Swift client for OpenStreetMap Overpass API.

Uses @functionBuilder to provide in-language DSL for query construction and Combine framework to propagate results.

Example project: cmrnavig

Example request (this will select roads in the coordinate bounding box):

let request = OverpassRequest {
    Union {
        Query(.way) {
            Bounding(.box(s: 51.248, w: 7.147, n: 51.252, e: 7.153))
            Tag(include: "highway")
        }

        Recurse(.down)
    }

    Print()
}

Another example (select all buildings):

let request = OverpassRequest {
    ForEach([Query.QueryType.relation, Query.QueryType.node]) { queryType in
        Union {
            Query(queryType) {
                Bounding(bound)
                Tag(include: "building")
            }

            Recurse(.down)
        }
    }

    Print()
}

Example with control flow:

let request = OverpassRequest {
    ForEach(bounds) { index, bound in
        Union(into: String(index)) {
            Query(.way) {
                Bounding(bound)
                Tag("highway", matches: "motorway|trunk")
            }

            If(true) {
                Recurse(.down)
            } {
                Recurse(.up)
                Recurse(.upRel)
            }

            Print(from: String(index))
        }
    }
}

Using client to send requests:

let client = OverpassClient(URL(string: "https://lz4.overpass-api.de/api/interpreter")!)
client.request(request).sink {
    print($0)
}