The Generic Package Containers.Ordered_Maps
Author: JTC1/SC22/WG9/ARG, by Randall Brukardt, ARG Editor

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# A.18.6 The Generic Package Containers.Ordered_Maps

#### Static Semantics

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The generic library package Containers.Ordered_Maps has the following declaration:
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with Ada.Iterator_Interfaces;
generic
type Key_Type is private;
type Element_Type is private;
with function "<" (Left, Right : Key_Type) return Boolean is <>;
with function "=" (Left, Right : Element_Type) return Boolean is <>;
package Ada.Containers.Ordered_Maps is
pragma Preelaborate(Ordered_Maps);
pragma Remote_Types(Ordered_Maps);
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function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
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type Map is tagged private
with Constant_Indexing => Constant_Reference,
Variable_Indexing => Reference,
Default_Iterator => Iterate,
Iterator_Element => Element_Type;
pragma Preelaborable_Initialization(Map);
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type Cursor is private;
pragma Preelaborable_Initialization(Cursor);
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Empty_Map : constant Map;
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No_Element : constant Cursor;
7.1/3
function Has_Element (Position : Cursor) return Boolean;
7.2/3
package Map_Iterator_Interfaces is new
Ada.Iterator_Interfaces (Cursor, Has_Element);
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function "=" (Left, Right : Map) return Boolean;
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function Length (Container : Map) return Count_Type;
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function Is_Empty (Container : Map) return Boolean;
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procedure Clear (Container : in out Map);
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function Key (Position : Cursor) return Key_Type;
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function Element (Position : Cursor) return Element_Type;
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procedure Replace_Element (Container : in out Map;
Position : in Cursor;
New_Item : in Element_Type);
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procedure Query_Element
(Position : in Cursor;
Process : not null access procedure (Key : in Key_Type;
Element : in Element_Type));
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procedure Update_Element
(Container : in out Map;
Position : in Cursor;
Process : not null access procedure
(Key : in Key_Type;
Element : in out Element_Type));
16.1/3
type Constant_Reference_Type
(Element : not null access constant Element_Type) is private
with Implicit_Dereference => Element;
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type Reference_Type (Element : not null access Element_Type) is private
with Implicit_Dereference => Element;
16.3/3
function Constant_Reference (Container : aliased in Map;
Position : in Cursor)
return Constant_Reference_Type;
16.4/3
function Reference (Container : aliased in out Map;
Position : in Cursor)
return Reference_Type;
16.5/3
function Constant_Reference (Container : aliased in Map;
Key : in Key_Type)
return Constant_Reference_Type;
16.6/3
function Reference (Container : aliased in out Map;
Key : in Key_Type)
return Reference_Type;
16.7/3
procedure Assign (Target : in out Map; Source : in Map);
16.8/3
function Copy (Source : Map) return Map;
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procedure Move (Target : in out Map;
Source : in out Map);
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procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type;
Position : out Cursor;
Inserted : out Boolean);
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procedure Insert (Container : in out Map;
Key : in Key_Type;
Position : out Cursor;
Inserted : out Boolean);
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procedure Insert (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type);
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procedure Include (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type);
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procedure Replace (Container : in out Map;
Key : in Key_Type;
New_Item : in Element_Type);
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procedure Exclude (Container : in out Map;
Key : in Key_Type);
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procedure Delete (Container : in out Map;
Key : in Key_Type);
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procedure Delete (Container : in out Map;
Position : in out Cursor);
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procedure Delete_First (Container : in out Map);
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procedure Delete_Last (Container : in out Map);
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function First (Container : Map) return Cursor;
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function First_Element (Container : Map) return Element_Type;
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function First_Key (Container : Map) return Key_Type;
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function Last (Container : Map) return Cursor;
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function Last_Element (Container : Map) return Element_Type;
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function Last_Key (Container : Map) return Key_Type;
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function Next (Position : Cursor) return Cursor;
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procedure Next (Position : in out Cursor);
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function Previous (Position : Cursor) return Cursor;
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procedure Previous (Position : in out Cursor);
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function Find (Container : Map;
Key : Key_Type) return Cursor;
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function Element (Container : Map;
Key : Key_Type) return Element_Type;
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function Floor (Container : Map;
Key : Key_Type) return Cursor;
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function Ceiling (Container : Map;
Key : Key_Type) return Cursor;
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function Contains (Container : Map;
Key : Key_Type) return Boolean;
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This paragraph was deleted.
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function "<" (Left, Right : Cursor) return Boolean;
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function ">" (Left, Right : Cursor) return Boolean;
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function "<" (Left : Cursor; Right : Key_Type) return Boolean;
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function ">" (Left : Cursor; Right : Key_Type) return Boolean;
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function "<" (Left : Key_Type; Right : Cursor) return Boolean;
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function ">" (Left : Key_Type; Right : Cursor) return Boolean;
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procedure Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor));
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procedure Reverse_Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor));
51.1/3
function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Reversible_Iterator'Class;
51.2/3
function Iterate (Container : in Map; Start : in Cursor)
return Map_Iterator_Interfaces.Reversible_Iterator'Class;
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private
53/2
... -- not specified by the language
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end Ada.Containers.Ordered_Maps;
