Case statements for conditionals

index/alire-index-alire.ads

@@ -112,7 +112,13 @@ package Alire.Index.Alire is
                            On_Condition
                              (Operating_System = GNU_Linux,
                               Comment ("Long life the penguin")) and
-                         --  Conditions on operating system
+                           --  Conditions on operating system
+
+                           Case_Operating_System_Is
+                             ((GNU_Linux => Comment ("Longerer life to the penguin"),
+                               OSX       => Comment ("Oh shiny!"),
+                               others    => Comment ("Pick your poison"))) and
+                           --  Also as Case-like statements
 
                            On_Condition
                              (Compiler = GNAT_Unknown, -- /= also works

index/alire-index-gnatcoll.ads

@@ -29,15 +29,21 @@ package Alire.Index.GNATCOLL is
                        Private_Properties =>
                          GPR_External ("BUILD", "PROD") and
                          GPR_External ("LIBRARY_TYPE", "static-pic") and
-                         On_Condition
-                           (Operating_System = GNU_Linux,
-                            GPR_External ("GNATCOLL_OS", "unix")) and
-                         On_Condition
-                           (Operating_System = Windows,
-                            GPR_External ("GNATCOLL_OS", "windows")) and
-                         On_Condition
-                           (Operating_System = OSX,
-                            GPR_External ("GNATCOLL_OS", "osx")));
+                         Case_Operating_System_Is
+                           ((GNU_Linux  => GPR_External ("GNATCOLL_OS", "unix"),
+                             OSX        => GPR_External ("GNATCOLL_OS", "osx"),
+                             Windows    => GPR_External ("GNATCOLL_OS", "windows"),
+                             OS_Unknown => GPR_External ("GNATCOLL_OS", "ERROR")))
+--                           On_Condition
+--                             (Operating_System = GNU_Linux,
+--                              GPR_External ("GNATCOLL_OS", "unix")) and
+--                           On_Condition
+--                             (Operating_System = Windows,
+--                              GPR_External ("GNATCOLL_OS", "windows")) and
+--                           On_Condition
+--                             (Operating_System = OSX,
+                       --                              GPR_External ("GNATCOLL_OS", "osx"))
+                      );
 
    package Slim is
 

src/alire-conditional_values.adb

@@ -149,4 +149,26 @@ package body Alire.Conditional_Values is
       end if;
    end Iterate_Children;
 
+   ---------------------
+   -- Case_Statements --
+   ---------------------
+
+   package body Case_Statements is
+
+      function Case_Is (Arr : Arrays) return Conditional_Value is
+         Case_Is : Conditional_Value := Arr (Arr'Last);
+         --  Since we get the whole array,
+         --    by exhaustion at worst the last must be true
+      begin
+         for I in reverse Arr'First .. Enum'Pred (Arr'Last) loop
+            Case_Is := New_Conditional (If_X   => Requisite_Equal (I),
+                                        Then_X => Arr (I),
+                                        Else_X => Case_Is);
+         end loop;
+
+         return Case_Is;
+      end Case_Is;
+
+   end Case_Statements;
+
 end Alire.Conditional_Values;

src/alire-conditional_values.ads

@@ -71,6 +71,18 @@ package Alire.Conditional_Values with Preelaborate is
    function False_Value (This : Conditional_Value) return Conditional_Value
      with Pre => This.Kind = Condition;
 
+   generic
+      type Enum is (<>);
+      with function Requisite_Equal (V : Enum) return Requisites.Tree;
+      --  Function which creates an equality requisite on V
+   package Case_Statements is
+
+      type Arrays is array (Enum) of Conditional_Value;
+
+      function Case_Is (Arr : Arrays) return Conditional_Value;
+
+   end Case_Statements;
+
 private
 
    type Inner_Node is abstract tagged null record;

src/alire-index.ads

@@ -256,6 +256,16 @@ package Alire.Index is
                           When_False : Release_Properties := No_Properties) 
                           return       Release_Properties renames Conditional.For_Properties.New_Conditional;
    --  Conditional properties
+   
+   function Case_Compiler_Is (Arr : Requisites.Platform.Compiler_Cases.Arrays) 
+                              return Release_Properties
+                              renames Requisites.Platform.Compiler_Cases.Case_Is;
+   --  Case on compile values
+   --  TODO: Cases on other enum properties (platform, etc)
+   
+   function Case_Operating_System_Is (Arr : Requisites.Platform.Op_System_Cases.Arrays) 
+                                      return Release_Properties
+                                      renames Requisites.Platform.Op_System_Cases.Case_Is;
 
    --  Attributes (named pairs of label-value)
    --  We need them as Properties.Vector (inside conditionals) but also as

src/alire-requisites-comparables.ads

@@ -45,6 +45,9 @@ package Alire.Requisites.Comparables with Preelaborate is
    function ">=" (L : Comparable; R : Value) return Tree;
    function ">=" (L : Value; R : Comparable) return Tree;
 
+   function Is_Equal_To (V : Value) return Tree;
+   --  Non-operator function useful elsewhere for case statements
+
 private
 
    type Kinds is (Base, Equality, Ordering);
@@ -93,4 +96,7 @@ private
 
    function "<" (L : Value; R : Comparable) return Tree is (R >= L);
 
+   function Is_Equal_To (V : Value) return Tree is
+      (Trees.Leaf (Comparable'(Kind => Equality, Value => V)));
+
 end Alire.Requisites.Comparables;

src/alire-requisites-platform.ads

@@ -1,3 +1,4 @@
+with Alire.Conditional;
 with Alire.Platforms;
 with Alire.Properties.Platform;
 
@@ -17,6 +18,9 @@ package Alire.Requisites.Platform with Preelaborate is
       PrPl.Operating_Systems.Element,
       "OS");
 
+   package Op_System_Cases is new Conditional.For_Properties.Case_Statements
+     (Ps.Operating_Systems, Op_Systems.Is_Equal_To);
+
    package Compilers is new Comparables
      (Ps.Compilers, Ps."<", Ps.Compilers'Image,
       PrPl.Compilers.Property,
@@ -29,6 +33,9 @@ package Alire.Requisites.Platform with Preelaborate is
    function Compiler_Is_Native return Tree is
      (Compiler >= GNAT_FSF_Old and Compiler < GNAT_GPL_Old);
 
+   package Compiler_Cases is new Conditional.For_Properties.Case_Statements
+     (Ps.Compilers, Compilers.Is_Equal_To);
+
    package Distributions is new Comparables
      (Ps.Distributions, Ps."<", Ps.Distributions'Image,
       PrPl.Distributions.Property,