From 05d73706a1d9868d75a3ae26849050dc6549f57b Mon Sep 17 00:00:00 2001
From: Nathan Varner <nathanmvarner@protonmail.com>
Date: Tue, 7 Mar 2023 02:28:28 -0500
Subject: [PATCH] [routing] Recognize empty lane directions as none

Needed for: #1404

Signed-off-by: Nathan Varner <nathanmvarner@protonmail.com>
---
 .../routing_tests/turns_generator_test.cpp    | 23 +++++++++++++++++++
 routing/turns.cpp                             | 20 ++++++++++++----
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/routing/routing_tests/turns_generator_test.cpp b/routing/routing_tests/turns_generator_test.cpp
index 5b5c3b0269..694e51355d 100644
--- a/routing/routing_tests/turns_generator_test.cpp
+++ b/routing/routing_tests/turns_generator_test.cpp
@@ -108,6 +108,18 @@ UNIT_TEST(TestParseSingleLane)
   TEST(ParseSingleLane("left", ';', result), ());
   TEST_EQUAL(result.size(), 1, ());
   TEST_EQUAL(result[0], LaneWay::Left, ());
+
+  TEST(ParseSingleLane("left;", ';', result), ());
+  TSingleLane expected3 = {LaneWay::Left, LaneWay::None};
+  TEST_EQUAL(result, expected3, ());
+
+  TEST(ParseSingleLane(";", ';', result), ());
+  TSingleLane expected4 = {LaneWay::None, LaneWay::None};
+  TEST_EQUAL(result, expected4, ());
+
+  TEST(ParseSingleLane("", ';', result), ());
+  TSingleLane expected5 = {LaneWay::None};
+  TEST_EQUAL(result, expected5, ());
 }
 
 UNIT_TEST(TestParseLanes)
@@ -162,6 +174,17 @@ UNIT_TEST(TestParseLanes)
   vector<SingleLaneInfo> const expected7 = {
       {LaneWay::Left}, {LaneWay::Left}, {LaneWay::Through}, {LaneWay::Through}, {LaneWay::Right}};
   TEST_EQUAL(result, expected7, ());
+
+  TEST(ParseLanes("|||||slight_right", result), ());
+  vector<SingleLaneInfo> const expected8 = {
+    {LaneWay::None},
+    {LaneWay::None},
+    {LaneWay::None},
+    {LaneWay::None},
+    {LaneWay::None},
+    {LaneWay::SlightRight}
+  };
+  TEST_EQUAL(result, expected8, ());
 }
 
 UNIT_TEST(TestFixupTurns)
diff --git a/routing/turns.cpp b/routing/turns.cpp
index 12b69754f7..536d2e27d5 100644
--- a/routing/turns.cpp
+++ b/routing/turns.cpp
@@ -22,8 +22,14 @@ namespace
 {
 /// The order is important. Starting with the most frequent tokens according to
 /// taginfo.openstreetmap.org we minimize the number of the comparisons in ParseSingleLane().
-array<pair<LaneWay, char const *>, static_cast<size_t>(LaneWay::Count)> const g_laneWayNames = {
-    {{LaneWay::Through, "through"},
+///
+/// A `none` lane can be represented either as "none" or as "". That means both "none" and ""
+/// should be considered names, even though they refer to the same thing. As a result,
+/// `LaneWay::None` appears twice in this array, which is one longer than the number of
+/// enum values.
+array<pair<LaneWay, char const *>, static_cast<size_t>(LaneWay::Count) + 1> const g_laneWayNames = {
+    {{LaneWay::None, ""},
+     {LaneWay::Through, "through"},
      {LaneWay::Left, "left"},
      {LaneWay::Right, "right"},
      {LaneWay::None, "none"},
@@ -34,7 +40,7 @@ array<pair<LaneWay, char const *>, static_cast<size_t>(LaneWay::Count)> const g_
      {LaneWay::SlightRight, "slight_right"},
      {LaneWay::SharpRight, "sharp_right"},
      {LaneWay::Reverse, "reverse"}}};
-static_assert(g_laneWayNames.size() == static_cast<size_t>(LaneWay::Count),
+static_assert(g_laneWayNames.size() == static_cast<size_t>(LaneWay::Count) + 1,
               "Check the size of g_laneWayNames");
 
 array<pair<CarDirection, char const *>, static_cast<size_t>(CarDirection::Count)> const
@@ -298,7 +304,13 @@ void SplitLanes(string const & lanesString, char delimiter, vector<string> & lan
 bool ParseSingleLane(string const & laneString, char delimiter, TSingleLane & lane)
 {
   lane.clear();
-  istringstream laneStream(laneString);
+  // When `laneString` ends with "" representing none, for example, in "right;",
+  // `getline` will not read any characters, so it exits the loop and does not
+  // handle the "". So, we add a delimiter to the end of `laneString`. Nonempty
+  // final tokens consume the delimiter and act as expected, and empty final tokens
+  // read a the delimiter, so `getline` sets `token` to the empty string rather than
+  // exiting the loop.
+  istringstream laneStream(laneString + delimiter);
   string token;
   while (getline(laneStream, token, delimiter))
   {