157 lines
3.7 KiB
OCaml
157 lines
3.7 KiB
OCaml
/***********************************************************************/
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/* */
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/* Objective Caml */
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/* */
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/* Xavier Leroy, projet Cristal, INRIA Rocquencourt */
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/* */
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/* Copyright 1996 Institut National de Recherche en Informatique et */
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/* Automatique. Distributed only by permission. */
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/* */
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/***********************************************************************/
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/* $Id$ */
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/* The grammar for lexer definitions */
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%{
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open Syntax
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(* Auxiliaries for the parser. *)
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let named_regexps =
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(Hashtbl.create 13 : (string, regular_expression) Hashtbl.t)
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let regexp_for_string s =
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let rec re_string n =
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if n >= String.length s then Epsilon
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else if succ n = String.length s then Characters([Char.code (s.[n])])
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else Sequence(Characters([Char.code (s.[n])]), re_string (succ n))
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in re_string 0
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let char_class c1 c2 =
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let rec cl n =
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if n > c2 then [] else n :: cl(succ n)
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in cl c1
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let all_chars = char_class 0 255
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let rec subtract l1 l2 =
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match l1 with
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[] -> []
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%}
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%token <string> Tident
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%token <int> Tchar
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%token <string> Tstring
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%token <Syntax.location> Taction
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%token Trule Tparse Tand Tequal Tend Tor Tunderscore Teof Tlbracket Trbracket
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%token Tstar Tmaybe Tplus Tlparen Trparen Tcaret Tdash Tlet
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%left Tor
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%left CONCAT
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%nonassoc Tmaybe
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%left Tstar
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%left Tplus
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%start lexer_definition
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%type <Syntax.lexer_definition> lexer_definition
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%%
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lexer_definition:
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header named_regexps Trule definition other_definitions header Tend
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{ {header = $1;
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entrypoints = $4 :: List.rev $5;
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trailer = $6} }
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;
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header:
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Taction
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{ $1 }
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| /*epsilon*/
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{ { start_pos = 0; end_pos = 0; start_line = 1; start_col = 0 } }
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;
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named_regexps:
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named_regexps Tlet Tident Tequal regexp
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{ Hashtbl.add named_regexps $3 $5 }
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| /*epsilon*/
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{ () }
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;
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other_definitions:
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other_definitions Tand definition
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{ $3::$1 }
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| /*epsilon*/
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{ [] }
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;
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definition:
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Tident Tequal entry
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{ ($1,$3) }
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;
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entry:
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Tparse case rest_of_entry
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{ $2::List.rev $3 }
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| Tparse rest_of_entry
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{ List.rev $2 }
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;
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rest_of_entry:
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rest_of_entry Tor case
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{ $3::$1 }
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{ [] }
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;
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case:
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regexp Taction
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{ ($1,$2) }
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;
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regexp:
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Tunderscore
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{ Characters all_chars }
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| Teof
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{ Characters [256] }
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| Tchar
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{ Characters [$1] }
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| Tstring
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{ regexp_for_string $1 }
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| Tlbracket char_class Trbracket
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{ Characters $2 }
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| regexp Tstar
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{ Repetition $1 }
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| regexp Tmaybe
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{ Alternative($1, Epsilon) }
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| regexp Tplus
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{ Sequence($1, Repetition $1) }
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| regexp Tor regexp
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{ Alternative($1,$3) }
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| regexp regexp %prec CONCAT
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{ Sequence($1,$2) }
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| Tlparen regexp Trparen
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{ $2 }
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| Tident
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{ try
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Hashtbl.find named_regexps $1
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with Not_found ->
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prerr_string "Reference to unbound regexp name `";
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prerr_string $1;
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prerr_string "' at char ";
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prerr_int (Parsing.symbol_start());
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prerr_newline();
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exit 2 }
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;
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char_class:
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Tcaret char_class1
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{ subtract all_chars $2 }
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| char_class1
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{ $1 }
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;
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char_class1:
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Tchar Tdash Tchar
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{ char_class $1 $3 }
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| Tchar
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{ [$1] }
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| char_class1 char_class1 %prec CONCAT
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{ $1 @ $2 }
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;
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%%
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