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Two keys K1 and K2 are equivalent if both K1 < K2 and K2 < K1 return False, using the generic formal "<" operator for keys. Function Equivalent_Keys returns True if Left and Right are equivalent, and False otherwise.
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The actual function for the generic formal function "<" on Key_Type values is expected to return the same value each time it is called with a particular pair of key values. It should define a strict weak ordering relationship (see A.18). If the actual for "<" behaves in some other manner, the behavior of this package is unspecified. Which subprograms of this package call "<" and how many times they call it, is unspecified.
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If the value of a key stored in a map is changed other than by an operation in this package such that at least one of "<" or "=" give different results, the behavior of this package is unspecified.
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The first node of a nonempty map is the one whose key is less than the key of all the other nodes in the map. The last node of a nonempty map is the one whose key is greater than the key of all the other elements in the map. The successor of a node is the node with the smallest key that is larger than the key of the given node. The predecessor of a node is the node with the largest key that is smaller than the key of the given node. All comparisons are done using the generic formal "<" operator for keys.
58.1/3
function Copy (Source : Map) return Map;
58.2/3
Returns a map whose keys and elements are initialized from the corresponding keys and elements of Source.
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procedure Delete_First (Container : in out Map);
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If Container is empty, Delete_First has no effect. Otherwise, the node designated by First (Container) is removed from Container. Delete_First tampers with the cursors of Container.
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procedure Delete_Last (Container : in out Map);
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If Container is empty, Delete_Last has no effect. Otherwise, the node designated by Last (Container) is removed from Container. Delete_Last tampers with the cursors of Container.
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function First_Element (Container : Map) return Element_Type;
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Equivalent to Element (First (Container)).
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function First_Key (Container : Map) return Key_Type;
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Equivalent to Key (First (Container)).
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function Last (Container : Map) return Cursor;
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Returns a cursor that designates the last node in Container. If Container is empty, returns No_Element.
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function Last_Element (Container : Map) return Element_Type;
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Equivalent to Element (Last (Container)).
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function Last_Key (Container : Map) return Key_Type;
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Equivalent to Key (Last (Container)).
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function Previous (Position : Cursor) return Cursor;
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If Position equals No_Element, then Previous returns No_Element. Otherwise, Previous returns a cursor designating the predecessor node of the one designated by Position. If Position designates the first element, then Previous returns No_Element.
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procedure Previous (Position : in out Cursor);
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Equivalent to Position := Previous (Position).
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function Floor (Container : Map;
Key : Key_Type) return Cursor;
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Floor searches for the last node whose key is not greater than Key, using the generic formal "<" operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
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function Ceiling (Container : Map;
Key : Key_Type) return Cursor;
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Ceiling searches for the first node whose key is not less than Key, using the generic formal "<" operator for keys. If such a node is found, a cursor that designates it is returned. Otherwise, No_Element is returned.
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function "<" (Left, Right : Cursor) return Boolean;
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Equivalent to Key (Left) < Key (Right).
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function ">" (Left, Right : Cursor) return Boolean;
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Equivalent to Key (Right) < Key (Left).
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function "<" (Left : Cursor; Right : Key_Type) return Boolean;
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Equivalent to Key (Left) < Right.
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function ">" (Left : Cursor; Right : Key_Type) return Boolean;
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Equivalent to Right < Key (Left).
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function "<" (Left : Key_Type; Right : Cursor) return Boolean;
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Equivalent to Left < Key (Right).
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function ">" (Left : Key_Type; Right : Cursor) return Boolean;
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Equivalent to Key (Right) < Left.
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procedure Reverse_Iterate
(Container : in Map;
Process : not null access procedure (Position : in Cursor));
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Iterates over the nodes in Container as per procedure Iterate, with the difference that the nodes are traversed in predecessor order, starting with the last node.
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function Iterate (Container : in Map)
return Map_Iterator_Interfaces.Reversible_Iterator'Class;
94.2/3
Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the first node and moving the cursor according to the successor relation when used as a forward iterator, and starting with the last node and moving the cursor according to the predecessor relation when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.
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function Iterate (Container : in Map; Start : in Cursor)
return Map_Iterator_Interfaces.Reversible_Iterator'Class;
94.4/3
If Start is not No_Element and does not designate an item in Container, then Program_Error is propagated. If Start is No_Element, then Constraint_Error is propagated. Otherwise, Iterate returns a reversible iterator object (see 5.5.1) that will generate a value for a loop parameter (see 5.5.2) designating each node in Container, starting with the node designated by Start and moving the cursor according to the successor relation when used as a forward iterator, or moving the cursor according to the predecessor relation when used as a reverse iterator. Tampering with the cursors of Container is prohibited while the iterator object exists (in particular, in the sequence_of_statements of the loop_statement whose iterator_specification denotes this object). The iterator object needs finalization.

#### Implementation Advice

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If N is the length of a map, then the worst-case time complexity of the Element, Insert, Include, Replace, Delete, Exclude and Find operations that take a key parameter should be O((log N)**2) or better. The worst-case time complexity of the subprograms that take a cursor parameter should be O(1).

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