TomTom::Matrix#points_from_way_costs: Use array instead of set

Using a set ended up not working out. I needed to be able to index into
the list in `#extract_costs_to_way_costs!`, and sets aren't indexable.
This is because they're supposed to be unordered, though modern Ruby
implements `Set` with `Hash` under the hood, which is ordered in Ruby.

I like the idea of having a data structure that automatically eliminates
duplicates, but it wasn't meant to be, because for the extraction to
`WayCost`s, I need an ordered list. Rather than create a new
`OrderedSet` type, I just went the simple route and used an Array,
eliminating the duplicates manually because I know when duplicates are
supposed to occur due to the nature of the data set.

Remove the `#eql?` and `#hash` methods from `TomTom::Matrix::Point`.
Because we're not longer using `Set`, these methods don't need to be
implemented.

Refs #6222

3 files changed, 22 insertions, 21 deletions

diff --git a/lib/tom_tom/matrix.rb b/lib/tom_tom/matrix.rb
index 55568ab66..8e0331cca 100644
--- a/lib/tom_tom/matrix.rb
+++ b/lib/tom_tom/matrix.rb
@@ -29,23 +29,30 @@ module TomTom
     end
 
     def points_from_way_costs(way_costs)
-      points = Set.new
+      points = []
 
       way_costs.each do |way_cost|
         departure_id, arrival_id = way_cost.id.split('-')
 
-        points.add(
-          TomTom::Matrix::Point.new(
-            way_cost.departure,
-            departure_id
-          )
+        departure = TomTom::Matrix::Point.new(
+          way_cost.departure,
+          departure_id
         )
-        points.add(
-          TomTom::Matrix::Point.new(
-            way_cost.arrival,
-            arrival_id
-          )
+        arrival = TomTom::Matrix::Point.new(
+          way_cost.arrival,
+          arrival_id
         )
+
+        # Don't add duplicate coordinates. This assumes that
+        # `way_costs` consists of an ordered route of points where
+        # each departure coordinate is the same as the preceding
+        # arrival coordinate.
+        if points.empty? ||
+            points.last.coordinates != departure.coordinates
+          points << departure
+        end
+
+        points << arrival
       end
 
       points
diff --git a/lib/tom_tom/matrix/point.rb b/lib/tom_tom/matrix/point.rb
index 4e9d11e68..435b4d4b0 100644
--- a/lib/tom_tom/matrix/point.rb
+++ b/lib/tom_tom/matrix/point.rb
@@ -13,12 +13,6 @@ module TomTom
           @coordinates == other.coordinates &&
           @id == other.id
       end
-
-      alias :eql? :==
-
-      def hash
-        @coordinates.hash + @id.hash
-      end
     end
   end
 end
diff --git a/spec/lib/tom_tom/matrix_spec.rb b/spec/lib/tom_tom/matrix_spec.rb
index e67e539b7..b63ebc70b 100644
--- a/spec/lib/tom_tom/matrix_spec.rb
+++ b/spec/lib/tom_tom/matrix_spec.rb
@@ -18,7 +18,7 @@ RSpec.describe TomTom::Matrix do
 
       expect(
         matrix.points_from_way_costs(way_costs)
-      ).to eq(Set.new([
+      ).to eq([
         TomTom::Matrix::Point.new(
           Geokit::LatLng.new(48.85086, 2.36143),
           '44'
@@ -31,13 +31,13 @@ RSpec.describe TomTom::Matrix do
           Geokit::LatLng.new(52.50867, 13.42879),
           '88'
         )
-      ]))
+      ])
     end
   end
 
   describe "#points_as_params" do
     it "transforms a set of LatLng points into a hash for use by TomTom Matrix" do
-      points = Set.new([
+      points = [
         TomTom::Matrix::Point.new(
           Geokit::LatLng.new(48.85086, 2.36143),
           '44'
@@ -50,7 +50,7 @@ RSpec.describe TomTom::Matrix do
           Geokit::LatLng.new(52.50867, 13.42879),
           '88'
         )
-      ])
+      ]
 
       expect(
         matrix.points_as_params(points)