with H2.Ascii; with H2.Pool; -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx -- TODO: delete these after debugging with Ada.Unchecked_Deallocation; -- for h2scm c interface. TOOD: move it to a separate file with Interfaces.C; with ada.text_io; with ada.wide_text_io; with ada.exceptions; -- TODO: delete above after debugging -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx package body H2.Scheme is package body Token is separate; package Ch is new Ascii(Object_Character); DEBUG_GC: Standard.Boolean := Standard.False; ----------------------------------------------------------------------------- -- PRIMITIVE DEFINITIONS ----------------------------------------------------------------------------- -- I define these constants to word around the limitation of not being -- able to use a string literal when the string type is a generic parameter. -- Why doesn't ada include a formal type support for different character -- and string types? This limitation is caused because the generic -- type I chosed to use to represent a character type is a discrete type. Label_And: constant Object_Character_Array := (Ch.LC_A, Ch.LC_N, Ch.LC_D); -- "and" Label_Begin: constant Object_Character_Array := (Ch.LC_B, Ch.LC_E, Ch.LC_G, Ch.LC_I, Ch.LC_N); -- "begin" Label_Case: constant Object_Character_Array := (Ch.LC_C, Ch.LC_A, Ch.LC_S, Ch.LC_E); -- "case" Label_Cond: constant Object_Character_Array := (Ch.LC_C, Ch.LC_O, Ch.LC_N, Ch.LC_D); -- "cond" Label_Define: constant Object_Character_Array := (Ch.LC_D, Ch.LC_E, Ch.LC_F, Ch.LC_I, Ch.LC_N, Ch.LC_E); -- "define" Label_Do: constant Object_Character_Array := (Ch.LC_D, Ch.LC_O); -- "do" Label_If: constant Object_Character_Array := (Ch.LC_I, Ch.LC_F); -- "if" Label_Lambda: constant Object_Character_Array := (Ch.LC_L, Ch.LC_A, Ch.LC_M, Ch.LC_B, Ch.LC_D, Ch.LC_A); -- "lambda" Label_Let: constant Object_Character_Array := (Ch.LC_L, Ch.LC_E, Ch.LC_T); -- "let" Label_Letast: constant Object_Character_Array := (Ch.LC_L, Ch.LC_E, Ch.LC_T, Ch.Asterisk); -- "let*" Label_Letrec: constant Object_Character_Array := (Ch.LC_L, Ch.LC_E, Ch.LC_T, Ch.LC_R, Ch.LC_E, Ch.LC_C); -- "letrec" Label_Or: constant Object_Character_Array := (Ch.LC_O, Ch.LC_R); -- "or" Label_Quasiquote: constant Object_Character_Array := (Ch.LC_Q, Ch.LC_U, Ch.LC_A, Ch.LC_S, Ch.LC_I, Ch.LC_Q, Ch.LC_U, Ch.LC_O, Ch.LC_T, Ch.LC_E); -- "quasiquote" Label_Quote: constant Object_Character_Array := (Ch.LC_Q, Ch.LC_U, Ch.LC_O, Ch.LC_T, Ch.LC_E); -- "quote" Label_Set: constant Object_Character_Array := (Ch.LC_S, Ch.LC_E, Ch.LC_T, Ch.Exclamation); -- "set!" Label_Callcc: constant Object_Character_Array := (Ch.LC_C, Ch.LC_A, Ch.LC_L, Ch.LC_L, Ch.Minus_Sign, Ch.LC_W, Ch.LC_I, Ch.LC_T, Ch.LC_H, Ch.Minus_Sign, Ch.LC_C, Ch.LC_U, Ch.LC_R, Ch.LC_R, Ch.LC_E, Ch.LC_N, Ch.LC_T, Ch.Minus_Sign, Ch.LC_C, Ch.LC_O, Ch.LC_N, Ch.LC_T, Ch.LC_I, Ch.LC_N, Ch.LC_U, Ch.LC_A, Ch.LC_T, Ch.LC_I, Ch.LC_O, Ch.LC_N); -- "call-with-current-continuation" Label_Car: constant Object_Character_Array := (Ch.LC_C, Ch.LC_A, Ch.LC_R); -- "car" Label_Cdr: constant Object_Character_Array := (Ch.LC_C, Ch.LC_D, Ch.LC_R); -- "cdr" Label_Cons: constant Object_Character_Array := (Ch.LC_C, Ch.LC_O, Ch.LC_N, Ch.LC_S); -- "cons" Label_EQ: constant Object_Character_Array := (1 => Ch.Equal_Sign); -- "=" Label_GE: constant Object_Character_Array := (Ch.Greater_Than_Sign, Ch.Equal_Sign); -- ">=" Label_GT: constant Object_Character_Array := (1 => Ch.Greater_Than_Sign); -- ">" Label_LE: constant Object_Character_Array := (Ch.Less_Than_Sign, Ch.Equal_Sign); -- "<=" Label_LT: constant Object_Character_Array := (1 => Ch.Less_Than_Sign); -- "<" Label_Minus: constant Object_Character_Array := (1 => Ch.Minus_Sign); -- "-" Label_Multiply: constant Object_Character_Array := (1 => Ch.Asterisk); -- "*" Label_Plus: constant Object_Character_Array := (1 => Ch.Plus_Sign); -- "+" Label_Quotient: constant Object_Character_Array := (Ch.LC_Q, Ch.LC_U, Ch.LC_O, Ch.LC_T, Ch.LC_I, Ch.LC_E, Ch.LC_N, Ch.LC_T); -- "quotient" Label_Remainder: constant Object_Character_Array := (Ch.LC_R, Ch.LC_E, Ch.LC_M, Ch.LC_A, Ch.LC_I, Ch.LC_N, Ch.LC_D, Ch.LC_E, Ch.LC_R); -- "remainder" Label_Setcar: constant Object_Character_Array := (Ch.LC_S, Ch.LC_E, Ch.LC_T, Ch.Minus_Sign, Ch.LC_C, Ch.LC_A, Ch.LC_R, Ch.Exclamation); -- "set-car!" Label_Setcdr: constant Object_Character_Array := (Ch.LC_S, Ch.LC_E, Ch.LC_T, Ch.Minus_Sign, Ch.LC_C, Ch.LC_D, Ch.LC_R, Ch.Exclamation); -- "set-cdr!" Label_Newline: constant Object_Character_Array := (Ch.LC_N, Ch.LC_E, Ch.LC_W, Ch.LC_L, Ch.LC_I, Ch.LC_N, Ch.LC_E); -- "newline" Label_Space: constant Object_Character_Array := (Ch.LC_S, Ch.LC_P, Ch.LC_A, Ch.LC_C, Ch.LC_E); -- "space" Label_Arrow: constant Object_Character_Array := (Ch.Equal_Sign, Ch.Greater_Than_Sign); -- "=>" ----------------------------------------------------------------------------- -- EXCEPTIONS ----------------------------------------------------------------------------- Allocation_Error: exception; Size_Error: exception; Syntax_Error: exception; Evaluation_Error: exception; Internal_Error: exception; IO_Error: exception; Stream_End_Error: exception; ----------------------------------------------------------------------------- -- INTERNALLY-USED TYPES ----------------------------------------------------------------------------- type Heap_Element_Pointer is access all Heap_Element; for Heap_Element_Pointer'Size use Object_Pointer_Bits; -- ensure that it can be overlaid by an ObjectPointer type Thin_Heap_Element_Array is array (1 .. Heap_Size'Last) of Heap_Element; type Thin_Heap_Element_Array_Pointer is access all Thin_Heap_Element_Array; for Thin_Heap_Element_Array_Pointer'Size use Object_Pointer_Bits; subtype Moved_Object_Record is Object_Record (Moved_Object, 0); type Opcode_Type is ( Opcode_Exit, Opcode_Evaluate_Result, Opcode_Evaluate_Object, Opcode_Finish_And_Syntax, Opcode_Finish_Or_Syntax, Opcode_Define_Finish, Opcode_Grouped_Call, -- (begin ...), closure apply, let body Opcode_If_Finish, Opcode_Let_Binding, Opcode_Letast_Binding, Opcode_Letast_Binding_Finish, Opcode_Let_Evaluation, Opcode_Let_Finish, Opcode_Procedure_Call, Opcode_Procedure_Call_Finish, Opcode_Set_Finish, Opcode_Apply, Opcode_Read_Object, Opcode_Read_List, Opcode_Read_List_Cdr, Opcode_Read_List_End, Opcode_Close_List, Opcode_Close_Quote, Opcode_Close_Quote_In_List ); for Opcode_Type'Size use Object_Integer'Size; ----------------------------------------------------------------------------- -- COMMON OBJECTS ----------------------------------------------------------------------------- Cons_Object_Size: constant Pointer_Object_Size := 2; Cons_Car_Index: constant Pointer_Object_Size := 1; Cons_Cdr_Index: constant Pointer_Object_Size := 2; Frame_Object_Size: constant Pointer_Object_Size := 6; Frame_Parent_Index: constant Pointer_Object_Size := 1; Frame_Opcode_Index: constant Pointer_Object_Size := 2; Frame_Operand_Index: constant Pointer_Object_Size := 3; Frame_Environment_Index: constant Pointer_Object_Size := 4; Frame_Intermediate_Index: constant Pointer_Object_Size := 5; Frame_Result_Index: constant Pointer_Object_Size := 6; Procedure_Object_Size: constant Pointer_Object_Size := 1; Procedure_Opcode_Index: constant Pointer_Object_Size := 1; Closure_Object_Size: constant Pointer_Object_Size := 2; Closure_Code_Index: constant Pointer_Object_Size := 1; Closure_Environment_Index: constant Pointer_Object_Size := 2; Continuation_Object_Size: constant Pointer_Object_Size := 1; Continuation_Frame_Index: constant Pointer_Object_Size := 1; procedure Set_New_Location (Object: in Object_Pointer; Ptr: in Heap_Element_Pointer); procedure Set_New_Location (Object: in Object_Pointer; Ptr: in Object_Pointer); pragma Inline (Set_New_Location); function Get_New_Location (Object: in Object_Pointer) return Object_Pointer; pragma Inline (Get_New_Location); ----------------------------------------------------------------------------- -- FOR DEBUGGING. REMVOE THESE LATER ----------------------------------------------------------------------------- procedure Output_Character_Array (Source: in Object_Character_Array) is -- for debugging only. begin for I in Source'Range loop --Ada.Text_IO.Put (Source(I)); -- TODO: note this is a hack for quick printing. Ada.Text_IO.Put (Standard.Character'Val(Object_Character'Pos(Source(I)))); end loop; end Output_Character_Array; ----------------------------------------------------------------------------- -- POINTER AND DATA CONVERSION ----------------------------------------------------------------------------- function Get_Pointer_Type (Pointer: in Object_Pointer) return Object_Pointer_Type is pragma Inline (Get_Pointer_Type); Word: Object_Word; for Word'Address use Pointer'Address; begin return Object_Pointer_Type(Word and Object_Word(Object_Pointer_Type_Mask)); end Get_Pointer_Type; function Is_Pointer (Pointer: in Object_Pointer) return Standard.Boolean is begin return Get_Pointer_Type(Pointer) = Object_Pointer_Type_Pointer; end Is_Pointer; function Is_Special_Pointer (Pointer: in Object_Pointer) return Standard.Boolean is begin -- though sepcial, these 3 pointers gets true for Is_Pointer. return Pointer = Nil_Pointer or else Pointer = True_Pointer or else Pointer = False_Pointer; end Is_Special_Pointer; function Is_Normal_Pointer (Pointer: in Object_Pointer) return Standard.Boolean is begin return Is_Pointer(Pointer) and then not Is_Special_Pointer(Pointer); end Is_Normal_Pointer; function Is_Integer (Pointer: in Object_Pointer) return Standard.Boolean is begin return Get_Pointer_Type(Pointer) = Object_Pointer_Type_Integer; end Is_Integer; function Is_Character (Pointer: in Object_Pointer) return Standard.Boolean is begin return Get_Pointer_Type(Pointer) = Object_Pointer_Type_Character; end Is_Character; function Is_Byte (Pointer: in Object_Pointer) return Standard.Boolean is begin return Get_Pointer_Type(Pointer) = Object_Pointer_Type_Byte; end Is_Byte; function Integer_To_Pointer (Int: in Object_Integer) return Object_Pointer is Pointer: Object_Pointer; Word: Object_Word; for Word'Address use Pointer'Address; begin if Int < 0 then -- change the sign of a negative number. -- '-Int' may violate the range of Object_Integer -- if it is Object_Integer'First. So I add 1 to 'Int' -- first to make it fall between Object_Integer'First + 1 -- .. 