Grammar/python.gram

# PEG grammar for Python

@trailer '''
void *
_PyPegen_parse(Parser *p)
{
    // Initialize keywords
    p->keywords = reserved_keywords;
    p->n_keyword_lists = n_keyword_lists;

    // Run parser
    void *result = NULL;
    if (p->start_rule == Py_file_input) {
        result = file_rule(p);
    } else if (p->start_rule == Py_single_input) {
        result = interactive_rule(p);
    } else if (p->start_rule == Py_eval_input) {
        result = eval_rule(p);
    } else if (p->start_rule == Py_func_type_input) {
        result = func_type_rule(p);
    } else if (p->start_rule == Py_fstring_input) {
        result = fstring_rule(p);
    }

    return result;
}

// The end
'''
file[mod_ty]: a=[statements] ENDMARKER { _PyPegen_make_module(p, a) }
interactive[mod_ty]: a=statement_newline { Interactive(a, p->arena) }
eval[mod_ty]: a=expressions NEWLINE* ENDMARKER { Expression(a, p->arena) }
func_type[mod_ty]: '(' a=[type_expressions] ')' '->' b=expression NEWLINE* ENDMARKER { FunctionType(a, b, p->arena) }
fstring[expr_ty]: star_expressions

# type_expressions allow */** but ignore them
type_expressions[asdl_seq*]:
    | a=','.expression+ ',' '*' b=expression ',' '**' c=expression {
        _PyPegen_seq_append_to_end(p, CHECK(_PyPegen_seq_append_to_end(p, a, b)), c) }
    | a=','.expression+ ',' '*' b=expression { _PyPegen_seq_append_to_end(p, a, b) }
    | a=','.expression+ ',' '**' b=expression { _PyPegen_seq_append_to_end(p, a, b) }
    | '*' a=expression ',' '**' b=expression {
        _PyPegen_seq_append_to_end(p, CHECK(_PyPegen_singleton_seq(p, a)), b) }
    | '*' a=expression { _PyPegen_singleton_seq(p, a) }
    | '**' a=expression { _PyPegen_singleton_seq(p, a) }
    | ','.expression+

statements[asdl_seq*]: a=statement+ { _PyPegen_seq_flatten(p, a) }
statement[asdl_seq*]: a=compound_stmt { _PyPegen_singleton_seq(p, a) } | simple_stmt
statement_newline[asdl_seq*]:
    | a=compound_stmt NEWLINE { _PyPegen_singleton_seq(p, a) }
    | simple_stmt
    | NEWLINE { _PyPegen_singleton_seq(p, CHECK(_Py_Pass(EXTRA))) }
    | ENDMARKER { _PyPegen_interactive_exit(p) }
simple_stmt[asdl_seq*]:
    | a=small_stmt !';' NEWLINE { _PyPegen_singleton_seq(p, a) } # Not needed, there for speedup
    | a=';'.small_stmt+ [';'] NEWLINE { a }
# NOTE: assignment MUST precede expression, else parsing a simple assignment
# will throw a SyntaxError.
small_stmt[stmt_ty] (memo):
    | assignment
    | e=star_expressions { _Py_Expr(e, EXTRA) }
    | &'return' return_stmt
    | &('import' | 'from') import_stmt
    | &'raise' raise_stmt
    | 'pass' { _Py_Pass(EXTRA) }
    | &'del' del_stmt
    | &'yield' yield_stmt
    | &'assert' assert_stmt
    | 'break' { _Py_Break(EXTRA) }
    | 'continue' { _Py_Continue(EXTRA) }
    | &'global' global_stmt
    | &'nonlocal' nonlocal_stmt
compound_stmt[stmt_ty]:
    | &('def' | '@' | ASYNC) function_def
    | &'if' if_stmt
    | &('class' | '@') class_def
    | &('with' | ASYNC) with_stmt
    | &('for' | ASYNC) for_stmt
    | &'try' try_stmt
    | &'while' while_stmt

# NOTE: annotated_rhs may start with 'yield'; yield_expr must start with 'yield'
assignment[stmt_ty]:
    | a=NAME ':' b=expression c=['=' d=annotated_rhs { d }] {
        CHECK_VERSION(
            6,
            "Variable annotation syntax is",
            _Py_AnnAssign(CHECK(_PyPegen_set_expr_context(p, a, Store)), b, c, 1, EXTRA)
        ) }
    | a=('(' b=single_target ')' { b }
         | single_subscript_attribute_target) ':' b=expression c=['=' d=annotated_rhs { d }] {
        CHECK_VERSION(6, "Variable annotations syntax is", _Py_AnnAssign(a, b, c, 0, EXTRA)) }
    | a=(z=star_targets '=' { z })+ b=(yield_expr | star_expressions) !'=' tc=[TYPE_COMMENT] {
         _Py_Assign(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
    | a=single_target b=augassign ~ c=(yield_expr | star_expressions) {
         _Py_AugAssign(a, b->kind, c, EXTRA) }
    | invalid_assignment

