In the best traditions, I partially answer to myself (below) but I've a new
question:
> - Does camlp4 allows me to mix lexers for different productions in the same
> extension ?
well, it seems it doesn't. Now I get this error:
Error: entries "psymbol" and "symbol" do not belong to the same grammar.
Fatal error: exception Failure("Grammar.extend error")
- Is there a deep reason why I cannot mix different grammars ?
- Is there a way of forcing this behaviour ?
On Fri, Feb 02, 2007 at 12:40:11PM +1100, Pietro Abate wrote:
> Hi all,
> I want to parsa a language like this one:
> l := l & l | l % l | Id
[...]
> of course the Genlex module is not immediately compatible with the Plexer
> interface so I'm a bit lost...
> - Is this the best way of doing it ?
don't know, maybe not.
> - How can I make the Genlex module compatible with the Plexer
> interface (example ?) ?
This should do the job (I think) even if ignore the location...
open Genlex
let lexer = Genlex.make_lexer [
"+";"-";"*";"/";"=";
"[";"]";"<";">";
"%";"&";"*";"?";"~"
];;
let getkwd = function Kwd s -> s | _ -> failwith "aa" ;;
let rec glexer = parser
[< 'Kwd ("+" | "-" | "*" | "/"
|"=" | "[" | "]" | "<"
|">" | "%" | "&" | "?" | "~" ) as s >] -> ("", getkwd s)
| [< 'Ident s >] -> ("LIDENT",s)
| [< >] -> ("EOI","")
;;
let lexer_gmake () = {
Token.tok_func =
Token.lexer_func_of_parser (fun s -> (glexer (lexer s), Token.dummy_loc));
Token.tok_using = (fun _ -> ());
Token.tok_removing = (fun _ -> ());
Token.tok_match = Token.default_match;
Token.tok_text = Token.lexer_text;
Token.tok_comm = None
}
;;
The full code of my example:
to compile:
#> camlp4o pa_extend.cmo pr_o.cmo pa_test.ml >> test.ml
#> ocamlfind ocamlc -package camlp4 camlp4.cma str.cma test.ml
------------ pa_test.ml ------------
open Genlex
type stype = Lid | Symbol of string ;;
let lexer = Genlex.make_lexer [
"+";"-";"*";"/";"=";
"[";"]";"<";">";
"%";"&";"*";"?";"~"
];;
let getkwd = function Kwd s -> s | _ -> failwith "fail getkwd" ;;
let rec glexer = parser
[< 'Kwd ("+" | "-" | "*" | "/"
|"=" | "[" | "]" | "<"
|">" | "%" | "&" | "?" | "~" ) as s >] -> ("", getkwd s)
| [< 'Ident s >] -> ("LIDENT",s)
| [< >] -> ("EOI","")
;;
let lexer_gmake () = {
Token.tok_func =
Token.lexer_func_of_parser (fun s -> (glexer (lexer s), Token.dummy_loc));
Token.tok_using = (fun _ -> ());
Token.tok_removing = (fun _ -> ());
Token.tok_match = Token.default_match;
Token.tok_text = Token.lexer_text;
Token.tok_comm = None
}
;;
let symbgrammar = Grammar.gcreate (lexer_gmake ());;
let symbol strm =
match Stream.peek strm with
|Some("",s) -> Stream.junk strm; s
|Some("LINDENT",s) -> Stream.junk strm; s
| _ -> raise Stream.Failure
;;
let symbol = Grammar.Entry.of_parser symbgrammar "symbol" symbol ;;
let grammar = Grammar.gcreate (Plexer.gmake ());;
let gram_list = Grammar.Entry.create grammar "gram_list";;
EXTEND
GLOBAL: gram_list;
gram_list: [[ grams = LIST1 gram; EOI -> grams ]];
gram: [[ p = LIDENT; ":="; rules = LIST1 rule SEP "|" -> (p,rules) ]];
rule: [[ psl = LIST1 psymbol -> psl ]];
psymbol: [[
"VAR" -> Lid
| e = symbol -> Symbol(e)
]];
END
;;
let apply s = Grammar.Entry.parse gram_list (Stream.of_string s);;
(apply "l := VAR");;
(apply "l := VAR & VAR");;
(apply "l := VAR U VAR");;
Je vous remercie énormément pour votre aide.
:)
p
--
++ Blog: http://blog.rsise.anu.edu.au/?q=pietro
++
++ "All great truths begin as blasphemies." -George Bernard Shaw
++ Please avoid sending me Word or PowerPoint attachments.
See http://www.fsf.org/philosophy/no-word-attachments.html
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