From fd6009308c554cfaa5a7635676f2784299e04dc1 Mon Sep 17 00:00:00 2001
From: Jean Privat <jean@pryen.org>
Date: Sun, 23 Jun 2024 16:00:10 -0400
Subject: [PATCH] nitcc: add Separator and Tail keyword

Signed-off-by: Jean Privat <jean@pryen.org>
---
 contrib/nitcc/src/nitcc.sablecc      |  9 +++
 contrib/nitcc/src/nitcc_semantic.nit | 98 ++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)

diff --git a/contrib/nitcc/src/nitcc.sablecc b/contrib/nitcc/src/nitcc.sablecc
index bf50f2a53e..7e6dd19a2c 100644
--- a/contrib/nitcc/src/nitcc.sablecc
+++ b/contrib/nitcc/src/nitcc.sablecc
@@ -112,8 +112,17 @@ elem =
 	{ques:} elem '?' |
 	{plus:} elem '+' |
 	{group:} '(' elem+ ')' |
+	{groupsep:} '(' elem+ separator [sep:]elem+ ')' mult |
 	{empty:} 'Empty' ;
 
+separator =
+	{sep:} 'Separator' |
+	{tail:} 'Tail' ;
+
+mult =
+	{star:} '*' |
+	{plus:} '+' ;
+
 priority =
 	{left:} 'Left' alts |
 	{right:} 'Right' alts |
diff --git a/contrib/nitcc/src/nitcc_semantic.nit b/contrib/nitcc/src/nitcc_semantic.nit
index 0c31ee944a..a4fc538a1c 100644
--- a/contrib/nitcc/src/nitcc_semantic.nit
+++ b/contrib/nitcc/src/nitcc_semantic.nit
@@ -149,6 +149,81 @@ private class CheckNameVisitor
 		return prod
 	end
 
+	# Pool of elements that are modified with Separator
+	var separatizes = new HashMap[Array[Element], Production]
+
+	# Create a separated version of an element `e1` where the last element is `e2`.
+	# This is used to implement `Separator` and `Tail` keywords.
+	#
+	# ```
+	# foo = x (bar Separator baz)+ y | z ;
+	# ```
+	#
+	# becomes
+	#
+	# ```
+	# foo = x abs1 y | z ;
+	# abs0 = bar baz ;
+	# abs1 = (one:) bar | {more:} abs0+ bar ;
+	# ```
+	fun separatize(e1, e2: Element): Production
+	do
+		var es = [e1, e2]
+		if separatizes.has_key(es) then return separatizes[es]
+		var name = "_sep{separatizes.length}"
+		var prod = new Production(name)
+		v1.gram.prods.add(prod)
+		var p = plusize(e1)
+		prod.spe = p
+		var alt1 = prod.new_alt("{name}_more", p, e2)
+		alt1.codes = [new CodePop, new CodePop, new CodeAdd: Code]
+		alt1.trans = true
+		var alt2 = prod.new_alt("{name}_one", e2)
+		alt2.codes = [new CodeNewNodes(alt1), new CodePop, new CodeAdd: Code]
+		alt2.trans = true
+		separatizes[es] = prod
+		return prod
+	end
+
+	# Pool of elements that are modified with Tail
+	var tailizes = new HashMap[Array[Element], Production]
+
+	# Create a separated version of an element `e1` where the last `e2` can be present.
+	# This is used to implement `Separator` and `Tail` keywords.
+	#
+	# ```
+	# foo = x (bar Separator baz)+ y | z ;
+	# ```
+	#
+	# becomes
+	#
+	# ```
+	# foo = x abs1 y | z ;
+	# abs0 = bar baz ;
+	# abs1 = (one:) bar | {more:} abs0+ bar | {tail:} abs0+;
+	# ```
+	fun tailize(e1, e2: Element): Production
+	do
+		var es = [e1, e2]
+		if tailizes.has_key(es) then return tailizes[es]
+		var name = "_tail{tailizes.length}"
+		var prod = new Production(name)
+		v1.gram.prods.add(prod)
+		var p = plusize(e1)
+		prod.spe = p
+		var alt1 = prod.new_alt("{name}_more", p, e2)
+		alt1.codes = [new CodePop, new CodePop, new CodeAdd: Code]
+		alt1.trans = true
+		var alt2 = prod.new_alt("{name}_one", e2)
+		alt2.codes = [new CodeNewNodes(alt1), new CodePop, new CodeAdd: Code]
+		alt2.trans = true
+		var alt3 = prod.new_alt("{name}_tail", p)
+		alt3.codes = [new CodePop]
+		alt3.trans = true
+		tailizes[es] = prod
+		return prod
+	end
+
 	# Pool of elements that are modified with ? (reuse them!)
 	var quesizes = new HashMap[Element, Production]
 
@@ -752,6 +827,29 @@ redef class Nelem_group
 	end
 end
 
+redef class Nelem_groupsep
+	redef fun accept_check_name_visitor(v) do
+		var old = v.elems
+		v.elems = new Array[Element]
+		n_elem.accept_check_name_visitor(v)
+		var prod1 = v.groupize(v.elems.clone)
+		n_sep.accept_check_name_visitor(v)
+		var prod2 = v.groupize(v.elems)
+		prod1.spe = prod2
+		v.elems = old
+		var prod
+		if n_separator isa Nseparator_sep then
+			prod = v.separatize(prod2, prod1)
+		else
+			prod = v.tailize(prod2, prod1)
+		end
+		if n_mult isa Nmult_star then
+			prod = v.quesize(prod)
+		end
+		set_elem(v, null, prod)
+	end
+end
+
 redef class Ntree_part
 	redef fun accept_collect_prod(v) do
 		print "NOT YET IMPLEMENTED: `Tree` part; it is ignored"