augassign[AugOperator*]:
    | '+=' { _PyPegen_augoperator(p, Add) }
    | '-=' { _PyPegen_augoperator(p, Sub) }
    | '*=' { _PyPegen_augoperator(p, Mult) }
    | '@=' { CHECK_VERSION(5, "The '@' operator is", _PyPegen_augoperator(p, MatMult)) }
    | '/=' { _PyPegen_augoperator(p, Div) }
    | '%=' { _PyPegen_augoperator(p, Mod) }
    | '&=' { _PyPegen_augoperator(p, BitAnd) }
    | '|=' { _PyPegen_augoperator(p, BitOr) }
    | '^=' { _PyPegen_augoperator(p, BitXor) }
    | '<<=' { _PyPegen_augoperator(p, LShift) }
    | '>>=' { _PyPegen_augoperator(p, RShift) }
    | '**=' { _PyPegen_augoperator(p, Pow) }
    | '//=' { _PyPegen_augoperator(p, FloorDiv) }

global_stmt[stmt_ty]: 'global' a=','.NAME+ {
    _Py_Global(CHECK(_PyPegen_map_names_to_ids(p, a)), EXTRA) }
nonlocal_stmt[stmt_ty]: 'nonlocal' a=','.NAME+ {
    _Py_Nonlocal(CHECK(_PyPegen_map_names_to_ids(p, a)), EXTRA) }

yield_stmt[stmt_ty]: y=yield_expr { _Py_Expr(y, EXTRA) }

assert_stmt[stmt_ty]: 'assert' a=expression b=[',' z=expression { z }] { _Py_Assert(a, b, EXTRA) }

del_stmt[stmt_ty]:
    | 'del' a=del_targets &(';' | NEWLINE) { _Py_Delete(a, EXTRA) }
    | invalid_del_stmt

import_stmt[stmt_ty]: import_name | import_from
import_name[stmt_ty]: 'import' a=dotted_as_names { _Py_Import(a, EXTRA) }
# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
import_from[stmt_ty]:
    | 'from' a=('.' | '...')* b=dotted_name 'import' c=import_from_targets {
        _Py_ImportFrom(b->v.Name.id, c, _PyPegen_seq_count_dots(a), EXTRA) }
    | 'from' a=('.' | '...')+ 'import' b=import_from_targets {
        _Py_ImportFrom(NULL, b, _PyPegen_seq_count_dots(a), EXTRA) }
import_from_targets[asdl_seq*]:
    | '(' a=import_from_as_names [','] ')' { a }
    | import_from_as_names !','
    | '*' { _PyPegen_singleton_seq(p, CHECK(_PyPegen_alias_for_star(p))) }
    | invalid_import_from_targets
import_from_as_names[asdl_seq*]:
    | a=','.import_from_as_name+ { a }
import_from_as_name[alias_ty]:
    | a=NAME b=['as' z=NAME { z }] { _Py_alias(a->v.Name.id,
                                               (b) ? ((expr_ty) b)->v.Name.id : NULL,
                                               p->arena) }
dotted_as_names[asdl_seq*]:
    | a=','.dotted_as_name+ { a }
dotted_as_name[alias_ty]:
    | a=dotted_name b=['as' z=NAME { z }] { _Py_alias(a->v.Name.id,
                                                      (b) ? ((expr_ty) b)->v.Name.id : NULL,
                                                      p->arena) }
dotted_name[expr_ty]:
    | a=dotted_name '.' b=NAME { _PyPegen_join_names_with_dot(p, a, b) }
    | NAME

if_stmt[stmt_ty]:
    | 'if' a=named_expression ':' b=block c=elif_stmt { _Py_If(a, b, CHECK(_PyPegen_singleton_seq(p, c)), EXTRA) }
    | 'if' a=named_expression ':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
elif_stmt[stmt_ty]:
    | 'elif' a=named_expression ':' b=block c=elif_stmt { _Py_If(a, b, CHECK(_PyPegen_singleton_seq(p, c)), EXTRA) }
    | 'elif' a=named_expression ':' b=block c=[else_block] { _Py_If(a, b, c, EXTRA) }
else_block[asdl_seq*]: 'else' ':' b=block { b }

while_stmt[stmt_ty]:
    | 'while' a=named_expression ':' b=block c=[else_block] { _Py_While(a, b, c, EXTRA) }

for_stmt[stmt_ty]:
    | 'for' t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
        _Py_For(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA) }
    | ASYNC 'for' t=star_targets 'in' ~ ex=star_expressions ':' tc=[TYPE_COMMENT] b=block el=[else_block] {
        CHECK_VERSION(5, "Async for loops are", _Py_AsyncFor(t, ex, b, el, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
    | invalid_for_target

with_stmt[stmt_ty]:
    | 'with' '(' a=','.with_item+ ','? ')' ':' b=block {
        _Py_With(a, b, NULL, EXTRA) }
    | 'with' a=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
        _Py_With(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA) }
    | ASYNC 'with' '(' a=','.with_item+ ','? ')' ':' b=block {
       CHECK_VERSION(5, "Async with statements are", _Py_AsyncWith(a, b, NULL, EXTRA)) }
    | ASYNC 'with' a=','.with_item+ ':' tc=[TYPE_COMMENT] b=block {
       CHECK_VERSION(5, "Async with statements are", _Py_AsyncWith(a, b, NEW_TYPE_COMMENT(p, tc), EXTRA)) }
with_item[withitem_ty]:
    | e=expression 'as' t=target &(',' | ')' | ':') { _Py_withitem(e, t, p->arena) }
    | invalid_with_item
    | e=expression { _Py_withitem(e, NULL, p->arena) }

