resto-directory 1.2 · OCaml Package

Parameters

module Encoding : Resto.ENCODING

Signature

module Service : module type of struct include Resto.MakeService(Encoding) end

type step =

| Static of string
(*
A literal chunk
*)
| Dynamic of Resto.Arg.descr
(*
A chunk which describes a argument to a service
*)
| DynamicTail of Resto.Arg.descr
(*
The remainder of the chunks are to be interpreted as a list of arguments
*)

The different chunks of a path

E.g., /archive/<year>/<months>/ has a Static "archive" step followed by a Dynamic _ step followed by a Dynamic _ step. Each Dynamic _ step has an Resto.Arg payload describing the chunk.

type conflict =

| CService of Resto.meth
(*
A collision with a service that has been already defined for the given method at the certain path.
*)
| CDir
(*
An incompatibility with the directory at a certain path.
*)
| CBuilder
(*
A collision with the builder part of another dynamic directory of a certain path.
*)
| CDynDescr of string * string
(*
A collision between the descriptions of two given dynamic directories.
*)
| CTail
(*
A collision with another dynamic tail directory of a certain path.
*)
| CTypes of Resto.Arg.descr * Resto.Arg.descr
(*
A typing incompatibility with an URI parameter of a certain type when another parameter type was expected.
*)
| CType of Resto.Arg.descr * string list
(*
A typing impompatibility with an URI parameter with the given subdirectories.
*)

Possible kind of conflictual error that can occur while registering services into a directory or while merging directories.

exception Conflict of step list * conflict

type ('query, 'input, 'output, 'error) types = {

query : 'query Resto.Query.t;
input : 'input Service.input;
output : 'output Encoding.t;
error : 'error Encoding.t;

}

type registered_service =

| Service : {
1. types : ('q, 'i, 'o, 'e) types;
2. handler : 'q -> 'i -> ('o, 'e) Answer.t Lwt.t;
} -> registered_service

type 'prefix t

Dispatch tree

type 'prefix directory = 'prefix t

type lookup_error = [

| `Not_found
| `Method_not_allowed of Resto.meth list
| `Cannot_parse_path of string list * Resto.Arg.descr * string

]

val string_of_step : step -> string

string_of_step step converts the given steps into a string.

val string_of_conflict_kind : conflict -> string

string_of_conflict_kind conflict_kind converts the given conflict_kind into a string.

val string_of_conflict : (step list * conflict) -> string

string_of_conflict conflict converts the given conflict into a string.

val lookup : 
  'prefix directory ->
  'prefix ->
  Resto.meth ->
  string list ->
  (registered_service, [> lookup_error ]) Stdlib.result Lwt.t

lookup d m p is Ok (Service _) if there is a service s registered in d and both the method of s is m and the path of s matches p. It is Error _ otherwise.

If it is Ok (Service _) then the returned value corresponds to the registered service.

val lookup_uri_desc : 
  'prefix directory ->
  'prefix ->
  Resto.meth ->
  string list ->
  (string, [> lookup_error ]) Stdlib.result Lwt.t

lookup_uri_desc d p is Ok u where u is a formated URI description, if there is a service s registered in d and the path of s matches p. It is Error _ otherwise.

For instance, given the following path p: "/entries-by-date/2022/01/10" where "2022", "01", and "10" are expected to be paramaters in the path of s, the function will evaluate in "/entries-by-date/<year>/<month>/<day>".

val allowed_methods : 
  'prefix directory ->
  'prefix ->
  string list ->
  (Resto.meth list, [> lookup_error ]) Stdlib.result Lwt.t

allowed_methods d p is the set of methods m such that lookup d m p is Ok _. In other words, it is the set of methods m such that a service has been registered in d for a path that matches p.

val transparent_lookup : 
  'prefix directory ->
  ('meth, 'prefix, 'params, 'query, 'input, 'output, 'error) Service.t ->
  'params ->
  'query ->
  'input ->
  [> ('output, 'error) Answer.t ] Lwt.t

val empty : 'prefix directory

Empty tree

val map : ('a -> 'b Lwt.t) -> 'b directory -> 'a directory

val prefix : ('pr, 'p) Resto.Path.path -> 'p directory -> 'pr directory

prefix p d is a directory of services which includes a service registered on the path p / q for each service registered on the path q in d.

raises [Invalid_argument]
if p is a dynamic path.

val merge : 
  ?strategy:[ `Raise | `Pick_left | `Pick_right ] ->
  'a directory ->
  'a directory ->
  'a directory

merge ~strategy d1 d2 is a directory which includes all the services of d1 and d2.

It is possible to merge both static and dynamic trees.

