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hcl/lib/h2-scheme.adb

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Ada
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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_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);
subtype Opcode_Type is Object_Integer range 0 .. 19;
Opcode_Exit: constant Opcode_Type := Opcode_Type'(0);
Opcode_Evaluate_Result: constant Opcode_Type := Opcode_Type'(1);
Opcode_Evaluate_Object: constant Opcode_Type := Opcode_Type'(2);
Opcode_Evaluate_Group: constant Opcode_Type := Opcode_Type'(3); -- (begin ...) and closure apply
Opcode_Finish_And_Syntax: constant Opcode_Type := Opcode_Type'(4);
Opcode_Finish_Define_Symbol: constant Opcode_Type := Opcode_Type'(5);
Opcode_Finish_If_Syntax: constant Opcode_Type := Opcode_Type'(6);
Opcode_Finish_Or_Syntax: constant Opcode_Type := Opcode_Type'(7);
Opcode_Finish_Set_Syntax: constant Opcode_Type := Opcode_Type'(8);
Opcode_Let_Binding: constant Opcode_Type := Opcode_Type'(9);
Opcode_Letast_Binding: constant Opcode_Type := Opcode_Type'(10);
Opcode_Let_Evaluation: constant Opcode_Type := Opcode_Type'(11);
Opcode_Let_Finish: constant Opcode_Type := Opcode_Type'(12);
Opcode_Apply: constant Opcode_Type := Opcode_Type'(13);
Opcode_Read_Object: constant Opcode_Type := Opcode_Type'(14);
Opcode_Read_List: constant Opcode_Type := Opcode_Type'(15);
Opcode_Read_List_Cdr: constant Opcode_Type := Opcode_Type'(16);
Opcode_Read_List_End: constant Opcode_Type := Opcode_Type'(17);
Opcode_Close_List: constant Opcode_Type := Opcode_Type'(18);
Opcode_Close_Quote: constant Opcode_Type := Opcode_Type'(19);
-----------------------------------------------------------------------------
-- 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 := 5;
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_Result_Index: constant Pointer_Object_Size := 5;
Mark_Object_Size: constant Pointer_Object_Size := 1;
Mark_Context_Index: constant Pointer_Object_Size := 1;
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;
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
-- Word: Object_Word;
-- for Word'Address use Pointer'Address;
--begin
-- return Word;
--end Pointer_To_Word;
pragma Inline (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: move away these utilities routines
--function To_Thin_Object_String_Pointer (Source: in Object_Pointer) return Thin_Object_String_Pointer is
-- type Character_Pointer is access all Object_Character;
-- Ptr: Thin_Object_String_Pointer;
-- X: Character_Pointer;
-- for X'Address use Ptr'Address;
-- pragma Import (Ada, X);
--begin
-- this method requires Object_Character_Array to have aliased Object_Character.
-- So i've commented out this function and turn to a different method below.
-- X := Source.Character_Slot(Source.Character_Slot'First)'Access;
-- return Ptr;
--end To_Thin_Object_String_Pointer;
--function To_Thin_Object_String_Pointer (Source: in Object_Pointer) return Thin_Object_String_Pointer is
-- function To_Thin_Pointer is new Ada.Unchecked_Conversion (System.Address, Thin_Object_String_Pointer);
--begin
-- return To_Thin_Pointer(Source.Character_Slot'Address);
--end To_Thin_Object_String_Pointer;
--function To_Thin_Object_String_Pointer (Source: in Object_Pointer) return Thin_Object_String_Pointer is
-- X: aliased Thin_Object_String;
-- for X'Address use Source.Character_Slot'Address;
--begin
-- return X'Unchecked_Access;
--end To_Thin_Object_String_Pointer;
--procedure Put_String (TS: in Thin_Object_String_Pointer);
--pragma Import (C, Put_String, "puts");
-- 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;
-----------------------------------------------------------------------------
-- 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;
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 out Heap_Element_Pointer;
Bytes: in Heap_Size) is
pragma Inline (Copy_Object_With_Size);
-- 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.
