Permalink
Find file
Fetching contributors…
Cannot retrieve contributors at this time
596 lines (596 sloc) 19 KB
Appendix A
(informative)
Grammar summary [gram]
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 (6.8, 7.1, 10.2) must be applied to distinguish expressions from declarations. Further, 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 typedef (7.1.3), namespace (7.3.1), class (clause 9), enumeration (7.2), and template (clause 14) declarations.
typedef-name: identifier
namespace-name: original-namespace-name
namespace-alias original-namespace-name:
identifier namespace-alias:
identifier
class-name: identifier
template-id enum-name:
identifier
template-name: identifier
Note that a typedef-name naming a class is also a class-name (9.1). A.2 Lexical conventions
hex-quad:
hexadecimal-digit hexadecimal-digit hexadecimal-digit hexadecimal-digit
[gram.lex]
A.2 Lexical conventions
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 "
Grammar summary 1024
pp-number: digit
. digit
pp-number digit pp-number nondigit pp-number e sign pp-number E sign pp-number .
identifier: identifier-nondigit
identifier identifier-nondigit identifier digit
identifier-nondigit: nondigit
universal-character-name
other implementation-defined characters
Draft
1025
Grammar summary
nondigit: one of abcdefghijklm nopqrstuvwxyz ABCDEFGHIJKLM NOPQRSTUVWXYZ_
digit: one of 0123456789
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 123456789
octal-digit: one of 01234567
hexadecimal-digit: one of 0123456789
abcdef ABCDEF
integer-suffix:
unsigned-suffix long-suffixopt unsigned-suffix long-long-suffixopt long-suffix unsigned-suffixopt long-long-suffix unsigned-suffixopt
unsigned-suffix: one of uU
long-suffix: one of lL
long-long-suffix: one of ll LL
A.2 Lexical conventions
Draft
A.2 Lexical conventions
character-literal:
’ c-char-sequence ’
u’ c-char-sequence ’ U’ 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
Grammar summary 1026
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 flFL
Draft
1027
Grammar summary
string-literal:
" s-char-sequenceopt "
u" s-char-sequenceopt " U" 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
Basic concepts
translation-unit: declaration-seqopt
A.3
Basic concepts
A.3
[gram.basic]
[gram.expr]
A.4 Expressions
primary-expression: literal
this
( expression )
id-expression id-expression:
unqualified-id
qualified-id unqualified-id:
identifier operator-function-id conversion-function-id ∼ class-name template-id
qualified-id:
::opt nested-name-specifier templateopt unqualified-id :: identifier
:: operator-function-id
:: template-id
nested-name-specifier: type-name ::
namespace-name ::
nested-name-specifier identifier ::
nested-name-specifier templateopt simple-template-id ::
Draft
A.4 Expressions
postfix-expression: primary-expression
postfix-expression [ expression ] postfix-expression ( expression-listopt ) simple-type-specifier ( expression-listopt ) typename-specifier ( expression-listopt ) postfix-expression . templateopt id-expression postfix-expression -> templateopt 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 ...opt
expression-list , assignment-expression ...opt
pseudo-destructor-name:
::opt nested-name-specifieropt type-name :: ∼ type-name
::opt nested-name-specifier template simple-template-id :: ∼ 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 )
sizeof ... ( identifier ) 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
Grammar summary 1028
new-placement:
( expression-list )
new-type-id:
type-specifier-seq new-declaratoropt
new-declarator:
ptr-operator new-declaratoropt direct-new-declarator
Draft
1029
Grammar summary
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
A.4 Expressions
Draft
A.5 Statements
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
Grammar summary 1030
assignment-operator: one of
= *= /= %= += -= >>= <<= &= ^= |=
expression: assignment-expression
expression , assignment-expression constant-expression:
conditional-expression
A.5 Statements
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 }
[gram.stmt]
Draft
1031
Grammar summary
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
A.6 Declarations
for-init-statement: expression-statement
simple-declaration
jump-statement:
break ;
continue ;
return expressionopt ; goto identifier ;
declaration-statement: block-declaration
A.6 Declarations
declaration-seq: declaration
declaration-seq declaration
declaration: block-declaration
function-definition template-declaration explicit-instantiation explicit-specialization linkage-specification namespace-definition
block-declaration: simple-declaration
asm-definition namespace-alias-definition using-declaration using-directive static_assert-declaration alias-declaration
alias-declaration:
using identifier = type-id
[gram.dcl]
Draft
A.6 Declarations
simple-declaration:
decl-specifier-seqopt init-declarator-listopt ;
static_assert-declaration:
static_assert ( constant-expression , string-literal ) ;
decl-specifier: storage-class-specifier
type-specifier function-specifier friend typedef
decl-specifier-seq:
decl-specifier-seqopt decl-specifier
storage-class-specifier:
register
static
extern
mutable
function-specifier:
inline
virtual
explicit
typedef-name: identifier
type-specifier: simple-type-specifier
class-specifier enum-specifier elaborated-type-specifier typename-specifier cv-qualifier
simple-type-specifier:
::opt nested-name-specifieropt type-name
::opt nested-name-specifier template simple-template-id char
char16_t
char32_t
wchar_t
bool
short
int
long
signed
unsigned
float
double
void
auto
Draft
Grammar summary 1032
1033
Grammar summary
type-name: class-name
enum-name typedef-name
elaborated-type-specifier:
class-key ::opt nested-name-specifieropt identifier
class-key ::opt nested-name-specifieropt templateopt simple-template-id enum ::opt nested-name-specifieropt identifier
enum-name: identifier
enum-specifier:
enum identifieropt { enumerator-listopt } enum identifieropt { enumerator-list , }
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 ;
Draft
A.6 Declarations
A.7 Declarators
using-directive:
using namespace ::opt
asm-definition:
asm ( string-literal ) ;
linkage-specification:
extern string-literal { declaration-seqopt } extern string-literal declaration
A.7 Declarators
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 direct-declarator [ constant-expressionopt ]
( declarator )
ptr-operator:
* cv-qualifier-seqopt
&
&&
::opt nested-name-specifier * cv-qualifier-seqopt
Grammar summary 1034
cv-qualifier-seq:
cv-qualifier cv-qualifier-seqopt
cv-qualifier:
const
volatile
declarator-id:
...opt id-expression
::opt nested-name-specifieropt class-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
...
