with H2.Pool;

package body H2.Scheme.Token is

	-----------------------------------------------------------------------------
	-- BUFFER MANAGEMENT
	-----------------------------------------------------------------------------
	procedure Clear_Buffer (Buffer: in out Buffer_Record) is
		pragma Inline (Clear_Buffer);
	begin
		Buffer.Last := 0;	
	end Clear_Buffer;

	procedure Purge_Buffer (Interp: in out Interpreter_Record;
	                        Buffer: in out Buffer_Record) is
	begin
		if Buffer.Len > 0 then
			declare
				subtype New_String is Object_String (1 .. Buffer.Len);
				type New_String_Pointer is access all New_String;
				for New_String_Pointer'Size use Object_Pointer_Bits;

				package Pool is new H2.Pool (New_String, New_String_Pointer, Interp.Storage_Pool);

				Tmp: New_String_Pointer;
				for Tmp'Address use Buffer.Ptr'Address;
				pragma Import (Ada, Tmp);
			begin
				Pool.Deallocate (Tmp);
			end;

			Buffer := (null, 0, 0);
		end if;
	end Purge_Buffer;

	procedure Append_Buffer (Interp: in out Interpreter_Record;
	                         Buffer: in out Buffer_Record; 
	                         Source: in     Object_String) is
		Incr: Standard.Natural;
	begin
		if Buffer.Last >= Buffer.Len then
			if Buffer.Len <= 0 then
				Incr := 1; -- TODO: increase to 128
			else
				Incr := Buffer.Len;	
			end if;
			if Incr < Source'Length then	
				Incr := Source'Length;
			end if;
			
			declare
				subtype New_String is Object_String (1 .. Buffer.Len + Incr);
				type New_String_Pointer is access all New_String;
				for New_String_Pointer'Size use Object_Pointer_Bits;

				package Pool is new H2.Pool (New_String, New_String_Pointer, Interp.Storage_Pool);

				T1: New_String_Pointer;
				T2: New_String_Pointer;
				for T2'Address use Buffer.Ptr'Address;
				pragma Import (Ada, T2);
			begin
				T1 := Pool.Allocate;
				if Buffer.Last > 0 then
					T1(1 .. Buffer.Last) := Buffer.Ptr(1 .. Buffer.Last);
				end if;
				Pool.Deallocate (T2);
				T2 := T1;
			end;

			Buffer.Len := Buffer.Len + Incr;
		end if;

		Buffer.Ptr(Buffer.Last + 1 .. Buffer.Last + Source'Length) := Source;
		Buffer.Last := Buffer.Last + Source'Length;
	end Append_Buffer;

	-----------------------------------------------------------------------------
	-- TOKEN MANAGEMENT
	-----------------------------------------------------------------------------
	procedure Purge (Interp: in out Interpreter_Record) is
	begin
		Purge_Buffer (Interp, Interp.Token.Value);
		Interp.Token := (End_Token, (null, 0, 0));
	end Purge;

	procedure Set (Interp: in out Interpreter_Record;
	                     Kind:   in     Token_Kind;
	                     Value:  in     Object_String) is
	begin
		Interp.Token.Kind := Kind;	
		Clear_Buffer (Interp.Token.Value);
		if Value'Length > 0 then
			Append_Buffer (Interp, Interp.Token.Value, Value);
		end if;
	end Set;

	procedure Append_String (Interp: in out Interpreter_Record;
	                               Value:  in     Object_String) is
	begin
		if Value'Length > 0 then
			Append_Buffer (Interp, Interp.Token.Value, Value);	
		end if;
	end Append_String;

	procedure Append_Character (Interp: in out Interpreter_Record;
	                                  Value:  in     Object_Character) is
		Tmp: Object_String(1..1) := (1 => Value);
	begin
		Append_Buffer (Interp, Interp.Token.Value, Tmp);
	end Append_Character;


end H2.Scheme.Token;