Lua maxspeed parsing refactoring (#5144)

* Lua maxspeed parsing refactoring

CHANGELOG.md

@@ -14,6 +14,7 @@
       - CHANGED: matching will now consider edges marked with is_startpoint=false, allowing matching over ferries and other previously non-matchable edge types. [#5297](https://github.com/Project-OSRM/osrm-backend/pull/5297)
     - Profile:
       - ADDED: Parse `source:maxspeed` and `maxspeed:type` tags to apply maxspeeds and add belgian flanders rural speed limit. [#5217](https://github.com/Project-OSRM/osrm-backend/pull/5217)
+      - CHANGED: Refactor maxspeed parsing to use common library. [#5144](https://github.com/Project-OSRM/osrm-backend/pull/5144)
 
 # 5.20.0
   - Changes from 5.19.0:

profiles/bicycle.lua

@@ -7,6 +7,7 @@ Sequence = require('lib/sequence')
 Handlers = require("lib/way_handlers")
 find_access_tag = require("lib/access").find_access_tag
 limit = require("lib/maxspeed").limit
+Measure = require("lib/measure")
 
 function setup()
   local default_speed = 15
@@ -206,20 +207,6 @@ function setup()
   }
 end
 
-local function parse_maxspeed(source)
-    if not source then
-        return 0
-    end
-    local n = tonumber(source:match("%d*"))
-    if not n then
-        n = 0
-    end
-    if string.match(source, "mph") or string.match(source, "mp/h") then
-        n = (n*1609)/1000
-    end
-    return n
-end
-
 function process_node(profile, node, result)
   -- parse access and barrier tags
   local highway = node:get_value_by_key("highway")
@@ -276,9 +263,9 @@ function handle_bicycle_tags(profile,way,result,data)
 
   -- other tags
   data.junction = way:get_value_by_key("junction")
-  data.maxspeed = parse_maxspeed(way:get_value_by_key ( "maxspeed") )
-  data.maxspeed_forward = parse_maxspeed(way:get_value_by_key( "maxspeed:forward"))
-  data.maxspeed_backward = parse_maxspeed(way:get_value_by_key( "maxspeed:backward"))
+  data.maxspeed = Measure.get_max_speed(way:get_value_by_key ("maxspeed")) or 0
+  data.maxspeed_forward = Measure.get_max_speed(way:get_value_by_key("maxspeed:forward")) or 0
+  data.maxspeed_backward = Measure.get_max_speed(way:get_value_by_key("maxspeed:backward")) or 0
   data.barrier = way:get_value_by_key("barrier")
   data.oneway = way:get_value_by_key("oneway")
   data.oneway_bicycle = way:get_value_by_key("oneway:bicycle")

profiles/lib/measure.lua

@@ -6,6 +6,18 @@ Measure = {}
 local inch_to_meters = 0.0254
 local feet_to_inches = 12
 local pound_to_kilograms = 0.45359237
+local miles_to_kilometers = 1.609
+
+-- Parse speed value as kilometers by hours.
+function Measure.parse_value_speed(source)
+  local n = tonumber(source:match("%d*"))
+  if n then
+    if string.match(source, "mph") or string.match(source, "mp/h") then
+      n = n * miles_to_kilometers
+    end
+    return n
+  end
+end
 
 --- Parse string as a height in meters.
 --- according to http://wiki.openstreetmap.org/wiki/Key:maxheight
@@ -42,6 +54,13 @@ function Measure.parse_value_kilograms(value)
   end
 end
 
+--- Get maxspeed of specified way in kilometers by hours.
+function Measure.get_max_speed(raw_value)
+  if raw_value then
+    return Measure.parse_value_speed(raw_value)
+  end
+end
+
 -- default maxheight value defined in https://wiki.openstreetmap.org/wiki/Key:maxheight#Non-numerical_values
 local default_maxheight = 4.5
 -- Available Non numerical values equal to 4.5; below_default and no_indications are not considered

profiles/lib/way_handlers.lua

@@ -450,12 +450,9 @@ function WayHandlers.parse_maxspeed(source,profile)
   if not source then
     return 0
   end
-  local n = tonumber(source:match("%d*"))
-  if n then
-    if string.match(source, "mph") or string.match(source, "mp/h") then
-      n = (n*1609)/1000
-    end
-  else
+
+  local n = Measure.get_max_speed(source)
+  if not n then
     -- parse maxspeed like FR:urban
     source = string.lower(source)
     n = profile.maxspeed_table[source]