Browse thread
Partial parsing
[
Home
]
[ Index:
by date
|
by threads
]
[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: | 2006-07-27 (22:58) |
From: | Fermin Reig <reig@a...> |
Subject: | Re: [Caml-list] Partial parsing |
Markus Mottl wrote: > Hi, > > one feature that I'd love to see with our lexing/parsing tools for > OCaml would be the possibility to perform partial lexing / parsing. > > For example, imagine that you read a message from a socket into a > string buffer, but it is not yet complete. You may not be able to > know that in advance, because that would require parsing it. > > What I'd like to be able to do is to e.g. call a lexer or parser > function on this buffer, and it will recognize as much as possible > with the option to continue parsing in another buffer. For this we > could e.g. define a type "parse_result": > > type parse_result = > | Done of result * int > | Cont of parse_fun > and parse_fun = pos : int -> len : int -> string -> parse_result > > If a full parse was detected, it would return e.g. "Done (result, > next_pos)", where "result" is the result of the successful parse, and > "next_pos" is the position in the buffer that contains the character > following the successfully parsed text. > [...] This sounds like a parsing problem suitable for the parser combinator approach. There, the result of a parse is a pair where one of the two components is the remaining of the input string. Many of the papers and implementations are from the Haskell folk, but I think there are some in Ocaml as well. HTH, Fermin