Source file fancy.ml

type 'a t = Pretty.t -> 'a -> Pretty.t

type ('ty, 'v) order =
  | Const : 'a t * 'a -> ('v, 'v) order
  | Atom : 'a t -> ('a -> 'v, 'v) order
  | Param : ('a t -> 'a -> 'v, 'v) order
  | New_line : ('v, 'v) order
  | Open : Pretty.box -> ('v, 'v) order
  | Close : ('v, 'v) order
  | Break : (int * int) -> ('v, 'v) order

let keval_order
  : type ty v. (Pretty.t -> v) -> Pretty.t -> (ty, v) order -> ty
  = fun k t -> function
    | Const (encoder, v) -> k (encoder t v)
    | Atom encoder -> fun v -> k (encoder t v)
    | Param -> fun encoder v -> k (encoder t v)
    | New_line -> Pretty.kpush k Pretty.new_line t
    | Open box -> Pretty.kpush k (Pretty.o box) t
    | Close -> Pretty.kpush k Pretty.close t
    | Break (len, indent) -> Pretty.kpush k (Pretty.break ~len ~indent) t

let const encoder v = Const (encoder, v)
let atom encoder = Atom encoder
let a = Param

let (!!) = atom
let ($) = const

let new_line = New_line

let tbox indent = Open (Pretty.tbox indent)
let bbox = Open Pretty.bbox
let box = Open Pretty.box
let close = Close

let break ~indent ~len = Break (indent, len)
let fws = Break (1, 1)
let spaces n = Break (n, 0)
let cut = Break (0, 1)

let using : ('b -> 'a) -> 'a t -> 'b t = fun f encoder t v -> encoder t (f v)

let list ~sep:(sep, e) encoder =
  let rec go t = function
    | [] -> t
    | [ x ] -> encoder t x
    | x :: r ->
      let t = encoder t x in
      let t = sep t e in
      go t r in go

let option encoder t = function
  | Some x -> encoder t x
  | None -> t

let char : char t = fun t x ->
  (* XXX(dinosaure): we should optimize it! *)
  let atom = Pretty.string ~breakable:false (String.make 1 x) in
  Pretty.push atom t

let string : string t = fun t x ->
  let atom = Pretty.string ~breakable:false x in
  Pretty.push atom t

let bytes : Bytes.t t = fun t x ->
  let atom = Pretty.bytes ~breakable:false x in
  Pretty.push atom t

let bigstring : Bigstringaf.t t = fun t x ->
  let atom = Pretty.bigstring ~breakable:false x in
  Pretty.push atom t

let breakable : string t = fun t x ->
  let atom = Pretty.string ~breakable:true x in
  Pretty.push atom t

type ('ty, 'v) fmt =
  | [] : ('v, 'v) fmt
  | (::) : ('x, 'v) order * ('v, 'r) fmt -> ('x, 'r) fmt

let rec concat
  : type a b c. (a, b) fmt -> (b, c) fmt -> (a, c) fmt
  = fun l1 l2 -> match l1, l2 with
    | [], l -> l
    | h :: t, l -> h :: concat t l

let rec keval : type ty v. (Pretty.t -> v) -> Pretty.t -> (ty, v) fmt -> ty =
 fun k t -> function
   | [] -> k t
   | x :: r ->
     let k t = keval k t r in
     keval_order k t x

external identity : 'a -> 'a = "%identity"

let eval : type ty. Pretty.t -> (ty, Pretty.t) fmt -> ty = fun t fmt -> keval identity t fmt