File : agpl-streams-memory_arrays.adb


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--                         ADAGIO - ADALID - AENEA.                         --

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--  $Id: agpl-streams-memory_arrays.adb,v 1.1 2004/02/24 15:26:10 Jano Exp $


--  Allows reading from a string viewed as an stream:


package body Agpl.Streams.Memory_arrays is

   ------------------------------------------------------------------------

   -- Read                                                               --

   ------------------------------------------------------------------------

   procedure Read (
      Stream : in out Stream_type;
      Item   : out Stream_Element_Array;
      Last   : out Stream_Element_Offset) is
      Pos    : Stream_element_offset renames Stream.Pos;
   begin
      if Pos > STream.Data'Last then
         raise Constraint_error;
      end if;
      if Item'Length > Stream.Data'Last - Pos + 1 then
         Item (Item'First .. Item'First + Stream.Data'Last - Pos) :=
            Stream.Data (Pos .. Stream.Data'Last);
         Last := Item'First + Stream.Data'Last - Pos;
         Pos  := Stream.Data'Last + 1;
      else
         Item := Stream.Data (Pos .. Pos + Item'Length - 1);
         Last := Item'Last;
         Pos  := Pos + Item'Length;
      end if;
   end Read;

   ------------------------------------------------------------------------

   -- Write                                                              --

   ------------------------------------------------------------------------

        procedure Write (
      Stream : in out Stream_type;
      Item   : in Stream_Element_Array) is
      Pos    : Stream_element_offset renames Stream.Pos;
   begin
      if Pos + Item'Length - 1 > Stream.Data'Length then
         raise Constraint_error;
      end if;
      Stream.Data (Pos .. Pos + Item'Length - 1) := Item;
      Pos := Pos + Item'Length;
   end Write;

   ------------------------------------------------------------------------

   -- Index                                                              --

   ------------------------------------------------------------------------

   function Index (Stream : in Stream_type) return Stream_element_offset is
   begin
      return Stream.Pos - Stream.Data'First;
   end Index;

   ------------------------------------------------------------------------

   -- Set_index                                                          --

   ------------------------------------------------------------------------

   -- Set starting position for read/write (First is 1)

   procedure Set_index (
      Stream : in out Stream_type;
      Index  : in     Stream_element_offset) is
   begin
      Stream.Pos := Stream.Data'First + Index - 1;
   end Set_index;

   ------------------------------------------------------------------------

   -- End_of_stream                                                      --

   ------------------------------------------------------------------------

   function End_of_stream (Stream : in Stream_type) return boolean is
   begin
      return Stream.Pos > Stream.Data.all'Last;
   end End_of_stream;
   
end Agpl.Streams.Memory_arrays;