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hcl/lib/h2-scheme.adb

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Ada
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with H2.Pool;
with System.Address_To_Access_Conversions;
with H2.Scheme.Token;
with Ada.Unchecked_Deallocation; -- for h2scm c interface. TOOD: move it to a separate file
with Interfaces.C;
-- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx
with Ada.Characters.Handling;
with Ada.Characters.Conversions;
with Ada.Wide_Characters.Handling;
-- TODO: delete these after debugging
with ada.text_io;
with ada.wide_text_io;
-- TODO: delete above after debugging
-- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXx
package body H2.Scheme is
function To_Object_String (Item: in Standard.String) return Object_String renames Ada.Characters.Conversions.To_Wide_String;
package Text_IO renames ada.Wide_Text_IO;
-----------------------------------------------------------------------------
-- 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 overlayed 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 .. 11;
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_Evaluate_Procedure: constant Opcode_Type := Opcode_Type'(4);
Opcode_Apply: constant Opcode_Type := Opcode_Type'(5);
Opcode_Read_Object: constant Opcode_Type := Opcode_Type'(6);
Opcode_Read_List: constant Opcode_Type := Opcode_Type'(7);
Opcode_Read_List_Cdr: constant Opcode_Type := Opcode_Type'(8);
Opcode_Read_List_End: constant Opcode_Type := Opcode_Type'(9);
Opcode_Close_List: constant Opcode_Type := Opcode_Type'(10);
Opcode_Close_Quote: constant Opcode_Type := Opcode_Type'(11);
-----------------------------------------------------------------------------
-- 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_Stack_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);
-----------------------------------------------------------------------------
-- 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_Word_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_Word_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;
-- Check if a character object contains a given string in the payload.
function Match (Object: in Object_Pointer;
Data: in Object_String) return Standard.Boolean is
Slot: Object_Character_Array renames Object.Character_Slot;
begin
return Slot(Slot'First .. Slot'Last - 1) = Object_Character_Array(Data);
end;
procedure Copy_String (Source: in Object_String;
Target: out Object_Character_Array) is
begin
-- This procedure is not generic. The size of the Source
-- and Target must be in the expected length.
pragma Assert (Source'Length + 1 = Target'Length);
-- Method 1. Naive. It doesn't look Adaish.
-- ---------------------------------------------------------------------
--declare
-- x: Storage_Count;
--begin
-- x := Target'First;
-- for index in Source'Range loop
-- Target(x) := Source(index);
-- x := x + 1;
-- end loop;
-- Target(x) := Object_Character'First; -- Object_Character'Val(0);
--end;
-- Method 2.
-- ObjectAda complains that the member of Object_String is not
-- aliased because Object_Character_Array is an array of aliased
-- Object_Character.It points to LRM 4.6(12); The component subtypes
-- shall statically match.
-- ---------------------------------------------------------------------
--Target(Target'First .. Target'Last - 1) := Object_Character_Array (Source(Source'First .. Source'Last));
--Target(Target'Last) := Object_Character'First; -- Object_Character'Val(0);
-- Method 3. Use unchecked conversion
declare
subtype Character_Array is Object_Character_Array (Target'First .. Target'Last - 1);
function To_Character_Array is new Ada.Unchecked_Conversion (Object_String, Character_Array);
begin
Target(Target'First .. Target'Last - 1) := To_Character_Array (Source);
Target(Target'Last) := Object_Character'First; -- Object_Character'Val(0);
end;
end Copy_String;
procedure Copy_String (Source: in Object_Character_Array;
Target: out Object_String) is
begin
pragma Assert (Source'Length = Target'Length + 1);
declare
subtype Character_Array is Object_Character_Array (Source'First .. Source'Last - 1);
subtype String_Array is Object_String (Target'Range);
function To_Character_Array is new Ada.Unchecked_Conversion (Character_Array, String_Array);
begin
Target := To_Character_Array (Source (Source'First .. Source'Last - 1));
end;
end Copy_String;
function Character_Array_To_String (Source: in Object_Character_Array) return Object_String is
begin
-- ObjectAda complains that the member of Object_String is not
-- aliased because Object_Character_Array is an array of aliased
-- Object_Character. It points to LRM 4.6(12); The component subtypes
-- shall statically match. So let me turn to unchecked conversion.
declare
subtype Character_Array is Object_Character_Array (Source'First .. Source'Last - 1);
subtype String_Array is Object_String (1 .. Source'Length - 1);
function To_Character_Array is new Ada.Unchecked_Conversion (Character_Array, String_Array);
begin
return To_Character_Array (Source (Source'First .. Source'Last - 1));
--return String_Array (Source (Source'First .. Source'Last - 1));
end;
end Character_Array_To_String;
-- TODO: move away these utilities routines
--function To_Thin_String_Pointer (Source: in Object_Pointer) return Thin_String_Pointer is
-- type Character_Pointer is access all Object_Character;
-- Ptr: Thin_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_String_Pointer;
--function To_Thin_String_Pointer (Source: in Object_Pointer) return Thin_String_Pointer is
-- function To_Thin_Pointer is new Ada.Unchecked_Conversion (System.Address, Thin_String_Pointer);
--begin
-- return To_Thin_Pointer(Source.Character_Slot'Address);
--end To_Thin_String_Pointer;
function To_Thin_String_Pointer (Source: in Object_Pointer) return Thin_String_Pointer is
X: aliased Thin_String;
for X'Address use Source.Character_Slot'Address;
begin
return X'Unchecked_Access;
end To_Thin_String_Pointer;
procedure Put_String (TS: in Thin_String_Pointer);
pragma Import (C, Put_String, "puts");
-- TODO: delete this procedure
procedure Print_Object_Pointer (Msg: in Object_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
Text_IO.Put_Line (Msg & To_Object_String(Object_Character'Image(Pointer_To_Character(Source))));
elsif Ptr_Type = Object_Pointer_Type_Integer then
Text_IO.Put_Line (Msg & To_Object_String(Object_Integer'Image(Pointer_To_Integer(Source))));
elsif Is_Special_Pointer (Source) then
Text_IO.Put_Line (Msg & " at " & To_Object_String(Object_Word'Image(W)));
elsif Source.Kind = Character_Object then
Text_IO.Put (Msg & " at " & To_Object_String(Object_Word'Image(W)) &
" at " & To_Object_String(Object_Kind'Image(Source.Kind)) &
" size " & To_Object_String(Object_Size'Image(Source.Size)) & " - ");
if Source.Kind = Moved_Object then
