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Add geometry functions in Lua / new insert syntax
This is the future of geometry processing in Lua. Geometries are not something happening magically behind the scenes as before, but they are (mostly) normal objects that can be manipulated in Lua. There are several functions to create those geometry objects from the OSM objects: * as_point() (for nodes) * as_linestring() (for ways) * as_polygon() (for ways) * as_multilinestring() (for relations) * as_multipolygon() (for relations) * as_geometrycollection() (for relations) Geometries can be manipulated with the following functions (all based on their equivalents in PostGIS): * area() (for polygons) * centroid() (for polygons) * geometries() for iterating over (multi)geometries * geometry_n() return the nth geometry from a (multi)geometry. * geometry_type() returns type as string ('POINT', 'LINESTRING', ...) * is_null() returns true if this is a null geometry * num_geometries() returns the number of geometries (0 for null geom, 1 for point/linestring/polygon, n for multi* and geometrycollection geoms). This can also be accessed as #geom (the usual Lua length operator) * segmentize(max_segment_length) (for linestrings) * simplify(tolerance) (for linestrings) * srid() * transform(target_srid) Some of these functions are using boost::geometry for their implementation. More functions can be implemented in the future as needed. There is a new syntax for inserting rows into a table. Instead of "add_row" the "insert" function is used. "add_row" is still available and it works as before. But the new geometry types only work with the "insert" command. The "insert" function also allows multiple geometry columns which wasn't possible with "add_row". See the file flex-config/new-insert-syntax.lua for an example that shows how to use the new capabilities.
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‎flex-config/new-insert-syntax.lua‎

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-- This config example file is released into the Public Domain.
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-- This is Lua config showing the handling of custom geometries.
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--
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-- This is "work in progress", changes are possible.
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--
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-- Note that the insert() function is used instead of the old add_row()!
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-- The following magic can be used to wrap the internal "insert" function
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local orig_insert = osm2pgsql.Table.insert
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local function my_insert(table, data)
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local json = require 'json'
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inserted, message, column, object = orig_insert(table, data)
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if not inserted then
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for key, value in pairs(data) do
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if type(value) == 'userdata' then
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data[key] = tostring(value)
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end
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end
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print("insert() failed: " .. message .. " column='" .. column .. "' object='" .. json.encode(object) .. "' data='" .. json.encode(data) .. "'")
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end
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end
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osm2pgsql.Table.insert = my_insert
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local tables = {}
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-- This table will get all nodes and areas with an "addr:street" tag, for
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-- areas we'll calculate the centroid.
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tables.addr = osm2pgsql.define_table({
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name = 'addr',
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ids = { type = 'any', id_column = 'osm_id', type_column = 'osm_type' },
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columns = {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'point', projection = 4326 },
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}
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})
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tables.ways = osm2pgsql.define_way_table('ways', {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'linestring', projection = 4326 },
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{ column = 'poly', type = 'polygon', projection = 4326 },
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{ column = 'geom3857', type = 'linestring', projection = 3857 },
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{ column = 'geomautoproj', type = 'linestring', projection = 3857 },
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})
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tables.major_roads = osm2pgsql.define_way_table('major_roads', {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'linestring' },
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{ column = 'sgeom', type = 'linestring' }
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})
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tables.polygons = osm2pgsql.define_area_table('polygons', {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'geometry', not_null = true },
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{ column = 'area4326', type = 'real' },
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{ column = 'area3857', type = 'real' }
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})
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tables.routes = osm2pgsql.define_relation_table('routes', {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'multilinestring', projection = 4326 },
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})
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tables.route_parts = osm2pgsql.define_relation_table('route_parts', {
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{ column = 'tags', type = 'jsonb' },
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{ column = 'geom', type = 'linestring', projection = 4326 },
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})
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-- Helper function to remove some of the tags we usually are not interested in.
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-- Returns true if there are no tags left.
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function clean_tags(tags)
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tags.odbl = nil
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tags.created_by = nil
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tags.source = nil
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tags['source:ref'] = nil
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return next(tags) == nil
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end
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-- Helper function that looks at the tags and decides if this is possibly
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-- an area.
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function has_area_tags(tags)
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if tags.area == 'yes' then
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return true
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end
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if tags.area == 'no' then
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return false
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end
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return tags.aeroway
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or tags.amenity
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or tags.building
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or tags.harbour
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or tags.historic
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or tags.landuse
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or tags.leisure
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or tags.man_made
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or tags.military
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or tags.natural
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or tags.office
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or tags.place
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or tags.power
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or tags.public_transport
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or tags.shop
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or tags.sport
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or tags.tourism
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or tags.water
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or tags.waterway
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or tags.wetland
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or tags['abandoned:aeroway']
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or tags['abandoned:amenity']
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or tags['abandoned:building']
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or tags['abandoned:landuse']
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or tags['abandoned:power']
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or tags['area:highway']
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end
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function osm2pgsql.process_node(object)
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if clean_tags(object.tags) then
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return
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end
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if object.tags['addr:street'] then
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tables.addr:insert({
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tags = object.tags,
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geom = object:as_point()
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})
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end
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end
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function osm2pgsql.process_way(object)
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if clean_tags(object.tags) then
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return
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end
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if object.is_closed and object.tags['addr:street'] then
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tables.addr:insert({
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tags = object.tags,
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geom = object:as_polygon():centroid()
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})
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end
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if object.tags.highway == 'motorway' or
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object.tags.highway == 'trunk' or
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object.tags.highway == 'primary' then
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tables.major_roads:insert({
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tags = object.tags,
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geom = object:as_linestring(),
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sgeom = object:as_linestring():simplify(100),
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})
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end
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-- A closed way that also has the right tags for an area is a polygon.
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if object.is_closed and has_area_tags(object.tags) then
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local g = object:as_polygon()
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local a = g:area()
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if a < 0.0000001 then
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tables.polygons:insert({
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tags = object.tags,
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geom = g,
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area4326 = a,
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area3857 = g:transform(3857):area()
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})
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end
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else
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tables.ways:insert({
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tags = object.tags,
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geom = object:as_linestring(),
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poly = object:as_polygon(),
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geom3857 = object:as_linestring():transform(3857), -- project geometry into target srid 3857
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geomautoproj = object:as_linestring() -- automatically projected into projection of target column
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})
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end
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end
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function osm2pgsql.process_relation(object)
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if clean_tags(object.tags) then
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return
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end
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local relation_type = object:grab_tag('type')
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if relation_type == 'multipolygon' then
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local g = object:as_multipolygon()
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local a = g:area()
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if a < 0.0000001 then
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tables.polygons:insert({
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tags = object.tags,
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geom = g,
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area4326 = a,
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area3857 = g:transform(3857):area()
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})
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end
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return
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end
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if relation_type == 'route' then
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local route_geom = object:as_multilinestring()
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if not route_geom:is_null() then
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tables.routes:insert({
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tags = object.tags,
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geom = route_geom
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})
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for line in route_geom:geometries() do
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tables.route_parts:insert({
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tags = object.tags,
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geom = line
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})
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end
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end
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end
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end
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‎src/CMakeLists.txt‎

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target_sources(osm2pgsql_lib PRIVATE
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flex-table.cpp
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flex-table-column.cpp
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flex-lua-geom.cpp
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geom-transform.cpp
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lua-utils.cpp
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output-flex.cpp

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