X-Git-Url: http://nitlanguage.org

diff --git a/lib/poset.nit b/lib/poset.nit
index e8f7e73..98205ac 100644
--- a/lib/poset.nit
+++ b/lib/poset.nit
@@ -17,6 +17,8 @@
 # Pre order sets and partial order set (ie hierarchies)
 module poset
 
+import serialization
+
 # Pre-order set graph.
 # This class models an incremental pre-order graph where new nodes and edges can be added (but not removed).
 # Pre-order graph has two characteristics:
@@ -71,9 +73,11 @@ module poset
 #
 # Thanks to the `[]` method, elements can be considered relatively to the poset.
 # SEE `POSetElement`
-class POSet[E: Object]
+class POSet[E]
 	super Collection[E]
 	super Comparator
+	super Cloneable
+	super Serializable
 
 	redef type COMPARED: E is fixed
 
@@ -149,20 +153,37 @@ class POSet[E: Object]
 		# Update the transitive reduction
 		if te.tos.has(f) then return # Skip the reduction if there is a loop
 
-		for x in te.dfroms.to_a do
+		# Remove transitive edges.
+		# Because the sets of direct is iterated, the list of edges to remove
+		# is stored and is applied after the iteration.
+		# The usual case is that no direct edges need to be removed,
+		# so start with a `null` list of edges.
+		var to_remove: nullable Array[E] = null
+		for x in te.dfroms do
 			var xe = self.elements[x]
 			if xe.tos.has(f) then
-				te.dfroms.remove(x)
+				if to_remove == null then to_remove = new Array[E]
+				to_remove.add x
 				xe.dtos.remove(t)
 			end
 		end
-		for x in fe.dtos.to_a do
+		if to_remove != null then
+			for x in to_remove do te.dfroms.remove(x)
+			to_remove.clear
+		end
+
+		for x in fe.dtos do
 			var xe = self.elements[x]
 			if xe.froms.has(t) then
 				xe.dfroms.remove(f)
-				fe.dtos.remove(x)
+				if to_remove == null then to_remove = new Array[E]
+				to_remove.add x
 			end
 		end
+		if to_remove != null then
+			for x in to_remove do fe.dtos.remove(x)
+		end
+
 		fe.dtos.add t
 		te.dfroms.add f
 	end
@@ -226,21 +247,26 @@ class POSet[E: Object]
 