try_stmt[stmt_ty]:
    | 'try' ':' b=block f=finally_block { _Py_Try(b, NULL, NULL, f, EXTRA) }
    | 'try' ':' b=block ex=except_block+ el=[else_block] f=[finally_block] { _Py_Try(b, ex, el, f, EXTRA) }
except_block[excepthandler_ty]:
    | 'except' e=expression t=['as' z=NAME { z }] ':' b=block {
        _Py_ExceptHandler(e, (t) ? ((expr_ty) t)->v.Name.id : NULL, b, EXTRA) }
    | 'except' ':' b=block { _Py_ExceptHandler(NULL, NULL, b, EXTRA) }
finally_block[asdl_seq*]: 'finally' ':' a=block { a }

return_stmt[stmt_ty]:
    | 'return' a=[star_expressions] { _Py_Return(a, EXTRA) }

raise_stmt[stmt_ty]:
    | 'raise' a=expression b=['from' z=expression { z }] { _Py_Raise(a, b, EXTRA) }
    | 'raise' { _Py_Raise(NULL, NULL, EXTRA) }

function_def[stmt_ty]:
    | d=decorators f=function_def_raw { _PyPegen_function_def_decorators(p, d, f) }
    | function_def_raw

function_def_raw[stmt_ty]:
    | 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] ':' tc=[func_type_comment] b=block {
        _Py_FunctionDef(n->v.Name.id,
                        (params) ? params : CHECK(_PyPegen_empty_arguments(p)),
                        b, NULL, a, NEW_TYPE_COMMENT(p, tc), EXTRA) }
    | ASYNC 'def' n=NAME '(' params=[params] ')' a=['->' z=expression { z }] ':' tc=[func_type_comment] b=block {
        CHECK_VERSION(
            5,
            "Async functions are",
            _Py_AsyncFunctionDef(n->v.Name.id,
                            (params) ? params : CHECK(_PyPegen_empty_arguments(p)),
                            b, NULL, a, NEW_TYPE_COMMENT(p, tc), EXTRA)
        ) }
func_type_comment[Token*]:
    | NEWLINE t=TYPE_COMMENT &(NEWLINE INDENT) { t }  # Must be followed by indented block
    | invalid_double_type_comments
    | TYPE_COMMENT

params[arguments_ty]:
    | invalid_parameters
    | parameters

parameters[arguments_ty]:
    | a=slash_no_default b=param_no_default* c=param_with_default* d=[star_etc] {
        _PyPegen_make_arguments(p, a, NULL, b, c, d) }
    | a=slash_with_default b=param_with_default* c=[star_etc] {
        _PyPegen_make_arguments(p, NULL, a, NULL, b, c) }
    | a=param_no_default+ b=param_with_default* c=[star_etc] {
        _PyPegen_make_arguments(p, NULL, NULL, a, b, c) }
    | a=param_with_default+ b=[star_etc] { _PyPegen_make_arguments(p, NULL, NULL, NULL, a, b)}
    | a=star_etc { _PyPegen_make_arguments(p, NULL, NULL, NULL, NULL, a) }

# Some duplication here because we can't write (',' | &')'),
# which is because we don't support empty alternatives (yet).
#
slash_no_default[asdl_seq*]:
    | a=param_no_default+ '/' ',' { a }
    | a=param_no_default+ '/' &')' { a }
slash_with_default[SlashWithDefault*]:
    | a=param_no_default* b=param_with_default+ '/' ',' { _PyPegen_slash_with_default(p, a, b) }
    | a=param_no_default* b=param_with_default+ '/' &')' { _PyPegen_slash_with_default(p, a, b) }

star_etc[StarEtc*]:
    | '*' a=param_no_default b=param_maybe_default* c=[kwds] {
        _PyPegen_star_etc(p, a, b, c) }
    | '*' ',' b=param_maybe_default+ c=[kwds] {
        _PyPegen_star_etc(p, NULL, b, c) }
    | a=kwds { _PyPegen_star_etc(p, NULL, NULL, a) }
    | invalid_star_etc

kwds[arg_ty]: '**' a=param_no_default { a }

# One parameter.  This *includes* a following comma and type comment.
#
# There are three styles:
# - No default
# - With default
# - Maybe with default
#
# There are two alternative forms of each, to deal with type comments:
# - Ends in a comma followed by an optional type comment
# - No comma, optional type comment, must be followed by close paren
# The latter form is for a final parameter without trailing comma.
#
param_no_default[arg_ty]:
    | a=param ',' tc=TYPE_COMMENT? { _PyPegen_add_type_comment_to_arg(p, a, tc) }
    | a=param tc=TYPE_COMMENT? &')' { _PyPegen_add_type_comment_to_arg(p, a, tc) }
param_with_default[NameDefaultPair*]:
    | a=param c=default ',' tc=TYPE_COMMENT? { _PyPegen_name_default_pair(p, a, c, tc) }
    | a=param c=default tc=TYPE_COMMENT? &')' { _PyPegen_name_default_pair(p, a, c, tc) }
param_maybe_default[NameDefaultPair*]:
    | a=param c=default? ',' tc=TYPE_COMMENT? { _PyPegen_name_default_pair(p, a, c, tc) }
    | a=param c=default? tc=TYPE_COMMENT? &')' { _PyPegen_name_default_pair(p, a, c, tc) }
param[arg_ty]: a=NAME b=annotation? { _Py_arg(a->v.Name.id, b, NULL, EXTRA) }

