The C++ Domain

Nuevo en la versión 1.0.

The C++ domain (name cpp) supports documenting C++ projects.

Directives for Declaring Entities

The following directives are available. All declarations can start with a visibility statement (public, private or protected).

.. cpp:class:: class specifier
.. cpp:struct:: class specifier

Describe a class/struct, possibly with specification of inheritance, e.g.,:

.. cpp:class:: MyClass : public MyBase, MyOtherBase

The difference between cpp:class and cpp:struct is only cosmetic: the prefix rendered in the output, and the specifier shown in the index.

The class can be directly declared inside a nested scope, e.g.,:

.. cpp:class:: OuterScope::MyClass : public MyBase, MyOtherBase

A class template can be declared:

.. cpp:class:: template<typename T, std::size_t N> std::array

or with a line break:

.. cpp:class:: template<typename T, std::size_t N> \
               std::array

Full and partial template specialisations can be declared:

.. cpp:class:: template<> \
               std::array<bool, 256>

.. cpp:class:: template<typename T> \
               std::array<T, 42>

Nuevo en la versión 2.0: The cpp:struct directive.

.. cpp:function:: (member) function prototype

Describe a function or member function, e.g.,:

.. cpp:function:: bool myMethod(int arg1, std::string arg2)

   A function with parameters and types.

.. cpp:function:: bool myMethod(int, double)

   A function with unnamed parameters.

.. cpp:function:: const T &MyClass::operator[](std::size_t i) const

   An overload for the indexing operator.

.. cpp:function:: operator bool() const

   A casting operator.

.. cpp:function:: constexpr void foo(std::string &bar[2]) noexcept

   A constexpr function.

.. cpp:function:: MyClass::MyClass(const MyClass&) = default

   A copy constructor with default implementation.

Function templates can also be described:

.. cpp:function:: template<typename U> \
                  void print(U &&u)

and function template specialisations:

.. cpp:function:: template<> \
                  void print(int i)
:single-line-parameter-list: (no value)

Ensures that the function’s parameters will be emitted on a single logical line, overriding cpp_maximum_signature_line_length and maximum_signature_line_length.

Nuevo en la versión 7.1.

.. cpp:member:: (member) variable declaration
.. cpp:var:: (member) variable declaration

Describe a variable or member variable, e.g.,:

.. cpp:member:: std::string MyClass::myMember

.. cpp:var:: std::string MyClass::myOtherMember[N][M]

.. cpp:member:: int a = 42

Variable templates can also be described:

.. cpp:member:: template<class T> \
                constexpr T pi = T(3.1415926535897932385)
.. cpp:type:: typedef declaration
.. cpp:type:: name
.. cpp:type:: type alias declaration

Describe a type as in a typedef declaration, a type alias declaration, or simply the name of a type with unspecified type, e.g.,:

.. cpp:type:: std::vector<int> MyList

   A typedef-like declaration of a type.

.. cpp:type:: MyContainer::const_iterator

   Declaration of a type alias with unspecified type.

.. cpp:type:: MyType = std::unordered_map<int, std::string>

   Declaration of a type alias.

A type alias can also be templated:

.. cpp:type:: template<typename T> \
              MyContainer = std::vector<T>

The example are rendered as follows.

typedef std::vector<int> MyList

A typedef-like declaration of a type.

type MyContainer::const_iterator

Declaration of a type alias with unspecified type.

using MyType = std::unordered_map<int, std::string>

Declaration of a type alias.

template<typename T>
using MyContainer = std::vector<T>
.. cpp:enum:: unscoped enum declaration
.. cpp:enum-struct:: scoped enum declaration
.. cpp:enum-class:: scoped enum declaration

Describe a (scoped) enum, possibly with the underlying type specified. Any enumerators declared inside an unscoped enum will be declared both in the enum scope and in the parent scope. Examples:

.. cpp:enum:: MyEnum

   An unscoped enum.

.. cpp:enum:: MySpecificEnum : long

   An unscoped enum with specified underlying type.