Text_IO.Put_Line (Character_Array_To_String (Get_New_Location(Source).Character_Slot));
else
Text_IO.Put_Line (Character_Array_To_String (Source.Character_Slot));
end if;
else
Text_IO.Put_Line (Msg & " at " & To_Object_String(Object_Word'Image(W)) & " at " & To_Object_String(Object_Kind'Image(Source.Kind)));
end if;
end Print_Object_Pointer;
function String_To_Integer_Pointer (Source: in Object_String) return Object_Pointer is
V: Object_Integer := 0;
Negative: Standard.Boolean := False;
First: Standard.Natural;
begin
-- TODO: BIGNUM, RANGE CHECK, ETC
pragma Assert (Source'Length > 0);
First := Source'First;
if Source(First) = '-' then
First := First + 1;
Negative := Standard.True;
elsif Source(First) = '+' then
First := First + 1;
end if;
for I in First .. Source'Last loop
V := V * 10 + Object_Character'Pos(Source(I)) - Object_Character'Pos('0');
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 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;
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(1..Bytes) := Src(1..Bytes);
end Copy_Object_With_Size;
procedure Collect_Garbage (Interp: in out Interpreter_Record) is
Last_Pos: Heap_Size;
New_Heap: Heap_Number;
--function To_Object_Pointer is new Ada.Unchecked_Conversion (Heap_Element_Pointer, Object_Pointer);
function Move_One_Object (Object: in Object_Pointer) return Object_Pointer is
begin
if Is_Special_Pointer (Object) then
Print_Object_Pointer ("Moving special ...", Object);
return Object;
end if;
if Object.Kind = Moved_Object then
Print_Object_Pointer ("Moving NOT ...", Object);
-- 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 (Object);
else
Print_Object_Pointer ("Moving REALLY ...", Object);
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 := Object.all'Size / System.Storage_Unit;
-- Allocate space in the new heap
Ptr := Allocate_Bytes_In_Heap (
Heap => Interp.Heap(New_Heap),
Heap_Bytes => 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 (Object, Ptr, Bytes); -- use this instead
pragma Assert (Object.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 (Object, Ptr);
Ada.Text_IO.Put_Line (Object_Word'Image(Pointer_To_Word(Object)) & Object_Word'Image(Pointer_To_Word(New_Object)));
Ada.Text_IO.Put_Line (" Flags....after " & Object_Kind'Image(Object.Kind) & " New Size " & Object_Size'Image(Object.Size) & " New Loc: " & Object_Word'Image(Pointer_To_Word(Object.New_Pointer)));
-- 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;
begin
Position := Start_Position;
--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
--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;
--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));
if Object.Kind = Pointer_Object then
for i in Object.Pointer_Slot'Range loop
if Is_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;
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);
declare
Car: Object_Pointer renames Cons.Pointer_Slot(Cons_Car_Index);
Cdr: Object_Pointer renames Cons.Pointer_Slot(Cons_Cdr_Index);
begin
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.
Text_IO.Put_Line ("COMPACT_SYMBOL_TABLE Unlinking " & Character_Array_To_String (Car.Character_Slot));
if Pred = Nil_Pointer then
Interp.Symbol_Table := Cdr;
else
Pred.Pointer_Slot(Cons_Cdr_Index) := Cdr;
end if;
end if;
Cons := Cdr;
end;
end loop;
end Compact_Symbol_Table;
begin
-- 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 objects in the root table
Print_Object_Pointer ("Root_Table ...", Interp.Root_Table);
Interp.Root_Table := Move_One_Object (Interp.Root_Table);
Interp.Mark := Move_One_Object (Interp.Mark);
-- Scane 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
Text_IO.Put_Line (">>> [COMPACTING SYMBOL TABLE]");
Compact_Symbol_Table;
Print_Object_Pointer (">>> [MOVING SYMBOL TABLE]", Interp.Symbol_Table);
-- Migrate the symbol table itself
Interp.Symbol_Table := Move_One_Object (Interp.Symbol_Table);
Text_IO.Put_Line (">>> [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;
Text_IO.Put_Line (">>> [GC DONE]");
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);
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 => Object_Character'First)
);
return Result;
end Allocate_Character_Object;
function Allocate_Character_Object (Interp: access Interpreter_Record;
Source: in Object_String) 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));
Copy_String (Source, Result.Character_Slot);
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;
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;
end if;
return Get_New_Location(Source);
end Verify_Pointer;
-----------------------------------------------------------------------------
function Make_Cons (Interp: access Interpreter_Record;
Car: in Object_Pointer;
Cdr: in Object_Pointer) return Object_Pointer is
Cons: Object_Pointer;
begin
Cons := Allocate_Pointer_Object (Interp, Cons_Object_Size, Nil_Pointer);
Cons.Pointer_Slot(Cons_Car_Index) := Verify_Pointer(Car); -- TODO: is this really a good idea? resise this...
Cons.Pointer_Slot(Cons_Cdr_Index) := Verify_Pointer(Cdr); -- If so, use Verify_pointer after Allocate_XXX
Cons.Tag := Cons_Object;
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 out 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 out 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 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 := Nil_Pointer;
Prev := Last_Cdr;
Ptr := Source;
loop
Next := Get_Cdr(Ptr);
Set_Cdr (Ptr, Prev);
Prev := Ptr;
if Is_Cons(Next) then
Ptr := Next;
else
exit;
end if;
end loop;
return Ptr;
end Reverse_Cons;
-----------------------------------------------------------------------------
function Make_String (Interp: access Interpreter_Record;
Source: in Object_String) return Object_Pointer is
Result: Object_Pointer;
begin
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_String) return Object_Pointer is
Ptr: 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
--Text_IO.Put_Line (Car.Kind'Img & Car.Tag'Img & Object_Word'Image(Pointer_To_Word(Car)));
pragma Assert (Car.Tag = Symbol_Object);
if Match(Car, Source) then
return Car;
--Print_Object_Pointer ("Make_Symbol Result (Existing) - " & Source, Car);
end if;
Ptr := Cdr;
end;
end loop;
--Text_IO.Put_Line ("Creating a symbol .. " & Source);
-- Create a symbol object
Ptr := Allocate_Character_Object (Interp, Source);
Ptr.Tag := Symbol_Object;
-- TODO: ensure that Result is not reclaimed by GC.
-- Make it GC-aweare. Protect Ptr
-- Link the symbol to the symbol table.
Interp.Symbol_Table := Make_Cons (Interp.Self, Ptr, Interp.Symbol_Table);
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;
-----------------------------------------------------------------------------
--
-- 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.
--
-- Interp.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, Interp.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. note that it's not Nil_Pointer.