annotation[expr_ty]: ':' a=expression { a }
default[expr_ty]: '=' a=expression { a }

decorators[asdl_seq*]: a=('@' f=named_expression NEWLINE { f })+ { a }

class_def[stmt_ty]:
    | a=decorators b=class_def_raw { _PyPegen_class_def_decorators(p, a, b) }
    | class_def_raw
class_def_raw[stmt_ty]:
    | 'class' a=NAME b=['(' z=[arguments] ')' { z }] ':' c=block {
        _Py_ClassDef(a->v.Name.id,
                     (b) ? ((expr_ty) b)->v.Call.args : NULL,
                     (b) ? ((expr_ty) b)->v.Call.keywords : NULL,
                     c, NULL, EXTRA) }

block[asdl_seq*] (memo):
    | NEWLINE INDENT a=statements DEDENT { a }
    | simple_stmt
    | invalid_block

expressions_list[asdl_seq*]: a=','.star_expression+ [','] { a }
star_expressions[expr_ty]:
    | a=star_expression b=(',' c=star_expression { c })+ [','] {
        _Py_Tuple(CHECK(_PyPegen_seq_insert_in_front(p, a, b)), Load, EXTRA) }
    | a=star_expression ',' { _Py_Tuple(CHECK(_PyPegen_singleton_seq(p, a)), Load, EXTRA) }
    | star_expression
star_expression[expr_ty] (memo):
    | '*' a=bitwise_or { _Py_Starred(a, Load, EXTRA) }
    | expression

star_named_expressions[asdl_seq*]: a=','.star_named_expression+ [','] { a }
star_named_expression[expr_ty]:
    | '*' a=bitwise_or { _Py_Starred(a, Load, EXTRA) }
    | named_expression
named_expression[expr_ty]:
    | a=NAME ':=' ~ b=expression { _Py_NamedExpr(CHECK(_PyPegen_set_expr_context(p, a, Store)), b, EXTRA) }
    | expression !':='
    | invalid_named_expression

annotated_rhs[expr_ty]: yield_expr | star_expressions

expressions[expr_ty]:
    | a=expression b=(',' c=expression { c })+ [','] {
        _Py_Tuple(CHECK(_PyPegen_seq_insert_in_front(p, a, b)), Load, EXTRA) }
    | a=expression ',' { _Py_Tuple(CHECK(_PyPegen_singleton_seq(p, a)), Load, EXTRA) }
    | expression
expression[expr_ty] (memo):
    | a=disjunction 'if' b=disjunction 'else' c=expression { _Py_IfExp(b, a, c, EXTRA) }
    | disjunction
    | lambdef

lambdef[expr_ty]:
    | 'lambda' a=[lambda_params] ':' b=expression { _Py_Lambda((a) ? a : CHECK(_PyPegen_empty_arguments(p)), b, EXTRA) }

lambda_params[arguments_ty]:
    | invalid_lambda_parameters
    | lambda_parameters

# lambda_parameters etc. duplicates parameters but without annotations
# or type comments, and if there's no comma after a parameter, we expect
# a colon, not a close parenthesis.  (For more, see parameters above.)
#
lambda_parameters[arguments_ty]:
    | a=lambda_slash_no_default b=lambda_param_no_default* c=lambda_param_with_default* d=[lambda_star_etc] {
        _PyPegen_make_arguments(p, a, NULL, b, c, d) }
    | a=lambda_slash_with_default b=lambda_param_with_default* c=[lambda_star_etc] {
        _PyPegen_make_arguments(p, NULL, a, NULL, b, c) }
    | a=lambda_param_no_default+ b=lambda_param_with_default* c=[lambda_star_etc] {
        _PyPegen_make_arguments(p, NULL, NULL, a, b, c) }
    | a=lambda_param_with_default+ b=[lambda_star_etc] { _PyPegen_make_arguments(p, NULL, NULL, NULL, a, b)}
    | a=lambda_star_etc { _PyPegen_make_arguments(p, NULL, NULL, NULL, NULL, a) }

lambda_slash_no_default[asdl_seq*]:
    | a=lambda_param_no_default+ '/' ',' { a }
    | a=lambda_param_no_default+ '/' &':' { a }
lambda_slash_with_default[SlashWithDefault*]:
    | a=lambda_param_no_default* b=lambda_param_with_default+ '/' ',' { _PyPegen_slash_with_default(p, a, b) }
    | a=lambda_param_no_default* b=lambda_param_with_default+ '/' &':' { _PyPegen_slash_with_default(p, a, b) }

