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diff --git a/doc/usage/domains/cpp.rst b/doc/usage/domains/cpp.rst new file mode 100644 index 0000000..6c9372b --- /dev/null +++ b/doc/usage/domains/cpp.rst @@ -0,0 +1,760 @@ +.. highlight:: rst + +============== +The C++ Domain +============== + +.. versionadded:: 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``). + +.. rst:directive:: .. 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 :rst:dir:`cpp:class` and :rst:dir:`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> + + .. versionadded:: 2.0 + The :rst:dir:`cpp:struct` directive. + +.. rst: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) + + .. rst:directive:option:: single-line-parameter-list + :type: no value + + Ensures that the function's parameters will be emitted on a single logical + line, overriding :confval:`cpp_maximum_signature_line_length` and + :confval:`maximum_signature_line_length`. + + .. versionadded:: 7.1 + +.. rst:directive:: .. 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) + +.. rst:directive:: .. 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. + + .. cpp:type:: std::vector<int> MyList + :no-contents-entry: + :no-index-entry: + + A typedef-like declaration of a type. + + .. cpp:type:: MyContainer::const_iterator + :no-contents-entry: + :no-index-entry: + + Declaration of a type alias with unspecified type. + + .. cpp:type:: MyType = std::unordered_map<int, std::string> + :no-contents-entry: + :no-index-entry: + + Declaration of a type alias. + + .. cpp:type:: template<typename T> \ + MyContainer = std::vector<T> + :no-contents-entry: + :no-index-entry: + +.. rst:directive:: .. 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. + +.. rst:directive:: .. 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 + +.. rst:directive:: .. cpp:union:: name + + Describe a union. + + .. versionadded:: 1.8 + +.. rst:directive:: .. cpp:concept:: template-parameter-list name + + .. warning:: 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: + + .. cpp:concept:: template<typename It> std::Iterator + :no-contents-entry: + :no-index-entry: + + 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. + + .. versionadded:: 1.5 + + +Options +~~~~~~~ + +Some directives support options: + +- ``:no-index-entry:`` and ``:no-contents-entry:``, see :ref:`basic-domain-markup`. +- ``:tparam-line-spec:``, for templated declarations. + If specified, each template parameter will be rendered on a separate line. + + .. versionadded:: 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: + +.. cpp:class:: Data + :no-contents-entry: + :no-index-entry: + + .. cpp:union:: @data + :no-contents-entry: + :no-index-entry: + + .. cpp:var:: int a + :no-contents-entry: + :no-index-entry: + + .. cpp:var:: double b + :no-contents-entry: + :no-index-entry: + +Explicit ref: :cpp:var:`Data::@data::a`. Short-hand ref: :cpp:var:`Data::a`. + +.. versionadded:: 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. + +.. rst:directive:: .. cpp:alias:: name or function signature + + Insert one or more alias declarations. Each entity can be specified + as they can in the :rst:role:`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 + + .. cpp:alias:: Data::a + overload_example::C::f + + whereas:: + + .. cpp:alias:: void overload_example::C::f(double d) const + void overload_example::C::f(double d) + + becomes + + .. cpp:alias:: void overload_example::C::f(double d) const + void overload_example::C::f(double d) + + .. versionadded:: 2.0 + + + .. rubric:: Options + + .. rst:directive:option:: 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. + + .. versionadded:: 3.5 + + .. rst:directive:option:: noroot + + Skip the mentioned declarations and only render nested declarations. + Requires ``maxdepth`` either 0 or at least 2. + + .. versionadded:: 3.5 + + +Constrained Templates +--------------------- + +.. warning:: 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. + +.. note:: 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. + +.. cpp:function:: std::Iterator{It} void advance(It &it) + :no-contents-entry: + :no-index-entry: + + A function template with a template parameter constrained to be an Iterator. + +.. cpp:class:: std::LessThanComparable{T} MySortedContainer + :no-contents-entry: + :no-index-entry: + + 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 +---------------------------- + +.. rst:role:: 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: + + .. cpp:var:: int a = 42 + :no-contents-entry: + :no-index-entry: + + .. cpp:function:: int f(int i) + :no-contents-entry: + :no-index-entry: + + 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>&`). + + .. versionadded:: 1.7 + The :rst:role:`cpp:expr` role. + + .. versionadded:: 1.8 + The :rst:role:`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. + +.. rst: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 + +.. rst:directive:: .. 