end Find_In_Environment_List;
procedure Set_Environment (Interp: in out Interpreter_Record;
Key: in Object_Pointer;
Value: in Object_Pointer) is
Arr: Object_Pointer;
begin
pragma Assert (Is_Symbol(Key));
Arr := Find_In_Environment_List(Interp.Self, Get_Car(Interp.Environment), Key);
if Arr = null then
-- Add a new key/value pair
-- TODO: make it GC-aware - protect Key and Value
Arr := Make_Array (Interp.Self, 3);
Arr.Pointer_Slot(1) := Key;
Arr.Pointer_Slot(2) := Value;
-- Chain the pair to the head of the list
Arr.Pointer_Slot(3) := Get_Car(Interp.Environment);
Set_Car (Interp.Environment, Arr);
else
-- overwrite an existing pair
Arr.Pointer_Slot(2) := Value;
end if;
end Set_Environment;
function Get_Environment (Interp: access Interpreter_Record;
Key: in Object_Pointer) return Object_Pointer is
Envir: Object_Pointer;
Arr: Object_Pointer;
begin
Envir := Interp.Environment;
while Envir /= Nil_Pointer loop
pragma Assert (Is_Cons(Envir));
Arr := Find_In_Environment_List(Interp, Get_Car(Envir), Key);
if Arr /= Nil_Pointer 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;
procedure Push_Environment (Interp: in out Interpreter_Record) is
pragma Inline (Push_Environment);
pragma Assert (Is_Cons(Interp.Environment));
begin
Interp.Environment := Make_Environment (Interp.Self, Interp.Environment);
end Push_Environment;
procedure Pop_Environment (Interp: in out Interpreter_Record) is
pragma Inline (Pop_Environment);
pragma Assert (Is_Cons(Interp.Environment));
begin
Interp.Environment := Get_Cdr(Interp.Environment);
end Pop_Environment;
-----------------------------------------------------------------------------
function Make_Syntax (Interp: access Interpreter_Record;
Opcode: in Syntax_Code;
Name: in Object_String) return Object_Pointer is
Result: Object_Pointer;
begin
Result := Make_Symbol (Interp, Name);
Result.Flags := Result.Flags or Syntax_Object;
Result.Scode := Opcode;
Text_IO.Put ("Creating Syntax Symbol ");
Put_String (To_Thin_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_String) return Object_Pointer is
-- this procedure is for internal use only
Symbol: Object_Pointer;
Proc: Object_Pointer;
begin
-- TODO: make temporaries GC-aware
-- 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 (Interp.Environment = Interp.Root_Environment);
pragma Assert (Get_Environment (Interp.Self, Symbol) = null);
Set_Environment (Interp.all, Symbol, Proc);
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_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;
begin
-- 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_Stack_Index) := Stack;
Frame.Pointer_Slot(Frame_Opcode_Index) := Opcode;
Frame.Pointer_Slot(Frame_Operand_Index) := Operand;
Frame.Pointer_Slot(Frame_Environment_Index) := Envir;
--Print_Object_Pointer ("Make_Frame Result - ", Result);
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));
--begin
-- Frame.Pointer_Slot(Frame_Result_Index) := Value;
--end Set_Frame_Result;
procedure Chain_Frame_Result (Interp: in out Interpreter_Record;
Frame: in out Object_Pointer;
Value: in Object_Pointer) is
pragma Inline (Chain_Frame_Result);
pragma Assert (Is_Frame(Frame));
Ret_Head: Object_Pointer renames Frame.Pointer_Slot(Frame_Result_Index);
begin
-- TODO: make it GC-aware
-- Add a new cons cell to the front
Ret_Head := Make_Cons (Interp.Self, Value, Ret_Head);
end Chain_Frame_Result;
procedure Clear_Frame_Result (Frame: in out 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;
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 out 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 Make_Mark (Interp: access Interpreter_Record;
Context: in Object_Integer) return Object_Pointer is
Mark: Object_Pointer;
begin
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;
begin
Closure := Allocate_Pointer_Object (Interp, Closure_Object_Size, Nil_Pointer);
Closure.Tag := Closure_Object;
Closure.Pointer_Slot(Closure_Code_Index) := Code;
Closure.Pointer_Slot(Closure_Environment_Index) := Envir;
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: in Constant_Object_String_Pointer) 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 => ' '),
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, "and");
Dummy := Make_Syntax (Interp.Self, Begin_Syntax, "begin");
Dummy := Make_Syntax (Interp.Self, Case_Syntax, "case");
Dummy := Make_Syntax (Interp.Self, Cond_Syntax, "cond");
Dummy := Make_Syntax (Interp.Self, Define_Syntax, "define");
Dummy := Make_Syntax (Interp.Self, If_Syntax, "if");
Dummy := Make_Syntax (Interp.Self, Lambda_Syntax, "lambda");
Dummy := Make_Syntax (Interp.Self, Let_Syntax, "let");
Dummy := Make_Syntax (Interp.Self, Letast_Syntax, "let*");
Dummy := Make_Syntax (Interp.Self, Letrec_Syntax, "letrec");
Dummy := Make_Syntax (Interp.Self, Or_Syntax, "or");
Dummy := Make_Syntax (Interp.Self, Quote_Syntax, "quote");
Dummy := Make_Syntax (Interp.Self, Set_Syntax, "set!");
end Make_Syntax_Objects;
procedure Make_Procedure_Objects is
Dummy: Object_Pointer;
begin
Dummy := Make_Procedure (Interp.Self, Car_Procedure, "car");
Dummy := Make_Procedure (Interp.Self, Cdr_Procedure, "cdr");
Dummy := Make_Procedure (Interp.Self, Setcar_Procedure, "setcar");
Dummy := Make_Procedure (Interp.Self, Setcdr_Procedure, "setcdr");
Dummy := Make_Procedure (Interp.Self, Add_Procedure, "+");
Dummy := Make_Procedure (Interp.Self, Subtract_Procedure, "-");
Dummy := Make_Procedure (Interp.Self, Multiply_Procedure, "*");
Dummy := Make_Procedure (Interp.Self, Divide_Procedure, "/");
end Make_Procedure_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.Root_Table := Nil_Pointer;
Interp.Symbol_Table := Nil_Pointer;
Interp.Base_Input.Stream := null;
Interp.Input := Interp.Base_Input'Unchecked_Access;
Interp.Token := (End_Token, (null, 0, 0));
-- TODO: disallow garbage collecion during initialization.
Text_IO.Put_Line ("1111111111");
Initialize_Heap (Initial_Heap_Size);
Interp.Mark := Make_Mark (Interp.Self, 0); -- to indicate the end of cons evluation
Interp.Root_Environment := Make_Environment (Interp.Self, Nil_Pointer);
Interp.Environment := Interp.Root_Environment;
Make_Syntax_Objects;
Make_Procedure_Objects;
Text_IO.Put_Line ("99999");
Text_IO.Put_Line (To_Object_String(IO_Character_Record'Size'Img));
Text_IO.Put_Line (To_Object_String(IO_Character_Record'Max_Size_In_Storage_Elements'Img));
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 =>
Text_IO.Put ("()");
when True_Word =>
Text_IO.Put ("#t");
when False_Word =>
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 =>
Text_IO.Put (Character_Array_To_String (Atom.Character_Slot));
when String_Object =>
Text_IO.Put ("""");
Text_IO.Put (Character_Array_To_String (Atom.Character_Slot));
Text_IO.Put ("""");
when Closure_Object =>
Text_IO.Put ("#Closure");
when Continuation_Object =>
Text_IO.Put ("#Continuation");
when Procedure_Object =>
Text_IO.Put ("#Procedure");
when Array_Object =>
Text_IO.Put ("#Array");
when Others =>
if Atom.Kind = Character_Object then
Text_IO.Put (Character_Array_To_String (Atom.Character_Slot));
else
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
Text_IO.Put (To_Object_String(Object_Integer'Image(X)));
end Print_Integer;
procedure Print_Character is
X: constant Object_Character := Pointer_To_Character (Atom);
begin
Text_IO.Put (To_OBject_String(Object_Character'Image(X)));
end Print_Character;
procedure Print_Byte is
X: constant Object_Byte := Pointer_To_Byte (Atom);
begin
Text_IO.Put (To_Object_String(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;
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
Text_IO.Put (" ");
Cons := Cdr;
exit when Cons = Nil_Pointer;
else
if Cdr /= Nil_Pointer then
Text_IO.Put (" . ");
Print_Atom (Cdr);
end if;
exit;
end if;
end loop;
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
-- 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
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_Stack_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
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.