lambda_star_etc[StarEtc*]:
    | '*' a=lambda_param_no_default b=lambda_param_maybe_default* c=[lambda_kwds] {
        _PyPegen_star_etc(p, a, b, c) }
    | '*' ',' b=lambda_param_maybe_default+ c=[lambda_kwds] {
        _PyPegen_star_etc(p, NULL, b, c) }
    | a=lambda_kwds { _PyPegen_star_etc(p, NULL, NULL, a) }
    | invalid_lambda_star_etc

lambda_kwds[arg_ty]: '**' a=lambda_param_no_default { a }

lambda_param_no_default[arg_ty]:
    | a=lambda_param ',' { a }
    | a=lambda_param &':' { a }
lambda_param_with_default[NameDefaultPair*]:
    | a=lambda_param c=default ',' { _PyPegen_name_default_pair(p, a, c, NULL) }
    | a=lambda_param c=default &':' { _PyPegen_name_default_pair(p, a, c, NULL) }
lambda_param_maybe_default[NameDefaultPair*]:
    | a=lambda_param c=default? ',' { _PyPegen_name_default_pair(p, a, c, NULL) }
    | a=lambda_param c=default? &':' { _PyPegen_name_default_pair(p, a, c, NULL) }
lambda_param[arg_ty]: a=NAME { _Py_arg(a->v.Name.id, NULL, NULL, EXTRA) }

disjunction[expr_ty] (memo):
    | a=conjunction b=('or' c=conjunction { c })+ { _Py_BoolOp(
        Or,
        CHECK(_PyPegen_seq_insert_in_front(p, a, b)),
        EXTRA) }
    | conjunction
conjunction[expr_ty] (memo):
    | a=inversion b=('and' c=inversion { c })+ { _Py_BoolOp(
        And,
        CHECK(_PyPegen_seq_insert_in_front(p, a, b)),
        EXTRA) }
    | inversion
inversion[expr_ty] (memo):
    | 'not' a=inversion { _Py_UnaryOp(Not, a, EXTRA) }
    | comparison
comparison[expr_ty]:
    | a=bitwise_or b=compare_op_bitwise_or_pair+ {
        _Py_Compare(a, CHECK(_PyPegen_get_cmpops(p, b)), CHECK(_PyPegen_get_exprs(p, b)), EXTRA) }
    | bitwise_or
compare_op_bitwise_or_pair[CmpopExprPair*]:
    | eq_bitwise_or
    | noteq_bitwise_or
    | lte_bitwise_or
    | lt_bitwise_or
    | gte_bitwise_or
    | gt_bitwise_or
    | notin_bitwise_or
    | in_bitwise_or
    | isnot_bitwise_or
    | is_bitwise_or
eq_bitwise_or[CmpopExprPair*]: '==' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, Eq, a) }
noteq_bitwise_or[CmpopExprPair*]:
    | (tok='!=' {_PyPegen_check_barry_as_flufl(p) ? NULL : tok}) a=bitwise_or {_PyPegen_cmpop_expr_pair(p, NotEq, a) }
lte_bitwise_or[CmpopExprPair*]: '<=' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, LtE, a) }
lt_bitwise_or[CmpopExprPair*]: '<' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, Lt, a) }
gte_bitwise_or[CmpopExprPair*]: '>=' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, GtE, a) }
gt_bitwise_or[CmpopExprPair*]: '>' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, Gt, a) }
notin_bitwise_or[CmpopExprPair*]: 'not' 'in' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, NotIn, a) }
in_bitwise_or[CmpopExprPair*]: 'in' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, In, a) }
isnot_bitwise_or[CmpopExprPair*]: 'is' 'not' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, IsNot, a) }
is_bitwise_or[CmpopExprPair*]: 'is' a=bitwise_or { _PyPegen_cmpop_expr_pair(p, Is, a) }

bitwise_or[expr_ty]:
    | a=bitwise_or '|' b=bitwise_xor { _Py_BinOp(a, BitOr, b, EXTRA) }
    | bitwise_xor
bitwise_xor[expr_ty]:
    | a=bitwise_xor '^' b=bitwise_and { _Py_BinOp(a, BitXor, b, EXTRA) }
    | bitwise_and
bitwise_and[expr_ty]:
    | a=bitwise_and '&' b=shift_expr { _Py_BinOp(a, BitAnd, b, EXTRA) }
    | shift_expr
shift_expr[expr_ty]:
    | a=shift_expr '<<' b=sum { _Py_BinOp(a, LShift, b, EXTRA) }
    | a=shift_expr '>>' b=sum { _Py_BinOp(a, RShift, b, EXTRA) }
    | sum