.. cpp:enum-class:: MyScopedEnum

   A scoped enum.

.. cpp:enum-struct:: protected MyScopedVisibilityEnum : std::underlying_type<MySpecificEnum>::type

   A scoped enum with non-default visibility, and with a specified
   underlying type.
.. cpp:enumerator:: name
.. cpp:enumerator:: name = constant

Describe an enumerator, optionally with its value defined, e.g.,:

.. cpp:enumerator:: MyEnum::myEnumerator

.. cpp:enumerator:: MyEnum::myOtherEnumerator = 42
.. cpp:union:: name

Describe a union.

Nuevo en la versión 1.8.

.. cpp:concept:: template-parameter-list name

Advertencia

The support for concepts is experimental. It is based on the current draft standard and the Concepts Technical Specification. The features may change as they evolve.

Describe a concept. It must have exactly 1 template parameter list. The name may be a nested name. Example:

.. cpp:concept:: template<typename It> std::Iterator

   Proxy to an element of a notional sequence that can be compared,
   indirected, or incremented.

   **Notation**

   .. cpp:var:: It r

      An lvalue.

   **Valid Expressions**

   - :cpp:expr:`*r`, when :cpp:expr:`r` is dereferenceable.
   - :cpp:expr:`++r`, with return type :cpp:expr:`It&`, when
     :cpp:expr:`r` is incrementable.

This will render as follows:

template<typename It>
concept std::Iterator

Proxy to an element of a notional sequence that can be compared, indirected, or incremented.

Notation

It r

An lvalue.

Valid Expressions

  • *r, when r is dereferenceable.

  • ++r, with return type It&, when r is incrementable.

Nuevo en la versión 1.5.

Opciones

Some directives support options:

  • :no-index-entry: and :no-contents-entry:, see Basic Markup.

  • :tparam-line-spec:, for templated declarations. If specified, each template parameter will be rendered on a separate line.

    Nuevo en la versión 1.6.

Anonymous Entities

C++ supports anonymous namespaces, classes, enums, and unions. For the sake of documentation they must be given some name that starts with @, e.g., @42 or @data. These names can also be used in cross-references and (type) expressions, though nested symbols will be found even when omitted. The @... name will always be rendered as [anonymous] (possibly as a link).

Example:

.. cpp:class:: Data

   .. cpp:union:: @data

      .. cpp:var:: int a

      .. cpp:var:: double b

Explicit ref: :cpp:var:`Data::@data::a`. Short-hand ref: :cpp:var:`Data::a`.

This will be rendered as:

class Data
union [anonymous]
int a
double b

Explicit ref: Data::[anonymous]::a. Short-hand ref: Data::a.

Nuevo en la versión 1.8.

Aliasing Declarations

Sometimes it may be helpful list declarations elsewhere than their main documentation, e.g., when creating a synopsis of a class interface. The following directive can be used for this purpose.

.. cpp:alias:: name or function signature

Insert one or more alias declarations. Each entity can be specified as they can in the cpp:any role. If the name of a function is given (as opposed to the complete signature), then all overloads of the function will be listed.

For example:

.. cpp:alias:: Data::a
               overload_example::C::f

becomes

int a
void f(double d) const
void f(double d)
void f(int i)
void f()

whereas:

.. cpp:alias:: void overload_example::C::f(double d) const
               void overload_example::C::f(double d)

becomes

void f(double d) const
void f(double d)

Nuevo en la versión 2.0.

Opciones

:maxdepth: int

Insert nested declarations as well, up to the total depth given. Use 0 for infinite depth and 1 for just the mentioned declaration. Defaults to 1.

Nuevo en la versión 3.5.

:noroot:

Skip the mentioned declarations and only render nested declarations. Requires maxdepth either 0 or at least 2.

Nuevo en la versión 3.5.

Constrained Templates

Advertencia

The support for concepts is experimental. It is based on the current draft standard and the Concepts Technical Specification. The features may change as they evolve.