Text_IO.Put (" . ");
Print_Atom (Operand);
end if;
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_Stack_Index); -- pop
end if;
end if;
when others =>
exit;
end case;
end loop;
--Print_Object (Source);
Text_IO.New_Line;
end Print;
procedure Evaluatex (Interp: in out Interpreter_Record) is
X: Object_Pointer;
begin
--Make_Cons (Interpreter, Nil_Pointer, Nil_Pointer, X);
--Make_Cons (Interpreter, Nil_Pointer, X, X);
--Make_Cons (Interpreter, Nil_Pointer, X, X);
--Make_Cons (Interpreter, Nil_Pointer, X, X);
Interp.Root_Table := Make_Symbol (Interp.Self, "lambda");
--Print_Object_Pointer (">>> Root_Table ...", Interp.Root_Table);
Collect_Garbage (Interp);
-- (define x 10)
X := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "define"),
Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "x"),
Make_Cons (
Interp.Self,
Integer_To_Pointer (10),
--Nil_Pointer
Integer_To_Pointer (10)
)
)
);
X := Make_Cons (Interp.Self, X, Make_Cons (Interp.Self, X, Integer_To_Pointer(10)));
--X := Make_Cons (Interp.Self, Nil_Pointer, Make_Cons (Interp.Self, Nil_Pointer, Integer_To_Pointer(TEN)));
--X := Make_Cons (Interp.Self, Nil_Pointer, Nil_Pointer);
--Read (Interp, X);
Print (Interp, X);
end Evaluatex;
procedure Make_Test_Object (Interp: in out Interpreter_Record; Result: out Object_Pointer) is
Y: Object_Pointer;
Z: Object_Pointer;
P: Object_Pointer;
B: Object_Pointer;
L: Object_Pointer;
Resultx: Object_Pointer;
begin
--(define x 10)
--Result := Make_Cons (
-- Interp.Self,
-- Make_Symbol (Interp.Self, "define"),
-- Make_Cons (
-- Interp.Self,
-- Make_Symbol (Interp.Self, "x"),
-- Make_Cons (
-- Interp.Self,
-- Integer_To_Pointer (10),
-- --Nil_Pointer
-- Integer_To_Pointer (10)
-- )
-- )
--);
Z := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "+"),
Make_Cons (
Interp.Self,
Integer_To_Pointer (3),
Make_Cons (
Interp.Self,
Integer_To_Pointer (9),
Nil_Pointer
)
)
);
Y := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "+"),
Make_Cons (
Interp.Self,
Integer_To_Pointer (100),
Make_Cons (
Interp.Self,
Z,
Nil_Pointer
)
)
);
Result := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "+"),
Make_Cons (
Interp.Self,
--Integer_To_Pointer (10),
Y,
Make_Cons (
Interp.Self,
Integer_To_Pointer (-5),
Make_Cons (
Interp.Self,
Y,
Integer_To_Pointer (20)
)
)
)
);
Z := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "begin"),
Make_COns (Interp.Self, Y, Nil_Pointer)
);
B := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "begin"),
Make_Cons (Interp.Self, Z, Nil_Pointer)
);
Result := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "+"),
Make_Cons (Interp.Self, Integer_To_Pointer(88), Make_Cons (Interp.Self, B, Nil_Pointer))
);
-- (lambda (x y) (+ x y))
P := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "x"),
Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "y"),
Nil_Pointer
)
);
B := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "+"),
Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "x"),
Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, "y"),
Nil_Pointer
)
)
);
L := Make_Cons (
Interp.Self,
Make_Symbol (Interp.Self, Object_String'("lambda")),
Make_Cons (
Interp.Self,
P,
Make_Cons (
Interp.Self,
B,
Nil_pointer
)
)
);
Result := Make_Cons (
Interp.Self,
L,
Make_Cons (
Interp.Self,
Integer_To_Pointer (9),
Make_Cons (
Interp.Self,
Integer_To_Pointer (7),
Nil_Pointer
)
)
);
Text_IO.PUt ("TEST OBJECT: ");
Print (Interp, Result);
end Make_Test_Object;
function Pointer_To_Opcode (Pointer: in Object_Pointer) return Opcode_Type is
pragma Inline (Pointer_To_Opcode);
begin
return 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);
end Opcode_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, Interp.Environment);
end Push_Frame;
--procedure Pop_Frame (Interp.Stack: out Object_Pointer;
-- Opcode: out Opcode_Type;
-- Operand: out Object_Pointer) is
-- pragma Inline (Pop_Frame);
--begin
-- pragma Assert (Interp.Stack /= Nil_Pointer);
-- Opcode := Pointer_To_Opcode(Interp.Stack.Pointer_Slot(Frame_Opcode_Index));
-- Operand := Interp.Stack.Pointer_Slot(Frame_Operand_Index);
-- Interp.Stack := Interp.Stack.Pointer_Slot(Frame_Stack_Index); -- pop
--end Pop_Frame;
procedure Pop_Frame (Interp: in out Interpreter_Record) is
pragma Inline (Pop_Frame);
begin
pragma Assert (Interp.Stack /= Nil_Pointer);
Interp.Environment := Interp.Stack.Pointer_Slot(Frame_Environment_Index); -- restore environment
Interp.Stack := Interp.Stack.Pointer_Slot(Frame_Stack_Index); -- pop
end Pop_Frame;
procedure Execute (Interp: in out Interpreter_Record) is
LC: IO_Character_Record renames Interp.Input.Iochar;
procedure Evaluate_Result is
pragma Inline (Evaluate_Result);
begin
-- The result from the previous frame is stored in the current frame.
-- This procedure takes the result and switch it to an operand and clears it.
-- It is used to evaluate the result of Read_Object in principle.
-- It takes only the head(car) element of the result chain.
-- Calling this function to evaluate the result of any arbitrary frame
-- other than 'Read_Object' is not recommended.
Set_Frame_Operand (Interp.Stack, Get_Car(Get_Frame_Result(Interp.Stack)));
Clear_Frame_Result (Interp.Stack);
Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Object);
end Evaluate_Result;
procedure Evaluate_Group is
pragma Inline (Evaluate_Group);
Operand: Object_Pointer;
Car: Object_Pointer;
Cdr: Object_Pointer;
begin
Operand := Get_Frame_Operand(Interp.Stack);
pragma Assert (Is_Normal_Pointer(Operand));
case Operand.Tag is
when Cons_Object =>
Car := Get_Car(Operand);
Cdr := Get_Cdr(Operand);
if Is_Cons(Cdr) then
-- Let the current frame remember the next expression list
Set_Frame_Operand (Interp.Stack, Cdr);
else
if Cdr /= Nil_Pointer then
-- The last CDR is not Nil.
Text_IO.Put_Line ("$$$$..................FUCKING CDR. FOR GROUP....................$$$$");
-- raise Syntax_Error;
end if;
-- Change the operand to a mark object so that the call to this
-- procedure after the evaluation of the last car goes to the
-- Mark_Object case.
Set_Frame_Operand (Interp.Stack, Interp.Mark);
end if;
-- Clear the return value from the previous expression.