 	# Write the POSet as a graphviz digraph.
 	#
-	# Nodes are identified with their `to_s`.
+	# Nodes are labeled with their `to_s` so homonymous nodes may appear.
 	# Edges are unlabeled.
-	fun write_dot(f: OStream)
+	fun write_dot(f: Writer)
 	do
 		f.write "digraph \{\n"
+		var ids = new HashMap[E, Int]
 		for x in elements.keys do
-			var xstr = x.to_s.escape_to_dot
-			f.write "\"{xstr}\";\n"
+			ids[x] = ids.length
+		end
+		for x in elements.keys do
+			var xstr = (x or else "null").to_s.escape_to_dot
+			var nx = "n{ids[x]}"
+			f.write "{nx}[label=\"{xstr}\"];\n"
 			var xe = self.elements[x]
 			for y in xe.dtos do
-				var ystr = y.to_s.escape_to_dot
+				var ny = "n{ids[y]}"
 				if self.has_edge(y,x) then
-					f.write "\"{xstr}\" -> \"{ystr}\"[dir=both];\n"
+					f.write "{nx} -> {ny}[dir=both];\n"
 				else
-					f.write "\"{xstr}\" -> \"{ystr}\";\n"
+					f.write "{nx} -> {ny};\n"
 				end
 			end
 		end
@@ -253,8 +279,7 @@ class POSet[E: Object]
 	# See `write_dot` for details.
 	fun show_dot
 	do
-		var f = new OProcess("dot", "-Txlib")
-		f.write "\}\n"
+		var f = new ProcessWriter("dot", "-Txlib")
 		write_dot(f)
 		f.close
 		f.wait
@@ -287,7 +312,7 @@ class POSet[E: Object]
 	# ~~~~
 	#
 	# Note that the linear extension is stable, unless a new node or a new edge is added.
-	redef fun compare(a, b: E): Int
+	redef fun compare(a, b)
 	do
 		var ae = self.elements[a]
 		var be = self.elements[b]
@@ -359,9 +384,129 @@ class POSet[E: Object]
 		sort(lin)
 		return lin
 	end
+
+	redef fun clone do return sub(self)
+
+	# Return an induced sub-poset
+	#
+	# The elements of the result are those given in argument.
+	#
+	# ~~~
+	# var pos = new POSet[String]
+	# pos.add_chain(["A", "B", "C", "D", "E"])
+	# pos.add_chain(["A", "X", "C", "Y", "E"])
+	#
+	# var pos2 = pos.sub(["A", "B", "D", "Y", "E"])
+	# assert pos2.has_exactly(["A", "B", "D", "Y", "E"])
+	# ~~~
+	#
+	# The full relationship is preserved between the provided elements.
+	#
+	# ~~~
+	# for e1 in pos2 do for e2 in pos2 do
+	#    assert pos2.has_edge(e1, e2) == pos.has_edge(e1, e2)
+	# end
+	# ~~~
+	#
+	# Not that by definition, the direct relationship is the transitive
+	# reduction of the full reduction. Thus, the direct relationship of the
+	# sub-poset may not be included in the direct relationship of self because an
+	# indirect edge becomes a direct one if all the intermediates elements
+	# are absent in the sub-poset.
+	#
+	# ~~~
+	# assert pos.has_direct_edge("B", "D")  == false
+	# assert pos2.has_direct_edge("B", "D") == true
+	#
+	# assert pos2["B"].direct_greaters.has_exactly(["D", "Y"])
+	# ~~~
+	#
+	# If the `elements` contains all then the result is a clone of self.
+	#
+	# ~~~
+	# var pos3 = pos.sub(pos)
+	# assert pos3 == pos
+	# assert pos3 == pos.clone
+	# ~~~
+	fun sub(elements: Collection[E]): POSet[E]
+	do
+		var res = new POSet[E]
+		for e in self do
+			if not elements.has(e) then continue
+			res.add_node(e)
+		end
+		for e in res do
+			for f in self[e].greaters do
+				if not elements.has(f) then continue
+				res.add_edge(e, f)
+			end
+		end
+		return res
+	end
+
+	# Two posets are equal if they contain the same elements and edges.
+	#
+	# ~~~
+	# var pos1 = new POSet[String]
+	# pos1.add_chain(["A", "B", "C", "D", "E"])
+	# pos1.add_chain(["A", "X", "C", "Y", "E"])
+	#
+	# var pos2 = new POSet[Object]
+	# pos2.add_edge("Y", "E")
+	# pos2.add_chain(["A", "X", "C", "D", "E"])
+	# pos2.add_chain(["A", "B", "C", "Y"])
+	#
+	# assert pos1 == pos2
+	#
+	# pos1.add_edge("D", "Y")
+	# assert pos1 != pos2
+	#
+	# pos2.add_edge("D", "Y")
+	# assert pos1 == pos2
+	#
+	# pos1.add_node("Z")
+	# assert pos1 != pos2
+	# ~~~
+	redef fun ==(other) do
+		if not other isa POSet[nullable Object] then return false
+		if not self.elements.keys.has_exactly(other.elements.keys) then return false
+		for e, ee in elements do
+			if ee.direct_greaters != other[e].direct_greaters then return false
+		end
+		assert hash == other.hash
+		return true
+	end
+
+	redef fun hash
+	do
+		var res = 0
+		for e, ee in elements do
+			if e == null then continue
+			res += e.hash
+			res += ee.direct_greaters.length
+		end
+		return res
+	end
+
+	redef fun core_serialize_to(serializer)
+	do
+		# Optimize written data because this structure has duplicated data
+		# For example, serializing the class hierarchy of a simple program where E is String
+		# result is before: 200k, after: 56k.
+		serializer.serialize_attribute("elements", elements)
+	end
+
+	redef init from_deserializer(deserializer)
+	do
+		deserializer.notify_of_creation self
+		var elements = deserializer.deserialize_attribute("elements")
+		if elements isa HashMap[E, POSetElement[E]] then
+			self.elements = elements
+		end
+	end
 end
 
