diff options
Diffstat (limited to 'gcc/ada/a-coorse.adb')
| -rw-r--r-- | gcc/ada/a-coorse.adb | 166 |
1 files changed, 141 insertions, 25 deletions
diff --git a/gcc/ada/a-coorse.adb b/gcc/ada/a-coorse.adb index 4c6476864b8..b4518f40b75 100644 --- a/gcc/ada/a-coorse.adb +++ b/gcc/ada/a-coorse.adb @@ -42,15 +42,17 @@ with System; use type System.Address; package body Ada.Containers.Ordered_Sets is - type Iterator is new - Ordered_Set_Iterator_Interfaces.Reversible_Iterator with record - Container : access constant Set; - Node : Node_Access; - end record; + type Iterator is new Limited_Controlled and + Set_Iterator_Interfaces.Reversible_Iterator with + record + Container : Set_Access; + Node : Node_Access; + end record; - overriding function First (Object : Iterator) return Cursor; + overriding procedure Finalize (Object : in out Iterator); - overriding function Last (Object : Iterator) return Cursor; + overriding function First (Object : Iterator) return Cursor; + overriding function Last (Object : Iterator) return Cursor; overriding function Next (Object : Iterator; @@ -512,6 +514,22 @@ package body Ada.Containers.Ordered_Sets is end if; end Exclude; + -------------- + -- Finalize -- + -------------- + + procedure Finalize (Object : in out Iterator) is + begin + if Object.Container /= null then + declare + B : Natural renames Object.Container.all.Tree.Busy; + + begin + B := B - 1; + end; + end if; + end Finalize; + ---------- -- Find -- ---------- @@ -537,9 +555,24 @@ package body Ada.Containers.Ordered_Sets is function First (Object : Iterator) return Cursor is begin - return (if Object.Container = null then No_Element - else Cursor'(Object.Container.all'Unrestricted_Access, - Object.Container.Tree.First)); + -- The value of the iterator object's Node component influences the + -- behavior of the First (and Last) selector function. + + -- When the Node component is null, this means the iterator object was + -- constructed without a start expression, in which case the (forward) + -- iteration starts from the (logical) beginning of the entire sequence + -- of items (corresponding to Container.First, for a forward iterator). + + -- Otherwise, this is iteration over a partial sequence of items. When + -- the Node component is non-null, the iterator object was constructed + -- with a start expression, that specifies the position from which the + -- (forward) partial iteration begins. + + if Object.Node = null then + return Object.Container.First; + else + return Cursor'(Object.Container, Object.Node); + end if; end First; ------------------- @@ -1145,7 +1178,7 @@ package body Ada.Containers.Ordered_Sets is Process (Cursor'(Container'Unrestricted_Access, Node)); end Process_Node; - T : Tree_Type renames Container.Tree'Unrestricted_Access.all; + T : Tree_Type renames Container'Unrestricted_Access.all.Tree; B : Natural renames T.Busy; -- Start of processing for Iterate @@ -1165,22 +1198,74 @@ package body Ada.Containers.Ordered_Sets is end Iterate; function Iterate (Container : Set) - return Ordered_Set_Iterator_Interfaces.Reversible_Iterator'class + return Set_Iterator_Interfaces.Reversible_Iterator'Class is + B : Natural renames Container'Unrestricted_Access.all.Tree.Busy; + begin - if Container.Length = 0 then - return Iterator'(null, null); - else - return Iterator'(Container'Unchecked_Access, Container.Tree.First); - end if; + -- The value of the Node component influences the behavior of the First + -- and Last selector functions of the iterator object. When the Node + -- component is null (as is the case here), this means the iterator + -- object was constructed without a start expression. This is a complete + -- iterator, meaning that the iteration starts from the (logical) + -- beginning of the sequence of items. + + -- Note: For a forward iterator, Container.First is the beginning, and + -- for a reverse iterator, Container.Last is the beginning. + + B := B + 1; + + return It : constant Iterator := + Iterator'(Limited_Controlled with + Container => Container'Unrestricted_Access, + Node => null); end Iterate; function Iterate (Container : Set; Start : Cursor) - return Ordered_Set_Iterator_Interfaces.Reversible_Iterator'class + return Set_Iterator_Interfaces.Reversible_Iterator'Class is - It : constant Iterator := (Container'Unchecked_Access, Start.Node); + B : Natural renames Container'Unrestricted_Access.all.Tree.Busy; + begin - return It; + -- It was formerly the case that when Start = No_Element, the partial + -- iterator was defined to behave the same as for a complete iterator, + -- and iterate over the entire sequence of items. However, those + -- semantics were unintuitive and arguably error-prone (it is too easy + -- to accidentally create an endless loop), and so they were changed, + -- per the ARG meeting in Denver on 2011/11. However, there was no + -- consensus about what positive meaning this corner case should have, + -- and so it was decided to simply raise an exception. This does imply, + -- however, that it is not possible to use a partial iterator to specify + -- an empty sequence of items. + + if Start = No_Element then + raise Constraint_Error with + "Start position for iterator equals No_Element"; + end if; + + if Start.Container /= Container'Unrestricted_Access then + raise Program_Error with + "Start cursor of Iterate designates wrong set"; + end if; + + pragma Assert (Vet (Container.Tree, Start.Node), + "Start cursor of Iterate is bad"); + + -- The value of the Node component influences the behavior of the First + -- and Last selector functions of the iterator object. When the Node + -- component is non-null (as is the case here), it means that this is a + -- partial iteration, over a subset of the complete sequence of + -- items. The iterator object was constructed with a start expression, + -- indicating the position from which the iteration begins. Note that + -- the start position has the same value irrespective of whether this is + -- a forward or reverse iteration. + + B := B + 1; + + return It : constant Iterator := + Iterator'(Limited_Controlled with + Container => Container'Unrestricted_Access, + Node => Start.Node); end Iterate; ---------- @@ -1196,9 +1281,24 @@ package body Ada.Containers.Ordered_Sets is function Last (Object : Iterator) return Cursor is begin - return (if Object.Container = null then No_Element - else Cursor'(Object.Container.all'Unrestricted_Access, - Object.Container.Tree.Last)); + -- The value of the iterator object's Node component influences the + -- behavior of the Last (and First) selector function. + + -- When the Node component is null, this means the iterator object was + -- constructed without a start expression, in which case the (reverse) + -- iteration starts from the (logical) beginning of the entire sequence + -- (corresponding to Container.Last, for a reverse iterator). + + -- Otherwise, this is iteration over a partial sequence of items. When + -- the Node component is non-null, the iterator object was constructed + -- with a start expression, that specifies the position from which the + -- (reverse) partial iteration begins. + + if Object.Node = null then + return Object.Container.Last; + else + return Cursor'(Object.Container, Object.Node); + end if; end Last; ------------------ @@ -1271,8 +1371,16 @@ package body Ada.Containers.Ordered_Sets is end Next; function Next (Object : Iterator; Position : Cursor) return Cursor is - pragma Unreferenced (Object); begin + if Position.Container = null then + return No_Element; + end if; + + if Position.Container /= Object.Container then + raise Program_Error with + "Position cursor of Next designates wrong set"; + end if; + return Next (Position); end Next; @@ -1322,8 +1430,16 @@ package body Ada.Containers.Ordered_Sets is end Previous; function Previous (Object : Iterator; Position : Cursor) return Cursor is - pragma Unreferenced (Object); begin + if Position.Container = null then + return No_Element; + end if; + + if Position.Container /= Object.Container then + raise Program_Error with + "Position cursor of Previous designates wrong set"; + end if; + return Previous (Position); end Previous; |