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* Genlex - Generic lexer
* Copyright (C) 2002 Jacques Garrigue
* 2008 David Teller (Contributor)
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version,
* with the special exception on linking described in file LICENSE.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
(** A generic lexical analyzer.
This module implements a simple ``standard'' lexical analyzer, presented
as a function from character streams to token streams. It implements
roughly the lexical conventions of Caml, but is parameterized by the
set of keywords of your language.
Example: a lexer suitable for a desk calculator is obtained by
{[ let lexer = make_lexer ["+";"-";"*";"/";"let";"="; "("; ")"] ]}
The associated parser would be a function from [token stream]
to, for instance, [int], and would have rules such as:
let parse_expr = parser
[< 'Int n >] -> n
| [< 'Kwd "("; n = parse_expr; 'Kwd ")" >] -> n
| [< n1 = parse_expr; n2 = parse_remainder n1 >] -> n2
and parse_remainder n1 = parser
[< 'Kwd "+"; n2 = parse_expr >] -> n1+n2
| ...
@author Jacques Garrigue
@author David Teller
(** The type of tokens. The lexical classes are: [Int] and [Float]
for integer and floating-point numbers; [String] for
string literals, enclosed in double quotes; [Char] for
character literals, enclosed in single quotes; [Ident] for
identifiers (either sequences of letters, digits, underscores
and quotes, or sequences of ``operator characters'' such as
[+], [*], etc); and [Kwd] for keywords (either identifiers or
single ``special characters'' such as [(], [}], etc). *)
type token = Genlex.token =
Kwd of string
| Ident of string
| Int of int
| Float of float
| String of string
| Char of char
val make_lexer : string list -> char Stream.t -> token Stream.t
(** Construct the lexer function. The first argument is the list of
keywords. An identifier [s] is returned as [Kwd s] if [s]
belongs to this list, and as [Ident s] otherwise.
A special character [s] is returned as [Kwd s] if [s]
belongs to this list, and cause a lexical error (exception
[Parse_error]) otherwise. Blanks and newlines are skipped.
Comments delimited by [(*] and [*)] are skipped as well,
and can be nested. *)
(* {6 Batteries extensions to genlex } *)
type lexer_error =
| IllegalCharacter of char
| NotReallyAChar
| NotReallyAnEscape
| EndOfStream
exception LexerError of lexer_error * int
type t
(** A lexer*)
val of_list : string list -> t
(** Create a lexer from a list of keywords*)
val to_stream_filter : t -> char Stream.t -> token Stream.t
(** Apply the lexer to a stream.*)
val to_enum_filter : t -> char BatEnum.t -> token BatEnum.t
(** Apply the lexer to an enum.*)
val to_lazy_list_filter: t -> char BatLazyList.t -> token BatLazyList.t
(** Apply the lexer to a lazy list.*)
val string_of_token : token -> string
(**{6 Extending to other languages}*)
open BatCharParser
module Languages :
module type Definition =
val comment_delimiters : (string * string) option
val line_comment_start : string option
val nested_comments : bool
val ident_start : (char, char, position) BatParserCo.t
val ident_letter : (char, char, position) BatParserCo.t
val op_start : (char, char, position) BatParserCo.t
val op_letter : (char, char, position) BatParserCo.t
val reserved_names : string list
val case_sensitive : bool
(**[true] if the language is case-sensitive, [false] otherwise.
If the language is not case-sensitive, every identifier is returned
as lower-case.*)
module Library :
module OCaml : Definition
module C : Definition
module Make(M:Definition) :
(**Create a lexer from a language definition*)
(** {6 High-level API} *)
(** Drop comments, present reserved operators and reserved
names as [Kwd], operators and identifiers as [Ident],
integer numbers as [Int], floating-point numbers as
[Float] and characters as [Char].
If the language is not [case_sensitive], identifiers and
keywords are returned in lower-case.
val feed : (char, position) BatParserCo.Source.t -> (token, position) BatParserCo.Source.t
(** {6 Medium-level API} *)
val start : (char, unit, position) BatParserCo.t
(**Remove any leading whitespaces*)
val ident : (char, string, position) BatParserCo.t
(**Accepts any non-reserved identifier/operator.
If the language is not [case_sensitive], the identifier
is returned in lower-case.*)
val kwd : (char, string, position) BatParserCo.t
(**Accepts any identifier.
If the language is not [case_sensitive], the identifier
is returned in lower-case.*)
val identifier : string -> (char, unit, position) BatParserCo.t
val keyword : string -> (char, unit, position) BatParserCo.t
val char_literal : (char, char, position) BatParserCo.t
(**Accepts a character literal, i.e. one character
(or an escape) between two quotes.*)
val string_literal :(char, string, position) BatParserCo.t
(**Accepts a string, i.e. one sequence of
characters or escapes between two double
quotes, on one line.*)
val integer: (char, int , position) BatParserCo.t
(**Parse an integer.*)
val float: (char, float , position) BatParserCo.t
(**Parse a floating-point number.*)
val number: (char, [`Float of float | `Integer of int] , position) BatParserCo.t
(**Parse either an integer or a floating-point number.*)
(** {6 Low-level API} *)
val char : char -> (char, char , position) BatParserCo.t
(** As {!CharParser.char}, but case-insensitive if specified
by {!case_sensitive}. *)
val string : string -> (char, string, position) BatParserCo.t
(** As {!CharParser.string}, but case-insensitive if specified
by {!case_sensitive}. *)
val line_comment : (char, unit , position) BatParserCo.t
val multiline_comment : (char, unit , position) BatParserCo.t
val comment : (char, unit , position) BatParserCo.t
val whitespaces : (char, unit , position) BatParserCo.t
(* val lexeme : (char, 'a , position) BatParserCo.t -> (char, 'a , position) BatParserCo.t*)
(**Apply this filter to your own parsers if you want them
to ignore following comments.*)
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