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Diffstat (limited to 'gcc-4.9/gcc/ada/a-cbprqu.adb')
| -rw-r--r-- | gcc-4.9/gcc/ada/a-cbprqu.adb | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/gcc-4.9/gcc/ada/a-cbprqu.adb b/gcc-4.9/gcc/ada/a-cbprqu.adb new file mode 100644 index 000000000..ce2fd69fa --- /dev/null +++ b/gcc-4.9/gcc/ada/a-cbprqu.adb @@ -0,0 +1,220 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT LIBRARY COMPONENTS -- +-- -- +-- ADA.CONTAINERS.BOUNDED_PRIORITY_QUEUES -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 2011, Free Software Foundation, Inc. -- +-- -- +-- GNAT is free software; you can redistribute it and/or modify it under -- +-- terms of the GNU General Public License as published by the Free Soft- -- +-- ware Foundation; either version 3, or (at your option) any later ver- -- +-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- +-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- +-- or FITNESS FOR A PARTICULAR PURPOSE. -- +-- -- +-- As a special exception under Section 7 of GPL version 3, you are granted -- +-- additional permissions described in the GCC Runtime Library Exception, -- +-- version 3.1, as published by the Free Software Foundation. -- +-- -- +-- You should have received a copy of the GNU General Public License and -- +-- a copy of the GCC Runtime Library Exception along with this program; -- +-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- +-- <http://www.gnu.org/licenses/>. -- +-- -- +-- This unit was originally developed by Matthew J Heaney. -- +------------------------------------------------------------------------------ + +package body Ada.Containers.Bounded_Priority_Queues is + + package body Implementation is + + ------------- + -- Dequeue -- + ------------- + + procedure Dequeue + (List : in out List_Type; + Element : out Queue_Interfaces.Element_Type) + is + begin + Element := List.Container.First_Element; + List.Container.Delete_First; + end Dequeue; + + procedure Dequeue + (List : in out List_Type; + At_Least : Queue_Priority; + Element : in out Queue_Interfaces.Element_Type; + Success : out Boolean) + is + begin + -- This operation dequeues a high priority item if it exists in the + -- queue. By "high priority" we mean an item whose priority is equal + -- or greater than the value At_Least. The generic formal operation + -- Before has the meaning "has higher priority than". To dequeue an + -- item (meaning that we return True as our Success value), we need + -- as our predicate the equivalent of "has equal or higher priority + -- than", but we cannot say that directly, so we require some logical + -- gymnastics to make it so. + + -- If E is the element at the head of the queue, and symbol ">" + -- refers to the "is higher priority than" function Before, then we + -- derive our predicate as follows: + + -- original: P(E) >= At_Least + -- same as: not (P(E) < At_Least) + -- same as: not (At_Least > P(E)) + -- same as: not Before (At_Least, P(E)) + + -- But that predicate needs to be true in order to successfully + -- dequeue an item. If it's false, it means no item is dequeued, and + -- we return False as the Success value. + + if List.Length = 0 + or else Before (At_Least, + Get_Priority (List.Container.First_Element)) + then + Success := False; + return; + end if; + + List.Dequeue (Element); + Success := True; + end Dequeue; + + ------------- + -- Enqueue -- + ------------- + + procedure Enqueue + (List : in out List_Type; + New_Item : Queue_Interfaces.Element_Type) + is + P : constant Queue_Priority := Get_Priority (New_Item); + + C : List_Types.Cursor; + use List_Types; + + Count : Count_Type; + + begin + C := List.Container.First; + while Has_Element (C) loop + + -- ??? why is following commented out ??? + -- if Before (P, Get_Priority (List.Constant_Reference (C))) then + + if Before (P, Get_Priority (Element (C))) then + List.Container.Insert (C, New_Item); + exit; + end if; + + Next (C); + end loop; + + if not Has_Element (C) then + List.Container.Append (New_Item); + end if; + + Count := List.Container.Length; + + if Count > List.Max_Length then + List.Max_Length := Count; + end if; + end Enqueue; + + ------------------- + -- First_Element -- + ------------------- + + function First_Element + (List : List_Type) return Queue_Interfaces.Element_Type + is + begin + + -- Use Constant_Reference for this. ??? + + return List.Container.First_Element; + end First_Element; + + ------------ + -- Length -- + ------------ + + function Length (List : List_Type) return Count_Type is + begin + return List.Container.Length; + end Length; + + ---------------- + -- Max_Length -- + ---------------- + + function Max_Length (List : List_Type) return Count_Type is + begin + return List.Max_Length; + end Max_Length; + + end Implementation; + + protected body Queue is + + ------------------ + -- Current_Use -- + ------------------ + + function Current_Use return Count_Type is + begin + return List.Length; + end Current_Use; + + -------------- + -- Dequeue -- + -------------- + + entry Dequeue (Element : out Queue_Interfaces.Element_Type) + when List.Length > 0 + is + begin + List.Dequeue (Element); + end Dequeue; + + -------------------------------- + -- Dequeue_Only_High_Priority -- + -------------------------------- + + procedure Dequeue_Only_High_Priority + (At_Least : Queue_Priority; + Element : in out Queue_Interfaces.Element_Type; + Success : out Boolean) + is + begin + List.Dequeue (At_Least, Element, Success); + end Dequeue_Only_High_Priority; + + -------------- + -- Enqueue -- + -------------- + + entry Enqueue (New_Item : Queue_Interfaces.Element_Type) + when List.Length < Capacity + is + begin + List.Enqueue (New_Item); + end Enqueue; + + --------------- + -- Peak_Use -- + --------------- + + function Peak_Use return Count_Type is + begin + return List.Max_Length; + end Peak_Use; + + end Queue; + +end Ada.Containers.Bounded_Priority_Queues; |