New feature: Check location of OSM objects against list of regions

.github/workflows/luacheck.yml

@@ -15,5 +15,5 @@ jobs:
           sudo apt-get install -yq --no-install-suggests --no-install-recommends lua-check
 
       - name: Run luacheck
-        run: luacheck flex-config/*.lua flex-config/gen/*.lua tests/data/*.lua tests/lua/tests.lua
+        run: luacheck flex-config/*.lua flex-config/*/*.lua tests/data/*.lua tests/lua/tests.lua
 

flex-config/locator/README.md

@@ -0,0 +1,9 @@
+# Flex Output Configuration for Locator
+
+These are config file examples for use with the *locator* functionality.
+
+First use the `import-countries.lua` to import country boundaries, then
+use these with the other config files.
+
+You should be able to run this on the planet file or on any extracts you want.
+

flex-config/locator/buildings.lua

@@ -0,0 +1,74 @@
+-- This config example file is released into the Public Domain.
+
+-- This file shows how to use a locator to tag all buildings with the country
+-- they are in.
+
+-- Define the "countries" locator and get all country geometries from the
+-- database. Use the import-countries.lua file to import them first, before
+-- you run this.
+local countries = osm2pgsql.define_locator({ name = 'countries' })
+
+-- The SELECT query must return the regions the locator will use. The first
+-- column must contain the name of the region, the second the geometry in
+-- WGS84 lon/lat coordinates.
+-- To improve the efficiency of the country lookup, we'll subdivide the
+-- country polygons into smaller pieces. (If you run this often, for instance
+-- when doing updates, do the subdivide first in the database and store the
+-- result in its own table.)
+countries:add_from_db('SELECT code, ST_Subdivide(geom, 200) FROM countries')
+
+-- You have to decide whether you are interested in getting all regions
+-- intersecting with any of the objects or only one of them.
+--
+-- * Getting all regions makes sure that you get everything, even if regions
+--   overlap or objects straddle the border between regions. Use the function
+--   all_intersecting() for that.
+-- * Getting only one region is faster because osm2pgsql can stop looking
+--   for matches after the first one. Use first_intersecting() for that.
+--   This makes sense if you only have a single region anyway or if your
+--   regions don't overlap or you are not so concerned with what happens at
+--   the borders.
+--
+-- Just for demonstration, we do both in this example, in the "country" and
+-- "countries" columns, respectively.
+local buildings = osm2pgsql.define_area_table('buildings', {
+
+    -- This will contain the country code of the first matching country
+    -- (which can be any of the countries because there is no order here).
+    { column = 'country', type = 'text' },
+
+    -- This array will contain the country codes of all matching countries.
+    { column = 'countries', sql_type = 'text[]' },
+    { column = 'tags', type = 'jsonb' },
+    { column = 'geom', type = 'polygon', not_null = true },
+})
+
+local function add(geom, tags)
+    buildings:insert({
+        country = countries:first_intersecting(geom), -- or use geom:centroid()
+
+        -- We have to create the format that PostgreSQL expects for text
+        -- arrays. We assume that the region names do not contain any special
+        -- characters, otherwise we would need to do some escaping here.
+        countries = '{' .. table.concat(countries:all_intersecting(geom), ',') .. '}',
+
+        tags = tags,
+        geom = geom,
+    })
+end
+
+function osm2pgsql.process_way(object)
+    if object.tags.building then
+        add(object:as_polygon(), object.tags)
+    end
+end
+
+function osm2pgsql.process_relation(object)
+    if object.tags.building then
+        local geom = object:as_multipolygon()
+        for p in geom:geometries() do
+            add(p, object.tags)
+        end
+    end
+end
+

