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Annex A (informative)
Grammar summary [gram]
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1 This summary of C++ syntax 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_)
must be applied to distinguish expressions from declarations. Fur
ther, access control, ambiguity, and type rules must be used to weed
out syntactically valid but meaningless constructs.
A.1 Keywords [gram.key]
1 New context-dependent keywords are introduced into a program by type
def (_dcl.typedef_), namespace (_namespace.def_), class (_class_),
enumeration (_dcl.enum_), and template (_temp_) declarations.
typedef-name:
identifier
namespace-name:
original-namespace-name
namespace-alias
original-namespace-name:
identifier
namespace-alias:
identifier
class-name:
identifier
template-class-id
enum-name:
identifier
template-name:
identifier
Note that a typedef-name naming a class is also a class-name
(_class.name_).
A.2 Lexical conventions [gram.lex]
hex-quad:
hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
universal-character-name:
??u hex-quad
??U hex-quad hex-quad
preprocessing-token:
header-name
identifier
pp-number
character-literal
string-literal
preprocessing-op-or-punc
each non-white-space character that cannot be one of the above
token:
identifier
keyword
literal
operator
punctuator
header-name:
<h-char-sequence>
"q-char-sequence"
h-char-sequence:
h-char
h-char-sequence h-char
h-char:
any member of the source character set except
new-line and >
q-char-sequence:
q-char
q-char-sequence q-char
q-char:
any member of the source character set except
new-line and "
pp-number:
digit
. digit
pp-number digit
pp-number nondigit
pp-number e sign
pp-number E sign
pp-number .
identifier:
nondigit
identifier nondigit
identifier digit
nondigit: one of
universal-character-name
_ 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
preprocessing-op-or-punc: one of
{ } [ ] # ## ( )
<: :> <% %> %: %:%: ; : ...
new delete ? :: . .*
+ - * / % ^ & | ~
! = < > += -= *= /= %=
^= &= |= << >> >>= <<= == !=
<= >= && || ++ -- , ->* ->
and and_eq bitand bitor compl not not_eq or or_eq
xor xor_eq
literal:
integer-literal
character-literal
floating-literal
string-literal
boolean-literal
integer-literal:
decimal-literal integer-suffixopt
octal-literal integer-suffixopt
hexadecimal-literal integer-suffixopt
decimal-literal:
nonzero-digit
decimal-literal digit
octal-literal:
0
octal-literal octal-digit
hexadecimal-literal:
0x hexadecimal-digit
0X hexadecimal-digit
hexadecimal-literal hexadecimal-digit
nonzero-digit: one of
1 2 3 4 5 6 7 8 9
octal-digit: one of
0 1 2 3 4 5 6 7
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
integer-suffix:
unsigned-suffix long-suffixopt
long-suffix unsigned-suffixopt
unsigned-suffix: one of
u U
long-suffix: one of
l L
character-literal:
'c-char-sequence'
L'c-char-sequence'
c-char-sequence:
c-char
c-char-sequence c-char
c-char:
any member of the source character set except
the single-quote ', backslash \, or new-line character
escape-sequence
universal-character-name
escape-sequence:
simple-escape-sequence
octal-escape-sequence
hexadecimal-escape-sequence
simple-escape-sequence: one of
\' \" \? \\
\a \b \f \n \r \t \v
octal-escape-sequence:
\ octal-digit
\ octal-digit octal-digit
\ octal-digit octal-digit octal-digit
hexadecimal-escape-sequence:
\x hexadecimal-digit
hexadecimal-escape-sequence hexadecimal-digit
floating-literal:
fractional-constant exponent-partopt floating-suffixopt
digit-sequence exponent-part floating-suffixopt
fractional-constant:
digit-sequenceopt . digit-sequence
digit-sequence .
