;
+e = '-' a | b '+' | '0';
+a = e ;
+b = e ;
diff --git a/contrib/nitcc/tests/amb3.input b/contrib/nitcc/tests/amb3.input
new file mode 100644
index 0000000000..b2901ea97c
--- /dev/null
+++ b/contrib/nitcc/tests/amb3.input
@@ -0,0 +1 @@
+a b
diff --git a/contrib/nitcc/tests/amb3.sablecc b/contrib/nitcc/tests/amb3.sablecc
new file mode 100644
index 0000000000..bdc84b7444
--- /dev/null
+++ b/contrib/nitcc/tests/amb3.sablecc
@@ -0,0 +1,5 @@
+Grammar amb;
+Parser
+Ignored #10, #32;
+e = x 'b' | 'a' x ;
+x = 'a' | 'b';
diff --git a/contrib/nitcc/tests/calc0.input b/contrib/nitcc/tests/calc0.input
new file mode 100644
index 0000000000..0523cb5cd7
--- /dev/null
+++ b/contrib/nitcc/tests/calc0.input
@@ -0,0 +1 @@
+1+2+3*(4+5)
diff --git a/contrib/nitcc/tests/calc0.sablecc b/contrib/nitcc/tests/calc0.sablecc
new file mode 100644
index 0000000000..87386e79dd
--- /dev/null
+++ b/contrib/nitcc/tests/calc0.sablecc
@@ -0,0 +1,11 @@
+Grammar calc;
+Lexer
+n = ('0'..'9')+ ;
+Parser
+Ignored #10, #32;
+e
+	= e '+' e
+	| e '*' e
+	| '(' e ')'
+	| n
+	;
diff --git a/contrib/nitcc/tests/eq.input b/contrib/nitcc/tests/eq.input
new file mode 100644
index 0000000000..e3280dd06b
--- /dev/null
+++ b/contrib/nitcc/tests/eq.input
@@ -0,0 +1 @@
+id=id=id
diff --git a/contrib/nitcc/tests/eq.sablecc b/contrib/nitcc/tests/eq.sablecc
new file mode 100644
index 0000000000..7f1e196143
--- /dev/null
+++ b/contrib/nitcc/tests/eq.sablecc
@@ -0,0 +1,9 @@
+Grammar eq;
+Parser
+Ignored #10, #32;
+e =
+	var '=' e |
+	var ;
+c =
+	e '=' e ;
+var = 'id' ;
diff --git a/contrib/nitcc/tests/eq2.input b/contrib/nitcc/tests/eq2.input
new file mode 100644
index 0000000000..e3280dd06b
--- /dev/null
+++ b/contrib/nitcc/tests/eq2.input
@@ -0,0 +1 @@
+id=id=id
diff --git a/contrib/nitcc/tests/eq2.sablecc b/contrib/nitcc/tests/eq2.sablecc
new file mode 100644
index 0000000000..7c5db34ec1
--- /dev/null
+++ b/contrib/nitcc/tests/eq2.sablecc
@@ -0,0 +1,10 @@
+Grammar eq;
+Parser
+Ignored #10, #32;
+e =
+	var '=' e |
+	'assert' c |
+	var ;
+c =
+	e '=' e ;
+var = 'id' ;
diff --git a/contrib/nitcc/tests/eq3.input b/contrib/nitcc/tests/eq3.input
new file mode 100644
index 0000000000..e3280dd06b
--- /dev/null
+++ b/contrib/nitcc/tests/eq3.input
@@ -0,0 +1 @@
+id=id=id
diff --git a/contrib/nitcc/tests/eq3.sablecc b/contrib/nitcc/tests/eq3.sablecc
new file mode 100644
index 0000000000..33bb02da82
--- /dev/null
+++ b/contrib/nitcc/tests/eq3.sablecc
@@ -0,0 +1,10 @@
+Grammar eq;
+Parser
+Ignored #10, #32;
+e =
+	var '=' e |
+	c |
+	var ;
+c =
+	e '=' e ;
+var = 'id' ;
diff --git a/contrib/nitcc/tests/geom.input b/contrib/nitcc/tests/geom.input
new file mode 100644
index 0000000000..4b169b1f5a
--- /dev/null
+++ b/contrib/nitcc/tests/geom.input
@@ -0,0 +1 @@
+triangle 0x0 0@0 centre circle 0x0 0@0
diff --git a/contrib/nitcc/tests/geom.sablecc b/contrib/nitcc/tests/geom.sablecc
new file mode 100644
index 0000000000..8026a54e76
--- /dev/null
+++ b/contrib/nitcc/tests/geom.sablecc
@@ -0,0 +1,8 @@
+Grammar geom;
+Parser
+Ignored #10, #32;
+forme =
+	'triangle' point point point |
+	'circle' point point ;
+point = num 'x' num | num '@' num | 'centre' forme;
+num = '0';
diff --git a/contrib/nitcc/tests/lg.input b/contrib/nitcc/tests/lg.input
new file mode 100644
