------------------------------------------------------------------------------
--                                                                          --
--                         GNAT COMPILER COMPONENTS                         --
--                                                                          --
--            G N A T . D I R E C T O R Y _ O P E R A T I O N S             --
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------------------------------------------------------------------------------

--  Directory operations

--  This package provides routines for manipulating directories. A directory
--  can be treated as a file, using open and close routines, and a scanning
--  routine is provided for iterating through the entries in a directory.

--  See also child package GNAT.Directory_Operations.Iteration

with Ada.Strings.Maps;

package GNAT.Directory_Operations is

   subtype Dir_Name_Str is String;
   --  A subtype used in this package to represent string values that are
   --  directory names. A directory name is a prefix for files that appear
   --  with in the directory. This means that for UNIX systems, the string
   --  includes a final '/', and for DOS-like systems, it includes a final
   --  '\' character. It can also include drive letters if the operating
   --  system provides for this. The final '/' or '\' in a Dir_Name_Str is
   --  optional when passed as a procedure or function in parameter.

   type Dir_Type is limited private;
   --  A value used to reference a directory. Conceptually this value includes
   --  the identity of the directory, and a sequential position within it.

   Null_Dir : constant Dir_Type;
   --  Represent the value for an uninitialized or closed directory

   Directory_Error : exception;
   --  Exception raised if the directory cannot be opened, read, closed,
   --  created or if it is not possible to change the current execution
   --  environment directory.

   Dir_Separator : constant Character;
   --  Running system default directory separator

   --------------------------------
   -- Basic Directory operations --
   --------------------------------

   procedure Change_Dir (Dir_Name : Dir_Name_Str);
   --  Changes the working directory of the current execution environment
   --  to the directory named by Dir_Name. Raises Directory_Error if Dir_Name
   --  does not exist.

   procedure Make_Dir (Dir_Name : Dir_Name_Str);
   --  Create a new directory named Dir_Name. Raises Directory_Error if
   --  Dir_Name cannot be created.

   procedure Remove_Dir (Dir_Name : Dir_Name_Str);
   --  Remove the directory named Dir_Name. Raises Directory_Error if Dir_Name
   --  cannot be removed.

   function Get_Current_Dir return Dir_Name_Str;
   --  Returns the current working directory for the execution environment.

   procedure Get_Current_Dir (Dir : out Dir_Name_Str; Last : out Natural);
   --  Returns the current working directory for the execution environment
   --  The name is returned in Dir_Name. Last is the index in Dir_Name such
   --  that Dir_Name (Last) is the last character written. If Dir_Name is
   --  too small for the directory name, the name will be truncated before
   --  being copied to Dir_Name.

   -------------------------
   -- Pathname Operations --
   -------------------------

   subtype Path_Name is String;
   --  All routines using Path_Name handle both styles (UNIX and DOS) of
   --  directory separators (either slash or back slash).

   function Dir_Name (Path : Path_Name) return Dir_Name_Str;
   --  Returns directory name for Path. This is similar to the UNIX dirname
   --  command. Everything after the last directory separator is removed. If
   --  there is no directory separator the current working directory is
   --  returned.

   function Base_Name
     (Path   : Path_Name;
      Suffix : String    := "")
      return   String;
   --  Any directory prefix is removed. If Suffix is non-empty and is a
   --  suffix of Path, it is removed. This is equivalent to the UNIX basename
   --  command. The following rule is always true:
   --
   --    'Path' and 'Dir_Name (Path) & Directory_Separator & Base_Name (Path)'
   --    represent the same file.
   --
   --  This function is not case-sensitive on systems that have a non
   --  case-sensitive file system like Windows, OS/2 and VMS.

   function File_Extension (Path : Path_Name) return String;
   --  Return the file extension. This is the string after the last dot
   --  character in File_Name (Path). It returns the empty string if no
   --  extension is found. The returned value does contains the file
   --  extension separator (dot character).

   function File_Name (Path : Path_Name) return String;
   --  Returns the file name and the file extension if present. It removes all
   --  path information. This is equivalent to Base_Name with default Extension
   --  value.

   type Path_Style is (UNIX, DOS, System_Default);

   function Normalize_Pathname
     (Path  : Path_Name;
      Style : Path_Style := System_Default)
      return  Path_Name;
   --  Removes all double directory separator and converts all '\' to '/' if
   --  Style is UNIX and converts all '/' to '\' if Style is set to DOS. This
   --  function will help to provide a consistent naming scheme running for
   --  different environments. If style is set to System_Default the routine
   --  will use the default directory separator on the running environment.

   function Expand_Path (Path : Path_Name) return Path_Name;
   --  Returns Path with environment variables (string preceded by a dollar
   --  sign) replaced by the current environment variable value. For example,
   --  $HOME/mydir will be replaced by /home/joe/mydir if $HOME environment
   --  variable is set to /home/joe. The variable can be surrounded by the
   --  characters '{' and '}' (curly bracket) if needed as in ${HOME}/mydir.
   --  If an environment variable does not exists the variable will be replaced
   --  by the empty string. Two dollar signs are replaced by a single dollar
   --  sign. Note that a variable must start with a letter. If there is no
   --  closing curly bracket for an opening one there is no translation done,
   --  so for example ${VAR/toto is returned as ${VAR/toto.

   ---------------
   -- Iterators --
   ---------------

   procedure Open (Dir : out Dir_Type; Dir_Name : Dir_Name_Str);
   --  Opens the directory named by Dir_Name and returns a Dir_Type value
   --  that refers to this directory, and is positioned at the first entry.
   --  Raises Directory_Error if Dir_Name cannot be accessed. In that case
   --  Dir will be set to Null_Dir.

   procedure Close (Dir : in out Dir_Type);
   --  Closes the directory stream refered to by Dir. After calling Close
   --  Is_Open will return False. Dir will be set to Null_Dir.
   --  Raises Directory_Error if Dir has not be opened (Dir = Null_Dir).

   function Is_Open (Dir : Dir_Type) return Boolean;
   --  Returns True if Dir is open, or False otherwise.

   procedure Read
     (Dir  : in out Dir_Type;
      Str  : out String;
      Last : out Natural);
   --  Reads the next entry from the directory and sets Str to the name
   --  of that entry. Last is the index in Str such that Str (Last) is the
   --  last character written. Last is 0 when there are no more files in the
   --  directory. If Str is too small for the file name, the file name will
   --  be truncated before being copied to Str. The list of files returned
   --  includes directories in systems providing a hierarchical directory
   --  structure, including . (the current directory) and .. (the parent
   --  directory) in systems providing these entries. The directory is
   --  returned in target-OS form. Raises Directory_Error if Dir has not
   --  be opened (Dir = Null_Dir).

   function Read_Is_Thread_Safe return Boolean;
   --  Indicates if procedure Read is thread safe. On systems where the
   --  target system supports this functionality, Read is thread safe,
   --  and this function returns True (e.g. this will be the case on any
   --  UNIX or UNIX-like system providing a correct implementation of the
   --  function readdir_r). If the system cannot provide a thread safe
   --  implementation of Read, then this function returns False.

private

   type Dir_Type_Value;
   type Dir_Type is access Dir_Type_Value;

   Null_Dir : constant Dir_Type := null;

   pragma Import (C, Dir_Separator, "__gnat_dir_separator");

   Dir_Seps : constant Ada.Strings.Maps.Character_Set :=
                Ada.Strings.Maps.To_Set ("/\");
   --  UNIX and DOS style directory separators.

end GNAT.Directory_Operations;