exponent-part:
e signopt digit-sequence
E signopt digit-sequence
sign: one of
+ -
digit-sequence:
digit
digit-sequence digit
floating-suffix: one of
f l F L
string-literal:
"s-char-sequenceopt"
L"s-char-sequenceopt"
s-char-sequence:
s-char
s-char-sequence s-char
s-char:
any member of the source character set except
the double-quote ", backslash \, or new-line character
escape-sequence
universal-character-name
boolean-literal:
false
true
A.3 Basic concepts [gram.basic]
translation unit:
declaration-seqopt
A.4 Expressions [gram.expr]
primary-expression:
literal
this
:: identifier
:: operator-function-id
:: qualified-id
( expression )
id-expression
id-expression:
unqualified-id
qualified-id
id-expression:
unqualified-id
qualified-id
unqualified-id:
identifier
operator-function-id
conversion-function-id
~ class-name
template-id
qualified-id:
nested-name-specifier templateopt unqualified-id
nested-name-specifier:
class-or-namespace-name :: nested-name-specifieropt
class-or-namespace-name:
class-name
namespace-name
postfix-expression:
primary-expression
postfix-expression [ expression ]
postfix-expression ( expression-listopt )
simple-type-specifier ( expression-listopt )
postfix-expression . templateopt ::opt id-expression
postfix-expression -> templateopt ::opt id-expression
postfix-expression . pseudo-destructor-name
postfix-expression -> pseudo-destructor-name
postfix-expression ++
postfix-expression --
dynamic_cast < type-id > ( expression )
static_cast < type-id > ( expression )
reinterpret_cast < type-id > ( expression )
const_cast < type-id > ( expression )
typeid ( expression )
typeid ( type-id )
expression-list:
assignment-expression
expression-list , assignment-expression
pseudo-destructor-name:
::opt nested-name-specifieropt type-name :: ~ type-name
::opt nested-name-specifieropt ~ type-name
unary-expression:
postfix-expression
++ cast-expression
-- cast-expression
unary-operator cast-expression
sizeof unary-expression
sizeof ( type-id )
new-expression
delete-expression
unary-operator: one of
* & + - ! ~
new-expression:
::opt new new-placementopt new-type-id new-initializeropt
::opt new new-placementopt ( type-id ) new-initializeropt
new-placement:
( expression-list )
new-type-id:
type-specifier-seq new-declaratoropt
new-declarator:
ptr-operator new-declaratoropt
direct-new-declarator
direct-new-declarator:
[ expression ]
direct-new-declarator [ constant-expression ]
new-initializer:
( expression-listopt )
delete-expression:
::opt delete cast-expression
::opt delete [ ] cast-expression
cast-expression:
unary-expression
( type-id ) cast-expression
pm-expression:
cast-expression
pm-expression .* cast-expression
pm-expression ->* cast-expression
multiplicative-expression:
pm-expression
multiplicative-expression * pm-expression
multiplicative-expression / pm-expression
multiplicative-expression % pm-expression
additive-expression:
multiplicative-expression
additive-expression + multiplicative-expression
additive-expression - multiplicative-expression
shift-expression:
additive-expression
shift-expression << additive-expression
shift-expression >> additive-expression
relational-expression:
shift-expression
relational-expression < shift-expression
relational-expression > shift-expression
relational-expression <= shift-expression
relational-expression >= shift-expression
equality-expression:
relational-expression
equality-expression == relational-expression
equality-expression != relational-expression
and-expression:
equality-expression
and-expression & equality-expression
exclusive-or-expression:
and-expression
exclusive-or-expression ^ and-expression
inclusive-or-expression:
exclusive-or-expression
inclusive-or-expression | exclusive-or-expression
logical-and-expression:
inclusive-or-expression
logical-and-expression && inclusive-or-expression
logical-or-expression:
logical-and-expression
logical-or-expression || logical-and-expression
conditional-expression:
logical-or-expression
logical-or-expression ? expression : assignment-expression
assignment-expression:
conditional-expression
logical-or-expression assignment-operator assignment-expression
throw-expression
assignment-operator: one of
= *= /= %= += -= >>= <<= &= ^= |=
expression:
assignment-expression
expression , assignment-expression
constant-expression:
conditional-expression
A.5 Statements [gram.stmt.stmt]
statement:
labeled-statement
expression-statement