index 0000000000..20afe73e05
--- /dev/null
+++ b/contrib/nitcc/tests/lg.input
@@ -0,0 +1 @@
+<0><0>>
diff --git a/contrib/nitcc/tests/lg.input2 b/contrib/nitcc/tests/lg.input2
new file mode 100644
index 0000000000..9b09d7781c
--- /dev/null
+++ b/contrib/nitcc/tests/lg.input2
@@ -0,0 +1 @@
+<0><0>0
diff --git a/contrib/nitcc/tests/lg.sablecc b/contrib/nitcc/tests/lg.sablecc
new file mode 100644
index 0000000000..c2a1e74804
--- /dev/null
+++ b/contrib/nitcc/tests/lg.sablecc
@@ -0,0 +1,6 @@
+Grammar lg;
+Parser
+Ignored #10, #32;
+e = e '<' a | e '>' a | a ;
+a = n | '<' e '>' ;
+n = '0' ;
diff --git a/contrib/nitcc/tests/lg2.input b/contrib/nitcc/tests/lg2.input
new file mode 100644
index 0000000000..20afe73e05
--- /dev/null
+++ b/contrib/nitcc/tests/lg2.input
@@ -0,0 +1 @@
+<0><0>>
diff --git a/contrib/nitcc/tests/lg2.input2 b/contrib/nitcc/tests/lg2.input2
new file mode 100644
index 0000000000..9b09d7781c
--- /dev/null
+++ b/contrib/nitcc/tests/lg2.input2
@@ -0,0 +1 @@
+<0><0>0
diff --git a/contrib/nitcc/tests/lg2.sablecc b/contrib/nitcc/tests/lg2.sablecc
new file mode 100644
index 0000000000..4277f3c56f
--- /dev/null
+++ b/contrib/nitcc/tests/lg2.sablecc
@@ -0,0 +1,5 @@
+Grammar lg;
+Parser
+Ignored #10, #32;
+e = e '<' e | e '>' e | n | '<' e '>' ;
+n = '0' ;
diff --git a/contrib/nitcc/tests/sav/amb.input.res b/contrib/nitcc/tests/sav/amb.input.res
new file mode 100644
index 0000000000..e8b4706101
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb.input.res
@@ -0,0 +1,4 @@
+Start
+  e_0
+    'id'@(1:1-1:3)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/amb.res b/contrib/nitcc/tests/sav/amb.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/amb2.input.res b/contrib/nitcc/tests/sav/amb2.input.res
new file mode 100644
index 0000000000..39f373159e
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb2.input.res
@@ -0,0 +1,10 @@
+Start
+  e_1
+    b
+      e_0
+        '-'@(1:1-1:2)
+        a
+          e_2
+            '0'@(1:2-1:3)
+    '+'@(1:3-1:4)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/amb2.res b/contrib/nitcc/tests/sav/amb2.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb2.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/amb3.input.res b/contrib/nitcc/tests/sav/amb3.input.res
new file mode 100644
index 0000000000..1c07b4c2cc
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb3.input.res
@@ -0,0 +1,6 @@
+Start
+  e_1
+    'a'@(1:1-1:2)
+    x_1
+      'b'@(1:3-1:4)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/amb3.res b/contrib/nitcc/tests/sav/amb3.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/amb3.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/calc0.input.res b/contrib/nitcc/tests/sav/calc0.input.res
new file mode 100644
index 0000000000..fb9d423071
--- /dev/null
+++ b/contrib/nitcc/tests/sav/calc0.input.res
@@ -0,0 +1,23 @@
+Start
+  e_0
+    e_3
+      n@(1:1-1:2)='1'
+    '+'@(1:2-1:3)
+    e_0
+      e_3
+        n@(1:3-1:4)='2'
+      '+'@(1:4-1:5)
+      e_1
+        e_3
+          n@(1:5-1:6)='3'
+        '*'@(1:6-1:7)
+        e_2
+          '('@(1:7-1:8)
+          e_0
+            e_3
+              n@(1:8-1:9)='4'
+            '+'@(1:9-1:10)
+            e_3
+              n@(1:10-1:11)='5'