nested-name-specifieropt namespace-name ;
Draft
exception-specificationopt
[gram.decl]
1035
Grammar summary
direct-abstract-declarator: direct-abstract-declaratoropt
( parameter-declaration-clause ) cv-qualifier-seqopt 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
A.8 Classes
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
decl-specifier-seqopt function-body:
compound-statement
initializer:
= initializer-clause
( expression-list )
declarator ctor-initializeropt declarator function-try-block
function-body
initializer-clause: assignment-expression
{ initializer-list ,opt } {}
initializer-list: initializer-clause ...opt
initializer-list , initializer-clause ...opt A.8 Classes
class-name: identifier
simple-template-id class-specifier:
class-head { member-specificationopt }
[gram.class]
class-head:
class-key identifieropt base-clauseopt
class-key nested-name-specifier identifier base-clauseopt
class-key nested-name-specifieropt simple-template-id base-clauseopt
class-key:
class
struct
union
Draft
exception-specificationopt
A.9
Derived classes
member-specification:
member-declaration member-specificationopt access-specifier : member-specificationopt
member-declaration:
decl-specifier-seqopt member-declarator-listopt ; function-definition ;opt
::opt nested-name-specifier templateopt using-declaration
static_assert-declaration
template-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
Derived classes
base-clause:
: base-specifier-list
base-specifier-list: base-specifier ...opt
base-specifier-list , base-specifier ...opt
base-specifier:
::opt nested-name-specifieropt class-name
Grammar summary 1036
A.9
[gram.derived]
A.10
[gram.special]
virtual access-specifieropt ::opt
nested-name-specifieropt class-name nested-name-specifieropt class-name
access-specifier virtualopt
access-specifier:
private
protected
public
Special member functions
::opt
conversion-function-id:
operator conversion-type-id
conversion-type-id:
type-specifier-seq conversion-declaratoropt
conversion-declarator:
ptr-operator conversion-declaratoropt
unqualified-id ;
Draft
1037
Grammar summary
ctor-initializer:
: mem-initializer-list
mem-initializer-list: mem-initializer ...opt
mem-initializer , mem-initializer-list ...opt mem-initializer:
mem-initializer-id ( expression-listopt )
mem-initializer-id:
::opt nested-name-specifieropt class-name identifier
A.11
Overloading
A.11 Overloading
operator-function-id: operator operator
A.12 Templates
template-declaration:
exportopt template < template-parameter-list > declaration
template-parameter-list: template-parameter
template-parameter-list , template-parameter
template-parameter: type-parameter
parameter-declaration
type-parameter:
class ...opt identifieropt
class identifieropt = type-id
typename ...opt identifieropt
typename identifieropt = type-id
template < template-parameter-list > class ...opt identifieropt template < template-parameter-list > class identifieropt = id-expression
simple-template-id:
template-name < template-argument-listopt >
template-id: simple-template-id
operator-function-id < template-argument-listopt > template-name:
identifier
template-argument-list: template-argument ...opt
template-argument-list , template-argument ...opt
Draft
[gram.over]
[gram.temp]
A.13
Exception handling
template-argument: constant-expression
Grammar summary 1038
A.13
explicit-instantiation:
externopt template declaration
explicit-specialization:
template < > declaration
Exception handling
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
[gram.except]
A.14
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 ...opt
type-id-list , type-id ...opt Preprocessing directives
preprocessing-file: groupopt
group: group-part
group group-part
[gram.cpp]
type-id id-expression
typename-specifier: typename ::opt typename ::opt
nested-name-specifier identifier nested-name-specifier templateopt
simple-template-id
Draft
1039
Grammar summary
group-part: if-section
control-line text-line
# non-directive
if-section:
if-group elif-groupsopt
if-group:
# if
# ifdef
# ifndef
elif-groups: elif-group
A.14 Preprocessing directives
elif-groups elif-group elif-group:
# elif
else-group:
# else
endif-line:
# endif
control-line:
# include
# define
# define
# define
# define
# undef
# line
# error
# pragma # new-line
constant-expression new-line groupopt new-line groupopt
new-line
pp-tokens new-line
identifier replacement-list new-line
identifier lparen identifier-listopt ) replacement-list new-line identifier lparen ... ) replacement-list new-line
else-groupopt
endif-line
constant-expression new-line groupopt identifier new-line groupopt
identifier new-line groupopt
identifier lparen identifier-list, ... identifier new-line
pp-tokens new-line
pp-tokensopt new-line pp-tokensopt new-line
) replacement-list new-line
text-line:
pp-tokensopt new-line
non-directive:
pp-tokensopt new-line
lparen:
a ( character not immediately preceded by white-space
identifier-list: identifier
identifier-list , identifier
replacement-list: pp-tokensopt
Draft
A.14
Preprocessing directives
pp-tokens: preprocessing-token
pp-tokens preprocessing-token
new-line:
the new-line character