compound-statement
selection-statement
iteration-statement
jump-statement
declaration-statement
try-block
labeled-statement:
identifier : statement
case constant-expression : statement
default : statement
expression-statement:
expressionopt ;
compound-statement:
{ statement-seqopt }
statement-seq:
statement
statement-seq statement
selection-statement:
if ( condition ) statement
if ( condition ) statement else statement
switch ( condition ) statement
condition:
expression
type-specifier-seq declarator = assignment-expression
iteration-statement:
while ( condition ) statement
do statement while ( expression ) ;
for ( for-init-statement conditionopt ; expressionopt ) statement
for-init-statement:
expression-statement
simple-declaration
jump-statement:
break ;
continue ;
return expressionopt ;
goto identifier ;
declaration-statement:
block-declaration
A.6 Declarations [gram.dcl.dcl]
declaration-seq:
declaration
declaration-seq declaration
declaration:
block-declaration
function-definition
template-declaration
linkage-specification
namespace-definition
block-declaration:
simple-declaration
asm-definition
namespace-alias-definition
using-declaration
using-directive
simple-declaration:
decl-specifier-seqopt init-declarator-listopt ;
decl-specifier-seqopt init-declarator-listopt ;
decl-specifier:
storage-class-specifier
type-specifier
function-specifier
friend
typedef
decl-specifier-seq:
decl-specifier-seqopt decl-specifier
storage-class-specifier:
auto
register
static
extern
mutable
function-specifier:
inline
virtual
explicit
typedef-name:
identifier
type-specifier:
simple-type-specifier
class-specifier
enum-specifier
elaborated-type-specifier
cv-qualifier
simple-type-specifier:
::opt nested-name-specifieropt type-name
char
wchar_t
bool
short
int
long
signed
unsigned
float
double
void
type-name:
class-name
enum-name
typedef-name
elaborated-type-specifier:
class-key ::opt nested-name-specifieropt identifier
enum ::opt nested-name-specifieropt identifier
enum-name:
identifier
enum-specifier:
enum identifieropt { enumerator-listopt }
enumerator-list:
enumerator-definition
enumerator-list , enumerator-definition
enumerator-definition:
enumerator
enumerator = constant-expression
enumerator:
identifier
namespace-name:
original-namespace-name
namespace-alias
original-namespace-name:
identifier
namespace-definition:
named-namespace-definition
unnamed-namespace-definition
named-namespace-definition:
original-namespace-definition
extension-namespace-definition
original-namespace-definition:
namespace identifier { namespace-body }
extension-namespace-definition:
namespace original-namespace-name { namespace-body }
unnamed-namespace-definition:
namespace { namespace-body }
namespace-body:
declaration-seqopt
namespace-alias:
identifier
namespace-alias-definition:
namespace identifier = qualified-namespace-specifier ;
qualified-namespace-specifier:
::opt nested-name-specifieropt namespace-name
using-declaration:
using typenameopt ::opt nested-name-specifier unqualified-id ;
using :: unqualified-id ;
using-directive:
using namespace ::opt nested-name-specifieropt namespace-name ;
asm-definition:
asm ( string-literal ) ;
linkage-specification:
extern string-literal { declaration-seqopt }
extern string-literal declaration
A.7 Declarators [gram.dcl.decl]
init-declarator-list:
init-declarator
init-declarator-list , init-declarator
init-declarator:
declarator initializeropt
declarator:
direct-declarator
ptr-operator declarator
direct-declarator:
declarator-id
direct-declarator ( parameter-declaration-clause ) cv-qualifier-seqopt exception-specificationopt
direct-declarator [ constant-expressionopt ]
( declarator )
ptr-operator:
* cv-qualifier-seqopt
&
::opt nested-name-specifier * cv-qualifier-seqopt
cv-qualifier-seq:
cv-qualifier cv-qualifier-seqopt
cv-qualifier:
const
volatile
declarator-id:
::opt id-expression
::opt nested-name-specifieropt type-name
type-id:
type-specifier-seq abstract-declaratoropt
type-specifier-seq:
type-specifier type-specifier-seqopt
abstract-declarator:
ptr-operator abstract-declaratoropt
direct-abstract-declarator
direct-abstract-declarator:
direct-abstract-declaratoropt ( parameter-declaration-clause ) cv-qualifier-seqopt exception-specificationopt
direct-abstract-declaratoropt [ constant-expressionopt ]
( abstract-declarator )
parameter-declaration-clause:
parameter-declaration-listopt ...opt
parameter-declaration-list , ...