-# View of an objet in a poset
+# View of an object in a poset
 # This class is a helper to handle specific queries on a same object
 #
 # For instance, one common usage is to add a specific attribute for each poset a class belong.
@@ -375,7 +520,9 @@ end
 # # ...
 # t.in_some_relation.greaters
 # ~~~
-class POSetElement[E: Object]
+class POSetElement[E]
+	super Serializable
+
 	# The poset self belong to
 	var poset: POSet[E]
 
@@ -491,6 +638,94 @@ class POSetElement[E: Object]
 			end
 		end
 		return min
+	end
 
+	redef fun core_serialize_to(serializer)
+	do
+		serializer.serialize_attribute("poset", poset)
+		serializer.serialize_attribute("element", element)
+		serializer.serialize_attribute("tos", tos)
+		serializer.serialize_attribute("froms", froms)
+		serializer.serialize_attribute("dtos", dtos)
+		serializer.serialize_attribute("dfroms", dfroms)
+		serializer.serialize_attribute("count", count)
+
+		# Don't serialize `froms`, `dtos` and `tos` as they duplicate information.
+		# TODO serialize them if a flag for extra info is set on `serializer`.
+	end
+
+	redef init from_deserializer(v)
+	do
+		# Code generated by the serialization_phase from the compiler frontend,
+		# copied here for compatibility with nith.
+
+		super
+		v.notify_of_creation self
+
+		var poset = v.deserialize_attribute("poset", "POSet[nullable Object]")
+		if v.deserialize_attribute_missing then
+			v.errors.add new Error("Deserialization Error: attribute `{class_name}::poset` missing from JSON object")
+		else if not poset isa POSet[E] then
+			v.errors.add new AttributeTypeError(self, "poset", poset, "POSet[nullable Object]")
+			if v.keep_going == false then return
+		else
+			self.poset = poset
+		end
+
+		var element = v.deserialize_attribute("element", "nullable Object")
+		if v.deserialize_attribute_missing then
+			v.errors.add new Error("Deserialization Error: attribute `{class_name}::element` missing from JSON object")
+		else if not element isa E then
+			v.errors.add new AttributeTypeError(self, "element", element, "nullable Object")
+			if v.keep_going == false then return
+		else
+			self.element = element
+		end
+
+		var tos = v.deserialize_attribute("tos", "HashSet[nullable Object]")
+		if v.deserialize_attribute_missing then
+		else if not tos isa HashSet[E] then
+			v.errors.add new AttributeTypeError(self, "tos", tos, "HashSet[nullable Object]")
+			if v.keep_going == false then return
+		else
+			self.tos = tos
+		end
+
+		var froms = v.deserialize_attribute("froms", "HashSet[nullable Object]")
+		if v.deserialize_attribute_missing then
+		else if not froms isa HashSet[E] then
+			v.errors.add new AttributeTypeError(self, "froms", froms, "HashSet[nullable Object]")
+			if v.keep_going == false then return
+		else
+			self.froms = froms
+		end
+
+		var dtos = v.deserialize_attribute("dtos", "HashSet[nullable Object]")
+		if v.deserialize_attribute_missing then
+		else if not dtos isa HashSet[E] then
+			v.errors.add new AttributeTypeError(self, "dtos", dtos, "HashSet[nullable Object]")
+			if v.keep_going == false then return
+		else
+			self.dtos = dtos
+		end
+
+		var dfroms = v.deserialize_attribute("dfroms", "HashSet[nullable Object]")
+		if v.deserialize_attribute_missing then
+		else if not dfroms isa HashSet[E] then
+			v.errors.add new AttributeTypeError(self, "dfroms", dfroms, "HashSet[nullable Object]")
+			if v.keep_going == false then return
+		else
+			self.dfroms = dfroms
+		end
+
+		var count = v.deserialize_attribute("count", "Int")
+		if v.deserialize_attribute_missing then
+			v.errors.add new Error("Deserialization Error: attribute `{class_name}::count` missing from JSON object")
+		else if not count isa Int then
+			v.errors.add new AttributeTypeError(self, "count", count, "Int")
+			if v.keep_going == false then return
+		else
+			self.count = count
+		end
 	end
 end