feedc0de/boost_optional
1
0
Fork 0
forked from boostorg/optional
Code Pull Requests Activity

Added func value_or_eval()

Browse Source
This commit is contained in:
Andrzej Krzemienski
2014-06-18 15:01:52 +02:00
parent a158b85bd6
commit d70114b3dc
14 changed files with 536 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

83
doc/20_reference.qbk
View File

@ -73,14 +73,17 @@
T const& operator *() const& ; ``[link reference_optional_operator_asterisk __GO_TO__]``
T& operator *() &; ``[link reference_optional_operator_asterisk __GO_TO__]``
T&& operator *() &&; ``[link reference_optional_operator_asterisk __GO_TO__]``
T operator *() &&; ``[link reference_optional_operator_asterisk_move __GO_TO__]``
T const& value() const& ; ``[link reference_optional_value __GO_TO__]``
T& value() & ; ``[link reference_optional_value __GO_TO__]``
T&& value() && ; ``[link reference_optional_value __GO_TO__]``
T value() && ; ``[link reference_optional_value_move __GO_TO__]``
template<class U> T value_or( U && v ) const& ; ``[link reference_optional_value_or __GO_TO__]``
template<class U> T value_or( U && v ) && ; ``[link reference_optional_value_or_move __GO_TO__]``
template<class F> T value_or_eval( F f ) const& ; ``[link reference_optional_value_or_call __GO_TO__]``
template<class F> T value_or_eval( F f ) && ; ``[link reference_optional_value_or_call_move __GO_TO__]``
T const* get_ptr() const ; ``[link reference_optional_get_ptr __GO_TO__]``
T* get_ptr() ; ``[link reference_optional_get_ptr __GO_TO__]``
@ -442,7 +445,7 @@ __SPACE__
* [*Effect:] Move-constructs an `optional`.
* [*Postconditions:] If `rhs` is initialized, `*this` is initialized and its
value is move constructed from `*rhs`; else `*this` is
value is move-constructed from `*rhs`; else `*this` is
uninitialized.
* [*Throws:] Whatever `T::T( U&& )` throws.
* [*Notes: ] `T::T( U&& )` is called if `rhs` is initialized, which requires a
@ -837,12 +840,11 @@ __SPACE__
[: `T const& optional<T` ['(not a ref)]`>::operator*() const& ;`]
[: `T& optional<T` ['(not a ref)]`>::operator*() &;`]
[: `T&& optional<T` ['(not a ref)]`>::operator*() &&;`]
* [*Requires:] `*this` is initialized
* [*Returns:] A reference to the contained value
* [*Throws:] Nothing.
* [*Notes:] The requirement is asserted via `BOOST_ASSERT()`. On compilers that do not support ref-qualifiers on member functions these three overloads are replaced with the classical two: a `const` and non-`const` member functions.
* [*Notes:] The requirement is asserted via `BOOST_ASSERT()`. On compilers that do not support ref-qualifiers on member functions these two overloads are replaced with the classical two: a `const` and non-`const` member functions.
* [*Example:]
``
T v ;
@ -856,6 +858,17 @@ assert ( *opt == w ) ;
__SPACE__
[#reference_optional_operator_asterisk_move]
[: `T optional<T` ['(not a ref)]`>::operator*() &&;`]
* [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__ and `*this` is initialized.
* [*Returns:] A move-constructed copy the contained value.
* [*Throws:] Whatever the `T`'s constructor selected for the move throws.
* [*Notes:] The requirement is asserted via `BOOST_ASSERT()`. On compilers that do not support ref-qualifiers on member functions this overload is not present.
__SPACE__
[: `T const& optional<T&>::operator*() const& ;`]
[: `T & optional<T&>::operator*() & ;`]
[: `T & optional<T&>::operator*() && ;`]
@ -881,11 +894,10 @@ __SPACE__
[: `T const& optional<T>::value() const& ;`]
[: `T& optional<T>::value() & ;`]
[: `T&& optional<T>::value() && ;`]
* [*Returns:] A reference to the contained value, if `*this` is initialized.
* [*Throws:] An instance of `bad_optional_access`, if `*this` is not initialized.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions these three overloads are replaced with the classical two: a `const` and non-`const` member functions.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions these two overloads are replaced with the classical two: a `const` and non-`const` member functions.
* [*Example:]
``
T v ;
@ -900,6 +912,18 @@ catch(bad_optional_access&) {
assert ( true );
}
``
__SPACE__
[#reference_optional_value_move]
[: `T optional<T>::value() && ;`]
* [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__.
* [*Returns:] A move-constructed copy of the contained value, if `*this` is initialized.
* [*Throws:] An instance of `bad_optional_access`, if `*this` is not initialized.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions this overload is not present.
__SPACE__
@ -908,7 +932,7 @@ __SPACE__
[: `template<class U> T optional<T>::value_or(U && v) const& ;`]
* [*Requires:] `T` is __COPY_CONSTRUCTIBLE__ and `U &&` is convertible to `T`.
* [*Returns:] `bool(*this) ? **this : static_cast<T>(forward<U>(v))`.
* [*Returns:] `bool(*this) ? **this : static_cast<T>(std::forward<U>(v))`.
* [*Throws:] Any exception thrown by the selected constructor of `T`.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions this overload is replaced with the `const`-qualified member function. On compilers without rvalue reference support the type of `v` becomes `U const&`.
@ -919,9 +943,48 @@ __SPACE__
[: `template<class U> T optional<T>::value_or(U && v) && ;`]
* [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__ and `U &&` is convertible to `T`.
* [*Returns:] `bool(*this) ? std::move(**this) : static_cast<T>(forward<U>(v))`.
* [*Returns:] `bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(v))`.
* [*Throws:] Any exception thrown by the selected constructor of `T`.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions this overload is replaced with the classical non-`const`-qualified member function. On compilers without rvalue reference support the type of `v` becomes `U const&`.
* [*Notes:] On compilers that do not support ref-qualifiers on member functions this overload is not present.
__SPACE__
[#reference_optional_value_or_call]
[: `template<class F> T optional<T>::value_or_eval(F f) const& ;`]
* [*Requires:] `T` is __COPY_CONSTRUCTIBLE__ and `F` models a __SGI_GENERATOR__ whose result type is convertible to `T`.
* [*Returns:] `bool(*this) ? **this : static_cast<T>(f())`.
* [*Throws:] Any exception thrown by the selected constructor of `T` or by `f`.
* [*Notes:] Function `f` is only evaluated if `bool(*this) == false`. On compilers that do not support ref-qualifiers on member functions this overload is replaced with the `const`-qualified member function.
* [*Example:]
``
int complain_and_0()
{
clog << "no value returned, using default" << endl;
return 0;
}
optional<int> o1 = 1;
optional<int> oN = none;
int i = o1.value_or_eval(complain_and_0); // fun not called
assert (i == 1);
int j = oN.value_or_eval(complain_and_0); // fun called
assert (i == 0);
``
__SPACE__
[#reference_optional_value_or_call_move]
[: `template<class F> T optional<T>::value_or_eval(F f) && ;`]
* [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__ and `F` models a __SGI_GENERATOR__ whose result type is convertible to `T`.
* [*Returns:] `bool(*this) ? std::move(**this) : static_cast<T>(f())`.
* [*Throws:] Any exception thrown by the selected constructor of `T` or by `f`.
* [*Notes:] Function `f` is only evaluated if `bool(*this) == false`. On compilers that do not support ref-qualifiers on member functions this overload is not present.
__SPACE__