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(* camlp4r *)
(***********************************************************************)
(* *)
(* Camlp4 *)
(* *)
(* Daniel de Rauglaudre, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1998 Institut National de Recherche en Informatique et *)
(* Automatique. Distributed only by permission. *)
(* *)
(***********************************************************************)
(* $Id: token.mli,v 2.1 1998/12/04 18:29:13 ddr Exp $ *)
(* Module [Token]: tokens for grammars *)
type t = (string * string);
type pattern = (string * string);
(* Token and token patterns. Token are build by the lexer. Token
patterns come from the EXTEND statement.
- The first string is the constructor name (must start with
an uppercase character). When it is empty, the second string
is supposed to be a keyword.
- The second string is the constructor parameter. Empty if it
has no parameter.
- The way tokens pattern are interpreted to parse tokens is
done by the lexer, function [tparse] below. *)
exception Error of string;
(* An lexing error exception to be used by lexers. *)
type location_function = int -> (int * int);
(* The type for a function associating a number of a token in a stream
(starting from 0) to its source location. *)
type lexer =
{ func : Stream.t char -> (Stream.t t * location_function);
using : pattern -> unit;
removing : pattern -> unit;
tparse : pattern -> Stream.t t -> string;
text : pattern -> string }
;
(* The type for a lexer used by Camlp4 grammars.
- The field [func] is the lexer function. The character stream is the
input stream to be lexed. The result is a pair of a tokens stream
and a location function for this tokens stream.
- The field [using] is a function telling the lexer that the grammar
uses this token (pattern). The lexer can check that its constructor
is correct, and interpret some kind of tokens as keywords (to record
them in its tables). Called by [EXTEND] statements.
- The field [removing] is a function telling the lexer that the grammar
does not uses the given token (pattern) any more. If the lexer has a
notion of "keywords", it can release it from its tables. Called by
[DELETE_RULE] statements.
- The field [tparse] is a function returning the parsing function
associated with each token pattern.
- The field [text] returns the name of some token pattern,
used in error messages. *)
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