(***********************************************************************)
(*                                                                     *)
(*                           Objective Caml                            *)
(*                                                                     *)
(*            Xavier Leroy, projet Cristal, INRIA Rocquencourt         *)
(*                                                                     *)
(*  Copyright 1996 Institut National de Recherche en Informatique et   *)
(*  en Automatique.  All rights reserved.  This file is distributed    *)
(*  under the terms of the GNU Library General Public License, with    *)
(*  the special exception on linking described in file ../LICENSE.     *)
(*                                                                     *)
(***********************************************************************)

(* $Id: lexing.mli,v 1.26 2002/04/18 07:27:42 garrigue Exp $ *)

(** The run-time library for lexers generated by [ocamllex]. *)

(** {6 Lexer buffers} *)


type lexbuf =
  { refill_buff : lexbuf -> unit;
    mutable lex_buffer : string;
    mutable lex_buffer_len : int;
    mutable lex_abs_pos : int;
    mutable lex_start_pos : int;
    mutable lex_curr_pos : int;
    mutable lex_last_pos : int;
    mutable lex_last_action : int;
    mutable lex_eof_reached : bool }
(** The type of lexer buffers. A lexer buffer is the argument passed
   to the scanning functions defined by the generated scanners.
   The lexer buffer holds the current state of the scanner, plus
   a function to refill the buffer from the input. *)

val from_channel : in_channel -> lexbuf
(** Create a lexer buffer on the given input channel.
   [Lexing.from_channel inchan] returns a lexer buffer which reads
   from the input channel [inchan], at the current reading position. *)

val from_string : string -> lexbuf
(** Create a lexer buffer which reads from
   the given string. Reading starts from the first character in
   the string. An end-of-input condition is generated when the
   end of the string is reached. *)

val from_function : (string -> int -> int) -> lexbuf
(** Create a lexer buffer with the given function as its reading method.
   When the scanner needs more characters, it will call the given
   function, giving it a character string [s] and a character
   count [n]. The function should put [n] characters or less in [s],
   starting at character number 0, and return the number of characters
   provided. A return value of 0 means end of input. *)


(** {6 Functions for lexer semantic actions} *)


(** The following functions can be called from the semantic actions
   of lexer definitions (the ML code enclosed in braces that
   computes the value returned by lexing functions). They give
   access to the character string matched by the regular expression
   associated with the semantic action. These functions must be
   applied to the argument [lexbuf], which, in the code generated by
   [ocamllex], is bound to the lexer buffer passed to the parsing
   function. *)

val lexeme : lexbuf -> string
(** [Lexing.lexeme lexbuf] returns the string matched by
           the regular expression. *)

val lexeme_char : lexbuf -> int -> char
(** [Lexing.lexeme_char lexbuf i] returns character number [i] in
   the matched string. *)

val lexeme_start : lexbuf -> int
(** [Lexing.lexeme_start lexbuf] returns the position in the
   input stream of the first character of the matched string.
   The first character of the stream has position 0. *)

val lexeme_end : lexbuf -> int
(** [Lexing.lexeme_end lexbuf] returns the position in the input stream
   of the character following the last character of the matched
   string. The first character of the stream has position 0. *)

(**/**)

(** {6  } *)

(** The following definitions are used by the generated scanners only.
   They are not intended to be used by user programs. *)

type lex_tables =
  { lex_base : string;
    lex_backtrk : string;
    lex_default : string;
    lex_trans : string;
    lex_check : string }

external engine : lex_tables -> int -> lexbuf -> int = "lex_engine"
