Eliminating alr dependency

src/alire-boolean_trees.ads

@@ -0,0 +1,73 @@
+private with Ada.Containers.Indefinite_Holders;
+private with Ada.Containers.Indefinite_Multiway_Trees;
+
+generic
+   type Value     (<>) is private;
+   type Condition (<>) is private;
+   with function Check (C : Condition; V : Value) return Boolean;
+package Alire.Boolean_Trees with Preelaborate is
+
+   --  A package to represent trees of logical expressions
+
+   type Tree is tagged private;
+
+   Empty_Tree : constant Tree;
+
+   --  Tree building
+
+   function Leaf (C : Condition) return Tree;
+   function "+"  (C : Condition) return Tree renames Leaf;
+
+   function "and" (L, R : Tree) return Tree
+     with Pre => L /= Empty_Tree and then R /= Empty_Tree;
+   function "and" (L : Tree; R : Condition) return Tree is (L and Leaf (R));
+   function "and" (L : Condition; R : Tree) return Tree is (Leaf (L) and R);
+   function "and" (L : Condition; R : Condition) return Tree is (Leaf (L) and Leaf (R));
+
+   function "or"  (L, R : Tree) return Tree
+     with Pre => L /= Empty_Tree and then R /= Empty_Tree;
+   function "or"  (L : Tree; R : Condition) return Tree is (L or  Leaf (R));
+   function "or"  (L : Condition; R : Tree) return Tree is (Leaf (L) or R);
+   function "or"  (L : Condition; R : Condition) return Tree is (Leaf (L) or  Leaf (R));
+
+   function "not" (T : Tree) return Tree
+     with Pre => T /= Empty_Tree;
+   function "not" (C : Condition) return Tree is (not Leaf (C));
+
+   --  Tree evaluation
+
+   function Check (T : Tree; V : Value) return Boolean;
+
+   --  Access
+
+   function Is_Empty (T : Tree) return Boolean;
+
+   --  Debugging
+
+   procedure Print_Skeleton (T : Tree);
+
+private
+
+   type Node_Kinds is (Leaf, And_Node, Or_Node, Not_Node);
+
+   package Values is new Ada.Containers.Indefinite_Holders (Value);
+   package Conditions is new Ada.Containers.Indefinite_Holders (Condition);
+
+   type Node (Kind : Node_Kinds) is record
+      case Kind is
+         when Leaf =>
+            Condition : Conditions.Holder;
+         when others =>
+            null;
+      end case;
+   end record;
+
+   package Trees is new Ada.Containers.Indefinite_Multiway_Trees (Node);
+
+   type Tree is new Trees.Tree with null record;
+
+   Empty_Tree : constant Tree := (Trees.Empty_Tree with null record);
+
+   function Is_Empty (T : Tree) return Boolean is (Trees.Is_Empty (Trees.Tree (T)));
+
+end Alire.Boolean_Trees;