0 and typecast it with an extra increment. --Word := Object_Word (-(Int + 1)) + 1; -- Let me use Object_Signed_Word instead of the trick shown above Word := Object_Word(-Object_Signed_Word(Int)); -- shift the number to the left by 2 and -- set the highest bit on by force. Word := (Word * (2 ** Object_Pointer_Type_Bits)) or Object_Word(Object_Pointer_Type_Integer) or (2 ** (Word'Size - 1)); else Word := Object_Word(Int); -- Shift 'Word' to the left by 2 and set the integer mark. Word := (Word * (2 ** Object_Pointer_Type_Bits)) or Object_Word(Object_Pointer_Type_Integer); end if; --return Object_Label_To_Object_Pointer (Word); return Pointer; end Integer_To_Pointer; function Character_To_Pointer (Char: in Object_Character) return Object_Pointer is Pointer: Object_Pointer; Word: Object_Word; for Word'Address use Pointer'Address; begin -- Note: Object_Character may get defined to Wide_Wide_Character. -- and Wide_Wide_Character'Last is #16#7FFFFFFF#. Such a large value -- may get lost when it's shifted left by 2 if Object_Word is 32 bits long -- or short. In reality, the last Unicode code point assigned is far -- less than #16#7FFFFFFF# as of this writing. So I should not be -- worried about it for the time being. Word := Object_Character'Pos(Char); Word := (Word * (2 ** Object_Pointer_Type_Bits)) or Object_Word(Object_Pointer_Type_Character); --return Object_Label_To_Object_Pointer (Word); return Pointer; end Character_To_Pointer; function Byte_To_Pointer (Byte: in Object_Byte) return Object_Pointer is Pointer: Object_Pointer; Word: Object_Word; for Word'Address use Pointer'Address; begin Word := Object_Word(Byte); Word := (Word * (2 ** Object_Pointer_Type_Bits)) or Object_Word(Object_Pointer_Type_Byte); return Pointer; end Byte_To_Pointer; function Pointer_To_Word is new Ada.Unchecked_Conversion (Object_Pointer, Object_Word); --function Pointer_To_Word (Pointer: in Object_Pointer) return Object_Word is -- pragma Inline (Pointer_To_Word); -- Word: Object_Word; -- for Word'Address use Pointer'Address; --begin -- return Word; --end Pointer_To_Word; function Pointer_To_Integer (Pointer: in Object_Pointer) return Object_Integer is Word: Object_Word := Pointer_To_Word (Pointer); begin if (Word and (2 ** (Word'Size - 1))) /= 0 then -- if the highest bit is set, it's a negative number -- originally. strip it off and shift 'Word' to the right by 2. return Object_Integer (-Object_Signed_Word (Word and not (2 ** (Word'Size - 1))) / (2 ** Object_Pointer_Type_Bits)); else -- shift Word to the right by Object_Pointer_Type_Bits. return Object_Integer (Word / (2 ** Object_Pointer_Type_Bits)); end if; end Pointer_To_Integer; function Pointer_To_Character (Pointer: in Object_Pointer) return Object_Character is Word: Object_Word := Pointer_To_Word (Pointer); begin return Object_Character'Val(Word / (2 ** Object_Pointer_Type_Bits)); end Pointer_To_Character; function Pointer_To_Byte (Pointer: in Object_Pointer) return Object_Byte is Word: Object_Word := Pointer_To_Word (Pointer); begin return Object_Byte(Word / (2 ** Object_Pointer_Type_Bits)); end Pointer_To_Byte; -- TODO: delete this procedure procedure Print_Object_Pointer (Msg: in Standard.String; Source: in Object_Pointer) is W: Object_Word; for W'Address use Source'Address; Ptr_Type: Object_Pointer_Type; begin Ptr_Type := Get_Pointer_Type(Source); if Ptr_Type = Object_Pointer_Type_Character then Ada.Text_IO.Put_Line (Msg & Object_Character'Image(Pointer_To_Character(Source))); elsif Ptr_Type = Object_Pointer_Type_Integer then Ada.Text_IO.Put_Line (Msg & Object_Integer'Image(Pointer_To_Integer(Source))); elsif Is_Special_Pointer(Source) then Ada.Text_IO.Put_Line (Msg & " at " & Object_Word'Image(W)); elsif Source.Kind = Character_Object then Ada.Text_IO.Put (Msg & " at " & Object_Word'Image(W) & " at " & Object_Kind'Image(Source.Kind) & " size " & Object_Size'Image(Source.Size) & " - "); if Source.Kind = Moved_Object then Output_Character_Array (Get_New_Location(Source).Character_Slot); else Output_Character_Array (Source.Character_Slot); end if; else Ada.Text_IO.Put_Line (Msg & " at " & Object_Word'Image(W) & " kind: " & Object_Kind'Image(Source.Kind) & " size: " & Object_Size'Image(Source.Size) & " tag: " & Object_Tag'Image(Source.Tag)); end if; end Print_Object_Pointer; function String_To_Integer_Pointer (Source: in Object_Character_Array) return Object_Pointer is V: Object_Integer := 0; Negative: Standard.Boolean := False; First: Object_Size; begin -- TODO: BIGNUM, RANGE CHECK, ETC pragma Assert (Source'Length > 0); First := Source'First; if Source(First) = Ch.Minus_Sign then First := First + 1; Negative := Standard.True; elsif Source(First) = Ch.Plus_Sign then First := First + 1; end if; for I in First .. Source'Last loop V := V * 10 + Object_Character'Pos(Source(I)) - Object_Character'Pos(Ch.Zero); end loop; if Negative then V := -V; end if; return Integer_To_Pointer(V); end String_To_Integer_Pointer; ----------------------------------------------------------------------------- -- MORE CONVERSIONS ----------------------------------------------------------------------------- --function Pointer_To_Opcode (Pointer: in Object_Pointer) return Opcode_Type renames Pointer_To_Integer; --function Opcode_To_Pointer (Opcode: in Opcode_Type) return Object_Pointer renames Integer_To_Pointer; function Pointer_To_Opcode (Pointer: in Object_Pointer) return Opcode_Type is pragma Inline (Pointer_To_Opcode); begin return Opcode_Type'Val(Pointer_To_Integer(Pointer)); end Pointer_To_Opcode; function Opcode_To_Pointer (Opcode: in Opcode_Type) return Object_Pointer is pragma Inline (Opcode_To_Pointer); begin return Integer_To_Pointer(Opcode_Type'Pos(Opcode)); end Opcode_To_Pointer; function Token_To_Pointer (Interp: access Interpreter_Record; Token: in Token_Record) return Object_Pointer is begin case Token.Kind is when Integer_Token => -- TODO: bignum return String_To_Integer_Pointer(Token.Value.Ptr.all(1..Token.Value.Last)); when Character_Token => pragma Assert (Token.Value.Last = 1); return Character_To_Pointer(Token.Value.Ptr.all(1)); when String_Token => return Make_String (Interp, Token.Value.Ptr.all(1..Token.Value.Last)); when Identifier_Token => return Make_Symbol (Interp, Token.Value.Ptr.all(1..Token.Value.Last)); when True_Token => return True_Pointer; when False_Token => return False_Pointer; when others => return null; end case; end Token_To_Pointer; ----------------------------------------------------------------------------- -- MEMORY MANAGEMENT ----------------------------------------------------------------------------- -- (define x ()) -- (define x #()) -- (define x $()) -- (define x #( -- (#a . 10) ; a is a synbol -- (b . 20) ; b is a variable. resolve b at the eval-time and use it. -- ("c" . 30) ; "c" is a string -- ) -- ) -- (clone x y) -- deep copy -- (define y x) -- reference assignment -- (set! x.a 20) -- syntaic sugar -- (set! (get x #a) 20) -- (define x (make-hash)) -- I wanted to reuse the Size field to store the pointer to -- the new location. GCC-GNAT 3.2.3 suffered from various constraint -- check errors. So i gave up on this procedure. -------------------------------------------------------------------- --procedure Set_New_Location (Object: in Object_Pointer; Ptr: in Heap_Element_Pointer) is --New_Addr: Heap_Element_Pointer; --for New_Addr'Address use Object.Size'Address; --pragma Import (Ada, New_Addr); --begin --New_Addr := Ptr; --end Set_New_Location; --function Get_New_Location (Object: in Object_Pointer) return Object_Pointer is --New_Ptr: Object_Pointer; --for New_Ptr'Address use Object.Size'Address; --pragma Import (Ada, New_Ptr); --begin --return New_Ptr; --end; -- Instead, I created a new object kind that indicates a moved object. -- The original object is replaced by this special object. this special -- object takes up the smallest space that a valid object can take. So -- it is safe to overlay it on any normal objects. procedure Set_New_Location (Object: in Object_Pointer; Ptr: in Heap_Element_Pointer) is Moved_Object: Moved_Object_Record; for Moved_Object'Address use Object.all'Address; -- pramga Import must not be specified here as I'm counting -- on the default initialization of Moved_Object to overwrite -- the Kind discriminant in particular. --pragma Import (Ada, Moved_Object); -- this must not be used. function To_Object_Pointer is new Ada.Unchecked_Conversion (Heap_Element_Pointer, Object_Pointer); begin Moved_Object.New_Pointer := To_Object_Pointer (Ptr); end Set_New_Location; procedure Set_New_Location (Object: in Object_Pointer; Ptr: in Object_Pointer) is Moved_Object: Moved_Object_Record; for Moved_Object'Address use Object.all'Address; --pragma Import (Ada, Moved_Object); -- this must not be used. begin Moved_Object.New_Pointer := Ptr; end Set_New_Location; function Get_New_Location (Object: in Object_Pointer) return Object_Pointer is begin return Object.New_Pointer; end Get_New_Location; function Verify_Pointer (Source: in Object_Pointer) return Object_Pointer is pragma Inline (Verify_Pointer); begin if not Is_Normal_Pointer(Source) or else Source.Kind /= Moved_Object then return Source; else return Get_New_Location(Source); end if; end Verify_Pointer; function Allocate_Bytes_In_Heap (Heap: access Heap_Record; Heap_Bytes: in Heap_Size) return Heap_Element_Pointer is Avail: Heap_Size; Result: Heap_Element_Pointer; Real_Bytes: Heap_Size := Heap_Bytes; begin if Real_Bytes < Moved_Object_Record'Max_Size_In_Storage_Elements then -- Guarantee the minimum object size to be greater than or -- equal to the size of a moved object for GC to work. Real_Bytes := Moved_Object_Record'Max_Size_In_Storage_Elements; -- Note: Extra attention must be paid when calculating the -- actual bytes allocated for an object. Scan_New_Heap() also -- makes similar adjustment to skip actual allocated bytes. end if; Avail := Heap.Size - Heap.Bound; if Real_Bytes > Avail then return null; end if; Result := Heap.Space(Heap.Bound + 1)'Unchecked_Access; Heap.Bound := Heap.Bound + Real_Bytes; return Result; end Allocate_Bytes_In_Heap; function Get_Heap_Number (Interp: access Interpreter_Record; Source: in Object_Pointer) return Heap_Number is -- for debugging SW: Object_Word; for SW'Address use Source'Address; H1: Heap_Element_Pointer := Interp.Heap(0).Space(1)'Unchecked_Access; H2: Heap_Element_Pointer := Interp.Heap(1).Space(1)'Unchecked_Access; HW1: Object_Word; for HW1'Address use H1'Address; HW2: Object_Word; for HW2'Address use H2'Address; begin if SW >= HW1 and then SW < HW1 + Object_Word(Interp.Heap(0).Size) then return 0; end if; if SW >= HW2 and then SW < HW2 + Object_Word(Interp.Heap(1).Size) then return 1; end if; if Source = Nil_Pointer then ada.text_io.put_line ("HEAP SOURCE IS NIL"); return 0; end if; raise Internal_Error; end Get_Heap_Number; procedure Copy_Object (Source: in Object_Pointer; Target: in out Heap_Element_Pointer) is pragma Inline (Copy_Object); subtype Target_Object_Record is Object_Record (Source.Kind, Source.Size); type Target_Object_Pointer is access all Target_Object_Record; Target_Object: Target_Object_Pointer; for Target_Object'Address use Target'Address; pragma Import (Ada, Target_Object); begin -- This procedure should work. but gnat 4.3.2 on whiite(ppc32,wii) -- produced erroneous code when it was called from Move_One_Object(). -- Target_Object_Record'Size, Target_Object.all'Size, and -- Target_Object_Record'Max_Size_In_Stroage_Elements were not -- always correct. For example, for a character object containing -- the string "lambda", Target_Object.all'Size returned 72 while -- it's supposed to be 96. Use Copy_Object_With_Size() below instead. Target_Object.all := Source.all; pragma Assert (Source.all'Size = Target_Object.all'Size); end Copy_Object; procedure Copy_Object_With_Size (Source: in Object_Pointer; Target: in Heap_Element_Pointer; Bytes: in Heap_Size) is pragma Inline (Copy_Object_With_Size); pragma Assert (Bytes > 0); -- This procedure uses a more crude type for copying objects. -- It's the result of an effort to work around some compiler -- issues mentioned above. -- The work around, however, still didn't work well with gnat-3.15p. -- The overlaying(thus overlaid) pointer is initialized to null -- despite pragma Import. --Tgt: Thin_Heap_Element_Array_Pointer; --for Tgt'Address use Target'Address; --pragma Import (Ada, Tgt); --Src: Thin_Heap_Element_Array_Pointer; --for Src'Address use Source'Address; --pragma Import (Ada, Src); -- So let me turn to unchecked conversion instead. function Conv1 is new Ada.Unchecked_Conversion (Object_Pointer, Thin_Heap_Element_Array_Pointer); function Conv2 is new Ada.Unchecked_Conversion (Heap_Element_Pointer, Thin_Heap_Element_Array_Pointer); Src: Thin_Heap_Element_Array_Pointer := Conv1(Source); Tgt: Thin_Heap_Element_Array_Pointer := Conv2(Target); begin Tgt(Tgt'First .. Tgt'First + Bytes - 1) := Src(Src'First .. Src'First + Bytes - 1); end Copy_Object_With_Size; procedure Collect_Garbage (Interp: in out Interpreter_Record) is Last_Pos: Heap_Size; New_Heap: Heap_Number; Original_Symbol_Table: Object_Pointer; --function To_Object_Pointer is new Ada.Unchecked_Conversion (Heap_Element_Pointer, Object_Pointer); function Move_One_Object (Source: in Object_Pointer) return Object_Pointer is begin pragma Assert (Is_Normal_Pointer(Source)); if Source.Kind = Moved_Object then -- the object has moved to the new heap. -- the size field has been updated to the new object -- in the 'else' block below. i can simply return it -- without further migration. return Get_New_Location (Source); else declare Bytes: Heap_Size; -- This variable holds the allocation result Ptr: Heap_Element_Pointer; -- Create an overlay for type conversion New_Object: Object_Pointer; for New_Object'Address use Ptr'Address; pragma Import (Ada, New_Object); begin -- Target_Object_Record'Max_Size_In_Storage_Elements gave -- some erroneous values when compiled with GNAT 4.3.2 on -- WII(ppc) Debian. --Bytes := Target_Object_Record'Max_Size_In_Storage_Elements; Bytes := Source.all'Size / System.Storage_Unit; -- Allocate space in the new heap Ptr := Allocate_Bytes_In_Heap(Interp.Heap(New_Heap), Bytes); -- Allocation here must not fail because -- I'm allocating the new space in a new heap for -- moving an existing object in the current heap. -- It must not fail, assuming the new heap is as large -- as the old heap, and garbage collection doesn't -- allocate more objects than in the old heap. pragma Assert (Ptr /= null); -- This minimum size adjustment is not needed when copying -- an object as it's ok to have garbage in the trailing space. -- See Allocate_Bytes_In_Heap() and Scan_New_Heap() for more info. --if Bytes < Moved_Object_Record'Max_Size_In_Storage_Elements then -- Bytes := Moved_Object_Record'Max_Size_In_Storage_Elements; --end if; -- Copy the payload to the new object --Copy_Object (Object, Ptr); -- not reliable with some compilers Copy_Object_With_Size (Source, Ptr, Bytes); -- use this instead pragma Assert (Source.all'Size = New_Object.all'Size); pragma Assert (Bytes = New_Object.all'Size / System.Storage_Unit); -- Let the size field of the old object point to the -- new object allocated in the new heap. It is returned -- in the 'if' block at the beginning of this function -- if the object is marked with FLAG_MOVED; Set_New_Location (Source, Ptr); -- Return the new object return New_Object; end; end if; end Move_One_Object; function Scan_New_Heap (Start_Position: in Heap_Size) return Heap_Size is Ptr: Heap_Element_Pointer; Position: Heap_Size := Start_Position; begin --Ada.Text_IO.Put_Line ("Start Scanning New Heap from " & Heap_Size'Image(Start_Position) & " Bound: " & Heap_Size'Image (Interp.Heap(New_Heap).Bound)); while Position <= Interp.Heap(New_Heap).Bound loop --Ada.Text_IO.Put_Line (">>> Scanning New Heap from " & Heap_Size'Image (Position) & " Bound: " & Heap_Size'Image (Interp.Heap(New_Heap).Bound)); Ptr := Interp.Heap(New_Heap).Space(Position)'Unchecked_Access; declare -- There is a overlaid pointer initialization problem despite -- "pragma Import()" in gnat-3.15p. --Object: Object_Pointer; --for Object'Address use Ptr'Address; --pragma Import (Ada, Object); -- So let me turn to unchecked conversion. function Conv1 is new Ada.Unchecked_Conversion (Heap_Element_Pointer, Object_Pointer); Object: Object_Pointer := Conv1(Ptr); --subtype Target_Object_Record is Object_Record (Object.Kind, Object.Size); Bytes: Heap_Size; begin --Bytes := Target_Object_Record'Max_Size_In_Storage_Elements; Bytes := Object.all'Size / System.Storage_Unit; if Bytes < Moved_Object_Record'Max_Size_In_Storage_Elements then -- Allocate_Bytes_In_Heap() guarantee the minimum object size. -- The size must be guaranteed here when scanning a heap. Bytes := Moved_Object_Record'Max_Size_In_Storage_Elements; end if; if Object.Kind = Pointer_Object then --Ada.Text_IO.Put_Line (">>> Scanning Obj " & Object_Kind'Image(Object.Kind) & " Size: " & Object_Size'Image(Object.Size) & " At " & Object_Word'Image(Pointer_To_Word(Object)) & " Bytes " & Heap_Size'Image(Bytes)); --Print_Object_Pointer (">>> Scanning :", Object); for i in Object.Pointer_Slot'Range loop if Is_Normal_Pointer(Object.Pointer_Slot(i)) then Object.Pointer_Slot(i) := Move_One_Object(Object.Pointer_Slot(i)); end if; end loop; end if; Position := Position + Bytes; end; end loop; return Position; end Scan_New_Heap; procedure Compact_Symbol_Table is Pred: Object_Pointer; Cons: Object_Pointer; Car: Object_Pointer; Cdr: Object_Pointer; begin -- TODO: Change code here if the symbol table structure is changed to a hash table. Pred := Nil_Pointer; Cons := Interp.Symbol_Table; while Cons /= Nil_Pointer loop pragma Assert (Cons.Tag = Cons_Object); Car := Cons.Pointer_Slot(Cons_Car_Index); Cdr := Cons.Pointer_Slot(Cons_Cdr_Index); pragma Assert (Car.Kind = Moved_Object or else Car.Tag = Symbol_Object); if Car.Kind /= Moved_Object and then (Car.Flags and Syntax_Object) = 0 then -- A non-syntax symbol has not been moved. -- Unlink the cons cell from the symbol table. if Pred = Nil_Pointer then Interp.Symbol_Table := Cdr; else Pred.Pointer_Slot(Cons_Cdr_Index) := Cdr; end if; else Pred := Cons; end if; Cons := Cdr; end loop; end