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);
begin
Tgt(Tgt'First .. Tgt'First + Bytes) := Src(Src'First .. Src'First + Bytes);
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);
-- 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
Object: Object_Pointer;
for Object'Address use Ptr'Address;
pragma Import (Ada, Object); -- not really needed
--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 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
--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] ROOT OBJECTS ...", Interp.Mark);
--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);
Interp.Mark := Move_One_Object(Interp.Mark);
-- 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;
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;
Stack: in Object_Pointer; -- current stack pointer
Opcode: in Object_Pointer;
Operand: in Object_Pointer;
Envir: in Object_Pointer) return Object_Pointer is
Frame: Object_Pointer;
Aliased_Stack: aliased Object_Pointer := Stack;
Aliased_Opcode: aliased Object_Pointer := Opcode;
Aliased_Operand: aliased Object_Pointer := Operand;
Aliased_Envir: aliased Object_Pointer := Envir;
begin
Push_Top (Interp.all, Aliased_Stack'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);
-- 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_Stack;
Frame.Pointer_Slot(Frame_Opcode_Index) := Aliased_Opcode;
Frame.Pointer_Slot(Frame_Operand_Index) := Aliased_Operand;
Frame.Pointer_Slot(Frame_Environment_Index) := Aliased_Envir;
--Print_Object_Pointer ("Make_Frame Result - ", Result);
Pop_Tops (Interp.all, 4);
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_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 out Object_Pointer;
Value: in Object_Pointer) is
pragma Inline (Set_Frame_Result);
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 (Is_Cons(Value));
begin
Frame.Pointer_Slot(Frame_Result_Index) := Value;
end Set_Frame_Result;
procedure Chain_Frame_Result (Interp: in out Interpreter_Record;
Frame: in Object_Pointer; -- TODO: remove this parameter
Value: in Object_Pointer) is
pragma Inline (Chain_Frame_Result);
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_Result_Index) :=
-- Make_Cons(Interp.Self, Value, Frame.Pointer_Slot(Frame_Result_Index));
--Pop_Tops (Interp, 1);
-- This seems to cause a problem if Interp.Stack changes in Make_Cons().
--Interp.Stack.Pointer_Slot(Frame_Result_Index) :=
-- Make_Cons(Interp.Self, Value, Interp.Stack.Pointer_Slot(Frame_Result_Index));
-- So, let's separate the evaluation and the assignment.
V := Make_Cons(Interp.Self, Value, Interp.Stack.Pointer_Slot(Frame_Result_Index));
Interp.Stack.Pointer_Slot(Frame_Result_Index) := V;
end Chain_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_Integer(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) := Integer_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;
-----------------------------------------------------------------------------
--
-- 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_Mark (Interp: access Interpreter_Record;
Context: in Object_Integer) return Object_Pointer is
Mark: Object_Pointer;
begin
-- TODO: allocate it in a static heap, not in a normal heap.
Mark := Allocate_Pointer_Object (Interp, Mark_Object_Size, Nil_Pointer);
Mark.Pointer_Slot(Mark_Context_Index) := Integer_To_Pointer(Context);
Mark.Tag := Mark_Object;
return Mark;
end Make_Mark;
-----------------------------------------------------------------------------
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;
-----------------------------------------------------------------------------
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, 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.Mark := Make_Mark(Interp.Self, 0); -- to indicate the end of cons evaluation
Interp.Root_Environment := Make_Environment(Interp.Self, Nil_Pointer);
Interp.Root_Frame := Make_Frame(Interp.Self, Nil_Pointer, Integer_To_Pointer(Opcode_Exit), Nil_Pointer, Interp.Root_Environment);
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 =>
Ada.Text_IO.Put ("#Continuation");
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);
elsif Atom.Tag = Mark_Object then
Ada.Text_IO.Put ("#INTERNAL MARK#");
else
Ada.Text_IO.Put ("#NOIMPL#");
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
ADA.TEXT_IO.PUT_LINE ("XXXXXXXXXXXXXXXXXXXXXXXXX NO PROINTING XXXXXXXXXXXXXXXXXXXXXXXxxx");
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); -- 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); -- 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); -- 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;
--Print_Object (Source);
Ada.Text_IO.New_Line;
end Print;
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;
procedure Push_Frame (Interp: in out Interpreter_Record;
Opcode: in Opcode_Type;
Operand: in Object_Pointer) is
pragma Inline (Push_Frame);
begin
Interp.Stack := Make_Frame(Interp.Self, Interp.Stack, Opcode_To_Pointer(Opcode),
Operand, Get_Frame_Environment(Interp.Stack));
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 := Make_Frame(Interp.Self, Interp.Stack, Opcode_To_Pointer(Opcode), Operand, Envir);
end Push_Frame_With_Environment;
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 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);
-- There must be only 1 value chained to the top-level frame
-- once evaluation is over.
pragma Assert (Get_Cdr(Result) = Nil_Pointer);
Result := Get_Car(Result); -- Get the only value chained
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
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);
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);
-- TODO: this result must be kept at some where that GC dowsn't sweep.
Result := Get_Frame_Result(Interp.Stack);
pragma Assert (Get_Cdr(Result) = Nil_Pointer);
Result := Get_Car(Result);
Clear_Frame_Result (Interp.Stack);
Ada.Text_IO.Put ("RESULT>>>>>");
Print (Interp, Result);
Ada.Text_IO.Put_Line (">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LOOP ITERATION XXXXXX CHECKPOINT");
end loop;
exception
when Stream_End_Error =>
-- this is not a real error. this indicates the end of input stream.
Ada.Text_IO.Put_LINE ("=== BYE ===");
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;
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