In case of static trees, the resulting merge will occur in a eager way at function call.
In case of dynamic trees and because of their nature, the resulting merging directory can't however be computed directly: We don't know the subtree of such a tree before resolving it whith a proper argument key and thus don't have a way to merge it directly at function call. In such a case, the merging computation will be delayed at resolving time. This may not be a problem in most cases. But merging directories containing a lot of nested dynamic directories should still be avoided as it may impact queries performances.

As a few elements that constitutes a directory tree are not mergeable, it may be possible to come upon a collision case during a merge. Unmergeable elements are:

Services
Dynamic directories description.

If one or more of these elements from d1 collides with one or more element from d2, the function will make a choice depending on the given merging strategy:

`Raise will raise a Conflict exception. This is the default choice.
`Pick_left will pick the element from d1 to be part of the resulting directory.
`Pick_right will pick the element from d2 to be part of the resulting directory.

raises [Conflict]
if:
- One or more unmergeable element from d1 collides with one or more unmergeable element from d2 and the merging strategy is `Raise or unspecified.
- Sub-directories can't be merged because of a structural conflict. For instance, if a path leads from d1 to a sub-directory d1' that is an URI parameter, but path also leads from d2 to a sub-directory d2' that is only a static segment of the URI.
- Sub-directories can't be merged because of a typing conflict. For instance, if a path leads from d1 to a sub-directory d1' that is an URI parameter of type int, but path, also leads from d2 to a sub-directory d2' that is an URI parameter of type float.

val register : 
  'prefix directory ->
  ('meth, 'prefix, 'params, 'query, 'input, 'output, 'error) Service.t ->
  ('params -> 'query -> 'input -> [< ('output, 'error) Answer.t ] Lwt.t) ->
  'prefix directory

register d s h is a directory that contains all the services registered in d plus the service s. Requests to the service s are handled by the handler h.

val register0 : 
  unit directory ->
  ('m, unit, unit, 'q, 'i, 'o, 'e) Service.t ->
  ('q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  unit directory

Registring handler in service tree. Curryfied variant.

val register1 : 
  'prefix directory ->
  ('m, 'prefix, unit * 'a, 'q, 'i, 'o, 'e) Service.t ->
  ('a -> 'q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  'prefix directory

val register2 : 
  'prefix directory ->
  ('m, 'prefix, (unit * 'a) * 'b, 'q, 'i, 'o, 'e) Service.t ->
  ('a -> 'b -> 'q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  'prefix directory

val register3 : 
  'prefix directory ->
  ('m, 'prefix, ((unit * 'a) * 'b) * 'c, 'q, 'i, 'o, 'e) Service.t ->
  ('a -> 'b -> 'c -> 'q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  'prefix directory

val register4 : 
  'prefix directory ->
  ('m, 'prefix, (((unit * 'a) * 'b) * 'c) * 'd, 'q, 'i, 'o, 'e) Service.t ->
  ('a -> 'b -> 'c -> 'd -> 'q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  'prefix directory

val register5 : 
  'prefix directory ->
  ('m, 'prefix, ((((unit * 'a) * 'b) * 'c) * 'd) * 'f, 'q, 'i, 'o, 'e)
    Service.t ->
  ('a -> 'b -> 'c -> 'd -> 'f -> 'q -> 'i -> [< ('o, 'e) Answer.t ] Lwt.t) ->
  'prefix directory

val register_dynamic_directory : 
  ?descr:string ->
  'prefix directory ->
  ('prefix, 'a) Resto.Path.path ->
  ('a -> 'a directory Lwt.t) ->
  'prefix directory

Registring dynamic subtree.

val register_dynamic_directory1 : 
  ?descr:string ->
  'prefix directory ->
  ('prefix, unit * 'a) Resto.Path.path ->
  ('a -> (unit * 'a) directory Lwt.t) ->
  'prefix directory

Registring dynamic subtree. (Curryfied variant)

val register_dynamic_directory2 : 
  ?descr:string ->
  'prefix directory ->
  ('prefix, (unit * 'a) * 'b) Resto.Path.path ->
  ('a -> 'b -> ((unit * 'a) * 'b) directory Lwt.t) ->
  'prefix directory

val register_dynamic_directory3 : 
  ?descr:string ->
  'prefix directory ->
  ('prefix, ((unit * 'a) * 'b) * 'c) Resto.Path.path ->
  ('a -> 'b -> 'c -> (((unit * 'a) * 'b) * 'c) directory Lwt.t) ->
  'prefix directory

val register_describe_directory_service : 
  'prefix directory ->
  ('prefix, 'prefix, 'error) Service.description_service ->
  'prefix directory

Registring a description service.

val describe_directory : 
  recurse:bool ->
  ?arg:'a ->
  'a directory ->
  Encoding.schema Resto.Description.directory Lwt.t

package resto-directory

Parameters

Signature