Topojsone (p.topojsone.0.1.0.doc.topojsone.Topojsone)

module Jsone = Geojsone.Jsone

module Ezjsone = Geojsone.Ezjsone

Sourcemodule Err : sig ... end

Topojsone comes with an implementation of a TopoJSON parser using Ezjsone. This is like Ezjsonm but uses Jsone for providing a non-blocking interface.

Sourcemodule Topojson : Topojson.S with type json = Ezjsone.value

Sources and Sinks

Topojsone is intended to be used with a non-blocking IO library using OCaml 5's effect support to provide a direct-style buffer filling and buffer writing functions.

Here's an example using the Eio library:

  let src_of_flow ?(size = 2048) flow =
    let buff = Cstruct.create size in
    fun () ->
      let got = Eio.Flow.(single_read flow buff) in
      let t = Cstruct.sub buff 0 got in
      t

  let with_src cwd f func =
    Eio.Path.(with_open_in (cwd / f)) @@ fun ic -> func @@ src_of_flow ic

  let buffer_to_dst buf bs =
    Eio.Flow.(copy (cstruct_source [ bs ]) (Eio.Flow.buffer_sink buf))

Mapping

Maps are functions that allow you to manipulate common structure in TopoJson objects. These will be written directly back to the destination that you provide.

Source

val map_object : 
  ((string * Topojson.Geometry.t) -> string * Topojson.Geometry.t) ->
  Jsone.src ->
  Jsone.dst ->
  (unit, Err.t) result

map_object f src dst will apply f to all TopoJson objects. The map will recurse into TopoJson Object. Note for the moment if you have a single geometry object as your document, this will not work.

Folding

Source

val fold_object : 
  ('acc -> (string * Topojson.Geometry.t) -> 'acc) ->
  'acc ->
  Jsone.src ->
  ('acc, Err.t) result

fold_object f initial_acc src is much like map_object but allows you to accumulate some result that is then returned to you.