sum[expr_ty]:
    | a=sum '+' b=term { _Py_BinOp(a, Add, b, EXTRA) }
    | a=sum '-' b=term { _Py_BinOp(a, Sub, b, EXTRA) }
    | term
term[expr_ty]:
    | a=term '*' b=factor { _Py_BinOp(a, Mult, b, EXTRA) }
    | a=term '/' b=factor { _Py_BinOp(a, Div, b, EXTRA) }
    | a=term '//' b=factor { _Py_BinOp(a, FloorDiv, b, EXTRA) }
    | a=term '%' b=factor { _Py_BinOp(a, Mod, b, EXTRA) }
    | a=term '@' b=factor { CHECK_VERSION(5, "The '@' operator is", _Py_BinOp(a, MatMult, b, EXTRA)) }
    | factor
factor[expr_ty] (memo):
    | '+' a=factor { _Py_UnaryOp(UAdd, a, EXTRA) }
    | '-' a=factor { _Py_UnaryOp(USub, a, EXTRA) }
    | '~' a=factor { _Py_UnaryOp(Invert, a, EXTRA) }
    | power
power[expr_ty]:
    | a=await_primary '**' b=factor { _Py_BinOp(a, Pow, b, EXTRA) }
    | await_primary
await_primary[expr_ty] (memo):
    | AWAIT a=primary { CHECK_VERSION(5, "Await expressions are", _Py_Await(a, EXTRA)) }
    | primary
primary[expr_ty]:
    | a=primary '.' b=NAME { _Py_Attribute(a, b->v.Name.id, Load, EXTRA) }
    | a=primary b=genexp { _Py_Call(a, CHECK(_PyPegen_singleton_seq(p, b)), NULL, EXTRA) }
    | a=primary '(' b=[arguments] ')' {
        _Py_Call(a,
                 (b) ? ((expr_ty) b)->v.Call.args : NULL,
                 (b) ? ((expr_ty) b)->v.Call.keywords : NULL,
                 EXTRA) }
    | a=primary '[' b=slices ']' { _Py_Subscript(a, b, Load, EXTRA) }
    | atom

slices[expr_ty]:
    | a=slice !',' { a }
    | a=','.slice+ [','] { _Py_Tuple(a, Load, EXTRA) }
slice[expr_ty]:
    | a=[expression] ':' b=[expression] c=[':' d=[expression] { d }] { _Py_Slice(a, b, c, EXTRA) }
    | a=expression { a }
atom[expr_ty]:
    | NAME
    | 'True' { _Py_Constant(Py_True, NULL, EXTRA) }
    | 'False' { _Py_Constant(Py_False, NULL, EXTRA) }
    | 'None' { _Py_Constant(Py_None, NULL, EXTRA) }
    | &STRING strings
    | NUMBER
    | &'(' (tuple | group | genexp)
    | &'[' (list | listcomp)
    | &'{' (dict | set | dictcomp | setcomp)
    | '...' { _Py_Constant(Py_Ellipsis, NULL, EXTRA) }

strings[expr_ty] (memo): a=STRING+ { _PyPegen_concatenate_strings(p, a) }
list[expr_ty]:
    | '[' a=[star_named_expressions] ']' { _Py_List(a, Load, EXTRA) }
listcomp[expr_ty]:
    | '[' a=named_expression ~ b=for_if_clauses ']' { _Py_ListComp(a, b, EXTRA) }
    | invalid_comprehension
tuple[expr_ty]:
    | '(' a=[y=star_named_expression ',' z=[star_named_expressions] { _PyPegen_seq_insert_in_front(p, y, z) } ] ')' {
        _Py_Tuple(a, Load, EXTRA) }
group[expr_ty]:
    | '(' a=(yield_expr | named_expression) ')' { a }
    | invalid_group
genexp[expr_ty]:
    | '(' a=expression ~ b=for_if_clauses ')' { _Py_GeneratorExp(a, b, EXTRA) }
    | invalid_comprehension
set[expr_ty]: '{' a=expressions_list '}' { _Py_Set(a, EXTRA) }
setcomp[expr_ty]:
    | '{' a=expression ~ b=for_if_clauses '}' { _Py_SetComp(a, b, EXTRA) }
    | invalid_comprehension
dict[expr_ty]:
    | '{' a=[double_starred_kvpairs] '}' {
        _Py_Dict(CHECK(_PyPegen_get_keys(p, a)), CHECK(_PyPegen_get_values(p, a)), EXTRA) }
dictcomp[expr_ty]:
    | '{' a=kvpair b=for_if_clauses '}' { _Py_DictComp(a->key, a->value, b, EXTRA) }
    | invalid_dict_comprehension
double_starred_kvpairs[asdl_seq*]: a=','.double_starred_kvpair+ [','] { a }
double_starred_kvpair[KeyValuePair*]:
    | '**' a=bitwise_or { _PyPegen_key_value_pair(p, NULL, a) }
    | kvpair
kvpair[KeyValuePair*]: a=expression ':' b=expression { _PyPegen_key_value_pair(p, a, b) }
for_if_clauses[asdl_seq*]:
    | for_if_clause+
for_if_clause[comprehension_ty]:
    | ASYNC 'for' a=star_targets 'in' ~ b=disjunction c=('if' z=disjunction { z })* {
        CHECK_VERSION(6, "Async comprehensions are", _Py_comprehension(a, b, c, 1, p->arena)) }
    | 'for' a=star_targets 'in' ~ b=disjunction c=('if' z=disjunction { z })* {
        _Py_comprehension(a, b, c, 0, p->arena) }
    | invalid_for_target