Compact_Symbol_Table; begin ada.text_io.put_line ("[GC BEGIN]"); --declare --Avail: Heap_Size; --begin --Avail := Interp.Heap(Interp.Current_Heap).Size - Interp.Heap(Interp.Current_Heap).Bound; --Ada.Text_IO.Put_Line (">>> [GC BEGIN] BOUND: " & Heap_Size'Image(Interp.Heap(Interp.Current_Heap).Bound) & " AVAIL: " & Heap_Size'Image(Avail)); --end; -- As the Heap_Number type is a modular type that can -- represent 0 and 1, incrementing it gives the next value. New_Heap := Interp.Current_Heap + 1; -- Migrate some root objects --Print_Object_Pointer (">>> [GC] Stack BEFORE ...", Interp.Stack); if Is_Normal_Pointer(Interp.Stack) then Interp.Stack := Move_One_Object(Interp.Stack); end if; Interp.Root_Environment := Move_One_Object(Interp.Root_Environment); Interp.Root_Frame := Move_One_Object(Interp.Root_Frame); -- Migrate temporary object pointers for I in Interp.Top.Data'First .. Interp.Top.Last loop if Interp.Top.Data(I).all = Interp.Symbol_Table then -- The symbol table must stay before compaction. -- Skip migrating a temporary object pointer if it -- is pointing to the symbol table. Remember that -- such skipping has happened. Original_Symbol_Table := Interp.Symbol_Table; elsif Interp.Top.Data(I).all /= null and then Is_Normal_Pointer(Interp.Top.Data(I).all) then Interp.Top.Data(I).all := Move_One_Object(Interp.Top.Data(I).all); end if; end loop; -- Migrate some known symbols Interp.Symbol.Arrow := Move_One_Object(Interp.Symbol.Arrow); Interp.Symbol.Quasiquote := Move_One_Object(Interp.Symbol.Quasiquote); Interp.Symbol.Quote := Move_One_Object(Interp.Symbol.Quote); --Ada.Text_IO.Put_Line (">>> [GC SCANNING NEW HEAP]"); -- Scan the heap Last_Pos := Scan_New_Heap(Interp.Heap(New_Heap).Space'First); -- Traverse the symbol table for unreferenced symbols. -- If the symbol has not moved to the new heap, the symbol -- is not referenced by any other objects than the symbol -- table itself --Ada.Text_IO.Put_Line (">>> [GC COMPACTING SYMBOL TABLE]"); Compact_Symbol_Table; --Print_Object_Pointer (">>> [GC MOVING SYMBOL TABLE]", Interp.Symbol_Table); -- Migrate the symbol table itself Interp.Symbol_Table := Move_One_Object(Interp.Symbol_Table); -- Update temporary object pointers that were pointing to the symbol table if Original_Symbol_Table /= null then for I in Interp.Top.Data'First .. Interp.Top.Last loop if Interp.Top.Data(I).all = Original_Symbol_Table then -- update to the new symbol table Interp.Top.Data(I).all := Interp.Symbol_Table; end if; end loop; end if; --Ada.Text_IO.Put_Line (">>> [GC SCANNING HEAP AGAIN AFTER SYMBOL TABLE MIGRATION]"); -- Scan the new heap again from the end position of -- the previous scan to move referenced objects by -- the symbol table. Last_Pos := Scan_New_Heap(Last_Pos); -- Swap the current heap and the new heap Interp.Heap(Interp.Current_Heap).Bound := 0; Interp.Current_Heap := New_Heap; --declare --Avail: Heap_Size; --begin --Avail := Interp.Heap(Interp.Current_Heap).Size - Interp.Heap(Interp.Current_Heap).Bound; --Print_Object_Pointer (">>> [GC DONE] Stack ...", Interp.Stack); --Ada.Text_IO.Put_Line (">>> [GC DONE] BOUND: " & Heap_Size'Image(Interp.Heap(Interp.Current_Heap).Bound) & " AVAIL: " & Heap_Size'Image(Avail)); --Ada.Text_IO.Put_Line (">>> [GC DONE] ----------------------------------------------------------"); --end; ada.text_io.put_line ("[GC END]"); end Collect_Garbage; function Allocate_Bytes (Interp: access Interpreter_Record; Bytes: in Heap_Size) return Heap_Element_Pointer is -- I use this temporary variable not to change Result -- if Allocation_Error should be raised. Tmp: Heap_Element_Pointer; begin pragma Assert (Bytes > 0); -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX if DEBUG_GC then Collect_Garbage (Interp.all); end if; -- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Tmp := Allocate_Bytes_In_Heap (Interp.Heap(Interp.Current_Heap), Bytes); if Tmp = null and then (Interp.Trait.Trait_Bits and No_Garbage_Collection) = 0 then Collect_Garbage (Interp.all); Tmp := Allocate_Bytes_In_Heap (Interp.Heap(Interp.Current_Heap), Bytes); if Tmp = null then raise Allocation_Error; end if; end if; return Tmp; end Allocate_Bytes; function Allocate_Pointer_Object (Interp: access Interpreter_Record; Size: in Pointer_Object_Size; Initial: in Object_Pointer) return Object_Pointer is subtype Pointer_Object_Record is Object_Record (Pointer_Object, Size); type Pointer_Object_Pointer is access all Pointer_Object_Record; Ptr: Heap_Element_Pointer; Obj_Ptr: Pointer_Object_Pointer; for Obj_Ptr'Address use Ptr'Address; pragma Import (Ada, Obj_Ptr); Result: Object_Pointer; for Result'Address use Ptr'Address; pragma Import (Ada, Result); begin Ptr := Allocate_Bytes ( Interp, Heap_Size'(Pointer_Object_Record'Max_Size_In_Storage_Elements) ); Obj_Ptr.all := ( Kind => Pointer_Object, Size => Size, Flags => 0, Scode => 0, Tag => Unknown_Object, Pointer_Slot => (others => Initial) ); return Result; end Allocate_Pointer_Object; function Allocate_Character_Object (Interp: access Interpreter_Record; Size: in Character_Object_Size) return Object_Pointer is subtype Character_Object_Record is Object_Record (Character_Object, Size); type Character_Object_Pointer is access all Character_Object_Record; Ptr: Heap_Element_Pointer; Obj_Ptr: Character_Object_Pointer; for Obj_Ptr'Address use Ptr'Address; pragma Import (Ada, Obj_Ptr); Result: Object_Pointer; for Result'Address use Ptr'Address; pragma Import (Ada, Result); begin Ptr := Allocate_Bytes ( Interp.Self, Heap_Size'(Character_Object_Record'Max_Size_In_Storage_Elements) ); Obj_Ptr.all := ( Kind => Character_Object, Size => Size, Flags => 0, Scode => 0, Tag => Unknown_Object, Character_Slot => (others => Ch.NUL), Character_Terminator => Ch.NUL ); return Result; end Allocate_Character_Object; function Allocate_Character_Object (Interp: access Interpreter_Record; Source: in Object_Character_Array) return Object_Pointer is Result: Object_Pointer; begin if Source'Length > Character_Object_Size'Last then raise Size_Error; end if; Result := Allocate_Character_Object (Interp, Character_Object_Size'(Source'Length)); Result.Character_Slot := Source; return Result; end Allocate_Character_Object; function Allocate_Byte_Object (Interp: access Interpreter_Record; Size: in Byte_Object_Size) return Object_Pointer is subtype Byte_Object_Record is Object_Record (Byte_Object, Size); type Byte_Object_Pointer is access all Byte_Object_Record; Ptr: Heap_Element_Pointer; Obj_Ptr: Byte_Object_Pointer; for Obj_Ptr'Address use Ptr'Address; pragma Import (Ada, Obj_Ptr); Result: Object_Pointer; for Result'Address use Ptr'Address; pragma Import (Ada, Result); begin Ptr := Allocate_Bytes (Interp.Self, Heap_Size'(Byte_Object_Record'Max_Size_In_Storage_Elements)); Obj_Ptr.all := ( Kind => Byte_Object, Size => Size, Flags => 0, Scode => 0, Tag => Unknown_Object, Byte_Slot => (others => 0) ); return Result; end Allocate_Byte_Object; ----------------------------------------------------------------------------- procedure Push_Top (Interp: in out Interpreter_Record; Source: access Object_Pointer) is Top: Top_Record renames Interp.Top; begin if Top.Last >= Top.Data'Last then -- Something is wrong. Too many temporary object pointers raise Internal_Error; -- TODO: change the exception to something else. end if; Top.Last := Top.Last + 1; Top.Data(Top.Last) := Top_Datum(Source); end Push_Top; procedure Pop_Tops (Interp: in out Interpreter_Record; Count: in Object_Size) is Top: Top_Record renames Interp.Top; begin if Top.Last < Count then -- Something is wrong. Too few temporary object pointers raise Internal_Error; -- TODO: change the exception to something else. end if; Top.Last := Top.Last - Count; end Pop_Tops; procedure Clear_Tops (Interp: in out Interpreter_Record) is pragma Inline (Clear_Tops); Top: Top_Record renames Interp.Top; begin Top.Last := Top.Data'First - 1; end Clear_Tops; ----------------------------------------------------------------------------- function Make_Cons (Interp: access Interpreter_Record; Car: in Object_Pointer; Cdr: in Object_Pointer) return Object_Pointer is Cons: Object_Pointer; Aliased_Car: aliased Object_Pointer := Car; Aliased_Cdr: aliased Object_Pointer := Cdr; begin Push_Top (Interp.all, Aliased_Car'Unchecked_Access); Push_Top (Interp.all, Aliased_Cdr'Unchecked_Access); Cons := Allocate_Pointer_Object (Interp, Cons_Object_Size, Nil_Pointer); Cons.Pointer_Slot(Cons_Car_Index) := Aliased_Car; Cons.Pointer_Slot(Cons_Cdr_Index) := Aliased_Cdr; Cons.Tag := Cons_Object; Pop_Tops (Interp.all, 2); return Cons; end Make_Cons; function Is_Cons (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Cons); begin return Is_Normal_Pointer(Source) and then Source.Tag = Cons_Object; end Is_Cons; function Get_Car (Source: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Car); pragma Assert (Is_Cons(Source)); begin return Source.Pointer_Slot(Cons_Car_Index); end Get_Car; procedure Set_Car (Source: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Car); pragma Assert (Is_Cons(Source)); begin Source.Pointer_Slot(Cons_Car_Index) := Value; end Set_Car; function Get_Cdr (Source: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Cdr); pragma Assert (Is_Cons(Source)); begin return Source.Pointer_Slot(Cons_Cdr_Index); end Get_Cdr; procedure Set_Cdr (Source: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Cdr); pragma Assert (Is_Cons(Source)); begin Source.Pointer_Slot(Cons_Cdr_Index) := Value; end Set_Cdr; function Get_Last_Cdr (Source: in Object_Pointer) return Object_Pointer is pragma Assert (Is_Cons(Source)); Ptr: Object_Pointer := Source; begin loop Ptr := Get_Cdr(Ptr); exit when not Is_Cons(Ptr); end loop; return Ptr; end Get_Last_Cdr; function Reverse_Cons (Source: in Object_Pointer; Last_Cdr: in Object_Pointer := Nil_Pointer) return Object_Pointer is pragma Assert (Is_Cons(Source)); -- Note: The non-nil cdr in the last cons cell gets lost. -- e.g.) Reversing (1 2 3 . 