ada/envs.ads

   1 with Ada.Containers.Hashed_Maps;
   2 with Ada.Strings.Unbounded.Hash;
   3 with Smart_Pointers;
   4 limited with Types;
   5
   6 package Envs is
   7
   8    type Env_Handle is private;
   9
  10    Null_Env_Handle : constant Env_Handle;
  11
  12    function New_Env (Outer : Env_Handle := Null_Env_Handle) return Env_Handle;
  13
  14    -- Set adds an element to the environment E.
  15    procedure Set
  16      (E : Env_Handle;
  17       Key : String;
  18       Elem : Smart_Pointers.Smart_Pointer);
  19
  20    -- Get finds a key in the E env.  If it can't be found it looks
  21    -- in an outer env.  If it runs out of envs, Not Found is raised.
  22    function Get (E : Env_Handle; Key : String) return Smart_Pointers.Smart_Pointer;
  23
  24    Not_Found : exception;
  25
  26    procedure Set_Outer
  27      (E : Env_Handle; Outer_Env : Env_Handle);
  28
  29    -- Sym and Exprs are lists.  Bind Sets Keys in Syms to the corresponding
  30    -- expression in Exprs.  Returns true if all the parameters were bound.
  31    function Bind (Env : Env_Handle; Syms, Exprs : Types.List_Mal_Type)
  32    return Boolean;
  33
  34    function To_String (E : Env_Handle) return String;
  35
  36    Debug : Boolean := False;
  37
  38 private
  39
  40    type Env_Handle is new Smart_Pointers.Smart_Pointer;
  41
  42    Null_Env_Handle : constant Env_Handle :=
  43      Env_Handle (Smart_Pointers.Null_Smart_Pointer);
  44
  45    function Is_Null (E : Env_Handle) return Boolean;
  46
  47    package String_Mal_Hash is new Ada.Containers.Hashed_Maps
  48      (Key_Type        => Ada.Strings.Unbounded.Unbounded_String,
  49       Element_Type    => Smart_Pointers.Smart_Pointer,
  50       Hash            => Ada.Strings.Unbounded.Hash,
  51       Equivalent_Keys => Ada.Strings.Unbounded."=",
  52       "="             => Smart_Pointers."=");
  53
  54    type Env is new Smart_Pointers.Base_Class with record
  55       The_Map : String_Mal_Hash.Map;
  56       Outer_Env : Env_Handle;
  57       Level: Natural;
  58    end record;
  59
  60    type Env_Ptr is access all Env;
  61
  62    function Deref (SP : Env_Handle) return Env_Ptr;
  63
  64 end Envs;