1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT RUN-TIME COMPONENTS                         --
4--                                                                          --
5--                          G N A T . I O _ A U X                           --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--                     Copyright (C) 1995-2010, AdaCore                     --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32with Interfaces.C_Streams; use Interfaces.C_Streams;
33
34package body GNAT.IO_Aux is
35
36   Buflen : constant := 2000;
37   --  Buffer length. Works for any non-zero value, larger values take
38   --  more stack space, smaller values require more recursion.
39
40   -----------------
41   -- File_Exists --
42   -----------------
43
44   function File_Exists (Name : String) return Boolean
45   is
46      Namestr : aliased String (1 .. Name'Length + 1);
47      --  Name as given with ASCII.NUL appended
48
49   begin
50      Namestr (1 .. Name'Length) := Name;
51      Namestr (Name'Length + 1)  := ASCII.NUL;
52      return file_exists (Namestr'Address) /= 0;
53   end File_Exists;
54
55   --------------
56   -- Get_Line --
57   --------------
58
59   --  Current_Input case
60
61   function Get_Line return String is
62      Buffer : String (1 .. Buflen);
63      --  Buffer to read in chunks of remaining line. Will work with any
64      --  size buffer. We choose a length so that most of the time no
65      --  recursion will be required.
66
67      Last : Natural;
68
69   begin
70      Ada.Text_IO.Get_Line (Buffer, Last);
71
72      --  If the buffer is not full, then we are all done
73
74      if Last < Buffer'Last then
75         return Buffer (1 .. Last);
76
77      --  Otherwise, we still have characters left on the line. Note that
78      --  as specified by (RM A.10.7(19)) the end of line is not skipped
79      --  in this case, even if we are right at it now.
80
81      else
82         return Buffer & GNAT.IO_Aux.Get_Line;
83      end if;
84   end Get_Line;
85
86   --  Case of reading from a specified file. Note that we could certainly
87   --  share code between these two versions, but these are very short
88   --  routines, and we may as well aim for maximum speed, cutting out an
89   --  intermediate call (calls returning string may be somewhat slow)
90
91   function Get_Line (File : Ada.Text_IO.File_Type) return String is
92      Buffer : String (1 .. Buflen);
93      Last   : Natural;
94
95   begin
96      Ada.Text_IO.Get_Line (File, Buffer, Last);
97
98      if Last < Buffer'Last then
99         return Buffer (1 .. Last);
100      else
101         return Buffer & Get_Line (File);
102      end if;
103   end Get_Line;
104
105end GNAT.IO_Aux;
106