(* Pretty printing *)

(* This module implements a pretty-printing facility to format text
   within ``pretty-printing boxes''. The pretty-printer breaks lines
   at specified break hints, and indents lines according to the box structure.
*)

(* The behaviour of pretty-printing commands is unspecified
   if there is no opened pretty-printing box. *)

(*** Boxes *)
val open_vbox : int -> unit
        (* [open_vbox d] opens a new pretty-printing box
           with offset [d]. 
           This box is ``vertical'': every break hint inside this
           box leads to a new line.
           When a new line is printed in the box, [d] is added to the
           current indentation. *)
val open_hbox : unit -> unit
        (* [open_hbox ()] opens a new pretty-printing box.
           This box is ``horizontal'': the line is not List.split in this box
           (new lines may still occur inside boxes nested deeper). *)
val open_hvbox : int -> unit
        (* [open_hovbox d] opens a new pretty-printing box
           with offset [d]. 
           This box is ``horizontal-vertical'': it behaves as an
           ``horizontal'' box if it fits on a single line,
           otherwise it behaves as a ``vertical'' box.
           When a new line is printed in the box, [d] is added to the
           current indentation. *)
val open_hovbox : int -> unit
        (* [open_hovbox d] opens a new pretty-printing box
           with offset [d]. 
           This box is ``horizontal or vertical'': break hints
           inside this box may lead to a new line, if there is no more room
           on the line to print the remainder of the box.
           When a new line is printed in the box, [d] is added to the
           current indentation. *)
val close_box : unit -> unit
        (* Close the most recently opened pretty-printing box. *)

(*** Formatting functions *)
val print_string : string -> unit
        (* [print_string str] prints [str] in the current box. *)
val print_as : int -> string -> unit
        (* [print_as len str] prints [str] in the
           current box. The pretty-printer formats [str] as if
           it were of length [len]. *)
val print_int : int -> unit
        (* Print an integer in the current box. *)
val print_float : float -> unit
        (* Print a floating point number in the current box. *)
val print_char : char -> unit
        (* Print a character in the current box. *)
val print_bool : bool -> unit
        (* Print an boolean in the current box. *)

(*** Break hints *)
val print_break : int -> int -> unit
        (* Insert a break hint in a pretty-printing box.
           [print_break nspaces offset] indicates that the line may
           be List.split (a newline character is printed) at this point,
           if the contents of the current box does not fit on one line.
           If the line is List.split at that point, [offset] is added to
           the current indentation. If the line is not List.split,
           [nspaces] spaces are printed. *)
val print_cut : unit -> unit
        (* [print_cut ()] is equivalent to [print_break 0 0].
           This allows line splitting at the current point, without printing
           spaces or adding indentation. *)
val print_space : unit -> unit
        (* [print_space ()] is equivalent to [print_break 1 0].
           This either prints one space or splits the line at that point. *)
val force_newline : unit -> unit
        (* Force a newline in the current box. *)

val print_flush : unit -> unit
        (* Flush the pretty printer: all opened boxes are closed,
           and all pending text is displayed. *)
val print_newline : unit -> unit
        (* Equivalent to [print_flush] followed by a new line. *)

val print_if_newline : unit -> unit
        (* If the preceding line has not been List.split, the next
           formatting command is ignored. *)

(*** Tabulations *)
val open_tbox : unit -> unit
        (* Open a tabulation box. *)
val close_tbox : unit -> unit
        (* Close the most recently opened tabulation box. *)
val print_tbreak : int -> int -> unit
        (* Break hint in a tabulation box.
           [print_tbreak spaces offset] moves the insertion point to
           the next tabulation ([spaces] being added to this position).
           Nothing occurs if insertion point is already on a
           tabulation mark.
           If there is no next tabulation on the line, then a newline
           is printed and the insertion point moves to the first
           tabulation of the box.
           If a new line is printed, [offset] is added to the current
           indentation. *)
val set_tab : unit -> unit
        (* Set a tabulation mark at the current insertion point. *)
val print_tab : unit -> unit
        (* [print_tab ()] is equivalent to [print_tbreak (0,0)]. *)

(*** Margin *)
val set_margin : int -> unit
        (* [set_margin d] sets the val of the right margin
           to [d] (in characters): this val is used to detect line
           overflows that leads to List.split lines.
           Nothing happens if [d] is not greater than 1. *)
val get_margin : unit -> int
        (* Return the position of the right margin. *)

(*** Maximum indentation limit *)
val set_max_indent : int -> unit
        (* [set_max_indent d] sets the val of the maximum
           indentation limit to [d] (in characters):
           once this limit is reached, boxes are rejected to the left,
           if they do not fit on the current line.
           Nothing happens if [d] is not greater than 1. *)
val get_max_indent : unit -> int
        (* Return the val of the maximum indentation limit (in
           characters). *)

(*** Formatting depth: maximum number of boxes allowed before ellipsis *)
val set_max_boxes : int -> unit
        (* [set_max_boxes max] sets the maximum number
           of boxes simultaneously opened.
           Material inside boxes nested deeper is printed as an
           ellipsis (more precisely as the text returned by
           [get_ellipsis_text]).
           Nothing happens if [max] is not greater than 1. *)
val get_max_boxes : unit -> int
        (* Return the maximum number of boxes allowed before ellipsis. *)

(*** Ellipsis *)
val set_ellipsis_text : string -> unit
        (* Set the text of the ellipsis printed when too many boxes
           are opened (a single dot, [.], by default). *)
val get_ellipsis_text : unit -> string
        (* Return the text of the ellipsis. *)

(*** Redirecting formatter output *)
val set_formatter_output : out_channel -> unit
        (* Redirect the pretty-printer output to the given channel. *)
val get_formatter_output : unit -> out_channel
        (* Return the channel connected to the pretty-printer. *)