Clear_Frame_Result (Interp.Stack);
-- Arrange to evaluate the current expression
Push_Frame (Interp, Opcode_Evaluate_Object, Car);
when Mark_Object =>
Operand := Get_Frame_Result (Interp.Stack);
Pop_Frame (Interp); -- Done
-- There must be only 1 return value chained in the Group frame.
pragma Assert (Get_Cdr(Operand) = Nil_Pointer);
-- Transfer the only return value to the upper chain
Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
when others =>
raise Internal_Error;
end case;
end Evaluate_Group;
procedure Evaluate_Object is
pragma Inline (Evaluate_Object);
Operand: Object_Pointer;
Car: Object_Pointer;
Cdr: Object_Pointer;
begin
<<Start_Over>>
Operand := Get_Frame_Operand(Interp.Stack);
if not Is_Normal_Pointer(Operand) then
-- integer, character, specal pointers
-- TODO: some normal pointers may point to literal objects. e.g.) bignum
goto Literal;
end if;
case Operand.Tag is
when Symbol_Object => -- Is_Symbol(Operand)
-- TODO: find it in the Environment hierarchy.. not in the current environemnt.
Car := Get_Environment (Interp.Self, Operand);
if Car = null then
-- unbound
Text_IO.Put_Line ("Unbound symbol....");
Print (Interp, Operand);
raise Evaluation_Error;
else
-- symbol found in the environment
Operand := Car;
goto Literal; -- In fact, this is not a literal, but can be handled in the same way
end if;
when Cons_Object => -- Is_Cons(Operand)
Car := Get_Car(Operand);
Cdr := Get_Cdr(Operand);
if Is_Syntax(Car) then
-- special syntax symbol. normal evaluate rule doesn't
-- apply for special syntax objects.
case Car.Scode is
when Begin_Syntax =>
Operand := Cdr; -- Skip "begin"
if not Is_Cons(Operand) then
-- e.g) (begin)
-- (begin . 10)
Text_IO.Put_LINE ("FUCKNING CDR FOR BEGIN");
raise Syntax_Error;
--Pop_Frame (Interp); -- Done
else
Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Group);
Set_Frame_Operand (Interp.Stack, Operand);
if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
-- I call Evaluate_Group for optimization here.
Evaluate_Group; -- for optimization only. not really needed.
-- I can jump to Start_Over because Evaluate_Group called
-- above pushes an Opcode_Evaluate_Object frame.
pragma Assert (Get_Frame_Opcode(Interp.Stack) = Opcode_Evaluate_Object);
goto Start_Over; -- for optimization only. not really needed.
end if;
end if;
when Define_Syntax =>
-- (define x 10)
-- (define (add x y) (+ x y)) -> (define add (lambda (x y) (+ x y)))
Operand := Cdr; -- Skip "define"
if not Is_Cons(Operand) then
-- e.g) (define)
-- (define . 10)
Text_IO.Put_LINE ("FUCKNING CDR FOR DEFINE");
raise Syntax_Error;
elsif Get_Cdr(Operand) /= Nil_Pointer then
-- TODO: IMPLEMENT OTHER CHECK
end if;
--Pop_Frame (Interp); -- Done
--Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
-- TODO: IMPLEMENT DEFINE.
when Lambda_Syntax =>
-- (lambda (x y) (+ x y));
Operand := Cdr; -- Skip "lambda"
if not Is_Cons(Operand) then
-- e.g) (lambda)
-- (lambda . 10)
Text_IO.Put_LINE ("FUCKNING CDR FOR BEGIN");
raise Syntax_Error;
--Pop_Frame (Interp); -- Done
else
if not Is_Cons(Get_Car(Operand)) then
Text_IO.Put_Line ("INVALID PARRAMETER LIST");
raise Syntax_Error;
--Pop_Frame (Interp); -- Done
end if;
--Print (Interp, Get_Cdr(Operand));
if not Is_Cons(Get_Cdr(Operand)) then
Text_IO.Put_Line ("NO BODY");
raise Syntax_Error;
--Pop_Frame (Interp); -- Done
end if;
declare
Closure: Object_Pointer;
begin
Closure := Make_Closure (Interp.Self, Operand, Interp.Environment);
Pop_Frame (Interp); -- Done
Chain_Frame_Result (Interp, Interp.Stack, Closure);
end;
end if;
when Quote_Syntax =>
Operand := Cdr; -- Skip "quote"
if not Is_Cons(Operand) then
-- e.g) (quote)
-- (quote . 10)
Text_IO.Put_LINE ("FUCKNING CDR FOR QUOTE");
raise Syntax_Error;
elsif Get_Cdr(Operand) /= Nil_Pointer then
Text_IO.Put_LINE ("WRONG NUMBER OF ARGUMENTS FOR QUOTE");
raise Syntax_Error;
end if;
Pop_Frame (Interp); -- Done
Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
when others =>
Text_IO.Put_Line ("Unknown syntax");
Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Syntax); -- Switch to syntax evaluation
end case;
else
if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
while not Is_Normal_Pointer(Car) loop
-- This while block is for optimization only. It's not really needed.
-- If I know that the next object to evaluate is a literal object,
-- I can simply reverse-chain it to the return field of the current
-- frame without pushing another frame dedicated for it.
-- TODO: some normal pointers may point to a literal object. e.g.) bignum
Chain_Frame_Result (Interp, Interp.Stack, Car);
if Is_Cons(Cdr) then
Operand := Cdr;
Car := Get_Car(Operand);
Cdr := Get_Cdr(Operand);
else
-- last cons
Operand := Reverse_Cons(Get_Frame_Result(Interp.Stack));
Clear_Frame_Result (Interp.Stack);
Set_Frame_Opcode (Interp.Stack, Opcode_Apply);
Set_Frame_Operand (Interp.Stack, Operand);
return;
end if;
end loop;
end if;
if Is_Cons(Cdr) then
-- Not the last cons cell yet
Set_Frame_Operand (Interp.Stack, Cdr); -- change the operand for the next call
else
-- Reached the last cons cell
if Cdr /= Nil_Pointer then
-- The last CDR is not Nil.
Text_IO.Put_Line ("$$$$..................FUCKING CDR.....................$$$$");
-- raise Syntax_Error;
end if;
-- Change the operand to a mark object so that the call to this
-- procedure after the evaluation of the last car goes to the
-- Mark_Object case.
Set_Frame_Operand (Interp.Stack, Interp.Mark);
end if;
-- Arrange to evaluate the car object
if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
Push_Frame (Interp, Opcode_Evaluate_Object, Car);
goto Start_Over; -- for optimization only. not really needed.
end if;
end if;
when Mark_Object =>
-- TODO: you can use the mark context to differentiate context
-- Get the evaluation result stored in the current stack frame by
-- various sub-Opcode_Evaluate_Object frames. the return value
-- chain must be reversed Chain_Frame_Result reverse-chains values.
Operand := Reverse_Cons(Get_Frame_Result(Interp.Stack));
-- Refresh the current stack frame to Opcode_Apply.
-- This should be faster than Popping the current frame and pushing
-- a new frame.