Nota

Sphinx does not currently support requires clauses.

Placeholders

Declarations may use the name of a concept to introduce constrained template parameters, or the keyword auto to introduce unconstrained template parameters:

.. cpp:function:: void f(auto &&arg)

   A function template with a single unconstrained template parameter.

.. cpp:function:: void f(std::Iterator it)

   A function template with a single template parameter, constrained by the
   Iterator concept.

Template Introductions

Simple constrained function or class templates can be declared with a template introduction instead of a template parameter list:

.. cpp:function:: std::Iterator{It} void advance(It &it)

    A function template with a template parameter constrained to be an
    Iterator.

.. cpp:class:: std::LessThanComparable{T} MySortedContainer

    A class template with a template parameter constrained to be
    LessThanComparable.

They are rendered as follows.

std::Iterator{It}
void advance(It &it)

A function template with a template parameter constrained to be an Iterator.

std::LessThanComparable{T}
class MySortedContainer

A class template with a template parameter constrained to be LessThanComparable.

Note however that no checking is performed with respect to parameter compatibility. E.g., Iterator{A, B, C} will be accepted as an introduction even though it would not be valid C++.

Inline Expressions and Types

:cpp:expr:
:cpp:texpr:

Insert a C++ expression or type either as inline code (cpp:expr) or inline text (cpp:texpr). For example:

.. cpp:var:: int a = 42

.. cpp:function:: int f(int i)

An expression: :cpp:expr:`a * f(a)` (or as text: :cpp:texpr:`a * f(a)`).

A type: :cpp:expr:`const MySortedContainer<int>&`
(or as text :cpp:texpr:`const MySortedContainer<int>&`).

will be rendered as follows:

int a = 42
int f(int i)

An expression: a * f(a) (or as text: a * f(a)).

A type: const MySortedContainer<int>& (or as text const MySortedContainer<int>&).

Nuevo en la versión 1.7: The cpp:expr role.

Nuevo en la versión 1.8: The cpp:texpr role.

Namespacing

Declarations in the C++ domain are as default placed in global scope. The current scope can be changed using three namespace directives. They manage a stack declarations where cpp:namespace resets the stack and changes a given scope.

The cpp:namespace-push directive changes the scope to a given inner scope of the current one.

The cpp:namespace-pop directive undoes the most recent cpp:namespace-push directive.

.. cpp:namespace:: scope specification

Changes the current scope for the subsequent objects to the given scope, and resets the namespace directive stack. Note that the namespace does not need to correspond to C++ namespaces, but can end in names of classes, e.g.,:

.. cpp:namespace:: Namespace1::Namespace2::SomeClass::AnInnerClass

All subsequent objects will be defined as if their name were declared with the scope prepended. The subsequent cross-references will be searched for starting in the current scope.

Using NULL, 0, or nullptr as the scope will change to global scope.

A namespace declaration can also be templated, e.g.,:

.. cpp:class:: template<typename T> \
               std::vector

.. cpp:namespace:: template<typename T> std::vector

.. cpp:function:: std::size_t size() const

declares size as a member function of the class template std::vector. Equivalently this could have been declared using:

.. cpp:class:: template<typename T> \
               std::vector

   .. cpp:function:: std::size_t size() const

or:

.. cpp:class:: template<typename T> \
               std::vector
.. cpp:namespace-push:: scope specification

Change the scope relatively to the current scope. For example, after:

.. cpp:namespace:: A::B

.. cpp:namespace-push:: C::D

the current scope will be A::B::C::D.

Nuevo en la versión 1.4.

.. cpp:namespace-pop::

Undo the previous cpp:namespace-push directive (not just pop a scope). For example, after:

.. cpp:namespace:: A::B

.. cpp:namespace-push:: C::D

.. cpp:namespace-pop::

the current scope will be A::B (not A::B::C).

If no previous cpp:namespace-push directive has been used, but only a cpp:namespace directive, then the current scope will be reset to global scope. That is, .. cpp:namespace:: A::B is equivalent to:

.. cpp:namespace:: nullptr

.. cpp:namespace-push:: A::B

Nuevo en la versión 1.4.

