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(***********************************************************************)
(* *)
(* Objective Caml *)
(* *)
(* Damien Doligez, projet Para, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* en Automatique. All rights reserved. This file is distributed *)
(* under the terms of the GNU Library General Public License. *)
(* *)
(***********************************************************************)
(* $Id$ *)
(* Module [Arg]: parsing of command line arguments *)
(* This module provides a general mechanism for extracting options and
arguments from the command line to the program.
*)
(* Syntax of command lines:
A keyword is a character string starting with a [-].
An option is a keyword alone or followed by an argument.
The types of keywords are: [Unit], [Set], [Clear], [String],
[Int], [Float], and [Rest]. [Unit], [Set] and [Clear] keywords take
no argument. [String], [Int], and [Float] keywords take the following
word on the command line as an argument. A [Rest] keyword takes the
remaining of the command line as (string) arguments.
Arguments not preceded by a keyword are called anonymous arguments.
*)
(* Examples ([cmd] is assumed to be the command name):
- [cmd -flag ](a unit option)
- [cmd -int 1 ](an int option with argument [1])
- [cmd -string foobar ](a string option with argument ["foobar"])
- [cmd -float 12.34 ](a float option with argument [12.34])
- [cmd a b c ](three anonymous arguments: ["a"], ["b"], and ["c"])
- [cmd a b -- c d ](two anonymous arguments and a rest option with
- [ ] two arguments)
*)
type spec =
| Unit of (unit -> unit) (* Call the function with unit argument *)
| Set of bool ref (* Set the reference to true *)
| Clear of bool ref (* Set the reference to false *)
| String of (string -> unit) (* Call the function with a string argument *)
| Int of (int -> unit) (* Call the function with an int argument *)
| Float of (float -> unit) (* Call the function with a float argument *)
| Rest of (string -> unit) (* Stop interpreting keywords and call the
function with each remaining argument *)
(* The concrete type describing the behavior associated
with a keyword. *)
val parse : keywords:(string * spec * string) list ->
others:(string -> unit) -> errmsg:string -> unit
(*
[Arg.parse speclist anonfun usage_msg] parses the command line.
[speclist] is a list of triples [(key, spec, doc)].
[key] is the option keyword, it must start with a ['-'] character.
[spec] gives the option type and the function to call when this option
is found on the command line.
[doc] is a one-line description of this option.
[anonfun] is called on anonymous arguments.
The functions in [spec] and [anonfun] are called in the same order
as their arguments appear on the command line.
If an error occurs, [Arg.parse] exits the program, after printing
an error message as follows:
- The reason for the error: unknown option, invalid or missing argument, etc.
- [usage_msg]
- The list of options, each followed by the corresponding [doc] string.
For the user to be able to specify anonymous arguments starting with a
[-], include for example [("-", String anonfun, doc)] in [speclist].
By default, [parse] recognizes a unit option [-help], which will
display [usage_msg] and the list of options, and exit the program.
You can override this behaviour by specifying your own [-help]
option in [speclist].
*)
exception Bad of string
(*
Functions in [spec] or [anonfun] can raise [Arg.Bad] with an error
message to reject invalid arguments.
*)
val usage : keywords:(string * spec * string) list -> errmsg:string -> unit
(*
[Arg.usage speclist usage_msg] prints an error message including
the list of valid options. This is the same message that
[Arg.parse] prints in case of error.
[speclist] and [usage_msg] are the same as for [Arg.parse].
*)
val current : int ref;;
(*
Position (in [Sys.argv]) of the argument being processed. You can
change this value, e.g. to force [Arg.parse] to skip some arguments.
*)
|