yield_expr[expr_ty]:
    | 'yield' 'from' a=expression { _Py_YieldFrom(a, EXTRA) }
    | 'yield' a=[star_expressions] { _Py_Yield(a, EXTRA) }

arguments[expr_ty] (memo):
    | a=args [','] &')' { a }
    | incorrect_arguments
args[expr_ty]:
    | a=starred_expression b=[',' c=args { c }] {
        _Py_Call(_PyPegen_dummy_name(p),
                 (b) ? CHECK(_PyPegen_seq_insert_in_front(p, a, ((expr_ty) b)->v.Call.args))
                     : CHECK(_PyPegen_singleton_seq(p, a)),
                 (b) ? ((expr_ty) b)->v.Call.keywords : NULL,
                 EXTRA) }
    | a=kwargs { _Py_Call(_PyPegen_dummy_name(p),
                          CHECK_NULL_ALLOWED(_PyPegen_seq_extract_starred_exprs(p, a)),
                          CHECK_NULL_ALLOWED(_PyPegen_seq_delete_starred_exprs(p, a)),
                          EXTRA) }
    | a=named_expression b=[',' c=args { c }] {
        _Py_Call(_PyPegen_dummy_name(p),
                 (b) ? CHECK(_PyPegen_seq_insert_in_front(p, a, ((expr_ty) b)->v.Call.args))
                     : CHECK(_PyPegen_singleton_seq(p, a)),
                 (b) ? ((expr_ty) b)->v.Call.keywords : NULL,
                 EXTRA) }
kwargs[asdl_seq*]:
    | a=','.kwarg_or_starred+ ',' b=','.kwarg_or_double_starred+ { _PyPegen_join_sequences(p, a, b) }
    | ','.kwarg_or_starred+
    | ','.kwarg_or_double_starred+
starred_expression[expr_ty]:
    | '*' a=expression { _Py_Starred(a, Load, EXTRA) }
kwarg_or_starred[KeywordOrStarred*]:
    | a=NAME '=' b=expression {
        _PyPegen_keyword_or_starred(p, CHECK(_Py_keyword(a->v.Name.id, b, EXTRA)), 1) }
    | a=starred_expression { _PyPegen_keyword_or_starred(p, a, 0) }
    | invalid_kwarg
kwarg_or_double_starred[KeywordOrStarred*]:
    | a=NAME '=' b=expression {
        _PyPegen_keyword_or_starred(p, CHECK(_Py_keyword(a->v.Name.id, b, EXTRA)), 1) }
    | '**' a=expression { _PyPegen_keyword_or_starred(p, CHECK(_Py_keyword(NULL, a, EXTRA)), 1) }
    | invalid_kwarg

# NOTE: star_targets may contain *bitwise_or, targets may not.
star_targets[expr_ty]:
    | a=star_target !',' { a }
    | a=star_target b=(',' c=star_target { c })* [','] {
        _Py_Tuple(CHECK(_PyPegen_seq_insert_in_front(p, a, b)), Store, EXTRA) }
star_targets_seq[asdl_seq*]: a=','.star_target+ [','] { a }
star_target[expr_ty] (memo):
    | '*' a=(!'*' star_target) {
        _Py_Starred(CHECK(_PyPegen_set_expr_context(p, a, Store)), Store, EXTRA) }
    | a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Store, EXTRA) }
    | a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Store, EXTRA) }
    | star_atom
star_atom[expr_ty]:
    | a=NAME { _PyPegen_set_expr_context(p, a, Store) }
    | '(' a=star_target ')' { _PyPegen_set_expr_context(p, a, Store) }
    | '(' a=[star_targets_seq] ')' { _Py_Tuple(a, Store, EXTRA) }
    | '[' a=[star_targets_seq] ']' { _Py_List(a, Store, EXTRA) }

single_target[expr_ty]:
    | single_subscript_attribute_target
    | a=NAME { _PyPegen_set_expr_context(p, a, Store) }
    | '(' a=single_target ')' { a }
single_subscript_attribute_target[expr_ty]:
    | a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Store, EXTRA) }
    | a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Store, EXTRA) }

del_targets[asdl_seq*]: a=','.del_target+ [','] { a }
del_target[expr_ty] (memo):
    | a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Del, EXTRA) }
    | a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Del, EXTRA) }
    | del_t_atom
del_t_atom[expr_ty]:
    | a=NAME { _PyPegen_set_expr_context(p, a, Del) }
    | '(' a=del_target ')' { _PyPegen_set_expr_context(p, a, Del) }
    | '(' a=[del_targets] ')' { _Py_Tuple(a, Del, EXTRA) }
    | '[' a=[del_targets] ']' { _Py_List(a, Del, EXTRA) }

