Add `boundary=protected_area` parks

Update the **class** of the **park* layer in a backward-compatible way.

The class for `boundary=protected_area` parks is the lower-case of the
[`protection_title`](http://wiki.openstreetmap.org/wiki/key:protection_title)
value with blanks replaced by `_`.
`national_park` is the class of `protection_title=National Park` and `boundary=national_park`.
`nature_reserve` is the class of `protection_title=Nature Reserve` and `leisure=nature_reserve`.
The class for other [`protection_title`](http://wiki.openstreetmap.org/wiki/key:protection_title)
values is similarly assigned.

Resolve https://github.com/openmaptiles/openmaptiles/issues/760

layers/park/layer.sql

@@ -6,59 +6,67 @@ RETURNS TABLE(osm_id bigint, geometry geometry, class text, name text, name_en t
     SELECT osm_id, geometry, class, name, name_en, name_de, tags, rank
     FROM (
     SELECT osm_id, geometry,
-        COALESCE(NULLIF(boundary, ''), NULLIF(leisure, '')) AS class,
+        COALESCE(
+            LOWER(REPLACE(NULLIF(protection_title, ''), ' ', '_')),
+            NULLIF(boundary, ''),
+            NULLIF(leisure, '')
+        ) AS class,
         name, name_en, name_de, tags,
         NULL::int as rank
         FROM (
         -- etldoc: osm_park_polygon_gen8 -> layer_park:z6
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen8
         WHERE zoom_level = 6 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen7 -> layer_park:z7
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen7
         WHERE zoom_level = 7 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen6 -> layer_park:z8
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen6
         WHERE zoom_level = 8 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen5 -> layer_park:z9
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen5
         WHERE zoom_level = 9 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen4 -> layer_park:z10
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen4
         WHERE zoom_level = 10 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen3 -> layer_park:z11
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen3
         WHERE zoom_level = 11 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen2 -> layer_park:z12
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen2
         WHERE zoom_level = 12 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon_gen1 -> layer_park:z13
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon_gen1
         WHERE zoom_level = 13 AND geometry && bbox
         UNION ALL
         -- etldoc: osm_park_polygon -> layer_park:z14
-        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, NULL::int as scalerank
+        SELECT osm_id, geometry, name, name_en, name_de, tags, leisure, boundary, protection_title, NULL::int as scalerank
         FROM osm_park_polygon
         WHERE zoom_level >= 14 AND geometry && bbox
     ) AS park_polygon
 
     UNION ALL
     SELECT osm_id, geometry_point AS geometry,
-        COALESCE(NULLIF(boundary, ''), NULLIF(leisure, '')) AS class,
+        COALESCE(
+            LOWER(REPLACE(NULLIF(protection_title, ''), ' ', '_')),
+            NULLIF(boundary, ''),
+            NULLIF(leisure, '')
+        ) AS class,
         name, name_en, name_de, tags,
         row_number() OVER (
            PARTITION BY LabelGrid(geometry_point, 100 * pixel_width)
@@ -69,55 +77,55 @@ RETURNS TABLE(osm_id bigint, geometry geometry, class text, name text, name_en t
         )::int AS "rank"
         FROM (
         -- etldoc: osm_park_polygon_gen8 -> layer_park:z6
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen8
         WHERE zoom_level = 6 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen7 -> layer_park:z7
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen7
         WHERE zoom_level = 7 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen6 -> layer_park:z8
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen6
         WHERE zoom_level = 8 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen5 -> layer_park:z9
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen5
         WHERE zoom_level = 9 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen4 -> layer_park:z10
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen4
         WHERE zoom_level = 10 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen3 -> layer_park:z11
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen3
         WHERE zoom_level = 11 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen2 -> layer_park:z12
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen2
         WHERE zoom_level = 12 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon_gen1 -> layer_park:z13
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon_gen1
         WHERE zoom_level = 13 AND geometry_point && bbox
         UNION ALL
 
         -- etldoc: osm_park_polygon -> layer_park:z14
-        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, area
+        SELECT osm_id, geometry_point, name, name_en, name_de, tags, leisure, boundary, protection_title, area
         FROM osm_park_polygon
         WHERE zoom_level >= 14 AND geometry_point && bbox
     ) AS park_point

layers/park/mapping.yaml

@@ -77,6 +77,9 @@ tables:
     - name: boundary
       key: boundary
       type: string
+    - name: protection_title
+      key: protection_title
+      type: string
     - name: area
       type: area
     mapping:
@@ -84,3 +87,4 @@ tables:
       - nature_reserve
       boundary:
       - national_park
+      - protected_area

layers/park/park.yaml

@@ -1,15 +1,22 @@
 layer:
   id: "park"
   description: |
-      The park layer contains parks from OpenStreetMap tagged with either [`boundary=national_park`](http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dnational_park) or [`leisure=nature_reserve`](http://wiki.openstreetmap.org/wiki/Tag:leisure%3Dnature_reserve).
+      The park layer contains parks from OpenStreetMap tagged with
+      [`boundary=national_park`](http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dnational_park),
+      [`boundary=protected_area`](http://wiki.openstreetmap.org/wiki/Tag:boundary%3Dprotected_area),
+      or [`leisure=nature_reserve`](http://wiki.openstreetmap.org/wiki/Tag:leisure%3Dnature_reserve).
   buffer_size: 4
   fields:
     class:
       description: |
           Use the **class** to differentiate between different parks.
-      values:
-      - national_park
-      - nature_reserve
+          The class for `boundary=protected_area` parks is the lower-case of the
+          [`protection_title`](http://wiki.openstreetmap.org/wiki/key:protection_title)
+          value with blanks replaced by `_`.
+          `national_park` is the class of `protection_title=National Park` and `boundary=national_park`.
+          `nature_reserve` is the class of `protection_title=Nature Reserve` and `leisure=nature_reserve`.
+          The class for other [`protection_title`](http://wiki.openstreetmap.org/wiki/key:protection_title) 
+          values is similarly assigned.
     name: The OSM [`name`](http://wiki.openstreetmap.org/wiki/Key:name) value of the park (point features only).
     name_en: English name `name:en` if available, otherwise `name` (point features only).
     name_de: German name `name:de` if available, otherwise `name` or `name:en` (point features only).