------------------------------------------------------------------------------
--                                                                          --
--                         GNAT RUN-TIME COMPONENTS                         --
--                                                                          --
--                     A D A . C O M M A N D _ L I N E                      --
--                                                                          --
--                                 S p e c                                  --
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--          Copyright (C) 1992-2025, Free Software Foundation, Inc.         --
--                                                                          --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
-- apply solely to the  contents of the part following the private keyword. --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- <http://www.gnu.org/licenses/>.                                          --
--                                                                          --
-- GNAT was originally developed  by the GNAT team at  New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
--                                                                          --
------------------------------------------------------------------------------

--  This language package providing support for obtaining the values of its
--  command line arguments and to set the exit status of the program as defined
--  by ARM A.15.

package Ada.Command_Line is
   pragma Preelaborate;

   function Argument_Count return Natural;
   --  If the external execution environment supports passing arguments to a
   --  program, then Argument_Count returns the number of arguments passed to
   --  the program invoking the function. Otherwise it return 0.
   --
   --  In GNAT: Corresponds to (argc - 1) in C.

   pragma Assertion_Policy (Pre => Ignore);
   --  We need to ignore the precondition of Argument, below, so that we don't
   --  raise Assertion_Error. The body raises Constraint_Error. It would be
   --  cleaner to add "or else raise Constraint_Error" to the precondition, but
   --  SPARK does not yet support raise expressions.

   function Argument (Number : Positive) return String with
      Pre => Number <= Argument_Count;
   --  If the external execution environment supports passing arguments to
   --  a program, then Argument returns an implementation-defined value
   --  corresponding to the argument at relative position Number. If Number
   --  is outside the range 1 .. Argument_Count, then Constraint_Error is
   --  propagated.
   --
   --  in GNAT: Corresponds to argv [n] (for n > 0) in C.

   function Command_Name return String;
   --  If the external execution environment supports passing arguments to
   --  a program, then Command_Name returns an implementation-defined value
   --  corresponding to the name of the command invoking the program.
   --  Otherwise Command_Name returns the null string.
   --
   --  in GNAT: Corresponds to argv [0] in C.

   type Exit_Status is new Integer;

   Success : constant Exit_Status;
   Failure : constant Exit_Status;

   procedure Set_Exit_Status (Code : Exit_Status);

   ------------------------------------
   -- Note on Interface Requirements --
   ------------------------------------

   --  Services in this package are not supported during the elaboration of an
   --  auto-initialized Stand-Alone Library.

   --  If the main program is in Ada, this package works as specified without
   --  any other work than the normal steps of WITH'ing the package and then
   --  calling the desired routines.

   --  If the main program is not in Ada, then the information must be made
   --  available for this package to work correctly. In particular, it is
   --  required that the global variable "gnat_argc" contain the number of
   --  arguments, and that the global variable "gnat_argv" points to an
   --  array of null-terminated strings, the first entry being the command
   --  name, and the remaining entries being the command arguments.

   --  These correspond to the normal argc/argv variables passed to a C
   --  main program, and the following is an example of a complete C main
   --  program that stores the required information:

   --    main(int argc, char **argv, char **envp)
   --    {
   --       extern int    gnat_argc;
   --       extern char **gnat_argv;
   --       extern char **gnat_envp;
   --       gnat_argc = argc;
   --       gnat_argv = argv;
   --       gnat_envp = envp;

   --       adainit();
   --       adamain();
   --       adafinal();
   --    }

   --  The assignment statements ensure that the necessary information is
   --  available for finding the command name and command line arguments.

private
   Success : constant Exit_Status := 0;
   Failure : constant Exit_Status := 1;

   --  The following locations support the operation of the package
   --  Ada.Command_Line.Remove, which provides facilities for logically
   --  removing arguments from the command line. If one of the remove
   --  procedures is called in this unit, then Remove_Args/Remove_Count
   --  are set to indicate which arguments are removed. If no such calls
   --  have been made, then Remove_Args is null.

   Remove_Count : Natural;
   --  Number of arguments reflecting removals. Not defined unless
   --  Remove_Args is non-null.

   type Arg_Nums is array (Positive range <>) of Positive;
   type Arg_Nums_Ptr is access Arg_Nums;
   --  An array that maps logical argument numbers (reflecting removal)
   --  to physical argument numbers (e.g. if the first argument has been
   --  removed, but not the second, then Arg_Nums (1) will be set to 2.

   Remove_Args : Arg_Nums_Ptr := null;
   --  Left set to null if no remove calls have been made, otherwise set
   --  to point to an appropriate mapping array. Only the first Remove_Count
   --  elements are relevant.

   pragma Import (C, Set_Exit_Status, "__gnat_set_exit_status");

end Ada.Command_Line;