-- Envir := Get_Frame_Environment(Interp.Stack);
-- Pop_Frame (Interp); -- done
-- Push_Frame (Interp, Opcode_Apply, Operand, Envir);
Clear_Frame_Result (Interp.Stack);
Set_Frame_Opcode (Interp.Stack, Opcode_Apply);
Set_Frame_Operand (Interp.Stack, Operand);
when others =>
-- normal literal object
goto Literal;
end case;
return;
<<Literal>>
Pop_Frame (Interp); -- done
Text_IO.Put ("Return => ");
Print (Interp, Operand);
Chain_Frame_Result (Interp, Interp.Stack, Operand);
end Evaluate_Object;
procedure Evaluate_Procedure is
pragma Inline (Evaluate_Procedure);
begin
null;
end Evaluate_Procedure;
procedure Apply is
pragma Inline (Apply);
Operand: Object_Pointer;
Func: Object_Pointer;
Args: Object_Pointer;
procedure Apply_Car_Procedure is
begin
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Args));
end Apply_Car_Procedure;
procedure Apply_Cdr_Procedure is
begin
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, Get_Cdr(Args));
end Apply_Cdr_Procedure;
procedure Apply_Add_Procedure is
Ptr: Object_Pointer := Args;
Num: Object_Integer := 0; -- TODO: support BIGNUM
Car: Object_Pointer;
begin
while Ptr /= Nil_Pointer loop
-- TODO: check if car is an integer or bignum or something else.
-- if something else, error
Car := Get_Car(Ptr);
if not Is_Integer(Car) then
Ada.Text_IO.Put ("NOT INTEGER FOR ADD"); Print (Interp, Car);
raise Evaluation_Error;
end if;
Num := Num + Pointer_To_Integer(Car);
Ptr := Get_Cdr(Ptr);
end loop;
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, Integer_To_Pointer(Num));
end Apply_Add_Procedure;
procedure Apply_Subtract_Procedure is
Ptr: Object_Pointer := Args;
Num: Object_Integer := 0; -- TODO: support BIGNUM
Car: Object_Pointer;
begin
if Ptr /= Nil_Pointer then
Car := Get_Car(Ptr);
if not Is_Integer(Car) then
raise Evaluation_Error;
end if;
Num := Pointer_To_Integer(Car);
while Ptr /= Nil_Pointer loop
-- TODO: check if car is an integer or bignum or something else.
-- if something else, error
Car := Get_Car(Ptr);
if not Is_Integer(Car) then
raise Evaluation_Error;
end if;
Num := Num - Pointer_To_Integer(Car);
Ptr := Get_Cdr(Ptr);
end loop;
end if;
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, Integer_To_Pointer(Num));
end Apply_Subtract_Procedure;
procedure Apply_Closure is
Fbody: Object_Pointer;
Param: Object_Pointer;
Arg: Object_Pointer;
begin
-- For a closure created of "(lambda (x y) (+ x y) (* x y))"
-- Get_Closure_Code(Func) returns "((x y) (+ x y) (* x y))"
-- Push a new environmen for the closure
Interp.Environment := Make_Environment (Interp.Self, Get_Closure_Environment(Func));
-- TODO: GC. Func may be invalid if GC has been invoked.
Fbody := Get_Closure_Code(Func);
pragma Assert (Is_Cons(Fbody)); -- the reader must ensure this.
Param := Get_Car(Fbody); -- Parameter list
--Arg := Get_Car(Args); -- Actual argument list
Arg := Args; -- Actual argument list
Fbody := Get_Cdr (Fbody); -- Real function body
pragma Assert (Is_Cons(Fbody)); -- the reader must ensure this as wel..
while Is_Cons(Param) loop
if not Is_Cons(Arg) then
Print (Interp, Arg);
Text_IO.Put_Line (">>>> Too few arguments <<<<");
raise Evaluation_Error;
end if;
-- Insert the key/value pair into the environment
Set_Environment (Interp, Get_Car(Param), Get_Car(Arg));
Param := Get_Cdr(Param);
Arg := Get_Cdr(Arg);
end loop;
-- Perform cosmetic checks for the parameter list
if Param /= Nil_Pointer then
Text_IO.Put_Line (">>> GARBAGE IN PARAMETER LIST <<<");
raise Syntax_Error;
end if;
-- Perform cosmetic checks for the argument list
if Is_Cons(Arg) then
Text_IO.Put_Line (">>>> Two many arguments <<<<");
raise Evaluation_Error;
elsif Arg /= Nil_Pointer then
Text_IO.Put_Line (">>> GARBAGE IN ARGUMENT LIST <<<");
raise Syntax_Error;
end if;
-- TODO: GC. the environment construction can cause GC. so Fbody here may be invalid.
-- TODO: is it correct to keep the environement in the frame?
Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Group);
Set_Frame_Operand (Interp.Stack, Fbody);
Clear_Frame_Result (Interp.Stack);
end Apply_Closure;
begin
Operand := Get_Frame_Operand(Interp.Stack);
pragma Assert (Is_Cons(Operand));
Print (Interp, Operand);
Func := Get_Car(Operand);
if not Is_Normal_Pointer(Func) then
Text_IO.Put_Line ("INVALID FUNCTION TYPE");
raise Evaluation_Error;
end if;
Args := Get_Cdr(Operand);
-- No GC must be performed here.
-- Otherwise, Operand, Func, Args get invalidated
-- since GC doesn't update local variables.
case Func.Tag is
when Procedure_Object =>
case Get_Procedure_Opcode(Func) is
when Car_Procedure =>
Apply_Car_Procedure;
when Cdr_Procedure =>
Apply_Cdr_Procedure;
when Add_Procedure =>
Apply_Add_Procedure;
when Subtract_Procedure =>
Apply_Subtract_Procedure;
when others =>
raise Internal_Error;
end case;
when Closure_Object =>
Apply_Closure;
when Continuation_Object =>
null;
when others =>
Text_IO.Put_Line ("INVALID FUNCTION TYPE");
raise Internal_Error;
end case;
end Apply;
procedure Fetch_Character is
begin
-- TODO: calculate Interp.Input.Row, Interp.Input.Column
if Interp.Input.Pos >= Interp.Input.Last then
if Interp.Input.Flags /= 0 then
-- An error has occurred or EOF has been reached previously.
-- Note calling this procedure after EOF results in an error.
Interp.Input.Iochar := (Error_Character, Object_Character'First);
--return;
raise IO_Error;
end if;
Interp.Input.Pos := Interp.Input.Data'First - 1;
begin
Read (Interp.Input.Stream.all, Interp.Input.Data, Interp.Input.Last);
exception
when others =>
-- The callee can raise an exception upon errors.
-- If an exception is raised, data read into the buffer
-- is also ignored.