4) results in (3 2 1) Ptr: Object_Pointer; Next: Object_Pointer; Prev: Object_Pointer; begin Prev := Last_Cdr; Ptr := Source; loop Next := Get_Cdr(Ptr); Set_Cdr (Ptr, Prev); Prev := Ptr; exit when not Is_Cons(Next); Ptr := Next; end loop; return Ptr; end Reverse_Cons; ----------------------------------------------------------------------------- function Make_String (Interp: access Interpreter_Record; Source: in Object_Character_Array) return Object_Pointer is Result: Object_Pointer; begin Ada.Text_IO.Put_Line ("Make_String..."); Result := Allocate_Character_Object (Interp, Source); Result.Tag := String_Object; --Print_Object_Pointer ("Make_String Result - " & Source, Result); return Result; end Make_String; function Is_Symbol (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Symbol); begin return Is_Normal_Pointer (Source) and then Source.Tag = Symbol_Object; end Is_Symbol; function Make_Symbol (Interp: access Interpreter_Record; Source: in Object_Character_Array) return Object_Pointer is Ptr: aliased Object_Pointer; begin -- TODO: the current linked list implementation isn't efficient. -- change the symbol table to a hashable table. -- Find an existing symbol in the symbol table. Ptr := Interp.Symbol_Table; while Ptr /= Nil_Pointer loop pragma Assert (Is_Cons(Ptr)); declare Car: Object_Pointer renames Ptr.Pointer_Slot(Cons_Car_Index); Cdr: Object_Pointer renames Ptr.Pointer_Slot(Cons_Cdr_Index); begin pragma Assert (Car.Tag = Symbol_Object); if Car.Character_Slot = Source then -- the character string contents are the same. return Car; end if; Ptr := Cdr; end; end loop; -- Create a symbol object Ptr := Allocate_Character_Object(Interp, Source); Ptr.Tag := Symbol_Object; -- Make Ptr safe from GC Push_Top (Interp.all, Ptr'Unchecked_Access); -- Link the symbol to the symbol table. Interp.Symbol_Table := Make_Cons(Interp.Self, Ptr, Interp.Symbol_Table); Pop_Tops (Interp.all, 1); return Ptr; end Make_Symbol; ----------------------------------------------------------------------------- function Make_Array (Interp: access Interpreter_Record; Size: in Pointer_Object_Size) return Object_Pointer is Arr: Object_Pointer; begin Arr := Allocate_Pointer_Object (Interp, Size, Nil_Pointer); Arr.Tag := Array_Object; return Arr; end Make_Array; function Is_Array (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Array); begin return Is_Normal_Pointer(Source) and then Source.Tag = Array_Object; end Is_Array; ----------------------------------------------------------------------------- function Make_Frame (Interp: access Interpreter_Record; Parent: in Object_Pointer; -- current stack pointer Opcode: in Object_Pointer; Operand: in Object_Pointer; Envir: in Object_Pointer; Interm: in Object_Pointer) return Object_Pointer is Frame: Object_Pointer; Aliased_Parent: aliased Object_Pointer := Parent; Aliased_Opcode: aliased Object_Pointer := Opcode; Aliased_Operand: aliased Object_Pointer := Operand; Aliased_Envir: aliased Object_Pointer := Envir; Aliased_Interm: aliased Object_Pointer := Interm; begin Push_Top (Interp.all, Aliased_Parent'Unchecked_Access); Push_Top (Interp.all, Aliased_Opcode'Unchecked_Access); Push_Top (Interp.all, Aliased_Operand'Unchecked_Access); Push_Top (Interp.all, Aliased_Envir'Unchecked_Access); Push_Top (Interp.all, Aliased_Interm'Unchecked_Access); -- TODO: create a Frame in a special memory rather than in Heap Memory. -- Since it's used for stack, it can be made special. Frame := Allocate_Pointer_Object (Interp, Frame_Object_Size, Nil_Pointer); Frame.Tag := Frame_Object; Frame.Pointer_Slot(Frame_Parent_Index) := Aliased_Parent; Frame.Pointer_Slot(Frame_Opcode_Index) := Aliased_Opcode; Frame.Pointer_Slot(Frame_Operand_Index) := Aliased_Operand; Frame.Pointer_Slot(Frame_Environment_Index) := Aliased_Envir; Frame.Pointer_Slot(Frame_Intermediate_Index) := Aliased_Interm; Pop_Tops (Interp.all, 5); return Frame; end Make_Frame; function Is_Frame (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Frame); begin return Is_Normal_Pointer(Source) and then Source.Tag = Frame_Object; end Is_Frame; function Get_Frame_Intermediate (Frame: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Frame_Intermediate); pragma Assert (Is_Frame(Frame)); begin return Frame.Pointer_Slot(Frame_Intermediate_Index); end Get_Frame_Intermediate; procedure Set_Frame_Intermediate (Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Frame_Intermediate); pragma Assert (Is_Frame(Frame)); -- This procedure is not to set a single result, -- but to set the result chain. so it can be useful -- if you want to migrate a result chain from one frame -- to another. It's what this assertion is for. pragma Assert (Value = Nil_Pointer or else Is_Cons(Value)); begin Frame.Pointer_Slot(Frame_Intermediate_Index) := Value; end Set_Frame_Intermediate; procedure Chain_Frame_Intermediate (Interp: in out Interpreter_Record; Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Chain_Frame_Intermediate); pragma Assert (Is_Frame(Frame)); V: Object_Pointer; begin -- Add a new cons cell to the front --Push_Top (Interp, Frame'Unchecked_Access); --Frame.Pointer_Slot(Frame_Intermediate_Index) := -- Make_Cons(Interp.Self, Value, Frame.Pointer_Slot(Frame_Intermediate_Index)); --Pop_Tops (Interp, 1); -- This seems to cause a problem if Interp.Stack changes in Make_Cons(). --Interp.Stack.Pointer_Slot(Frame_Intermediate_Index) := -- Make_Cons(Interp.Self, Value, Interp.Stack.Pointer_Slot(Frame_Intermediate_Index)); -- So, let's separate the evaluation and the assignment. V := Make_Cons(Interp.Self, Value, Interp.Stack.Pointer_Slot(Frame_Intermediate_Index)); Interp.Stack.Pointer_Slot(Frame_Intermediate_Index) := V; end Chain_Frame_Intermediate; function Get_Frame_Result (Frame: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Frame_Result); pragma Assert (Is_Frame(Frame)); begin return Frame.Pointer_Slot(Frame_Result_Index); end Get_Frame_Result; procedure Set_Frame_Result (Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Frame_Result); pragma Assert (Is_Frame(Frame)); begin Frame.Pointer_Slot(Frame_Result_Index) := Value; end Set_Frame_Result; procedure Clear_Frame_Result (Frame: in Object_Pointer) is begin Frame.Pointer_Slot(Frame_Result_Index) := Nil_Pointer; end Clear_Frame_Result; function Get_Frame_Environment (Frame: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Frame_Environment); pragma Assert (Is_Frame(Frame)); begin return Frame.Pointer_Slot(Frame_Environment_Index); end Get_Frame_Environment; procedure Set_Frame_Environment (Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Frame_Environment); pragma Assert (Is_Frame(Frame)); begin Frame.Pointer_Slot(Frame_Environment_Index) := Value; end Set_Frame_Environment; function Get_Frame_Opcode (Frame: in Object_Pointer) return Opcode_Type is pragma Inline (Get_Frame_Opcode); pragma Assert (Is_Frame(Frame)); begin return Pointer_To_Opcode(Frame.Pointer_Slot(Frame_Opcode_Index)); end Get_Frame_Opcode; procedure Set_Frame_Opcode (Frame: in Object_Pointer; Opcode: in Opcode_Type) is pragma Inline (Set_Frame_Opcode); pragma Assert (Is_Frame(Frame)); begin Frame.Pointer_Slot(Frame_Opcode_Index) := Opcode_To_Pointer(Opcode); end Set_Frame_Opcode; function Get_Frame_Operand (Frame: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Frame_Operand); pragma Assert (Is_Frame(Frame)); begin return Frame.Pointer_Slot(Frame_Operand_Index); end Get_Frame_Operand; procedure Set_Frame_Operand (Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Frame_Operand); pragma Assert (Is_Frame(Frame)); begin Frame.Pointer_Slot(Frame_Operand_Index) := Value; end Set_Frame_Operand; function Get_Frame_Parent (Frame: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Frame_Parent); pragma Assert (Is_Frame(Frame)); begin return Frame.Pointer_Slot(Frame_Parent_Index); end Get_Frame_Parent; procedure Set_Frame_Parent (Frame: in Object_Pointer; Value: in Object_Pointer) is pragma Inline (Set_Frame_Parent); pragma Assert (Is_Frame(Frame)); begin Frame.Pointer_Slot(Frame_Parent_Index) := Value; end Set_Frame_Parent; procedure Switch_Frame (Frame: in Object_Pointer; Opcode: in Opcode_Type; Operand: in Object_Pointer; Interm: in Object_Pointer) is begin Set_Frame_Opcode (Frame, Opcode); Set_Frame_Operand (Frame, Operand); Set_Frame_Intermediate (Frame, Interm); Set_Frame_Result (Frame, Nil_Pointer); end Switch_Frame; ----------------------------------------------------------------------------- -- -- Environment is a cons cell whose slots represents: -- Car: Point to the first key/value pair. -- Cdr: Point to Parent environment -- -- A key/value pair is held in an array object consisting of 3 slots. -- #1: Key -- #2: Value -- #3: Link to the next key/value array. -- -- Frame.Environment Interp.Root_Environment -- | | -- | V -- | +----+----+ +----+----+ -- +---> | | | ----> | | | Nil| -- +-|--+----- +-|--+----- -- | | -- | +--> another list -- V -- +----+----+----+ +----+----+----+ +----+----+----+ +----+----+----+ -- list: | | | | | ----> | | | | | -----> | | | | | -----> | | | | | Nil| -- +-|--+-|-------+ +-|--+-|-------+ +-|--+-|-------+ +-|--+-|-------+ -- | | | | | | | | -- V V V V V V V V -- Key Value Key Value Key Value Key Value -- -- Upon initialization, Root_Frame.Environment is equal to Interp.Root_Environment. -- CDR(Interp.Root_Environment) is Nil_Pointer. -- -- TODO: Change environment implementation to a hash table or something similar function Make_Environment (Interp: access Interpreter_Record; Parent: in Object_Pointer) return Object_Pointer is pragma Inline (Make_Environment); begin return Make_Cons(Interp, Nil_Pointer, Parent); end Make_Environment; function Find_In_Environment_List (Interp: access Interpreter_Record; List: in Object_Pointer; Key: in Object_Pointer) return Object_Pointer is Arr: Object_Pointer; begin Arr := List; while Arr /= Nil_Pointer loop pragma Assert (Is_Array(Arr)); pragma Assert (Arr.Size = 3); if Arr.Pointer_Slot(1) = Key then return Arr; end if; Arr := Arr.Pointer_Slot(3); end loop; return null; -- not found. end Find_In_Environment_List; function Get_Environment (Interp: access Interpreter_Record; Key: in Object_Pointer) return Object_Pointer is Envir: Object_Pointer; Arr: Object_Pointer; begin pragma Assert (Is_Symbol(Key)); Envir := Get_Frame_Environment(Interp.Stack); while Envir /= Nil_Pointer loop pragma Assert (Is_Cons(Envir)); Arr := Find_In_Environment_List(Interp, Get_Car(Envir), Key); if Arr /= null then return Arr.Pointer_Slot(2); end if; -- Move on to the parent environment Envir := Get_Cdr(Envir); end loop; return null; -- not found end Get_Environment; function Set_Environment (Interp: access Interpreter_Record; Key: in Object_Pointer; Value: in Object_Pointer) return Object_Pointer is Envir: Object_Pointer; Arr: Object_Pointer; begin -- Search the whole environment chain unlike Put_Environment(). -- It is mainly for set!. pragma Assert (Is_Symbol(Key)); Envir := Get_Frame_Environment(Interp.Stack); while Envir /= Nil_Pointer loop pragma Assert (Is_Cons(Envir)); Arr := Find_In_Environment_List(Interp, Get_Car(Envir), Key); if Arr /= null then -- Overwrite an existing pair Arr.Pointer_Slot(2) := Value; return Value; end if; -- Move on to the parent environment Envir := Get_Cdr(Envir); end loop; return null; -- not found. not set end Set_Environment; procedure Put_Environment (Interp: in out Interpreter_Record; Key: in Object_Pointer; Value: in Object_Pointer) is Arr: Object_Pointer; Envir: aliased Object_Pointer; begin Envir := Get_Frame_Environment(Interp.Stack); -- Search the current environment only. It doesn't search the -- environment. If no key is found, add a new pair -- This is mainly for define. pragma Assert (Is_Symbol(Key)); pragma Assert (Is_Cons(Envir)); Arr := Find_In_Environment_List(Interp.Self, Get_Car(Envir), Key); if Arr /= null then -- Found. Update the existing one Arr.Pointer_Slot(2) := Value; else -- Add a new key/value pair in the current environment -- if no existing pair has been found. declare Aliased_Key: aliased Object_Pointer := Key; Aliased_Value: aliased Object_Pointer := Value; begin Push_Top (Interp, Envir'Unchecked_Access); Push_Top (Interp, Aliased_Key'Unchecked_Access); Push_Top (Interp, Aliased_Value'Unchecked_Access); Arr := Make_Array(Interp.Self, 3); Arr.Pointer_Slot(1) := Aliased_Key; Arr.Pointer_Slot(2) := Aliased_Value; -- Chain the pair to the head of the list Arr.Pointer_Slot(3) := Get_Car(Envir); Set_Car (Envir, Arr); Pop_Tops (Interp, 3); end; end if; end Put_Environment; ----------------------------------------------------------------------------- function Make_Syntax (Interp: access Interpreter_Record; Opcode: in Syntax_Code; Name: in Object_Character_Array) return Object_Pointer is Result: Object_Pointer; begin Result := Make_Symbol(Interp, Name); Result.Flags := Result.Flags or Syntax_Object; Result.Scode := Opcode; --Ada.Text_IO.Put ("Creating Syntax Symbol "); --Put_String (To_Thin_Object_String_Pointer (Result)); return Result; end Make_Syntax; function Is_Syntax (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Syntax); begin return Is_Symbol(Source) and then (Source.Flags and Syntax_Object) /= 0; end Is_Syntax; function Make_Procedure (Interp: access Interpreter_Record; Opcode: in Procedure_Code; Name: in Object_Character_Array) return Object_Pointer is -- this procedure is for internal use only Symbol: aliased Object_Pointer; Proc: aliased Object_Pointer; begin Push_Top (Interp.all, Symbol'Unchecked_Access); Push_Top (Interp.all, Proc'Unchecked_Access); -- Make a symbol for the procedure Symbol := Make_Symbol(Interp, Name); -- Make the actual procedure object Proc := Allocate_Pointer_Object(Interp, Procedure_Object_Size, Nil_Pointer); Proc.Tag := Procedure_Object; Proc.Pointer_Slot(Procedure_Opcode_Index) := Integer_To_Pointer(Opcode); -- Link it to the top environement pragma Assert (Get_Frame_Environment(Interp.Stack) = Interp.Root_Environment); pragma Assert (Get_Environment(Interp.Self, Symbol) = null); Put_Environment (Interp.all, Symbol, Proc); Pop_Tops (Interp.all, 2); return Proc; end Make_Procedure; function Is_Procedure (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Procedure); begin return Is_Normal_Pointer(Source) and then Source.Tag = Procedure_Object; end Is_Procedure; function Get_Procedure_Opcode (Proc: in Object_Pointer) return Procedure_Code is pragma Inline (Get_Procedure_Opcode); pragma Assert (Is_Procedure(Proc)); pragma Assert (Proc.Size = Procedure_Object_Size); begin return Pointer_To_Integer(Proc.Pointer_Slot(Procedure_Opcode_Index)); end Get_Procedure_Opcode; ----------------------------------------------------------------------------- function Make_Closure (Interp: access Interpreter_Record; Code: in Object_Pointer; Envir: in Object_Pointer) return Object_Pointer is Closure: Object_Pointer; Aliased_Code: aliased Object_Pointer := Code; Aliased_Envir: aliased Object_Pointer := Envir; begin Push_Top (Interp.all, Aliased_Code'Unchecked_Access); Push_Top (Interp.all, Aliased_Envir'Unchecked_Access); Closure := Allocate_Pointer_Object (Interp, Closure_Object_Size, Nil_Pointer); Closure.Tag := Closure_Object; Closure.Pointer_Slot(Closure_Code_Index) := Aliased_Code; Closure.Pointer_Slot(Closure_Environment_Index) := Aliased_Envir; Pop_Tops (Interp.all, 2); return Closure; end Make_Closure; function Is_Closure (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Closure); begin return Is_Normal_Pointer(Source) and then Source.Tag = Closure_Object; end Is_Closure; function Get_Closure_Code (Closure: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Closure_Code); pragma Assert (Is_Closure(Closure)); begin return Closure.Pointer_Slot(Closure_Code_Index); end Get_Closure_Code; function Get_Closure_Environment (Closure: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Closure_Environment); pragma Assert (Is_Closure(Closure)); begin return Closure.Pointer_Slot(Closure_Environment_Index); end Get_Closure_Environment; ----------------------------------------------------------------------------- function Make_Continuation (Interp: access Interpreter_Record; Frame: in Object_Pointer) return Object_Pointer is Cont: Object_Pointer; Aliased_Frame: aliased Object_Pointer := Frame; begin Push_Top (Interp.all, Aliased_Frame'Unchecked_Access); Cont := Allocate_Pointer_Object (Interp, Continuation_Object_Size, Nil_Pointer); Cont.Tag := Continuation_Object; Cont.Pointer_Slot(Continuation_Frame_Index) := Aliased_Frame; Pop_Tops (Interp.all, 1); return Cont; end Make_Continuation; function Is_Continuation (Source: in Object_Pointer) return Standard.Boolean is pragma Inline (Is_Continuation); begin return Is_Normal_Pointer(Source) and then Source.Tag = Continuation_Object; end Is_Continuation; function Get_Continuation_Frame (Cont: in Object_Pointer) return Object_Pointer is pragma Inline (Get_Continuation_Frame); pragma Assert (Is_Continuation(Cont)); begin return Cont.Pointer_Slot(Continuation_Frame_Index); end Get_Continuation_Frame; ----------------------------------------------------------------------------- procedure Deinitialize_Heap (Interp: in out Interpreter_Record) is begin for I in Interp.Heap'Range loop if Interp.Heap(I) /= null then declare subtype Target_Heap_Record is Heap_Record (Interp.Heap(I).Size); type Target_Heap_Pointer is access all Target_Heap_Record; package Pool is new H2.Pool (Target_Heap_Record, Target_Heap_Pointer, Interp.Storage_Pool); Heap: Target_Heap_Pointer; for Heap'Address use Interp.Heap(I)'Address; pragma Import (Ada, Heap); begin Pool.Deallocate (Heap); end; end if; end loop; end Deinitialize_Heap; procedure Close_Stream (Stream: in out Stream_Pointer) is begin Close (Stream.all); Stream := null; exception when others => Stream := null; -- ignore exception end Close_Stream; procedure Start_Named_Input_Stream (Interp: in out Interpreter_Record; Name: access Object_Character_Array) is package IO_Pool is new H2.Pool (IO_Record, IO_Pointer, Interp.Storage_Pool); IO: IO_Pointer := null; Stream: Stream_Pointer := null; begin begin IO := IO_Pool.Allocate; Interp.Stream.Allocate (Interp, Name, Stream); exception when others => if IO /= null then if Stream /= null then Interp.Stream.Deallocate (Interp, Stream); end if; IO_Pool.Deallocate (IO); end if; raise; end; --IO.Stream := Stream; --IO.Pos := IO.Data'First - 1; --IO.Last := IO.Data'First - 1; --IO.Flags := 0; --IO.Next := Interp.Input; --Interp.Input := IO; IO.all := IO_Record'( Stream => Stream, Data => (others => Object_Character'First), Pos | Last => IO.Data'First - 1, Flags => 0, Next => Interp.Input, Iochar => IO_Character_Record'(End_Character, Object_Character'First) ); Interp.Input := IO; end Start_Named_Input_Stream; procedure Stop_Named_Input_Stream (Interp: in out Interpreter_Record) is package IO_Pool is new H2.Pool (IO_Record, IO_Pointer, Interp.Storage_Pool); IO: IO_Pointer; begin pragma Assert (Interp.Input /= Interp.Base_Input'Unchecked_Access); IO := Interp.Input; Interp.Input := IO.Next; pragma Assert (IO.Stream /= null); Close_Stream (IO.Stream); Interp.Stream.Deallocate (Interp, IO.Stream); IO_Pool.Deallocate (IO); end Stop_Named_Input_Stream; ----------------------------------------------------------------------------- procedure Open (Interp: in out Interpreter_Record; Initial_Heap_Size: in Heap_Size; Storage_Pool: in Storage_Pool_Pointer := null) is procedure Initialize_Heap (Size: Heap_Size) is subtype Target_Heap_Record is Heap_Record (Size); type Target_Heap_Pointer is access all Target_Heap_Record; package Pool is new H2.Pool (Target_Heap_Record, Target_Heap_Pointer, Interp.Storage_Pool); begin for I in Interp.Heap'Range loop Interp.Heap(I) := null; -- just in case end loop; for I in Interp.Heap'Range loop declare Heap: Target_Heap_Pointer; for Heap'Address use Interp.Heap(I)'Address; pragma Import (Ada, Heap); begin Heap := Pool.Allocate; end; end loop; exception when others => Deinitialize_Heap (Interp); raise; end Initialize_Heap; procedure Make_Syntax_Objects is Dummy: Object_Pointer; begin Dummy := Make_Syntax (Interp.Self, And_Syntax, Label_And); -- "and" Dummy := Make_Syntax (Interp.Self, Begin_Syntax, Label_Begin); -- "begin" Dummy := Make_Syntax (Interp.Self, Case_Syntax, Label_Case); -- "case" Dummy := Make_Syntax (Interp.Self, Cond_Syntax, Label_Cond); -- "cond" Dummy := Make_Syntax (Interp.Self, Define_Syntax, Label_Define); -- "define" Dummy := Make_Syntax (Interp.Self, Do_Syntax, Label_Do); -- "do" Dummy := Make_Syntax (Interp.Self, If_Syntax, Label_If); -- "if" Dummy := Make_Syntax (Interp.Self, Lambda_Syntax, Label_Lambda); -- "lamba" Dummy := Make_Syntax (Interp.Self, Let_Syntax, Label_Let); -- "let" Dummy := Make_Syntax (Interp.Self, Letast_Syntax, Label_Letast); -- "let*" Dummy := Make_Syntax (Interp.Self, Letrec_Syntax, Label_Letrec); -- "letrec" Dummy := Make_Syntax (Interp.Self, Or_Syntax, Label_Or); -- "or" Interp.Symbol.Quote := Make_Syntax (Interp.Self, Quote_Syntax, Label_Quote); -- "quote" Interp.Symbol.Quasiquote := Make_Syntax (Interp.Self, Quasiquote_Syntax, Label_Quasiquote); -- "quasiquote" Dummy := Make_Syntax (Interp.Self, Set_Syntax, Label_Set); -- "set!" end Make_Syntax_Objects; procedure Make_Procedure_Objects is Dummy: Object_Pointer; begin Dummy := Make_Procedure (Interp.Self, Add_Procedure, Label_Plus); -- "+" Dummy := Make_Procedure (Interp.Self, Callcc_Procedure, Label_Callcc); -- "call-with-current-continuation" Dummy := Make_Procedure (Interp.Self, Car_Procedure, Label_Car); -- "car" Dummy := Make_Procedure (Interp.Self, Cdr_Procedure, Label_Cdr); -- "cdr" Dummy := Make_Procedure (Interp.Self, Cons_Procedure, Label_Cons); -- "cons" Dummy := Make_Procedure (Interp.Self, EQ_Procedure, Label_EQ); -- "=" Dummy := Make_Procedure (Interp.Self, GE_Procedure, Label_GE); -- ">=" Dummy := Make_Procedure (Interp.Self, GT_Procedure, Label_GT); -- ">" Dummy := Make_Procedure (Interp.Self, LE_Procedure, Label_LE); -- "<=" Dummy := Make_Procedure (Interp.Self, LT_Procedure, Label_LT); -- "<" Dummy := Make_Procedure (Interp.Self, Multiply_Procedure, Label_Multiply); -- "*" Dummy := Make_Procedure (Interp.Self, Quotient_Procedure, Label_Quotient); -- "quotient" Dummy := Make_Procedure (Interp.Self, Remainder_Procedure, Label_Remainder); -- "remainder" Dummy := Make_Procedure (Interp.Self, Setcar_Procedure, Label_Setcar); -- "set-car!" Dummy := Make_Procedure (Interp.Self, Setcdr_Procedure, Label_Setcdr); -- "set-cdr!" Dummy := Make_Procedure (Interp.Self, Subtract_Procedure, Label_Minus); -- "-" end Make_Procedure_Objects; procedure Make_Common_Symbol_Objects is begin Interp.Symbol.Arrow := Make_Symbol (Interp.Self, Label_Arrow); end Make_Common_Symbol_Objects; begin declare Aliased_Interp: aliased Interpreter_Record; for Aliased_Interp'Address use Interp'Address; pragma Import (Ada, Aliased_Interp); begin -- Store a pointer to the interpreter record itself. -- I use this pointer to call functions that accept the "access" -- type to work around the ada95 limitation of no "in out" as -- a function parameter. Accoring to Ada95 RM (6.2), both a -- non-private limited record type and a private type whose -- full type is a by-reference type are by-rereference types. -- So i assume that it's safe to create this aliased overlay -- to deceive the compiler. If Interpreter_Record is a tagged -- limited record type, this overlay is not needed since the -- type is considered aliased. Having this overlay, however, -- should be safe for both "tagged" and "non-tagged". -- Note: Making it a tagged limit record caused gnat 3.4.6 to -- crash with an internal bug report. --Interp.Self := Interp'Unchecked_Access; -- if tagged limited Interp.Self := Aliased_Interp'Unchecked_Access; end; Interp.Storage_Pool := Storage_Pool; Interp.Symbol_Table := Nil_Pointer; Interp.Base_Input.Stream := null; Interp.Input := Interp.Base_Input'Unchecked_Access; Interp.Token := (End_Token, (null, 0, 0)); Interp.Top := (Interp.Top.Data'First - 1, (others => null)); -- TODO: disallow garbage collecion during initialization. Initialize_Heap (Initial_Heap_Size); Interp.Root_Environment := Make_Environment(Interp.Self, Nil_Pointer); Interp.Root_Frame := Make_Frame(Interp.Self, Nil_Pointer, Opcode_To_Pointer(Opcode_Exit), Nil_Pointer, Interp.Root_Environment, Nil_Pointer); Interp.Stack := Interp.Root_Frame; Make_Syntax_Objects; Make_Procedure_Objects; Make_Common_Symbol_Objects; exception when others => Deinitialize_Heap (Interp); end Open; procedure Close (Interp: in out Interpreter_Record) is begin -- Destroy all unstacked named input streams while Interp.Input /= Interp.Base_Input'Unchecked_Access loop Stop_Named_Input_Stream (Interp); end loop; if Interp.Base_Input.Stream /= null then -- Close the main input stream. Close_Stream (Interp.Base_Input.Stream); end if; Deinitialize_Heap (Interp); Token.Purge (Interp); end Close; function Get_Storage_Pool (Interp: in Interpreter_Record) return Storage_Pool_Pointer is begin return Interp.Storage_Pool; end Get_Storage_Pool; procedure Set_Option (Interp: in out Interpreter_Record; Option: in Option_Record) is begin case Option.Kind is when Trait_Option => Interp.Trait := Option; when Stream_Option => Interp.Stream := Option; end case; end Set_Option; procedure Get_Option (Interp: in out Interpreter_Record; Option: in out Option_Record) is begin case Option.Kind is when Trait_Option => Option := Interp.Trait; when Stream_Option => Option := Interp.Stream; end case; end Get_Option; procedure Set_Input_Stream (Interp: in out Interpreter_Record; Stream: in out Stream_Record'Class) is begin --Open (Stream, Interp); Open (Stream); -- if Open raised an exception, it wouldn't reach here. -- so the existing stream still remains intact. if Interp.Base_Input.Stream /= null then Close_Stream (Interp.Base_Input.Stream); end if; Interp.Base_Input := IO_Record'( Stream => Stream'Unchecked_Access, Data => (others => Object_Character'First), Pos | Last => Interp.Base_Input.Data'First - 1, Flags => 0, Next => null, Iochar => IO_Character_Record'(End_Character, Object_Character'First) ); end Set_Input_Stream; --procedure Set_Output_Stream (Interp: in out Interpreter_Record; -- Stream: in out Stream_Record'Class) is --begin -- --end Set_Output_Stream; procedure Print (Interp: in out Interpreter_Record; Source: in Object_Pointer) is procedure Print_Atom (Atom: in Object_Pointer) is Ptr_Type: Object_Pointer_Type; procedure Print_Pointee is W: Object_Word; for W'Address use Atom'Address; begin case W is when Nil_Word => Ada.Text_IO.Put ("()"); when True_Word => Ada.Text_IO.Put ("#t"); when False_Word => Ada.Text_IO.Put ("#f"); when others => case Atom.Tag is when Cons_Object => -- Cons_Object must not reach here. raise Internal_Error; when Symbol_Object => Output_Character_Array (Atom.Character_Slot); when String_Object => Ada.Text_IO.Put (""""); Output_Character_Array (Atom.Character_Slot); Ada.Text_IO.Put (""""); when Closure_Object => Ada.Text_IO.Put ("#Closure"); when Continuation_Object => declare w: object_word; for w'address use Atom'address; begin Ada.Text_IO.Put ("#Continuation[" & object_word'image(w) & "]"); end; when Procedure_Object => Ada.Text_IO.Put ("#Procedure"); when Array_Object => Ada.Text_IO.Put ("#Array"); when Others => if Atom.Kind = Character_Object then Output_Character_Array (Atom.Character_Slot); else Ada.Text_IO.Put ("#NOIMPL# => " & Object_Tag'Image(Atom.Tag)); end if; end case; end case; end Print_Pointee; procedure Print_Integer is X: constant Object_Integer := Pointer_To_Integer (Atom); begin Ada.Text_IO.Put (Object_Integer'Image(X)); end Print_Integer; procedure Print_Character is X: constant Object_Character := Pointer_To_Character (Atom); begin Ada.Text_IO.Put (Object_Character'Image(X)); end Print_Character; procedure Print_Byte is X: constant Object_Byte := Pointer_To_Byte (Atom); begin Ada.Text_IO.Put (Object_Byte'Image(X)); end Print_Byte; begin Ptr_Type := Get_Pointer_Type(Atom); case Ptr_Type is when Object_Pointer_Type_Pointer => Print_Pointee; when Object_Pointer_Type_Integer => Print_Integer; when Object_Pointer_Type_Character => Print_Character; when