targets[asdl_seq*]: a=','.target+ [','] { a }
target[expr_ty] (memo):
    | a=t_primary '.' b=NAME !t_lookahead { _Py_Attribute(a, b->v.Name.id, Store, EXTRA) }
    | a=t_primary '[' b=slices ']' !t_lookahead { _Py_Subscript(a, b, Store, EXTRA) }
    | t_atom
t_primary[expr_ty]:
    | a=t_primary '.' b=NAME &t_lookahead { _Py_Attribute(a, b->v.Name.id, Load, EXTRA) }
    | a=t_primary '[' b=slices ']' &t_lookahead { _Py_Subscript(a, b, Load, EXTRA) }
    | a=t_primary b=genexp &t_lookahead { _Py_Call(a, CHECK(_PyPegen_singleton_seq(p, b)), NULL, EXTRA) }
    | a=t_primary '(' b=[arguments] ')' &t_lookahead {
        _Py_Call(a,
                 (b) ? ((expr_ty) b)->v.Call.args : NULL,
                 (b) ? ((expr_ty) b)->v.Call.keywords : NULL,
                 EXTRA) }
    | a=atom &t_lookahead { a }
t_lookahead: '(' | '[' | '.'
t_atom[expr_ty]:
    | a=NAME { _PyPegen_set_expr_context(p, a, Store) }
    | '(' a=target ')' { _PyPegen_set_expr_context(p, a, Store) }
    | '(' b=[targets] ')' { _Py_Tuple(b, Store, EXTRA) }
    | '[' b=[targets] ']' { _Py_List(b, Store, EXTRA) }


# From here on, there are rules for invalid syntax with specialised error messages
incorrect_arguments:
    | args ',' '*' { RAISE_SYNTAX_ERROR("iterable argument unpacking follows keyword argument unpacking") }
    | a=expression for_if_clauses ',' [args | expression for_if_clauses] {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "Generator expression must be parenthesized") }
    | a=args for_if_clauses { _PyPegen_nonparen_genexp_in_call(p, a) }
    | args ',' a=expression for_if_clauses {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "Generator expression must be parenthesized") }
    | a=args ',' args { _PyPegen_arguments_parsing_error(p, a) }
invalid_kwarg:
    | a=expression '=' {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
            a, "expression cannot contain assignment, perhaps you meant \"==\"?") }
invalid_named_expression:
    | a=expression ':=' expression {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(
            a, "cannot use assignment expressions with %s", _PyPegen_get_expr_name(a)) }
invalid_assignment:
    | a=list ':' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "only single target (not list) can be annotated") }
    | a=tuple ':' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "only single target (not tuple) can be annotated") }
    | a=star_named_expression ',' star_named_expressions* ':' {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "only single target (not tuple) can be annotated") }
    | a=expression ':' expression ['=' annotated_rhs] {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "illegal target for annotation") }
    | (star_targets '=')* a=star_expressions '=' {
        RAISE_SYNTAX_ERROR_INVALID_TARGET(STAR_TARGETS, a) }
    | (star_targets '=')* a=yield_expr '=' { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "assignment to yield expression not possible") }
    | a=star_expressions augassign (yield_expr | star_expressions) {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION( 
            a, 
            "'%s' is an illegal expression for augmented assignment",
            _PyPegen_get_expr_name(a)
        )}
invalid_del_stmt:
    | 'del' a=star_expressions {
        RAISE_SYNTAX_ERROR_INVALID_TARGET(DEL_TARGETS, a) }
invalid_block:
    | NEWLINE !INDENT { RAISE_INDENTATION_ERROR("expected an indented block") }
invalid_comprehension:
    | ('[' | '(' | '{') a=starred_expression for_if_clauses {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "iterable unpacking cannot be used in comprehension") }
invalid_dict_comprehension:
    | '{' a='**' bitwise_or for_if_clauses '}' {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "dict unpacking cannot be used in dict comprehension") }
invalid_parameters:
    | param_no_default* (slash_with_default | param_with_default+) param_no_default {
        RAISE_SYNTAX_ERROR("non-default argument follows default argument") }
invalid_lambda_parameters:
    | lambda_param_no_default* (lambda_slash_with_default | lambda_param_with_default+) lambda_param_no_default {
        RAISE_SYNTAX_ERROR("non-default argument follows default argument") }
invalid_star_etc:
    | '*' (')' | ',' (')' | '**')) { RAISE_SYNTAX_ERROR("named arguments must follow bare *") }
    | '*' ',' TYPE_COMMENT { RAISE_SYNTAX_ERROR("bare * has associated type comment") }
invalid_lambda_star_etc:
    | '*' (':' | ',' (':' | '**')) { RAISE_SYNTAX_ERROR("named arguments must follow bare *") }
invalid_double_type_comments:
    | TYPE_COMMENT NEWLINE TYPE_COMMENT NEWLINE INDENT {
        RAISE_SYNTAX_ERROR("Cannot have two type comments on def") }
invalid_with_item:
    | expression 'as' a=expression {
        RAISE_SYNTAX_ERROR_INVALID_TARGET(STAR_TARGETS, a) }

invalid_for_target:
    | ASYNC? 'for' a=star_expressions {
        RAISE_SYNTAX_ERROR_INVALID_TARGET(FOR_TARGETS, a) }

invalid_group:
    | '(' a=starred_expression ')' {
        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "can't use starred expression here") }
invalid_import_from_targets:
    | import_from_as_names ',' {
        RAISE_SYNTAX_ERROR("trailing comma not allowed without surrounding parentheses") }