From ebd46f068fbf11ea8793e9f7982b3a5291e21398 Mon Sep 17 00:00:00 2001
From: Teddy Wing
Date: Mon, 26 Mar 2018 15:52:43 +0200
Subject: 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
---
 lib/tom_tom/matrix.rb | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

(limited to 'lib/tom_tom/matrix.rb')

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
-- 
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