Handle HOV designated-only Lanes, resolves #2929

In https://github.com/Project-OSRM/osrm-backend/issues/2711 we made
`hov=designated` routability configurable.

We want to handle designated-only lanes in the same way. Example:

    hov:lanes:forward=designated|designated
    hov:lanes:backward=designated

should have more or less the same effects as

    hov=designated

In contrast

    hov:lanes:forward=designated|no|yes hov:lanes:backward=yes

should not be handled. See

    https://github.com/Project-OSRM/osrm-backend/issues/2711

for explanation wrt. tag semantics with the difference that
backward/forward only set the backward/forward mode to inaccessible.

References:
- http://wiki.openstreetmap.org/wiki/Key:hov#hov:lanes.3D.2A

features/car/access.feature

@@ -156,6 +156,25 @@ Feature: Car - Restricted access
             | primary | yes        | x     |
             | primary | no         | x     |
 
+    Scenario: Car - a way with all lanes HOV-designated is inaccessible by default (similar to hov=designated)
+        Then routability should be
+            | highway | hov:lanes:forward      | hov:lanes:backward     | hov:lanes              | oneway | forw | backw |
+            | primary | designated             | designated             |                        |        |      |       |
+            | primary |                        | designated             |                        |        | x    |       |
+            | primary | designated             |                        |                        |        |      | x     |
+            | primary | designated\|designated | designated\|designated |                        |        |      |       |
+            | primary | designated\|no         | designated\|no         |                        |        | x    | x     |
+            | primary | yes\|no                | yes\|no                |                        |        | x    | x     |
+            | primary |                        |                        |                        |        | x    | x     |
+            | primary | designated             |                        |                        | -1     |      |       |
+            | primary |                        | designated             |                        | -1     |      | x     |
+            | primary |                        |                        | designated             | yes    |      |       |
+            | primary |                        |                        | designated             | -1     |      |       |
+            | primary |                        |                        | designated\|designated | yes    |      |       |
+            | primary |                        |                        | designated\|designated | -1     |      |       |
+            | primary |                        |                        | designated\|yes        | yes    | x    |       |
+            | primary |                        |                        | designated\|no         | -1     |      | x     |
+
      Scenario: Car - these toll roads always work
         Then routability should be
             | highway | toll        | bothw |

profiles/car.lua

@@ -238,6 +238,10 @@ function way_function (way, result)
     return
   end
 
+  -- default to driving mode, may get overwritten below
+  result.forward_mode = mode.driving
+  result.backward_mode = mode.driving
+
   -- we dont route over areas
   local area = way:get_value_by_key("area")
   if ignore_areas and area and "yes" == area then
@@ -245,10 +249,58 @@ function way_function (way, result)
   end
 
   -- respect user-preference for HOV-only ways
-  local hov = way:get_value_by_key("hov")
+  if ignore_hov_ways then
-  if ignore_hov_ways and hov and "designated" == hov then
+    local hov = way:get_value_by_key("hov")
-    return
+    if hov and "designated" == hov then
-  end
+      return
+    end
+
+    -- also respect user-preference for HOV-only ways when all lanes are HOV-designated
+    local function has_all_designated_hov_lanes(lanes)
+      local all = true
+      for lane in lanes:gmatch("(%w+)") do
+        if lane and lane ~= "designated" then
+          all = false
+          break
+        end
+      end
+      return all
+    end
+
+    local hov_lanes = way:get_value_by_key("hov:lanes")
+    local hov_lanes_forward = way:get_value_by_key("hov:lanes:forward")
+    local hov_lanes_backward = way:get_value_by_key("hov:lanes:backward")
+
+    local hov_all_designated = hov_lanes and hov_lanes ~= ""
+                               and has_all_designated_hov_lanes(hov_lanes)
+
+    local hov_all_designated_forward = hov_lanes_forward and hov_lanes_forward ~= ""
+                                       and has_all_designated_hov_lanes(hov_lanes_forward)
+
+    local hov_all_designated_backward = hov_lanes_backward and hov_lanes_backward ~= ""
+                                        and has_all_designated_hov_lanes(hov_lanes_backward)
+
+    -- forward/backward lane depend on a way's direction
+    local oneway = way:get_value_by_key("oneway")
+    local reverse = oneway and oneway == "-1"
+
+    if hov_all_designated or hov_all_designated_forward then
+      if reverse then
+        result.backward_mode = mode.inaccessible
+      else
+        result.forward_mode = mode.inaccessible
+      end
+    end
+
+    if hov_all_designated_backward then
+      if reverse then
+        result.forward_mode = mode.inaccessible
+      else
+        result.backward_mode = mode.inaccessible
+      end
+    end
+
+  end -- hov handling
 
   -- respect user-preference for toll=yes ways
   local toll = way:get_value_by_key("toll")
@@ -278,9 +330,6 @@ function way_function (way, result)
     return
   end
 
-  result.forward_mode = mode.driving
-  result.backward_mode = mode.driving
-
   -- handling ferries and piers
   local route_speed = speed_profile[route]
   if (route_speed and route_speed > 0) then

taginfo.json

@@ -62,6 +62,24 @@
             "object_types": [ "way" ],
             "description": "Roads with hov=designated are ignored by default."
         },
+        {
+            "key": "hov:lanes",
+            "value": "designated",
+            "object_types": [ "way" ],
+            "description": "Roads with hov:lanes all-designated are ignored by default."
+        },
+        {
+            "key": "hov:lanes:forward",
+            "value": "designated",
+            "object_types": [ "way" ],
+            "description": "Roads with hov:lanes:forward all-designated are ignored by default."
+        },
+        {
+            "key": "hov:lanes:backward",
+            "value": "designated",
+            "object_types": [ "way" ],
+            "description": "Roads with hov:lanes:backward all-designated are ignored by default."
+        },
         {
             "key": "toll",
             "value": "yes",