142 lines
7.0 KiB
OCaml
142 lines
7.0 KiB
OCaml
(***********************************************************************)
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(* *)
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(* OCaml *)
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(* *)
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(* Damien Doligez, projet Para, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* en Automatique. All rights reserved. This file is distributed *)
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(* under the terms of the GNU Library General Public License, with *)
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(* the special exception on linking described in file ../LICENSE. *)
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(* *)
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(***********************************************************************)
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(* $Id$ *)
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(** Parsing of command line arguments.
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This module provides a general mechanism for extracting options and
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arguments from the command line to the program.
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Syntax of command lines:
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A keyword is a character string starting with a [-].
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An option is a keyword alone or followed by an argument.
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The types of keywords are: [Unit], [Bool], [Set], [Clear],
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[String], [Set_string], [Int], [Set_int], [Float], [Set_float],
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[Tuple], [Symbol], and [Rest].
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[Unit], [Set] and [Clear] keywords take no argument. A [Rest]
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keyword takes the remaining of the command line as arguments.
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Every other keyword takes the following word on the command line
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as argument.
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Arguments not preceded by a keyword are called anonymous arguments.
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Examples ([cmd] is assumed to be the command name):
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- [cmd -flag ](a unit option)
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- [cmd -int 1 ](an int option with argument [1])
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- [cmd -string foobar ](a string option with argument ["foobar"])
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- [cmd -float 12.34 ](a float option with argument [12.34])
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- [cmd a b c ](three anonymous arguments: ["a"], ["b"], and ["c"])
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- [cmd a b -- c d ](two anonymous arguments and a rest option with
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two arguments)
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*)
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type spec =
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| Unit of (unit -> unit) (** Call the function with unit argument *)
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| Bool of (bool -> unit) (** Call the function with a bool argument *)
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| Set of bool ref (** Set the reference to true *)
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| Clear of bool ref (** Set the reference to false *)
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| String of (string -> unit) (** Call the function with a string argument *)
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| Set_string of string ref (** Set the reference to the string argument *)
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| Int of (int -> unit) (** Call the function with an int argument *)
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| Set_int of int ref (** Set the reference to the int argument *)
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| Float of (float -> unit) (** Call the function with a float argument *)
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| Set_float of float ref (** Set the reference to the float argument *)
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| Tuple of spec list (** Take several arguments according to the
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spec list *)
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| Symbol of string list * (string -> unit)
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(** Take one of the symbols as argument and
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call the function with the symbol *)
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| Rest of (string -> unit) (** Stop interpreting keywords and call the
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function with each remaining argument *)
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(** The concrete type describing the behavior associated
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with a keyword. *)
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type key = string
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type doc = string
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type usage_msg = string
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type anon_fun = (string -> unit)
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val parse :
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(key * spec * doc) list -> anon_fun -> usage_msg -> unit
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(** [Arg.parse speclist anon_fun usage_msg] parses the command line.
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[speclist] is a list of triples [(key, spec, doc)].
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[key] is the option keyword, it must start with a ['-'] character.
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[spec] gives the option type and the function to call when this option
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is found on the command line.
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[doc] is a one-line description of this option.
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[anon_fun] is called on anonymous arguments.
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The functions in [spec] and [anon_fun] are called in the same order
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as their arguments appear on the command line.
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If an error occurs, [Arg.parse] exits the program, after printing
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to standard error an error message as follows:
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- The reason for the error: unknown option, invalid or missing argument, etc.
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- [usage_msg]
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- The list of options, each followed by the corresponding [doc] string.
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Beware: options that have an empty [doc] string will not be included in the
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list.
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For the user to be able to specify anonymous arguments starting with a
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[-], include for example [("-", String anon_fun, doc)] in [speclist].
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By default, [parse] recognizes two unit options, [-help] and [--help],
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which will print to standard output [usage_msg] and the list of
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options, and exit the program. You can override this behaviour
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by specifying your own [-help] and [--help] options in [speclist].
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*)
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val parse_argv : ?current: int ref -> string array ->
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(key * spec * doc) list -> anon_fun -> usage_msg -> unit
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(** [Arg.parse_argv ~current args speclist anon_fun usage_msg] parses
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the array [args] as if it were the command line. It uses and updates
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the value of [~current] (if given), or [Arg.current]. You must set
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it before calling [parse_argv]. The initial value of [current]
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is the index of the program name (argument 0) in the array.
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If an error occurs, [Arg.parse_argv] raises [Arg.Bad] with
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the error message as argument. If option [-help] or [--help] is
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given, [Arg.parse_argv] raises [Arg.Help] with the help message
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as argument.
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*)
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exception Help of string
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(** Raised by [Arg.parse_argv] when the user asks for help. *)
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exception Bad of string
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(** Functions in [spec] or [anon_fun] can raise [Arg.Bad] with an error
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message to reject invalid arguments.
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[Arg.Bad] is also raised by [Arg.parse_argv] in case of an error. *)
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val usage : (key * spec * doc) list -> usage_msg -> unit
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(** [Arg.usage speclist usage_msg] prints to standard error
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an error message that includes the list of valid options. This is
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the same message that {!Arg.parse} prints in case of error.
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[speclist] and [usage_msg] are the same as for [Arg.parse]. *)
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val usage_string : (key * spec * doc) list -> usage_msg -> string
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(** Returns the message that would have been printed by {!Arg.usage},
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if provided with the same parameters. *)
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val align: (key * spec * doc) list -> (key * spec * doc) list;;
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(** Align the documentation strings by inserting spaces at the first
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space, according to the length of the keyword. Use a
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space as the first character in a doc string if you want to
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align the whole string. The doc strings corresponding to
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[Symbol] arguments are aligned on the next line. *)
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val current : int ref
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(** Position (in {!Sys.argv}) of the argument being processed. You can
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change this value, e.g. to force {!Arg.parse} to skip some arguments.
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{!Arg.parse} uses the initial value of {!Arg.current} as the index of
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argument 0 (the program name) and starts parsing arguments
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at the next element. *)
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