+          ')'@(1:11-1:12)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/eq.input.res b/contrib/nitcc/tests/sav/eq.input.res
new file mode 100644
index 0000000000..7e18e33f4b
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq.input.res
@@ -0,0 +1,13 @@
+Start
+  e_0
+    var
+      'id'@(1:1-1:3)
+    '='@(1:3-1:4)
+    e_0
+      var
+        'id'@(1:4-1:6)
+      '='@(1:6-1:7)
+      e_1
+        var
+          'id'@(1:7-1:9)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/eq.res b/contrib/nitcc/tests/sav/eq.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/eq2.input.res b/contrib/nitcc/tests/sav/eq2.input.res
new file mode 100644
index 0000000000..b7528645f3
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq2.input.res
@@ -0,0 +1,13 @@
+Start
+  e_0
+    var
+      'id'@(1:1-1:3)
+    '='@(1:3-1:4)
+    e_0
+      var
+        'id'@(1:4-1:6)
+      '='@(1:6-1:7)
+      e_2
+        var
+          'id'@(1:7-1:9)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/eq2.res b/contrib/nitcc/tests/sav/eq2.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq2.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/eq3.input.res b/contrib/nitcc/tests/sav/eq3.input.res
new file mode 100644
index 0000000000..b7528645f3
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq3.input.res
@@ -0,0 +1,13 @@
+Start
+  e_0
+    var
+      'id'@(1:1-1:3)
+    '='@(1:3-1:4)
+    e_0
+      var
+        'id'@(1:4-1:6)
+      '='@(1:6-1:7)
+      e_2
+        var
+          'id'@(1:7-1:9)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/eq3.res b/contrib/nitcc/tests/sav/eq3.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/eq3.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/geom.input.res b/contrib/nitcc/tests/sav/geom.input.res
new file mode 100644
index 0000000000..516cc64e5d
--- /dev/null
+++ b/contrib/nitcc/tests/sav/geom.input.res
@@ -0,0 +1,32 @@
+Start
+  forme_0
+    'triangle'@(1:1-1:9)
+    point_0
+      num
+        '0'@(1:10-1:11)
+      'x'@(1:11-1:12)
+      num
+        '0'@(1:12-1:13)
+    point_1
+      num
+        '0'@(1:14-1:15)
+      '@'@(1:15-1:16)
+      num
+        '0'@(1:16-1:17)
+    point_2
+      'centre'@(1:18-1:24)
+      forme_1
+        'circle'@(1:25-1:31)
+        point_0
+          num
+            '0'@(1:32-1:33)
+          'x'@(1:33-1:34)
+          num
+            '0'@(1:34-1:35)
+        point_1
+          num
+            '0'@(1:36-1:37)
+          '@'@(1:37-1:38)
+          num
+            '0'@(1:38-1:39)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/lg.input.res b/contrib/nitcc/tests/sav/lg.input.res
new file mode 100644
index 0000000000..36b1985027
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg.input.res
@@ -0,0 +1,19 @@
+Start
+  e_2
+    a_1
+      '<'@(1:1-1:2)
+      e_1
+        e_2
+          a_0
+            n
+              '0'@(1:2-1:3)
+        '>'@(1:3-1:4)
+        a_1
+          '<'@(1:4-1:5)
+          e_2
+            a_0
+              n
+                '0'@(1:5-1:6)
+          '>'@(1:6-1:7)
+      '>'@(1:7-1:8)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/lg.input2.res b/contrib/nitcc/tests/sav/lg.input2.res
new file mode 100644
index 0000000000..f825a5aa70
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg.input2.res
@@ -0,0 +1,19 @@
