#
# 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
# 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
# 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
+ ids[x] = ids.length
+ end
for x in elements.keys do
var xstr = x.to_s.escape_to_dot
- f.write "\"{xstr}\";\n"
+ 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
# 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
#
# For instance, one common usage is to add a specific attribute for each poset a class belong.
#
-# class Thing
-# var in_some_relation: POSetElement[Thing]
-# var in_other_relation: POSetElement[Thing]
-# end
-# var t: Thing # ...
-# t.in_some_relation.greaters
-#
-class POSetElement[E: Object]
+# ~~~nitish
+# class Thing
+# var in_some_relation: POSetElement[Thing]
+# var in_other_relation: POSetElement[Thing]
+# end
+# var t: Thing
+# # ...
+# t.in_some_relation.greaters
+# ~~~
+class POSetElement[E]
# The poset self belong to
var poset: POSet[E]