Info field lists

All the C++ directives for declaring entities support the following info fields (see also Info field lists):

  • tparam: Description of a template parameter.

The cpp:function directive additionally supports the following fields:

  • param, parameter, arg, argument: Description of a parameter.

  • returns, return: Description of a return value.

  • retval, retvals: An alternative to returns for describing the result of the function.

  • throws, throw, exception: Description of a possibly thrown exception.

Nuevo en la versión 4.3: The retval field type.

Cross-referencing

These roles link to the given declaration types:

:cpp:any:
:cpp:class:
:cpp:struct:
:cpp:func:
:cpp:member:
:cpp:var:
:cpp:type:
:cpp:concept:
:cpp:enum:
:cpp:enumerator:

Reference a C++ declaration by name (see below for details). The name must be properly qualified relative to the position of the link.

Nuevo en la versión 2.0: The cpp:struct role as alias for the cpp:class role.

Note on References with Templates Parameters/Arguments

These roles follow the Sphinx Cross-referencing syntax rules. This means care must be taken when referencing a (partial) template specialization, e.g. if the link looks like this: :cpp:class:`MyClass<int>`. This is interpreted as a link to int with a title of MyClass. In this case, escape the opening angle bracket with a backslash, like this: :cpp:class:`MyClass\<int>`.

When a custom title is not needed it may be useful to use the roles for inline expressions, cpp:expr and cpp:texpr, where angle brackets do not need escaping.

Declarations without template parameters and template arguments

For linking to non-templated declarations the name must be a nested name, e.g., f or MyClass::f.

Overloaded (member) functions

When a (member) function is referenced using just its name, the reference will point to an arbitrary matching overload. The cpp:any and cpp:func roles use an alternative format, which simply is a complete function declaration. This will resolve to the exact matching overload. As example, consider the following class declaration:

class C
void f(double d) const
void f(double d)
void f(int i)
void f()

References using the cpp:func role:

Note that the add_function_parentheses configuration variable does not influence specific overload references.

Templated declarations

Assume the following declarations.

class Wrapper
template<typename TOuter>
class Outer
template<typename TInner>
class Inner

In general the reference must include the template parameter declarations, and template arguments for the prefix of qualified names. For example:

  • template\<typename TOuter> Wrapper::Outer (template<typename TOuter> Wrapper::Outer)

  • template\<typename TOuter> template\<typename TInner> Wrapper::Outer<TOuter>::Inner (template<typename TOuter> template<typename TInner> Wrapper::Outer<TOuter>::Inner)

Currently the lookup only succeed if the template parameter identifiers are equal strings. That is, template\<typename UOuter> Wrapper::Outer will not work.

As a shorthand notation, if a template parameter list is omitted, then the lookup will assume either a primary template or a non-template, but not a partial template specialisation. This means the following references work as well:

(Full) Template Specialisations

Assume the following declarations.

template<typename TOuter>
class Outer
template<typename TInner>
class Inner
template<>
class Outer<int>
template<typename TInner>
class Inner
template<>
class Inner<bool>

In general the reference must include a template parameter list for each template argument list. The full specialisation above can therefore be referenced with template\<> Outer\<int> (template<> Outer<int>) and template\<> template\<> Outer\<int>::Inner\<bool> (template<> template<> Outer<int>::Inner<bool>). As a shorthand the empty template parameter list can be omitted, e.g., Outer\<int> (Outer<int>) and Outer\<int>::Inner\<bool> (Outer<int>::Inner<bool>).

Partial Template Specialisations

Assume the following declaration.

template<typename T>
class Outer<T*>

References to partial specialisations must always include the template parameter lists, e.g., template\<typename T> Outer\<T*> (template<typename T> Outer<T*>). Currently the lookup only succeed if the template parameter identifiers are equal strings.

Configuration Variables

See Options for the C++ domain.