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|
/***********************************************************************/
/* */
/* Objective Caml */
/* */
/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
/* */
/* Copyright 1996 Institut National de Recherche en Informatique et */
/* Automatique. Distributed only by permission. */
/* */
/***********************************************************************/
/* $Id$ */
/* The grammar for lexer definitions */
%{
open Syntax
(* Auxiliaries for the parser. *)
let regexp_for_string s =
let rec re_string n =
if n >= String.length s then Epsilon
else if succ n = String.length s then Characters([Char.code (s.[n])])
else Sequence(Characters([Char.code (s.[n])]), re_string (succ n))
in re_string 0
let char_class c1 c2 =
let rec cl n =
if n > c2 then [] else n :: cl(succ n)
in cl c1
let all_chars = char_class 0 255
let rec subtract l1 l2 =
match l1 with
[] -> []
| a::r -> if List.mem a l2 then subtract r l2 else a :: subtract r l2
%}
%token <string> Tident
%token <int> Tchar
%token <string> Tstring
%token <Syntax.location> Taction
%token Trule Tparse Tand Tequal Tend Tor Tunderscore Teof Tlbracket Trbracket
%token Tstar Tmaybe Tplus Tlparen Trparen Tcaret Tdash
%left Tor
%left CONCAT
%nonassoc Tmaybe
%left Tstar
%left Tplus
%start lexer_definition
%type <Syntax.lexer_definition> lexer_definition
%%
lexer_definition:
header Trule definition other_definitions header Tend
{ {header = $1;
entrypoints = $3::(List.rev $4);
trailer = $5} }
;
header:
Taction
{ $1 }
|
{ Location(0,0) }
;
other_definitions:
other_definitions Tand definition
{ $3::$1 }
|
{ [] }
;
definition:
Tident Tequal entry
{ ($1,$3) }
;
entry:
Tparse case rest_of_entry
{ $2::List.rev $3 }
| Tparse rest_of_entry
{ List.rev $2 }
;
rest_of_entry:
rest_of_entry Tor case
{ $3::$1 }
|
{ [] }
;
case:
regexp Taction
{ ($1,$2) }
;
regexp:
Tunderscore
{ Characters all_chars }
| Teof
{ Characters [256] }
| Tchar
{ Characters [$1] }
| Tstring
{ regexp_for_string $1 }
| Tlbracket char_class Trbracket
{ Characters $2 }
| regexp Tstar
{ Repetition $1 }
| regexp Tmaybe
{ Alternative($1, Epsilon) }
| regexp Tplus
{ Sequence($1, Repetition $1) }
| regexp Tor regexp
{ Alternative($1,$3) }
| regexp regexp %prec CONCAT
{ Sequence($1,$2) }
| Tlparen regexp Trparen
{ $2 }
;
char_class:
Tcaret char_class1
{ subtract all_chars $2 }
| char_class1
{ $1 }
;
char_class1:
Tchar Tdash Tchar
{ char_class $1 $3 }
| Tchar
{ [$1] }
| char_class1 char_class1 %prec CONCAT
{ $1 @ $2 }
;
%%
|
