The signature and semantics of the priority queue operation
Dequeue_Only_High_Priority changed during the ARG meeting in Edinburgh (June
2011). That operation had been a protected entry in earlier drafts of
AI05-0159, but it was discovered that that operation as formerly specified was
not in fact implementable, so it was changed during the Edinburgh meeting to be
a protected procedure with a different signature and semantics. This revision
of the sources now fully implements the protected procedure
Dequeue_Only_High_Priority, to conform to its specification as described in the
most recent draft of the Ada 2012 RM.
Tested on x86_64-pc-linux-gnu, committed on trunk
2011-10-06 Matthew Heaney <hea...@adacore.com>
* a-cuprqu.ads, a-cuprqu.adb, a-cbprqu.ads, a-cbprqu.adb
(Dequeue_Only_High_Priority): Protected procedure now implemented.
Index: a-cbprqu.adb
===================================================================
--- a-cbprqu.adb (revision 179628)
+++ a-cbprqu.adb (working copy)
@@ -44,6 +44,24 @@
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
+ if List.Length = 0
+ or else not Before (At_Least, Get_Priority (List.First_Element))
+ then
+ Success := False;
+ return;
+ end if;
+
+ List.Dequeue (Element);
+ Success := True;
+ end Dequeue;
+
-------------
-- Enqueue --
-------------
@@ -83,6 +101,18 @@
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 --
------------
@@ -125,15 +155,19 @@
List.Dequeue (Element);
end Dequeue;
- -- ???
- -- entry Dequeue_Only_High_Priority
- -- (Low_Priority : Queue_Priority;
- -- Element : out Queue_Interfaces.Element_Type) when True
- -- is
- -- begin
- -- null;
- -- end Dequeue_Only_High_Priority;
+ --------------------------------
+ -- 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 --
--------------
Index: a-cbprqu.ads
===================================================================
--- a-cbprqu.ads (revision 179628)
+++ a-cbprqu.ads (working copy)
@@ -70,6 +70,15 @@
(List : in out List_Type;
Element : out Queue_Interfaces.Element_Type);
+ procedure Dequeue
+ (List : in out List_Type;
+ At_Least : Queue_Priority;
+ Element : in out Queue_Interfaces.Element_Type;
+ Success : out Boolean);
+
+ function First_Element
+ (List : List_Type) return Queue_Interfaces.Element_Type;
+
function Length (List : List_Type) return Count_Type;
function Max_Length (List : List_Type) return Count_Type;
@@ -102,12 +111,19 @@
overriding
entry Dequeue (Element : out Queue_Interfaces.Element_Type);
- -- ???
- -- not overriding
- -- entry Dequeue_Only_High_Priority
- -- (Low_Priority : Queue_Priority;
- -- Element : out Queue_Interfaces.Element_Type);
+ -- The priority queue operation Dequeue_Only_High_Priority had been a
+ -- protected entry in early drafts of AI05-0159, but it was discovered
+ -- that that operation as specified was not in fact implementable. The
+ -- operation was changed from an entry to a protected procedure per the
+ -- ARG meeting in Edinburgh (June 2011), with a different signature and
+ -- semantics.
+ not overriding
+ procedure Dequeue_Only_High_Priority
+ (At_Least : Queue_Priority;
+ Element : in out Queue_Interfaces.Element_Type;
+ Success : out Boolean);
+
overriding
function Current_Use return Count_Type;
@@ -115,6 +131,7 @@
function Peak_Use return Count_Type;
private
+
List : Implementation.List_Type (Capacity);
end Queue;
Index: a-cuprqu.adb
===================================================================
--- a-cuprqu.adb (revision 179628)
+++ a-cuprqu.adb (working copy)
@@ -65,6 +65,24 @@
Free (X);
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
+ if List.Length = 0
+ or else not Before (At_Least, Get_Priority (List.First.Element))
+ then
+ Success := False;
+ return;
+ end if;
+
+ List.Dequeue (Element);
+ Success := True;
+ end Dequeue;
+
-------------
-- Enqueue --
-------------
@@ -132,22 +150,6 @@
end loop;
end Finalize;
- ------------------------
- -- Have_High_Priority --
- ------------------------
-
- -- ???
- -- function Have_High_Priority
- -- (List : List_Type;
- -- Low_Priority : Queue_Priority) return Boolean
- -- is
- -- begin
- -- if List.Length = 0 then
- -- return False;
- -- end if;
- -- return Before (Get_Priority (List.First.Element), Low_Priority);
- -- end Have_High_Priority;
-
------------
-- Length --
------------
@@ -190,15 +192,19 @@
List.Dequeue (Element);
end Dequeue;
- -- ???
- -- entry Dequeue_Only_High_Priority
- -- (Low_Priority : Queue_Priority;
- -- Element : out Queue_Interfaces.Element_Type) when True
- -- is
- -- begin
- -- null;
- -- end Dequeue_Only_High_Priority;
+ --------------------------------
+ -- 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 --
-------------
Index: a-cuprqu.ads
===================================================================
--- a-cuprqu.ads (revision 179628)
+++ a-cuprqu.ads (working copy)
@@ -68,6 +68,12 @@
(List : in out List_Type;
Element : out Queue_Interfaces.Element_Type);
+ procedure Dequeue
+ (List : in out List_Type;
+ At_Least : Queue_Priority;
+ Element : in out Queue_Interfaces.Element_Type;
+ Success : out Boolean);
+
function Length (List : List_Type) return Count_Type;
function Max_Length (List : List_Type) return Count_Type;
@@ -91,37 +97,38 @@
overriding
procedure Finalize (List : in out List_Type);
- -- ???
- -- not overriding
- -- function Have_High_Priority
- -- (List : List_Type;
- -- Low_Priority : Queue_Priority) return Boolean;
-
end Implementation;
protected type Queue (Ceiling : System.Any_Priority := Default_Ceiling)
- -- ???
- -- with Priority => Ceiling is new Queue_Interfaces.Queue with
- is new Queue_Interfaces.Queue with
+ -- ???
+ -- with Priority => Ceiling is new Queue_Interfaces.Queue with
+ is new Queue_Interfaces.Queue with
- overriding
- entry Enqueue (New_Item : Queue_Interfaces.Element_Type);
+ overriding
+ entry Enqueue (New_Item : Queue_Interfaces.Element_Type);
- overriding
- entry Dequeue (Element : out Queue_Interfaces.Element_Type);
+ overriding
+ entry Dequeue (Element : out Queue_Interfaces.Element_Type);
- -- ???
- -- not overriding
- -- entry Dequeue_Only_High_Priority
- -- (Low_Priority : Queue_Priority;
- -- Element : out Queue_Interfaces.Element_Type);
+ -- The priority queue operation Dequeue_Only_High_Priority had been a
+ -- protected entry in early drafts of AI05-0159, but it was discovered
+ -- that that operation as specified was not in fact implementable. The
+ -- operation was changed from an entry to a protected procedure per the
+ -- ARG meeting in Edinburgh (June 2011), with a different signature and
+ -- semantics.
- overriding
- function Current_Use return Count_Type;
+ not overriding
+ procedure Dequeue_Only_High_Priority
+ (At_Least : Queue_Priority;
+ Element : in out Queue_Interfaces.Element_Type;
+ Success : out Boolean);
- overriding
- function Peak_Use return Count_Type;
+ overriding
+ function Current_Use return Count_Type;
+ overriding
+ function Peak_Use return Count_Type;
+
private
List : Implementation.List_Type;
