118 lines
4.5 KiB
Ada
118 lines
4.5 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT LIBRARY COMPONENTS --
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-- --
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-- A D A . S T R E A M S . S T O R A G E . B O U N D E D --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2020, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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------------------------------------------------------------------------------
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package body Ada.Streams.Storage.Bounded is
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----------
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-- Read --
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----------
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overriding procedure Read
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(Stream : in out Stream_Type; Item : out Stream_Element_Array;
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Last : out Stream_Element_Offset)
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is
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EA : Stream_Element_Array renames
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Stream.Elements (1 .. Element_Count (Stream));
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begin
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if Item'Length = 0 then
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Last := Item'First - 1;
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-- If the entire content of the stream fits in Item, then copy it and
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-- clear the stream. This is likely the usual case.
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elsif Element_Count (Stream) <= Item'Length then
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Last := Item'First + Element_Count (Stream) - 1;
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Item (Item'First .. Last) := EA;
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Clear (Stream);
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-- Otherwise, copy as much into Item as will fit. Then slide the
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-- remaining part of the stream down, and compute the new Count.
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-- We expect this to be the unusual case, so the cost of copying
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-- the remaining part probably doesn't matter.
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else
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Last := Item'Last;
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declare
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New_Count : constant Stream_Element_Count :=
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Element_Count (Stream) - Item'Length;
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begin
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Item := EA (1 .. Item'Length);
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EA (1 .. New_Count) :=
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EA (Element_Count (Stream) - New_Count + 1 ..
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Element_Count (Stream));
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Stream.Count := New_Count;
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end;
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end if;
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end Read;
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-----------
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-- Write --
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-----------
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overriding procedure Write
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(Stream : in out Stream_Type; Item : Stream_Element_Array)
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is
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begin
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if Element_Count (Stream) + Item'Length > Stream.Max_Elements then
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-- That is a precondition in the RM
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raise Constraint_Error;
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end if;
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declare
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New_Count : constant Stream_Element_Count :=
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Element_Count (Stream) + Item'Length;
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begin
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Stream.Elements (Element_Count (Stream) + 1 .. New_Count) := Item;
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Stream.Count := New_Count;
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end;
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end Write;
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-------------------
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-- Element_Count --
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-------------------
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overriding function Element_Count
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(Stream : Stream_Type) return Stream_Element_Count
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is
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begin
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return Stream.Count;
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end Element_Count;
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-----------
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-- Clear --
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-----------
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overriding procedure Clear (Stream : in out Stream_Type)
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is
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begin
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Stream.Count := 0;
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end Clear;
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end Ada.Streams.Storage.Bounded;
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