Additional test and docs coverage for opposite approach

CHANGELOG.md

@@ -4,6 +4,7 @@
       - ADDED: Add support for a keepalive_timeout flag. [#6674](https://github.com/Project-OSRM/osrm-backend/pull/6674)
       - ADDED: Add support for a default_radius flag. [#6575](https://github.com/Project-OSRM/osrm-backend/pull/6575)
       - ADDED: Add support for disabling feature datasets. [#6666](https://github.com/Project-OSRM/osrm-backend/pull/6666)
+      - ADDED: Add support for opposite approach request parameter. [#6842](https://github.com/Project-OSRM/osrm-backend/pull/6842)
     - Build:
       - ADDED: Add CI job which builds OSRM with gcc 12. [#6455](https://github.com/Project-OSRM/osrm-backend/pull/6455)
       - CHANGED: Upgrade to clang-tidy 15. [#6439](https://github.com/Project-OSRM/osrm-backend/pull/6439)

docs/http.md

@@ -35,7 +35,7 @@ To pass parameters to each location some options support an array-like encoding:
 |radiuses        |`{radius};{radius}[;{radius} ...]`                      |Limits the search to given radius in meters.                                                                                                                                                               |
 |generate\_hints |`true` (default), `false`                               |Adds a Hint to the response which can be used in subsequent requests, see `hints` parameter.                                                                                                               |
 |hints           |`{hint};{hint}[;{hint} ...]`                            |Hint from previous request to derive position in street network.                                                                                                                                           |
-|approaches      |`{approach};{approach}[;{approach} ...]`                |Keep waypoints on curbside.                                                                                                                                                                               |
+|approaches      |`{approach};{approach}[;{approach} ...]`                |Restrict the direction on the road network at a waypoint, relative to the input coordinate.                                                                                                                    |
 |exclude         |`{class}[,{class}]`                                     |Additive list of classes to avoid, the order does not matter.                                                                                                                                                  |
 |snapping        |`default` (default), `any`                              |Default snapping avoids is_startpoint (see profile) edges, `any` will snap to any edge in the graph                                                                                                        |
 |skip_waypoints  |`true`, `false` (default)                               |Removes waypoints from the response. Waypoints are still calculated, but not serialized. Could be useful in case you are interested in some other part of the response and do not want to transfer waste data. |
@@ -47,7 +47,7 @@ Where the elements follow the following format:
 |bearing     |`{value},{range}` `integer 0 .. 360,integer 0 .. 180`   |
 |radius      |`double >= 0` or `unlimited` (default)                  |
 |hint        |Base64 `string`                                         |
-|approach    |`curb` or `unrestricted` (default)                      |
+|approach    |`curb`, `opposite` or `unrestricted` (default)          |
 |class       |A class name determined by the profile or `none`.       |
 
 ```

docs/nodejs/api.md

@@ -63,7 +63,7 @@ Returns the fastest route between two or more coordinates while visiting the way
     -   `options.geometries` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Returned route geometry format (influences overview and per step). Can also be `geojson`. (optional, default `polyline`)
     -   `options.overview` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Add overview geometry either `full`, `simplified` according to highest zoom level it could be display on, or not at all (`false`). (optional, default `simplified`)
     -   `options.continue_straight` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)?** Forces the route to keep going straight at waypoints and don't do a uturn even if it would be faster. Default value depends on the profile.
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
                          `null`/`true`/`false`
     -   `options.waypoints` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Indices to coordinates to treat as waypoints. If not supplied, all coordinates are waypoints.  Must include first and last coordinate index.
     -   `options.format` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which output format to use, either `json`, or [`flatbuffers`](https://github.com/Project-OSRM/osrm-backend/tree/master/include/engine/api/flatbuffers).
@@ -101,7 +101,7 @@ Note: `coordinates` in the general options only supports a single `{longitude},{
     -   `options.generate_hints` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** Whether or not adds a Hint to the response which can be used in subsequent requests. (optional, default `true`)
     -   `options.number` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)** Number of nearest segments that should be returned.
         Must be an integer greater than or equal to `1`. (optional, default `1`)
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.format` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which output format to use, either `json`, or [`flatbuffers`](https://github.com/Project-OSRM/osrm-backend/tree/master/include/engine/api/flatbuffers).
     -   `options.snapping` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which edges can be snapped to, either `default`, or `any`.  `default` only snaps to edges marked by the profile as `is_startpoint`, `any` will allow snapping to any edge in the routing graph.
 -   `callback` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)** 
@@ -141,7 +141,7 @@ Optionally returns distance table.
     -   `options.sources` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** An array of `index` elements (`0 <= integer < #coordinates`) to use
                                          location with given index as source. Default is to use all.
     -   `options.destinations` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** An array of `index` elements (`0 <= integer < #coordinates`) to use location with given index as destination. Default is to use all.
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate.. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.fallback_speed` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)?** Replace `null` responses in result with as-the-crow-flies estimates based on `fallback_speed`.  Value is in metres/second.
     -   `options.fallback_coordinate` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Either `input` (default) or `snapped`.  If using a `fallback_speed`, use either the user-supplied coordinate (`input`), or the snapped coordinate (`snapped`) for calculating the as-the-crow-flies distance between two points.
     -   `options.scale_factor` **[Number](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Number)?** Multiply the table duration values in the table by this number for more controlled input into a route optimization solver.
@@ -298,7 +298,7 @@ Right now, the following combinations are possible:
     -   `options.roundtrip` **[Boolean](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** Return route is a roundtrip. (optional, default `true`)
     -   `options.source` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Return route starts at `any` or `first` coordinate. (optional, default `any`)
     -   `options.destination` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)** Return route ends at `any` or `last` coordinate. (optional, default `any`)
-    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Keep waypoints on curb side. Can be `null` (unrestricted, default) or `curb`.
+    -   `options.approaches` **[Array](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array)?** Restrict the direction on the road network at a waypoint, relative to the input coordinate. Can be `null` (unrestricted, default), `curb` or `opposite`.
     -   `options.snapping` **[String](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String)?** Which edges can be snapped to, either `default`, or `any`. `default` only snaps to edges marked by the profile as `is_startpoint`, `any` will allow snapping to any edge in the routing graph.
 -   `callback` **[Function](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Statements/function)**