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-- Programmed by Jedidiah Barber
-- Licensed under the Sunset License v1.0
-- See license.txt for further details
with
Ada.Strings.Unbounded;
private with
Ada.Containers.Ordered_Maps,
Ada.Containers.Vectors,
Ada.Finalization;
generic
type Element_Type is private;
package Kompsos is
type Variable is private;
type Variable_Array is array (Positive range <>) of Variable;
type Term is tagged private;
type Term_Array is array (Positive range <>) of Term;
-- Can also be constructed by supplying an empty array to T
-- or just declaring a Term without initial value.
Null_Term : constant Term;
function "="
(Left, Right : in Term)
return Boolean;
function T
(Item : in Element_Type)
return Term;
function T
(Item : in Variable)
return Term;
function T
(Items : in Term_Array)
return Term;
-- Might include subprograms to retrieve Term contents later?
type World is tagged private;
Empty_World : constant World;
function Fresh
(This : in out World)
return Variable;
function Fresh
(This : in out World;
Name : in String)
return Variable;
function Fresh
(This : in out World;
Name : in Ada.Strings.Unbounded.Unbounded_String)
return Variable;
function Unify
(This : in World;
Left : in Variable;
Right : in Element_Type)
return World;
procedure Unify
(This : in out World;
Left : in Variable;
Right : in Element_Type);
function Unify
(This : in World;
Left, Right : in Variable)
return World;
procedure Unify
(This : in out World;
Left, Right : in Variable);
function Unify
(This : in World;
Left : in Variable;
Right : in Term'Class)
return World;
procedure Unify
(This : in out World;
Left : in Variable;
Right : in Term'Class);
function Unify
(This : in World;
Left, Right : in Term'Class)
return World;
procedure Unify
(This : in out World;
Left, Right : in Term'Class);
function Disjunct
(Left, Right : in World)
return World;
procedure Disjunct
(This : in out World;
Right : in World);
private
package SU renames Ada.Strings.Unbounded;
function "+"
(Item : in String)
return SU.Unbounded_String
renames SU.To_Unbounded_String;
function "-"
(Item : in SU.Unbounded_String)
return String
renames SU.To_String;
-- 2^32 possible variables per World is enough for anybody, right?
type ID_Number is mod 2 ** 32;
type Variable is record
Ident : ID_Number;
Name : SU.Unbounded_String;
end record;
type Term_Kind is (Atom_Term, Var_Term, Pair_Term);
type Term_Component (Kind : Term_Kind) is record
Count : Long_Integer;
case Kind is
when Atom_Term =>
Value : Element_Type;
when Var_Term =>
Refer : Variable;
when Pair_Term =>
Left, Right : Term;
end case;
end record;
type Term_Component_Access is access Term_Component;
type Term is new Ada.Finalization.Controlled with record
Actual : Term_Component_Access;
end record;
overriding procedure Initialize
(This : in out Term);
overriding procedure Adjust
(This : in out Term);
overriding procedure Finalize
(This : in out Term);
Null_Term : constant Term := (Ada.Finalization.Controlled with Actual => null);
package Name_Maps is new Ada.Containers.Ordered_Maps
(Key_Type => ID_Number,
Element_Type => SU.Unbounded_String,
"=" => SU."=");
package Binding_Maps is new Ada.Containers.Ordered_Maps
(Key_Type => ID_Number,
Element_Type => Term);
type State is record
LVars : Name_Maps.Map;
Subst : Binding_Maps.Map;
end record;
Empty_State : constant State :=
(LVars => Name_Maps.Empty_Map,
Subst => Binding_Maps.Empty_Map);
-- obviously this World definition will need revision for delays and generators
-- going to have to turn worlds into a similar sort of reference counted recursive
-- controlled type along the lines of what terms are, in order to make them into generators
package State_Vectors is new Ada.Containers.Vectors
(Index_Type => Positive,
Element_Type => State);
use type State_Vectors.Vector;
type World is tagged record
Possibles : State_Vectors.Vector;
Next_Ident : ID_Number;
end record;
Empty_World : constant World :=
(Possibles => State_Vectors.Empty_Vector & Empty_State,
Next_Ident => 0);
end Kompsos;
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