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Add support for return; (#678)

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This creates a ReturnExpression. A separate change should enforce that an implicit return of `()` is only allowed in functions that have an implicit return type of `()`, and I think the structure taken here should ease that.
This commit is contained in:
Jon Meow
2021-08-02 16:30:08 -07:00
committed by GitHub
parent b1993a6cd0
commit 6ae9cc3cf8
16 changed files with 114 additions and 33 deletions
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executable_semantics/syntax/parser.ypp
+23 -11
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@@ -92,6 +92,7 @@ void yy::parser::error(const location_type&, const std::string& message) {
%type <const Carbon::Statement*> statement
%type <const Carbon::Statement*> if_statement
%type <const Carbon::Statement*> optional_else
%type <std::pair<const Carbon::Expression*, bool>> return_expression
%type <const Carbon::Statement*> block
%type <const Carbon::Statement*> statement_list
%type <const Carbon::Expression*> expression
@@ -100,7 +101,7 @@ void yy::parser::error(const location_type&, const std::string& message) {
%type <std::vector<Carbon::GenericBinding>> deduced_param_list
%type <const Carbon::Pattern*> pattern
%type <const Carbon::Pattern*> non_expression_pattern
%type <const Carbon::Expression*> return_type
%type <std::pair<const Carbon::Expression*, bool>> return_type
%type <const Carbon::Expression*> paren_expression
%type <const Carbon::Expression*> tuple
%type <std::optional<std::string>> binding_lhs
@@ -264,7 +265,8 @@ expression:
{ $$ = Carbon::Expression::MakePrimitiveOperatorExpression(
yylineno, Carbon::Operator::Ptr, {$1}); }
| FNTY tuple return_type
{ $$ = Carbon::Expression::MakeFunctionTypeLiteral(yylineno, $2, $3); }
{ $$ = Carbon::Expression::MakeFunctionTypeLiteral(
yylineno, $2, $3.first, $3.second); }
;
designator: "." identifier { $$ = $2; }
;
@@ -415,8 +417,8 @@ statement:
{ $$ = Carbon::Statement::MakeBreak(yylineno); }
| CONTINUE ";"
{ $$ = Carbon::Statement::MakeContinue(yylineno); }
| RETURN expression ";"
{ $$ = Carbon::Statement::MakeReturn(yylineno, $2); }
| RETURN return_expression ";"
{ $$ = Carbon::Statement::MakeReturn(yylineno, $2.first, $2.second); }
| block
{ $$ = $1; }
| MATCH "(" expression ")" "{" clause_list "}"
@@ -440,6 +442,12 @@ optional_else:
| ELSE block
{ $$ = $2; }
;
return_expression:
// Empty
{ $$ = {Carbon::Expression::MakeTupleLiteral(yylineno, {}), true}; }
| expression
{ $$ = {$1, false}; }
;
statement_list:
// Empty
{ $$ = 0; }
@@ -452,9 +460,9 @@ block:
;
return_type:
// Empty
{ $$ = Carbon::Expression::MakeTupleLiteral(yylineno, {}); }
{ $$ = {Carbon::Expression::MakeTupleLiteral(yylineno, {}), true}; }
| ARROW expression %prec FNARROW
{ $$ = $2; }
{ $$ = {$2, false}; }
;
generic_binding:
identifier ":!" expression
@@ -486,21 +494,25 @@ function_definition:
FN identifier deduced_params maybe_empty_tuple_pattern return_type block
{
$$ = Carbon::FunctionDefinition(
yylineno, $2, $3, $4, Carbon::global_arena->New<Carbon::ExpressionPattern>($5), $6);
yylineno, $2, $3, $4,
Carbon::global_arena->New<Carbon::ExpressionPattern>($5.first),
$5.second, $6);
}
| FN identifier deduced_params maybe_empty_tuple_pattern DBLARROW expression ";"
{
$$ = Carbon::FunctionDefinition(
yylineno, $2, $3, $4,
Carbon::global_arena->New<Carbon::AutoPattern>(yylineno),
Carbon::Statement::MakeReturn(yylineno, $6));
yylineno, $2, $3, $4,
Carbon::global_arena->New<Carbon::AutoPattern>(yylineno), true,
Carbon::Statement::MakeReturn(yylineno, $6, false));
}
;
function_declaration:
FN identifier deduced_params maybe_empty_tuple_pattern return_type ";"
{
$$ = Carbon::FunctionDefinition(
yylineno, $2, $3, $4, Carbon::global_arena->New<Carbon::ExpressionPattern>($5), 0); }
yylineno, $2, $3, $4,
Carbon::global_arena->New<Carbon::ExpressionPattern>($5.first),
$5.second, nullptr); }
;
variable_declaration: identifier ":" pattern
{ $$ = Carbon::global_arena->New<Carbon::BindingPattern>(yylineno, $1, $3); }