Annex A (informative) Grammar summary [gram]

A.1 General [gram.general]

1
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This summary of C++ grammar is intended to be an aid to comprehension.
It is not an exact statement of the language.
In particular, the grammar described here accepts a superset of valid C++ constructs.
Disambiguation rules ([stmt.ambig], [dcl.spec], [class.member.lookup]) are applied to distinguish expressions from declarations.
Further, access control, ambiguity, and type rules are used to weed out syntactically valid but meaningless constructs.

A.2 Keywords [gram.key]

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New context-dependent keywords are introduced into a program by typedef ([dcl.typedef]), namespace ([namespace.def]), class ([class]), enumeration ([dcl.enum]), and template ([temp]) declarations.
typedef-name:
identifier
simple-template-id
namespace-name:
identifier
namespace-alias
namespace-alias:
identifier
class-name:
identifier
simple-template-id
enum-name:
identifier
template-name:
identifier
std-gram.ext

A.3 Lexical conventions [gram.lex]

n-char:
any member of the translation character set except the U+007d right curly bracket or new-line character
h-char:
any member of the translation character set except new-line and U+003e greater-than sign
q-char:
any member of the translation character set except new-line and U+0022 quotation mark
preprocessing-operator: one of
#        ##       %:       %:%:
operator-or-punctuator: one of
{        }        [        ]        (        )
<%       %>       <:       :>       ;        :        ...
?        ::       .        .*       ->       ->*      ~
!        +        -        *        /        %        ^        &        |
=        +=       -=       *=       /=       %=       ^=       &=       |=
==       !=       <        >        <=       >=       <=>      &&       ||
<<       >>       <<=      >>=      ++       --       ,
and      or       xor      not      bitand   bitor    compl
and_eq   or_eq    xor_eq   not_eq
identifier-start:
nondigit
an element of the translation character set with the Unicode property XID_Start
identifier-continue:
digit
nondigit
an element of the translation character set with the Unicode property XID_Continue
nondigit: one of
a b c d e f g h i j k l m
n o p q r s t u v w x y z
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z _
digit: one of
0 1 2 3 4 5 6 7 8 9
keyword:
any identifier listed in Table 5
import-keyword
module-keyword
export-keyword
binary-digit: one of
0 1
octal-digit: one of
0 1 2 3 4 5 6 7
nonzero-digit: one of
1 2 3 4 5 6 7 8 9
hexadecimal-prefix: one of
0x 0X
hexadecimal-digit: one of
0 1 2 3 4 5 6 7 8 9
a b c d e f
A B C D E F
unsigned-suffix: one of
u U
long-suffix: one of
l L
long-long-suffix: one of
ll LL
size-suffix: one of
z Z
encoding-prefix: one of
u8  u  U  L
basic-c-char:
any member of the translation character set except the U+0027 apostrophe,
   U+005c reverse solidus, or new-line character
simple-escape-sequence-char: one of
' " ? \ a b f n r t v
conditional-escape-sequence-char:
any member of the basic character set that is not an octal-digit, a simple-escape-sequence-char, or the characters N, o, u, U, or x
sign: one of
+ -
floating-point-suffix: one of
f l f16 f32 f64 f128 bf16 F L F16 F32 F64 F128 BF16
basic-s-char:
any member of the translation character set except the U+0022 quotation mark,
   U+005c reverse solidus, or new-line character
r-char:
any member of the translation character set, except a U+0029 right parenthesis followed by
   the initial d-char-sequence (which may be empty) followed by a U+0022 quotation mark
d-char:
any member of the basic character set except:
   U+0020 space, U+0028 left parenthesis, U+0029 right parenthesis, U+005c reverse solidus,
   U+0009 character tabulation, U+000b line tabulation, U+000c form feed, and new-line
boolean-literal:
false
true

A.4 Basics [gram.basic]

A.5 Expressions [gram.expr]

lambda-specifier:
consteval
constexpr
mutable
static
simple-capture:
identifier ...
& identifier ...
this
* this
fold-operator: one of
+   -   *   /   %   ^   &   |   <<   >>
+=  -=  *=  /=  %=  ^=  &=  |=  <<=  >>=  =
==  !=  <   >   <=  >=  &&  ||  ,   .*   ->*
requirement-body:
{ requirement-seq }
unary-operator: one of
* & + - ! ~
delete-expression:
:: delete cast-expression
:: delete [ ] cast-expression
assignment-operator: one of
= *= /= %= += -= >>= <<= &= ^= |=

A.6 Statements [gram.stmt]

selection-statement:
if constexpr ( init-statement condition ) statement
if constexpr ( init-statement condition ) statement else statement
if ! consteval compound-statement
if ! consteval compound-statement else statement
switch ( init-statement condition ) statement

A.7 Declarations [gram.dcl]

storage-class-specifier:
static
thread_local
extern
mutable
cv-qualifier:
const
volatile
function-body:
ctor-initializer compound-statement
function-try-block
= default ;
deleted-function-body
deleted-function-body:
= delete ;
= delete ( unevaluated-string ) ;
enum-key:
enum
enum class
enum struct
namespace-body:
declaration-seq
alignment-specifier:
alignas ( type-id ... )
alignas ( constant-expression ... )
balanced-token:
( balanced-token-seq )
[ balanced-token-seq ]
{ balanced-token-seq }
any token other than a parenthesis, a bracket, or a brace

A.8 Modules [gram.module]

private-module-fragment:
module-keyword : private ; declaration-seq

A.9 Classes [gram.class]

class-property-specifier:
final
trivially_relocatable_if_eligible
replaceable_if_eligible
class-key:
class
struct
union
virt-specifier:
override
final
access-specifier:
private
protected
public

A.10 Overloading [gram.over]

operator: one of
new      delete   new[]    delete[] co_await ( )        [ ]        ->       ->*
~        !        +        -        *        /        %        ^        &
|        =        +=       -=       *=       /=       %=       ^=       &=
|=       ==       !=       <        >        <=       >=       <=>      &&
||       <<       >>       <<=      >>=      ++       --       ,

A.11 Templates [gram.temp]

type-parameter-key:
class
typename

A.12 Exception handling [gram.except]

A.13 Preprocessing directives [gram.cpp]

else-group:
# else    new-line group
endif-line:
# endif   new-line
lparen:
a ( character not immediately preceded by whitespace
pp-balanced-token:
( pp-balanced-token-seq )
[ pp-balanced-token-seq ]
{ pp-balanced-token-seq }
any pp-token except:
   parenthesis (U+0028 left parenthesis and U+0029 right parenthesis),
   bracket (U+005b left square bracket and U+005d right square bracket), or
   brace (U+007b left curly bracket and U+007d right curly bracket).
new-line:
the new-line character
has-include-expression:
__has_include ( header-name )
__has_include ( header-name-tokens )
has-attribute-expression:
__has_cpp_attribute ( pp-tokens )
pp-module:
export module pp-tokens ; new-line
pp-import:
export import header-name pp-tokens ; new-line
export import header-name-tokens pp-tokens ; new-line
export import pp-tokens ; new-line
va-opt-replacement:
__VA_OPT__ ( pp-tokens )