parameter-declaration-list:
parameter-declaration
parameter-declaration-list , parameter-declaration
parameter-declaration:
decl-specifier-seq declarator
decl-specifier-seq declarator = assignment-expression
decl-specifier-seq abstract-declaratoropt
decl-specifier-seq abstract-declaratoropt = assignment-expression
function-definition:
decl-specifier-seqopt declarator ctor-initializeropt function-body
decl-specifier-seqopt declarator function-try-block
function-body:
compound-statement
initializer:
= initializer-clause
( expression-list )
initializer-clause:
assignment-expression
{ initializer-list ,opt }
{ }
initializer-list:
initializer-clause
initializer-list , initializer-clause
A.8 Classes [gram.class]
class-name:
identifier
template-id
class-specifier:
class-head { member-specificationopt }
class-head:
class-key identifieropt base-clauseopt
class-key nested-name-specifier identifier base-clauseopt
class-key:
class
struct
union
member-specification:
member-declaration member-specificationopt
access-specifier : member-specificationopt
member-declaration:
decl-specifier-seqopt member-declarator-listopt ;
function-definition ;opt
qualified-id ;
using-declaration
member-declarator-list:
member-declarator
member-declarator-list , member-declarator
member-declarator:
declarator pure-specifieropt
declarator constant-initializeropt
identifieropt : constant-expression
pure-specifier:
= 0
constant-initializer:
= constant-expression
A.9 Derived classes [gram.class.derived]
base-clause:
: base-specifier-list
base-specifier-list:
base-specifier
base-specifier-list , base-specifier
base-specifier:
::opt nested-name-specifieropt class-name
virtual access-specifieropt ::opt nested-name-specifieropt class-name
access-specifier virtualopt ::opt nested-name-specifieropt class-name
access-specifier:
private
protected
public
A.10 Special member functions [gram.special]
conversion-function-id:
operator conversion-type-id
conversion-type-id:
type-specifier-seq conversion-declaratoropt
conversion-declarator:
ptr-operator conversion-declaratoropt
ctor-initializer:
: mem-initializer-list
mem-initializer-list:
mem-initializer
mem-initializer , mem-initializer-list
mem-initializer:
mem-initializer-id ( expression-listopt )
mem-initializer-id:
::opt nested-name-specifieropt class-name
identifier
A.11 Overloading [gram.over]
operator-function-id:
operator operator
operator: one of
new delete new[] delete[]
+ - * / % ^ & | ~
! = < > += -= *= /= %=
^= &= |= << >> >>= <<= == !=
<= >= && || ++ -- , ->* ->
() []
A.12 Templates [gram.temp]
template-declaration:
template < template-parameter-list > declaration
template-parameter-list:
template-parameter
template-parameter-list , template-parameter
template-parameter:
type-parameter
parameter-declaration
type-parameter:
class identifieropt
class identifieropt = type-id
typename identifieropt
typename identifieropt = type-id
template < template-parameter-list > class identifieropt
template < template-parameter-list > class identifieropt = template-name
template-id:
template-name < template-argument-list >
template-name:
identifier
template-argument-list:
template-argument
template-argument-list , template-argument
template-argument:
assignment-expression
type-id
template-name
elaborated-type-specifier:
. . .
typename ::opt nested-name-specifier identifier full-template-argument-listopt
. . .
full-template-argument-list:
< template-argument-list >
explicit-instantiation:
template declaration
specialization:
template < > declaration
A.13 Exception handling [gram.except]
try-block:
try compound-statement handler-seq
function-try-block:
try ctor-initializeropt function-body handler-seq
handler-seq:
handler handler-seqopt
handler:
catch ( exception-declaration ) compound-statement
exception-declaration:
type-specifier-seq declarator
type-specifier-seq abstract-declarator
type-specifier-seq
...
throw-expression:
throw assignment-expressionopt
exception-specification:
throw ( type-id-listopt )
type-id-list:
type-id
type-id-list , type-id