Re: [Caml-list] extract info from file

[Martin Jambon <martin_jambon@emailuser.net>]

On Wed, 26 Jan 2005, Yan Jun Daisy Chen wrote:

> I am trying to extract comments in a text file i.e. text between (* and
> *).  I declared a globle sting variable, buff to store them, and want to
> store all the comments extracted in a list of string. Is the sting
> variable size fixed once I initialise it?
>
> The code I came up with is:
>
> open Unix;;
>
> let fileReader = openfile "student.cd" [O_RDONLY] 0o640;;
> let buff = ref "file: ";;
> let fileSize = (fstat fileReader).st_size;;
> (*let fileSize = 50;;*)
> let noOfChar = ref 0;;
>
> let extract_comment ()  =
>   let openIndex = 0 in
>   noOfChar := read fileReader !buff openIndex fileSize;
>   (*print_string !buff;	print_newline();
>   print_int !noOfChar;	print_newline();;*)
>
>
> let main () =
>   (*let fileContent = read fileReader !buff 0 5 in
>   print_int fileContent;*)
>   extract_comment();;
>
> main ();;
>
> Is there a simpler way to do this?

Sure:
1) Install my favorite library, Micmatch :-)
2) Use the following code (which does what you are asking for):

(* micmatch foo.ml < some_file *)
open Micmatch

let _ =
  let parse_contents = MAP "(*" (_* Lazy as s) "*)" -> `Comment s in
  let comments =
    Text.map
      (function
	   `Text _ -> raise Text.Skip
	 | `Comment s -> s)
      (parse_contents (Text.channel_contents stdin)) in

  List.iter print_endline comments

(***)

Martin

--
Martin Jambon, PhD
Researcher in Structural Bioinformatics since the 20th Century
The Burnham Institute http://www.burnham.org
San Diego, California