+NParserError@(2:1-2:1)=''
+Nodes[Node]
+  '<'@(1:1-1:2)
+  e_2
+    a_0
+      n
+        '0'@(1:2-1:3)
+  '>'@(1:3-1:4)
+  '<'@(1:4-1:5)
+  e_1
+    e_2
+      a_0
+        n
+          '0'@(1:5-1:6)
+    '>'@(1:6-1:7)
+    a_0
+      n
+        '0'@(1:7-1:8)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/lg.res b/contrib/nitcc/tests/sav/lg.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg.res
@@ -0,0 +1 @@
+Error: there is conflicts
diff --git a/contrib/nitcc/tests/sav/lg2.input.res b/contrib/nitcc/tests/sav/lg2.input.res
new file mode 100644
index 0000000000..30257925c5
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg2.input.res
@@ -0,0 +1,15 @@
+NParserError@(2:1-2:1)=''
+Nodes[Node]
+  '<'@(1:1-1:2)
+  e_2
+    n
+      '0'@(1:2-1:3)
+  '>'@(1:3-1:4)
+  e_3
+    '<'@(1:4-1:5)
+    e_2
+      n
+        '0'@(1:5-1:6)
+    '>'@(1:6-1:7)
+  '>'@(1:7-1:8)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/lg2.input2.res b/contrib/nitcc/tests/sav/lg2.input2.res
new file mode 100644
index 0000000000..f6b978e66b
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg2.input2.res
@@ -0,0 +1,17 @@
+NParserError@(2:1-2:1)=''
+Nodes[Node]
+  '<'@(1:1-1:2)
+  e_2
+    n
+      '0'@(1:2-1:3)
+  '>'@(1:3-1:4)
+  '<'@(1:4-1:5)
+  e_1
+    e_2
+      n
+        '0'@(1:5-1:6)
+    '>'@(1:6-1:7)
+    e_2
+      n
+        '0'@(1:7-1:8)
+  Eof@(2:1-2:1)=''
diff --git a/contrib/nitcc/tests/sav/lg2.res b/contrib/nitcc/tests/sav/lg2.res
new file mode 100644
index 0000000000..05b05f7966
--- /dev/null
+++ b/contrib/nitcc/tests/sav/lg2.res
@@ -0,0 +1 @@
+Error: there is conflicts

From a45fd3d85891dc1ef17d9be11caa5e2925915964 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Sat, 20 Jul 2024 11:39:42 -0400
Subject: [PATCH 8/8] nitcc: grammar make find_exit not loop

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/grammar.nit | 29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

diff --git a/contrib/nitcc/src/grammar.nit b/contrib/nitcc/src/grammar.nit
index fc9e13280a..f4b724b791 100644
--- a/contrib/nitcc/src/grammar.nit
+++ b/contrib/nitcc/src/grammar.nit
@@ -1092,22 +1092,6 @@ class LRState
 	# Is the state LR0?
 	fun is_lr0: Bool do return reduces.length <= 1 and shifts.is_empty or reduces.is_empty
 
-	# The item that reduces the most
-	# Is used by `find_exit`
-	fun exit_item: Item
-	do
-		var exit_candidate = core.first
-		for i in core do
-			if i.alt.prod.accept then return i
-			if i.pos > exit_candidate.pos then
-				exit_candidate = i
-			else if i.pos == exit_candidate.pos and i.alt.elems.length < exit_candidate.alt.elems.length then
-				exit_candidate = i
-			end
-		end
-		return exit_candidate
-	end
-
 	# Compute guards and conflicts
 	fun analysis
 	do
@@ -1389,8 +1373,17 @@ class LREngine
 
 	fun find_exit: Array[Element]
 	do
-		while state != null do
-			var item = state.exit_item
+		var set = new HashSet[LRState]
+		loop
+			var state = self.state
+			if state == null then break
+			if set.has(state) then
+				# We are looping, just abort
+				break
+			end
+			set.add(state)
+			# Heuristic, the first item is an accepting one or something that exit without looping
+			var item = state.core.first
 			for e in item.future do shift(e)
 			reduce(item.alt)
 		end