I am developping a genereic program which filters data with Ada.
I tried to do that with a list and with a tree.
The program with lists implementation works perfectly.
My probleme is with the tree.
I have different generic packages :
Arbre_Binaire_Recherche_g.ads
generic
TYPE Element IS PRIVATE;
WITH FUNCTION "="(E1,E2 : IN Element) RETURN Boolean;
WITH FUNCTION "<"(E1,E2 : IN Element) RETURN Boolean;
WITH PROCEDURE Liberer_Element(E : IN OUT Element);
WITH FUNCTION Element_To_String(E : IN Element) RETURN String;
package Arbre_Binaire_Recherche_g is
[...]
with function critere(E : in element) return Boolean;
procedure Filtrer(A : in Arbre; B : out Arbre);
private
TYPE Noeud;
TYPE Arbre IS ACCESS Noeud;
TYPE Noeud IS RECORD
Info : Element;
Gauche : Arbre;
Droite : Arbre;
END RECORD;
END Arbre_Binaire_Recherche_g;
This is the filter procedure, with the generic function critere :
Arbre_Binaire_Recherche_g.adb
procedure Filtrer(A : in Arbre ; B : out Arbre) is
begin
if not Est_Vide(A) then
Filtrer(A.Gauche, B);
if critere(A.all.Info) then
Inserer_element(B, A.all.info);
end if;
Filtrer(A.Droite, B);
end if;
end Filtrer;
abr_acteurs.ads
WITH Arbre_Binaire_Recherche_G, Acteurs;
USE Acteurs;
package ABR_acteurs is new Arbre_Binaire_Recherche_G(acteur,"=","<",Liberer_acteur,Acteur_To_String);
There are also acteurs.ads and acteurs.adb but it's not important here.
And then, the client : Tester_ABR_Acteur :
WITH ABR_Acteurs, Acteurs, Ada.Text_Io, Arbre_Binaire_Recherche_G;
use Ada.Text_Io, Abr_Acteurs;
PROCEDURE Tester_ABR_Acteurs is
function Filtrage (Act : Acteurs.Acteur) return Boolean is
begin
return true;
end Filtrage;
procedure Filtrer_acteur is new Arbre_Binaire_Recherche_G.Filtrer(Filtrage);
[...]
But, at compilation, there is the error :
invalid prefix in selected component "Arbre_Binaire_Recherche_G"
At line :
procedure Filtrer_acteur is new Arbre_Binaire_Recherche_G.Filtrer(Filtrage);
In client file.
There is the error, if I do this instanciation.
But if I put my generic critere function with an other generic procedure / function, like this :
Arbre_Binaire_Recherche_g.ads
generic
TYPE Element IS PRIVATE;
WITH FUNCTION "="(E1,E2 : IN Element) RETURN Boolean;
WITH FUNCTION "<"(E1,E2 : IN Element) RETURN Boolean;
WITH PROCEDURE Liberer_Element(E : IN OUT Element);
WITH FUNCTION Element_To_String(E : IN Element) RETURN String;
with function critere(E : in element) return Boolean;
Then I instantiate like this :
abr_acteurs.ads
package ABR_acteurs is new Arbre_Binaire_Recherche_G(acteur,"=","<",Liberer_acteur,Acteur_To_String, Critere_acteur);
There is no error, and everything works correctly!
I can't find out where the problem is !
================================================================
I do exactly the same with my list implementation, with generic function at the end of my generic package, and it works correctly! I don't understand..
Does anyone have an idea?
[Update]
My generic function : with function critere(E : in element) return Boolean; is in the procedure : procedure Filtrer(A : in Arbre; B : out Arbre);, like that :
procedure Filtrer(A : in Arbre ; B : out Arbre) is
begin
if not Est_Vide(A) then
Filtrer_hihi(A.Gauche, B);
Here there is critere(A.all.Info)
if critere(A.all.Info) then
Inserer_element(B, A.all.info);
end if;
Filtrer_hihi(A.Droite, B);
end if;
end Filtrer;
So, it's normal if I instantiated my procedure in this way, because (Refer to 2.)
- That's how I proceeded with my generic list :
package liste_ordonnee_g.ads
with Ada.Unchecked_Deallocation;
generic
type Element is private;
with function "<"(E1, E2 : in Element) return Boolean;
with function "="(E1, E2 : in Element) return Boolean;
with procedure Liberer_Element(E : in out Element);
with function Element_To_String(E : in Element) return String;
package Liste_Ordonnee_G is
type Liste is private;
[...]
generic
with function Critere(E:Element) return Boolean;
function Filtrer(L : Liste) return Liste;
private
type Cellule;
type Lien is access Cellule;
type Cellule is record
Info : Element;
Suiv : Lien;
end record;
type Liste is record
Debut : Lien;
Cardinal : Natural;
end record;
-- procedure de liberation de la memoire occupee par la cellule
procedure Liberer_Cellule is new Ada.Unchecked_Deallocation(Cellule, Lien);
end Liste_Ordonnee_G;
liste_ordonnee_g.adb
function Filtrer(L : Liste) return Liste is
New_Liste : Liste;
Aux :Lien ;
begin
Creer_Liste(New_Liste);
Aux := L.Debut;
while Aux /= null loop
Here there is critere(A.all.Info)
if Critere(Aux.all.Info) then
Inserer(Aux.all.Info, New_Liste);
end if;
Aux := Aux.all.Suiv;
end loop;
return New_Liste;
end Filtrer;
Here, I instantiate my generic package WITHOUT the function critere :
liste_ordonnee_acteurs.ads
with Acteurs, Liste_Ordonnee_G;
use Acteurs;
PACKAGE Liste_Ordonnee_Acteurs IS new Liste_Ordonnee_G(Acteur, "<", "=", Liberer_Acteur, Acteur_To_String);
And in my client file : I instanciate my generic procedure filtrer with the critere :
Test_Liste_Ordonnee_Acteurs.adb
function Filtrage (A : Acteurs.Acteur) return Boolean is
begin
return Acteurs.Annee(A) = 2000;
end Filtrage;
function Filtrer is new Liste_Ordonnee_Acteurs.filtrer(Filtrage);
List implementation works correctly! I don't understand why tree implementation doesn't work :( ..