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[Caml-list] genlex ...
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Date: -- (:)
From: Pietro Abate <Pietro.Abate@a...>
Subject: [Caml-list] genlex ...
Hi all,
I'm re-writing the parser of my application and I'd like to write a kind
of generic parser that can parse a language that I can change dynamically... 
In other words... My application is composed by a library, a set of
modules that are compiled separately and dynamically loaded and an
application that get the name of a module, a file and it parses the file
differently regarding the definions that it loads from the dynamic

My point is that I want to have a generic parser that given a set of
keyword is able to parse different input.

so far I realized that I cannot do that with lex/yacc as they need a
compilation step (I could generate the lex/yacc file from the dynamic
module, but I think it's too messy...). But I can use Genlex.

Since I'm using Dynlink it's strightforward to load at runtime a
different set of keyword and initialized the lexer as :
let flexer = make_lexer Stub.variable_keyword_list

but at this point I don't know how to use the Genlex.parser to feed it
with my generic rules (every connective is declared as left assoc or non
assoc and the generic language is a calculator-like one ... )

I'd like to write something like

	| LBRACK expr RBRACK         { $2 } 
	| expr (keyword buf) expr    { Tree(keyword_lookup buf,$1,$3)
	| (keyword buf) expr         { Leaf(keyword_lookup buf,$2)
	| IDENT                      { Var($1)

where (keyword buf) is a function that returns 'Kwd if buf is a keyword
or fails ... Or using Genlex.parser as :

let rec parse_level1 = parser
	[< e1 = parse_level0; e = parse_level11 e1 >] -> e
and parse_level11 e1 = parser
	[< (keyword buf); e2 = parse_level1 >] ->
	| [< >] -> e1
and parse_level0 = parser
	[< (keyword buf); e = parse_level0 >] ->
is it possible ? does anybody can give me a small example ?


Civilization advances by extending the number
of important operations which we can perform 
without thinking. (Alfred North Whitehead)

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