47 lines
1.9 KiB
OCaml
47 lines
1.9 KiB
OCaml
(* 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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There are four types of keywords: Unit, String, Int, and Float.
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Unit keywords do not take an argument.
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String, Int, and Float keywords take the following word on the command line
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as an 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 1 2 3 ](three anonymous arguments: ["1"], ["2"], and ["3"])
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- [cmd 1 2 -flag 3 -string bar 4]
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- [ ](four anonymous arguments, a unit option, and
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- [ ] a string option with argument ["bar"])
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*)
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type spec =
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String of (string -> unit)
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| Int of (int -> unit)
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| Unit of (unit -> unit)
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| Float of (float -> unit)
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(* The concrete type describing the behavior associated
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with a keyword. *)
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val parse : (string * spec) list -> (string -> unit) -> unit
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(* [parse speclist anonfun] parses the command line,
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calling the functions in [speclist] whenever appropriate,
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and [anonfun] on anonymous arguments.
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The functions are called in the same order as they appear
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on the command line.
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The strings in the [(string * spec) list] are keywords and must
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start with a [-], else they are ignored. *)
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exception Bad of string
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(* Functions in [speclist] or [anonfun] can raise [Bad] with
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an error message to reject invalid arguments. *)
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