Object_Pointer_Type_Byte => Print_Byte; end case; end Print_Atom; procedure Print_Object (Obj: in Object_Pointer) is Cons: Object_Pointer; Car: Object_Pointer; Cdr: Object_Pointer; begin if Is_Cons(Obj) then Cons := Obj; Ada.Text_IO.Put ("("); loop Car := Get_Car(Cons); if Is_Cons (Car) then Print_Object (Car); else Print_Atom (Car); end if; Cdr := Get_Cdr(Cons); if Is_Cons(Cdr) then Ada.Text_IO.Put (" "); Cons := Cdr; exit when Cons = Nil_Pointer; else if Cdr /= Nil_Pointer then Ada.Text_IO.Put (" . "); Print_Atom (Cdr); end if; exit; end if; end loop; Ada.Text_IO.Put (")"); else Print_Atom (Obj); end if; end Print_Object; Stack: Object_Pointer; -- TODO: make it into the interpreter_Record so that GC can workd Opcode: Object_Integer; Operand: Object_Pointer; begin if DEBUG_GC then Print_Object (Source); -- use a recursive version Ada.Text_IO.New_Line; return; end if; -- TODO: Let Make_Frame use a dedicated stack space that's apart from the heap. -- This way, the stack frame doesn't have to be managed by GC. -- TODO: use a interp.Stack. -- TODO: use Push_Frame Stack := Make_Frame (Interp.Self, Nil_Pointer, Integer_To_Pointer(0), Nil_Pointer, Nil_Pointer, Nil_Pointer); -- just for get_frame_environment... Opcode := 1; Operand := Source; loop case Opcode is when 1 => if Is_Cons(Operand) then -- push cdr Stack := Make_Frame (Interp.Self, Stack, Integer_To_Pointer(2), Get_Cdr(Operand), Nil_Pointer, Nil_Pointer); -- push cdr Ada.Text_IO.Put ("("); Operand := Get_Car(Operand); Opcode := 1; else Print_Atom (Operand); if Stack = Nil_Pointer then Opcode := 0; -- stack empty. arrange to exit Operand := True_Pointer; -- return value else Opcode := Pointer_To_Integer(Stack.Pointer_Slot(Frame_Opcode_Index)); Operand := Stack.Pointer_Slot(Frame_Operand_Index); Stack := Stack.Pointer_Slot(Frame_Parent_Index); -- pop end if; end if; when 2 => if Is_Cons(Operand) then -- push cdr Stack := Make_Frame (Interp.Self, Stack, Integer_To_Pointer(2), Get_Cdr(Operand), Nil_Pointer, Nil_Pointer); -- push Ada.Text_IO.Put (" "); Operand := Get_Car(Operand); -- car Opcode := 1; else if Operand /= Nil_Pointer then -- cdr of the last cons cell is not null. Ada.Text_IO.Put (" . "); Print_Atom (Operand); end if; Ada.Text_IO.Put (")"); if Stack = Nil_Pointer then Opcode := 0; -- stack empty. arrange to exit else Opcode := Pointer_To_Integer(Stack.Pointer_Slot(Frame_Opcode_Index)); Operand := Stack.Pointer_Slot(Frame_Operand_Index); Stack := Stack.Pointer_Slot(Frame_Parent_Index); -- pop end if; end if; when others => exit; end case; end loop; Ada.Text_IO.New_Line; end Print; function Insert_Frame (Interp: access Interpreter_Record; Parent: in Object_Pointer; Opcode: in Opcode_Type; Operand: in Object_Pointer; Envir: in Object_Pointer; Interm: in Object_Pointer) return Object_Pointer is pragma Inline (Insert_Frame); pragma Assert (Parent = Nil_Pointer or else Is_Frame(Parent)); begin return Make_Frame(Interp, Parent, Opcode_To_Pointer(Opcode), Operand, Envir, Interm); end Insert_Frame; procedure Push_Frame (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer) is pragma Inline (Push_Frame); begin Interp.Stack := Insert_Frame(Interp.Self, Interp.Stack, Opcode, Operand, Get_Frame_Environment(Interp.Stack), Nil_Pointer); end Push_Frame; procedure Push_Frame_With_Environment (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer; Envir: in Object_Pointer) is pragma Inline (Push_Frame_With_Environment); begin Interp.Stack := Insert_Frame(Interp.Self, Interp.Stack, Opcode, Operand, Envir, Nil_Pointer); end Push_Frame_With_Environment; procedure Push_Frame_With_Intermediate (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer; Interm: in Object_Pointer) is pragma Inline (Push_Frame_With_Intermediate); begin -- Place a new frame below the existing top frame. Interp.Stack := Insert_Frame (Interp.Self, Interp.Stack, Opcode, Operand, Get_Frame_Environment(Interp.Stack), Interm); end Push_Frame_With_Intermediate; procedure Push_Subframe (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer) is pragma Inline (Push_Subframe); begin -- Place a new frame below the existing top frame. Set_Frame_Parent (Interp.Stack, Insert_Frame(Interp.Self, Get_Frame_Parent(Interp.Stack), Opcode, Operand, Get_Frame_Environment(Interp.Stack), Nil_Pointer)); end Push_Subframe; procedure Push_Subframe_With_Environment (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer; Envir: in Object_Pointer) is pragma Inline (Push_Subframe_With_Environment); begin -- Place a new frame below the existing top frame. Set_Frame_Parent (Interp.Stack, Insert_Frame(Interp.Self, Get_Frame_Parent(Interp.Stack), Opcode, Operand, Envir, Nil_Pointer)); end Push_Subframe_With_Environment; procedure Push_Subframe_With_Intermediate (Interp: in out Interpreter_Record; Opcode: in Opcode_Type; Operand: in Object_Pointer; Interm: in Object_Pointer) is pragma Inline (Push_Subframe_With_Intermediate); begin -- Place a new frame below the existing top frame. Set_Frame_Parent (Interp.Stack, Insert_Frame(Interp.Self, Get_Frame_Parent(Interp.Stack), Opcode, Operand, Get_Frame_Environment(Interp.Stack), Interm)); end Push_Subframe_With_Intermediate; procedure Pop_Frame (Interp: in out Interpreter_Record) is pragma Inline (Pop_Frame); begin pragma Assert (Interp.Stack /= Interp.Root_Frame); pragma Assert (Interp.Stack /= Nil_Pointer); Interp.Stack := Interp.Stack.Pointer_Slot(Frame_Parent_Index); -- pop end Pop_Frame; procedure Return_Frame (Interp: in out Interpreter_Record; Value: in Object_Pointer) is pragma Inline (Return_Frame); begin -- Remove the current frame and return a value -- to a new active(top) frame. Pop_Frame (Interp); Set_Frame_Result (Interp.Stack, Value); end Return_Frame; procedure Execute (Interp: in out Interpreter_Record) is separate; procedure Evaluate (Interp: in out Interpreter_Record; Source: in Object_Pointer; Result: out Object_Pointer) is begin Result := Nil_Pointer; -- Perform some clean ups in case the procedure is called -- again after an exception is raised Clear_Tops (Interp); Interp.Stack := Interp.Root_Frame; Clear_Frame_Result (Interp.Stack); -- Push an actual frame for evaluation Push_Frame (Interp, Opcode_Evaluate_Object, Source); Execute (Interp); pragma Assert (Interp.Stack = Interp.Root_Frame); pragma Assert (Get_Frame_Opcode(Interp.Stack) = Opcode_Exit); Result := Get_Frame_Result(Interp.Stack); Clear_Frame_Result (Interp.Stack); end Evaluate; procedure Run_Loop (Interp: in out Interpreter_Record; Result: out Object_Pointer) is -- standard read-eval-print loop Aliased_Result: aliased Object_Pointer; begin pragma Assert (Interp.Base_Input.Stream /= null); DEBUG_GC := Standard.True; Result := Nil_Pointer; -- Perform some clean ups in case the procedure is called -- again after an exception is raised Clear_Tops (Interp); Interp.Stack := Interp.Root_Frame; Clear_Frame_Result (Interp.Stack); Push_Top (Interp, Aliased_Result'Unchecked_Access); loop pragma Assert (Interp.Stack = Interp.Root_Frame); pragma Assert (Get_Frame_Result(Interp.Stack) = Nil_Pointer); --Push_Frame (Interp, Opcode_Print_Result, Nil_Pointer); Push_Frame (Interp, Opcode_Evaluate_Result, Nil_Pointer); Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer); Execute (Interp); pragma Assert (Interp.Stack = Interp.Root_Frame); pragma Assert (Get_Frame_Opcode(Interp.Stack) = Opcode_Exit); Aliased_Result := Get_Frame_Result(Interp.Stack); Clear_Frame_Result (Interp.Stack); Ada.Text_IO.Put ("RESULT: "); Print (Interp, Aliased_Result); Ada.Text_IO.Put_Line (">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LOOP ITERATION XXXXXX CHECKPOINT"); end loop; -- Jump into the exception handler not to repeat the same code here. -- In fact, this part must not be reached since the loop above can't -- be broken. raise Stream_End_Error; exception when Stream_End_Error => -- this is not a real error. this indicates the end of input stream. Ada.Text_IO.Put_LINE ("=== BYE ==="); Pop_Tops (Interp, 1); if Aliased_Result /= null then Result := Aliased_Result; end if; when X: others => Ada.TEXT_IO.PUT_LINE ("ERROR ERROR ERROR -> " & Ada.Exceptions.Exception_Name(X)); raise; end Run_Loop; ----------------------------------------------------------------------------- -- -- function h2scm_open return Interpreter_Pointer; -- pragma Export (C, h2scm_open, "h2scm_open"); -- -- procedure h2scm_close (Interp: in out Interpreter_Pointer); -- pragma Export (C, h2scm_close, "h2scm_close"); -- -- function h2scm_evaluate (Interp: access Interpreter_Record; -- Source: in Object_Pointer) return Interfaces.C.int; -- pragma Export (C, h2scm_evaluate, "h2scm_evaluate"); -- -- procedure h2scm_dealloc is new -- Ada.Unchecked_Deallocation (Interpreter_Record, Interpreter_Pointer); -- -- function h2scm_open return Interpreter_Pointer is -- Interp: Interpreter_Pointer; -- begin -- begin -- Interp := new Interpreter_Record; -- exception -- when others => -- return null; -- end; -- -- begin -- Open (Interp.all, 1_000_000, null); -- exception -- when others => -- h2scm_dealloc (Interp); -- return null; -- end; -- -- return Interp; -- end h2scm_open; -- -- procedure h2scm_close (Interp: in out Interpreter_Pointer) is -- begin --Text_IO.Put_Line ("h2scm_close"); -- Close (Interp.all); -- h2scm_dealloc (Interp); -- end h2scm_close; -- -- function h2scm_evaluate (Interp: access Interpreter_Record; -- Source: in Object_Pointer) return Interfaces.C.int is -- begin -- return Interfaces.C.int(Interp.Heap(Interp.Current_Heap).Size); -- end h2scm_evaluate; end H2.Scheme;