flex-config/locator/iceland.lua

@@ -0,0 +1,32 @@
+-- This config example file is released into the Public Domain.
+
+-- This file shows how to use a locator with a bounding box to import only
+-- the data for a region. In this case only highways in Iceland are imported
+-- even if you run this on the full planet file.
+
+local iceland = osm2pgsql.define_locator({ name = 'iceland' })
+
+iceland:add_bbox('IS', -25.0, 62.0, -12.0, 68.0)
+
+local highways = osm2pgsql.define_way_table('highways', {
+    { column = 'hwtype', type = 'text', not_null = true },
+    { column = 'name', type = 'text' },
+    { column = 'ref', type = 'text' },
+    { column = 'geom', type = 'linestring', not_null = true },
+})
+
+function osm2pgsql.process_way(object)
+    local t = object.tags
+    if t.highway then
+        local geom = object:as_linestring()
+        local region = iceland:first_intersecting(geom)
+        if region then
+            highways:insert({
+                hwtype = t.highway,
+                name = t.name,
+                ref = t.ref,
+                geom = geom,
+            })
+        end
+    end
+end

flex-config/locator/import-countries.lua

@@ -0,0 +1,35 @@
+-- This config example file is released into the Public Domain.
+
+-- This file is part of the examples for using the locator function of
+-- osm2pgsql. It is used to import all country boundaries into a database.
+
+local countries = osm2pgsql.define_relation_table('countries', {
+    -- For the ISO3166-1 Alpha-2 country code
+    -- https://en.wikipedia.org/wiki/ISO_3166-1
+    { column = 'code', type = 'text', not_null = true },
+    -- Because we want to use the geometries for the locator feature they
+    -- must be in 4326! We use a polygon type here and will later split
+    -- multipolygons into their parts.
+    { column = 'geom', type = 'polygon', not_null = true, projection = 4326 },
+})
+
+function osm2pgsql.process_relation(object)
+    local t = object.tags
+
+    if t.boundary == 'administrative' and t.admin_level == '2' then
+        local code = t['ISO3166-1']
+
+        -- Ignore entries with syntactically invalid ISO code
+        if not code or not string.match(code, '^%u%u$') then
+            return
+        end
+
+        for geom in object:as_multipolygon():geometries() do
+            countries:insert({
+                code = code,
+                geom = geom,
+            })
+        end
+    end
+end
+

flex-config/locator/motorway-colours.lua

@@ -0,0 +1,40 @@
+-- This config example file is released into the Public Domain.
+
+-- This file shows how to use a locator to find the country-specific colour
+
+-- Define the "countries" locator and get all country geometries from the
+-- database. Use the import-countries.lua file to import them first, before
+-- you run this.
+local countries = osm2pgsql.define_locator({ name = 'countries' })
+countries:add_from_db('SELECT code, ST_Subdivide(geom, 200) FROM countries')
+
+local highways = osm2pgsql.define_way_table('highways', {
+    { column = 'hwtype', type = 'text' },
+    { column = 'country', type = 'text' },
+    { column = 'colour', type = 'text' },
+    { column = 'geom', type = 'linestring', not_null = true },
+})
+
+-- Each country uses their own colour for motorways. Here is the beginning
+-- of a list of some countries in Europe. Source:
+-- https://en.wikipedia.org/wiki/Comparison_of_European_road_signs
+local cc2colour = {
+    BE = '#2d00e5',
+    CH = '#128044',
+    DE = '#174688',
+    FR = '#333b97',
+    NL = '#064269',
+}
+
+function osm2pgsql.process_way(object)
+    if object.tags.highway then
+        local geom = object:as_linestring()
+        local cc = countries:first_intersecting(geom)
+        highways:insert({
+            hwtype = object.tags.highway,
+            country = cc,
+            colour = cc2colour[cc],
+            geom = geom,
+        })
+    end
+end

src/CMakeLists.txt

@@ -21,6 +21,7 @@ target_sources(osm2pgsql_lib PRIVATE
     flex-lua-expire-output.cpp
     flex-lua-geom.cpp
     flex-lua-index.cpp
+    flex-lua-locator.cpp
     flex-lua-table.cpp
     flex-table-column.cpp
     flex-table.cpp
@@ -33,6 +34,7 @@ target_sources(osm2pgsql_lib PRIVATE
     geom.cpp
     idlist.cpp
     input.cpp
+    locator.cpp
     logging.cpp
     lua-setup.cpp
     lua-utils.cpp