Interp.Input.Flags := Interp.Input.Flags and IO_Error_Occurred;
Interp.Input.Iochar := (Error_Character, Object_Character'First);
--return;
raise IO_Error;
end;
if Interp.Input.Last < Interp.Input.Data'First then
-- The callee must read 0 bytes on EOF
Interp.Input.Flags := Interp.Input.Flags and IO_End_Reached;
Interp.Input.Iochar := (End_Character, Object_Character'First);
return;
end if;
end if;
Interp.Input.Pos := Interp.Input.Pos + 1;
Interp.Input.Iochar := (Normal_Character, Interp.Input.Data(Interp.Input.Pos));
end Fetch_Character;
function Is_White_Space (X: in Object_Character) return Standard.Boolean is
begin
return X = ' ' or else
X = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.HT)) or else
X = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.VT)) or else
X = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.CR)) or else
X = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.LF)) or else
X = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.FF));
end Is_White_Space;
procedure Skip_Spaces_And_Comments is
begin
loop
exit when LC.Kind /= Normal_Character;
-- Normal character
if Is_White_Space(LC.Value) then
Fetch_Character;
elsif LC.Value = ';' then
-- Comment.
loop
Fetch_Character;
exit when LC.Kind = End_Character; -- EOF before LF
if LC.Kind = Normal_Character and then
LC.Value = Object_Character'Val(Standard.Character'Pos(Standard.ASCII.LF)) then
Fetch_Character; -- Read the next character after LF
exit;
end if;
end loop;
else
exit;
end if;
end loop;
end Skip_Spaces_And_Comments;
procedure Fetch_Token is
Tmp: Object_String(1..10); -- large enough???
begin
if not Interp.LC_Unfetched then
Fetch_Character;
else
-- Reuse the last character unfetched
Interp.LC_Unfetched := Standard.False;
end if;
Skip_Spaces_And_Comments;
if LC.Kind /= Normal_Character then
Token.Set (Interp, End_Token, "");
return;
end if;
-- TODO: Pass Token Location when calling Token.Set
case LC.Value is
when '(' =>
Token.Set (Interp, Left_Parenthesis_Token, "(");
when ')' =>
Token.Set (Interp, Right_Parenthesis_Token, ")");
when '.' =>
Token.Set (Interp, Period_Token, ".");
when ''' =>
Token.Set (Interp, Single_Quote_Token, "'");
when '"' =>
Fetch_Character;
Token.Set (Interp, String_Token, "");
loop
if LC.Kind /= Normal_Character then
-- String ended prematurely.
-- TODO: Set Error code, Error Number.... Error location
raise Syntax_Error;
end if;
if LC.Value = '\' then
Fetch_Character;
if LC.Kind /= Normal_Character then
-- String ended prematurely.
-- TODO: Set Error code, Error Number.... Error location
raise Syntax_Error;
end if;
-- TODO: escape letters??? \n \r \\ etc....
Token.Append_Character (Interp, LC.Value);
elsif LC.Value = '"' then
exit;
else
Token.Append_Character (Interp, LC.Value);
Fetch_Character;
end if;
end loop;
-- TODO:
when '#' =>
Fetch_Character;
-- TODO: t, false, etc
when '0' .. '9' =>
-- TODO; negative number, floating-point number, bignum, hexdecimal, etc
Token.Set (Interp, Integer_Token, "");
loop
Token.Append_Character (Interp, LC.Value);
Fetch_Character;
if LC.Kind /= Normal_Character or else
not (LC.Value in '0' .. '9') then
-- Unfetch the last character
Interp.LC_Unfetched := Standard.True;
exit;
end if;
end loop;
when '-' | '+' =>
Tmp(1) := LC.Value;
Fetch_Character;
if LC.Kind = Normal_Character and then
LC.Value in '0' .. '9' then
Token.Set (Interp, Integer_Token, Tmp(1..1));
loop
Token.Append_Character (Interp, LC.Value);
Fetch_Character;
if LC.Kind /= Normal_Character or else
not (LC.Value in '0' .. '9') then
-- Unfetch the last character
Interp.LC_Unfetched := Standard.True;
exit;
end if;
end loop;
else
Token.Set (Interp, Identifier_Token, Tmp(1..1));
loop
-- TODO: more characters
if LC.Kind /= Normal_Character or else
LC.Value = '(' or else LC.Value = ')' or else
LC.Value = ''' or else LC.Value = '"' or else
LC.Value = '#' or else LC.Value = ';' or else
Is_White_Space(LC.Value) then
-- Unfetch the last character
Interp.LC_Unfetched := Standard.True;
exit;
end if;
Token.Append_Character (Interp, LC.Value);
Fetch_Character;
end loop;
end if;
when others =>
Token.Set (Interp, Identifier_Token, "");
loop
Token.Append_Character (Interp, LC.Value);
Fetch_Character;
--exit when not Is_Ident_Char(C.Value);
-- TODO: more characters
if LC.Kind /= Normal_Character or else
LC.Value = '(' or else LC.Value = ')' or else
LC.Value = ''' or else LC.Value = '"' or else
LC.Value = '#' or else LC.Value = ';' or else
Is_White_Space(LC.Value) then
-- Unfetch the last character
Interp.LC_Unfetched := Standard.True;
exit;
end if;
end loop;
end case;
Text_IO.Put_Line (">>>>>>>>>>>>>>>>>>>>>>> Token: " & Interp.Token.Value.Ptr(1..Interp.Token.Value.Last));
end Fetch_Token;
procedure Read_List is
pragma Inline (Read_List);
V: Object_Pointer;
begin
-- This procedure reads each token in a list.
-- If the list contains no period, this procedure reads up to the
-- closing right paranthesis; If a period is contained, it transfers
-- the control over to Read_List_Cdr.
Fetch_Token;
case Interp.Token.Kind is
when End_Token =>
Ada.Text_IO.Put_Line ("ERROR: PREMATURE LIST END");
raise Syntax_Error;
when Left_Parenthesis_Token =>
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
when Right_Parenthesis_Token =>
V := Get_Frame_Result(Interp.Stack);
if V /= Nil_Pointer then
V := Reverse_Cons(V); -- TODO: GC
end if;
Pop_Frame (Interp);
Chain_Frame_Result (Interp, Interp.Stack, V);
when Period_Token =>
V := Get_Frame_Result(Interp.Stack);
if V = Nil_Pointer then
-- . immediately after (
raise Syntax_Error;
else
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_Cdr);
end if;
when Single_Quote_Token =>
Push_Frame (Interp, Opcode_Close_Quote, Nil_Pointer);
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
when Integer_Token =>
-- TODO: bignum
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
Chain_Frame_Result (Interp, Interp.Stack, V);
when String_Token =>
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Chain_Frame_Result (Interp, Interp.Stack, V);
when Identifier_Token =>
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Chain_Frame_Result (Interp, Interp.Stack, V);
when others =>
-- TODO: set various error info
raise Syntax_Error;
end case;
end Read_List;
procedure Read_List_Cdr is
pragma Inline (Read_List_Cdr);
V: Object_Pointer;
begin
-- This procedure reads the first token after a period has been read.
-- It transfers the control over to Read_List_End once it has read
-- and processed the token. It chains the value made of the token
-- to the front of the frame's return value list expecting Read_List_End
-- to handle the head item specially.