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``. + + .. versionadded:: 1.4 + +.. rst:directive:: .. 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 + + .. versionadded:: 1.4 + +Info field lists +---------------- + +All the C++ directives for declaring entities support the following +info fields (see also :ref:`info-field-lists`): + +* ``tparam``: Description of a template parameter. + +The :rst:dir:`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. + +.. versionadded:: 4.3 + The ``retval`` field type. + +.. _cpp-roles: + +Cross-referencing +----------------- + +These roles link to the given declaration types: + +.. rst:role:: 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. + + .. versionadded:: 2.0 + The :rst:role:`cpp:struct` role as alias for the :rst:role:`cpp:class` + role. + +.. admonition:: Note on References with Templates Parameters/Arguments + + These roles follow the Sphinx :ref:`xref-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, :rst:role:`cpp:expr` and :rst:role:`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 :rst:role:`cpp:any` and :rst:role:`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: + +.. cpp:namespace-push:: overload_example +.. cpp:class:: C + :no-contents-entry: + :no-index-entry: + + .. cpp:function:: void f(double d) const + :no-contents-entry: + :no-index-entry: + .. cpp:function:: void f(double d) + :no-contents-entry: + :no-index-entry: + .. cpp:function:: void f(int i) + :no-contents-entry: + :no-index-entry: + .. cpp:function:: void f() + :no-contents-entry: + :no-index-entry: + +References using the :rst:role:`cpp:func` role: + +- Arbitrary overload: ``C::f``, :cpp:func:`C::f` +- Also arbitrary overload: ``C::f()``, :cpp:func:`C::f()` +- Specific overload: ``void C::f()``, :cpp:func:`void C::f()` +- Specific overload: ``void C::f(int)``, :cpp:func:`void C::f(int)` +- Specific overload: ``void C::f(double)``, :cpp:func:`void C::f(double)` +- Specific overload: ``void C::f(double) const``, + :cpp:func:`void C::f(double) const` + +Note that the :confval:`add_function_parentheses` configuration variable +does not influence specific overload references. + +.. cpp:namespace-pop:: + + +Templated declarations +~~~~~~~~~~~~~~~~~~~~~~ + +Assume the following declarations. + +.. cpp:class:: Wrapper + :no-contents-entry: + :no-index-entry: + + .. cpp:class:: template<typename TOuter> \ + Outer + :no-contents-entry: + :no-index-entry: + + .. cpp:class:: template<typename TInner> \ + Inner + :no-contents-entry: + :no-index-entry: + +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`` + (:cpp:class:`template\<typename TOuter> Wrapper::Outer`) +- ``template\<typename TOuter> template\<typename TInner> Wrapper::Outer<TOuter>::Inner`` + (:cpp:class:`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: + +- ``Wrapper::Outer`` + (:cpp:class:`Wrapper::Outer`) +- ``Wrapper::Outer::Inner`` + (:cpp:class:`Wrapper::Outer::Inner`) +- ``template\<typename TInner> Wrapper::Outer::Inner`` + (:cpp:class:`template\<typename TInner> Wrapper::Outer::Inner`) + +(Full) Template Specialisations +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Assume the following declarations. + +.. cpp:class:: template<typename TOuter> \ + Outer + :no-contents-entry: + :no-index-entry: + + .. cpp:class:: template<typename TInner> \ + Inner + :no-contents-entry: + :no-index-entry: + +.. cpp:class:: template<> \ + Outer<int> + :no-contents-entry: + :no-index-entry: + + .. cpp:class:: template<typename TInner> \ + Inner + :no-contents-entry: + :no-index-entry: + + .. cpp:class:: template<> \ + Inner<bool> + :no-contents-entry: + :no-index-entry: + +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>`` (:cpp:class:`template\<> +Outer\<int>`) and ``template\<> template\<> Outer\<int>::Inner\<bool>`` +(:cpp:class:`template\<> template\<> Outer\<int>::Inner\<bool>`). As a +shorthand the empty template parameter list can be omitted, e.g., +``Outer\<int>`` (:cpp:class:`Outer\<int>`) and ``Outer\<int>::Inner\<bool>`` +(:cpp:class:`Outer\<int>::Inner\<bool>`). + +Partial Template Specialisations +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Assume the following declaration. + +.. cpp:class:: template<typename T> \ + Outer<T*> + :no-contents-entry: + :no-index-entry: + +References to partial specialisations must always include the template +parameter lists, e.g., ``template\<typename T> Outer\<T*>`` +(:cpp:class:`template\<typename T> Outer\<T*>`). Currently the lookup only +succeed if the template parameter identifiers are equal strings. + +Configuration Variables +----------------------- + +See :ref:`cpp-config`. |