Support nil literals

boot/stage16/cl.elna

@@ -34,6 +34,9 @@ type
 		value: Word;
 		length: Word
 	end;
+	_nil_node = record
+		kind: Word
+	end;
 	_variable_expression = record
 		kind: Word;
 		name: Word;
@@ -345,7 +348,8 @@ type
 		named_type_expression,
 		type_declaration,
 		module_declaration,
-		record_type_expression
+		record_type_expression,
+		null
 	);
 	InfoKind = (type_info, parameter_info, temporary_info, procedure_info);
 	TypeKind = (primitive, enumeration, _record);
@@ -979,6 +983,19 @@ begin
 	return result
 end;
 
+proc elna_rtl_unary(tac_instruction: Word, rtl_operator: Word, next_instruction: Word);
+var
+	result: Word;
+begin
+	result := elna_rtl_load_operand_value(tac_instruction, 2, ElnaRtlRegister.t0);
+	next_instruction^ := elna_rtl_instruction_create(rtl_operator);
+	elna_rtl_copy_operand(tac_instruction, 1, result);
+	elna_rtl_instruction_set_operand(result, 2, ElnaRtlOperand.register, ElnaRtlRegister.t0);
+	result := ElnaInstructionList_set_next(result, next_instruction^);
+
+	return result
+end;
+
 proc elna_rtl_instruction(tac_instruction: Word, next_instruction: Word);
 var
 	result: Word;
@@ -992,7 +1009,7 @@ begin
 	instruction_size := elna_rtl_instruction_size();
 	result := malloc(instruction_size);
 	instruction_kind := _elna_tac_instruction_get_kind(tac_instruction);
-	next_instruction^ := 0;
+	next_instruction^ := nil;
 
 	if instruction_kind = ElnaTacOperator.get_address then
 		operand_type := _elna_tac_instruction_get_operand_type(tac_instruction, 2);
@@ -1134,13 +1151,9 @@ begin
 	elsif instruction_kind = ElnaTacOperator.not_equal then
 		result := elna_rtl_binary_equality(tac_instruction, ElnaRtlOperator.snez, next_instruction)
 	elsif instruction_kind = ElnaTacOperator.negate then
-		result := elna_rtl_instruction_create(ElnaRtlOperator.neg);
-		elna_rtl_copy_operand(tac_instruction, 1, result);
-		elna_rtl_copy_operand(tac_instruction, 2, result)
+		result := elna_rtl_unary(tac_instruction, ElnaRtlOperator.neg, next_instruction)
 	elsif instruction_kind = ElnaTacOperator.complement then
-		result := elna_rtl_instruction_create(ElnaRtlOperator.not);
-		elna_rtl_copy_operand(tac_instruction, 1, result);
-		elna_rtl_copy_operand(tac_instruction, 2, result)
+		result := elna_rtl_unary(tac_instruction, ElnaRtlOperator.not, next_instruction)
 	elsif instruction_kind = ElnaTacOperator.jump then
 		result := elna_rtl_instruction_create(ElnaRtlOperator.j);
 		elna_rtl_copy_operand(tac_instruction, 1, result)
@@ -1543,6 +1556,18 @@ begin
 	return result
 end;
 
+proc _elna_parser_nil();
+var
+	result: Word;
+begin
+	_elna_lexer_skip_token();
+
+	result := malloc(_nil_node_size());
+	_nil_node_set_kind(result, NodeKind.null);
+
+	return result
+end;
+
 proc _elna_tac_integer_literal(integer_literal_node: Word, operand_type: Word, operand_value: Word, operand_length: Word);
 begin
 	operand_type^ := ElnaTacOperand.immediate;
@@ -1552,6 +1577,15 @@ begin
 	return 0
 end;
 
+proc _elna_tac_nil(nil_node: Word, operand_type: Word, operand_value: Word, operand_length: Word);
+begin
+	operand_type^ := ElnaTacOperand.immediate;
+	operand_value^ := 0;
+	operand_length^ := 0;
+
+	return 0
+end;
+
 proc _elna_parser_character_literal();
 var
 	character: Word;
@@ -1684,6 +1718,8 @@ begin
 		parser_node := _elna_parser_integer_literal()
 	elsif token_kind = ElnaLexerKind.string then
 		parser_node := _elna_parser_string_literal()
+	elsif token_kind = ElnaLexerKind.null then
+		parser_node := _elna_parser_nil()
 	elsif token_kind = ElnaLexerKind.identifier then
 		parser_node := _elna_parser_variable_expression()
 	end;
@@ -1735,6 +1771,8 @@ begin
 		instruction := _elna_tac_string_literal(parser_node, operand_type, operand_value, operand_length)
 	elsif node_kind = NodeKind.integer_literal then
 		instruction := _elna_tac_integer_literal(parser_node, operand_type, operand_value, operand_length)
+	elsif node_kind = NodeKind.null then
+		instruction := _elna_tac_nil(parser_node, operand_type, operand_value, operand_length)
 	else
 		instruction := _elna_tac_variable_expression(parser_node, symbol_table, operand_type, operand_value, operand_length)
 	end;
@@ -1826,7 +1864,7 @@ begin
 			operand_length^ := 0;
 
 			elna_instruction_list_concatenate(first_instruction, instruction)
-		else
+		elsif operator = 0 then
 			instruction := _elna_tac_instruction_create(ElnaTacOperator.copy);
 			_elna_tac_instruction_set_operand(instruction, 1, ElnaTacOperand.temporary, 6, 0);
 			_elna_tac_instruction_set_operand(instruction, 2, operand_type^, operand_value^, operand_length^);
@@ -1841,12 +1879,12 @@ begin
 	if operator = '-' then
 		instruction := _elna_tac_instruction_create(ElnaTacOperator.negate);
 		_elna_tac_instruction_set_operand(instruction, 1, ElnaTacOperand.temporary, 6, 0);
-		_elna_tac_instruction_set_operand(instruction, 2, ElnaTacOperand.temporary, 6, 0);
+		_elna_tac_instruction_set_operand(instruction, 2, operand_type^, operand_value^, operand_length^);
 		elna_instruction_list_concatenate(first_instruction, instruction)
 	elsif operator = '~' then
 		instruction := _elna_tac_instruction_create(ElnaTacOperator.complement);
 		_elna_tac_instruction_set_operand(instruction, 1, ElnaTacOperand.temporary, 6, 0);
-		_elna_tac_instruction_set_operand(instruction, 2, ElnaTacOperand.temporary, 6, 0);
+		_elna_tac_instruction_set_operand(instruction, 2, operand_type^, operand_value^, operand_length^);
 		elna_instruction_list_concatenate(first_instruction, instruction)
 	end;
 	return first_instruction