Fetch_Token;
case Interp.Token.Kind is
when End_Token =>
Ada.Text_IO.Put_Line ("ERROR: PREMATURE LIST END");
raise Syntax_Error;
when Left_Parenthesis_Token =>
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
when Single_Quote_Token =>
Ada.Text_IO.Put_Line ("ERROR: CDR QUOT LIST END");
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
Push_Frame (Interp, Opcode_Close_Quote, Nil_Pointer);
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
when Integer_Token =>
-- TODO: bignum
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
Chain_Frame_Result (Interp, Interp.Stack, V);
when String_Token =>
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
Chain_Frame_Result (Interp, Interp.Stack, V);
when Identifier_Token =>
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
Chain_Frame_Result (Interp, Interp.Stack, V);
when others =>
-- TODO: set various error info
raise Syntax_Error;
end case;
end Read_List_Cdr;
procedure Read_List_End is
pragma Inline (Read_List_End);
V: Object_Pointer;
A: Object_Pointer;
begin
Fetch_Token;
case Interp.Token.Kind is
when Right_Parenthesis_Token =>
V := Get_Frame_Result(Interp.Stack);
pragma Assert (V /= Nil_Pointer);
-- The first item in the chain is actually Cdr of the last cell.
V := Reverse_Cons(Get_Cdr(V), Get_Car(V)); -- TODO: GC
Pop_Frame (Interp);
Chain_Frame_Result (Interp, Interp.Stack, V);
when others =>
raise Syntax_Error;
end case;
end Read_List_End;
procedure Close_List is
pragma Inline (Close_List);
V: Object_Pointer;
begin
V := Get_Frame_Result(Interp.Stack);
pragma Assert (Get_Cdr(V) = Nil_Pointer);
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, Get_Car(V));
end Close_List;
procedure Close_Quote is
pragma Inline (Close_Quote);
V: Object_Pointer;
begin
-- TODO: use Interp.Quote_Syntax instead of Make_Symbol("quote")
Chain_Frame_Result (Interp, Interp.Stack, Make_Symbol(Interp.Self, "quote"));
V := Get_Frame_Result(Interp.Stack);
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, V);
end Close_Quote;
procedure Read_Object is
pragma Inline (Read_Object);
V: Object_Pointer;
begin
Fetch_Token;
case Interp.Token.Kind is
when End_Token =>
Ada.Text_IO.Put_Line ("INFO: NO MORE TOKEN ");
raise Stream_End_Error;
when Left_Parenthesis_Token =>
Set_Frame_Opcode (Interp.Stack, Opcode_Close_List);
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
when Single_Quote_Token =>
Set_Frame_Opcode (Interp.Stack, Opcode_Close_Quote);
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
when Integer_Token =>
-- TODO: bignum
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, V);
when String_Token =>
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, V);
when Identifier_Token =>
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
-- TODO: make V gc-aware
Pop_Frame (Interp); -- Done with the current frame
Chain_Frame_Result (Interp, Interp.Stack, V);
when others =>
-- TODO: set various error info
raise Syntax_Error;
end case;
end Read_Object;
begin
-- Stack frames looks like this upon initialization
--
-- | Opcode | Operand | Result
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | Source | Nil
-- bottom | Opcode_Exit | Nil | Nil
--
-- For a source (+ 1 2), it should look like this.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | Source | Nil
-- bottom | Opcode_Exit | Nil | Nil
--
-- The operand changes to the cdr of the source.
-- The symbol '+' is pushed to the stack with Opcode_Evaluate_Object.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | + | Nil
-- | Opcode_Evaluate_Object | (1 2) | Nil
-- bottom | Opcode_Exit | Nil | Nil
--
-- After the evaluation of the symbol, the pushed frame is removed
-- and the result is set to the return field.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | (1 2) | (#Proc+)
-- bottom | Opcode_Exit | Nil | Nil
--
-- The same action is taken to evaluate the literal 1.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | 1 | Nil
-- | Opcode_Evaluate_Object | (2) | (#Proc+)
-- bottom | Opcode_Exit | Nil | Nil
--
-- The result of the valuation is reverse-chained to the return field.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | (2) | (1 #Proc+)
-- bottom | Opcode_Exit | Nil | Nil
--
-- The same action is taken to evaluate the literal 2.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | 2 | Nil
-- | Opcode_Evaluate_Object | Mark | (1 #Proc+)
-- bottom | Opcode_Exit | Nil | Nil
--
-- The result of the valuation is reverse-chained to the return field.
-- -----------------------------------------------------------------
-- top | Opcode_Evaluate_Object | Mark | (2 1 #Proc+)
-- bottom | Opcode_Exit | Nil | Nil
--
-- Once evluation of each cons cell is complete, switch the top frame
-- to 'Apply' reversing the result field into the operand field and
-- nullifying the result field afterwards.
-- -----------------------------------------------------------------
-- top | Apply | (#Proc+ 1 2) | Nil
-- bottom | Opcode_Exit | Nil | Nil
--
-- The apply operation produces the final result and sets it to the
-- parent frame while removing the apply frame.
-- -----------------------------------------------------------------
-- top/bottom| Opcode_Exit | Nil | (3)
-- The caller must push some frames before calling this procedure
pragma Assert (Interp.Stack /= Nil_Pointer);
loop
case Get_Frame_Opcode(Interp.Stack) is
when Opcode_Exit =>
exit;
when Opcode_Evaluate_Result =>
Evaluate_Result;
when Opcode_Evaluate_Object =>
Evaluate_Object;
when Opcode_Evaluate_Group =>
Evaluate_Group;
when Opcode_Evaluate_Procedure =>
Evaluate_Procedure;
when Opcode_Apply =>
Apply;
when Opcode_Read_Object =>
Read_Object;
when Opcode_Read_List =>
Read_List;
when Opcode_Read_List_Cdr =>
Read_List_Cdr;
when Opcode_Read_List_End =>
Read_List_End;
when Opcode_Close_List =>
Close_List;
when Opcode_Close_Quote =>
Close_Quote;
end case;
end loop;
-- the stack must be empty when the loop is terminated
--pragma Assert (Interp.Stack = Nil_Pointer);
exception
when Stream_End_Error =>
raise;
when others =>
Text_IO.Put_Line ("EXCEPTION OCCURRED");
-- TODO: restore stack frame???
-- TODO: restore envirronemtn frame???
raise;
end Execute;
procedure Evaluate (Interp: in out Interpreter_Record;
Source: in Object_Pointer;
Result: out Object_Pointer) is
begin
pragma Assert (Interp.Stack = Nil_Pointer);
Interp.Stack := Nil_Pointer;
-- Push a pseudo-frame to terminate the evaluation loop
Push_Frame (Interp, Opcode_Exit, Nil_Pointer);
-- Push the actual frame for evaluation
Push_Frame (Interp, Opcode_Evaluate_Object, Source);
Execute (Interp);
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);
-- Get the only value chained
Result := Get_Car(Result);
Pop_Frame (Interp);
pragma Assert (Interp.Stack = Nil_Pointer);
end Evaluate;
procedure Run_Loop (Interp: in out Interpreter_Record;
Result: out Object_Pointer) is
-- standard read-eval-print loop
begin
Result := Nil_Pointer;
loop
pragma Assert (Interp.Stack = Nil_Pointer);
Interp.Stack := Nil_Pointer;
Push_Frame (Interp, Opcode_Exit, 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 (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);
Pop_Frame (Interp);
Ada.Text_IO.Put ("REsULT>>>>>");
Print (Interp, Result);
pragma Assert (Interp.Stack = Nil_Pointer);
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.
Text_IO.Put_LINE ("=== BYE ===");
when others =>
TEXT_IO.PUT_LINE ("ERROR ERROR ERROR");
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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