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various documentation fixes

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Andrzej Krzemienski
2014-06-20 16:25:57 +02:00
parent 4cbb67e505
commit 599c75a6d3
7 changed files with 211 additions and 222 deletions
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25
doc/01_quick_start.qbk
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@ -17,18 +17,18 @@
Let's write and use a converter function that converts an a `std::string` to an `int`. It is possible that for a given string (e.g. `"cat"`) there exist no value of type `int` capable of representing the conversion result. We do not consider such situation an error. We expect that the converter can be used only to check if the conversion is possible. A natural signature for this function can be:
#include <boost/optional.hpp>
boost::optionl<int> convert(const std::string& text);
boost::optional<int> convert(const std::string& text);
All necessary functionality can be included with one header `<boost/optional.hpp>`. The above function signature means that the function can either return a value of type `int` or a flag indicating that no value of `int` is available. This does not indicate an error. It is like one additional value of `int`. This is how we can use our function:
const std::string& text = /*... */;
boost::optionl<int> oi = convert(text); // move-construct
if (oi) // contextual conversion to bool
int i = *oi; // operator*
boost::optional<int> oi = convert(text); // move-construct
if (oi) // contextual conversion to bool
int i = *oi; // operator*
In order to test if `optional` contains a value, we use the contextual conversion to type `bool`. Because of this we can combine the initialization of the optional object and the test into one instruction:
if (boost::optionl<int> oi = convert(text))
if (boost::optional<int> oi = convert(text))
int i = *oi;
We extract the contained value with `operator*` (and with `operator->` where it makes sense). An attempt to extract the contained value of an uninitialized optional object is an ['undefined behaviour] (UB). This implementation guards the call with `BOOST_ASSERT`. Therefore you should be sure that the contained value is there before extracting. For instance, the following code is reasonably UB-safe:
@ -50,16 +50,19 @@ This version throws an exception upon an attempt to access a non-existent contai
This uses the `atoi`-like approach to conversions: if `text` does not represent an integral number just return `0`. Finally, you can provide a callback to be called when trying to access the contained value fails:
int l = convert(text).value_or_eval([]() -> int {
cout << "could not convert; using -1 instead" << endl;
int fallback_to_default()
{
cerr << "could not convert; using -1 instead" << endl;
return -1;
});
}
int l = convert(text).value_or_eval(fallback_to_default);
This will call the provided callback and return whatever the callback returns. The callback can have side effects: they will only be observed when the optional object does not contain a value.
Now, let's consider how function `convert` can be implemented.
boost::optionl<int> convert(const std::string& text)
boost::optional<int> convert(const std::string& text)
{
std::stringstream s(text);
int i;
@ -77,9 +80,9 @@ Observe the two return statements. `return i` uses the converting constructor th
We could write function `convert` in a slightly different manner, so that it has a single `return`-statement:
boost::optionl<int> convert(const std::string& text)
boost::optional<int> convert(const std::string& text)
{
boost::optionl<int> ans;
boost::optional<int> ans;
std::stringstream s(text);
int i;
if ((s >> i) && s.get() == std::char_traits<char>::eof())

122
doc/20_reference.qbk
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@ -661,19 +661,17 @@ __SPACE__
[: `optional& optional<T` ['(not a ref)]`>::operator= ( optional&& rhs ) noexcept(`['see below]`);`]
* [*Effect:] Move-assigns another `optional` to an `optional`.
* [*Postconditions:] If `rhs` is initialized, `*this` is initialized and
its value is moved from `*rhs`, `rhs` remains initialized; else `*this` is uninitialized.
* [*Throws:] Whatever `T::operator( T&& )` or `T::T( T && )` throws.
* [*Requires:] `T` is __MOVE_CONSTRUCTIBLE__ and `MoveAssignable`.
* [*Effects:]
* If `!*this && !rhs` no effect, otherwise
* if `bool(*this) && !rhs`, destroys the contained value by calling `val->T::~T()`, otherwise
* if `!*this && bool(rhs)`, initializes the contained value as if direct-initializing an object of type `T` with `std::move(*rhs)`, otherwise
* (if `bool(*this) && bool(rhs)`) assigns `std::move(*rhs)` to the contained value.
* [*Postconditions:] `bool(rhs) == bool(*this)`.
* [*Remarks:] The expression inside `noexcept` is equivalent to `is_nothrow_move_constructible<T>::value && is_nothrow_move_assignable<T>::value`.
* [*Notes:] If both `*this` and `rhs` are initially initialized, `T`'s
['move assignment operator] is used. If `*this` is initially initialized but `rhs` is
uninitialized, `T`'s [destructor] is called. If `*this` is initially uninitialized
but `rhs` is initialized, `T`'s ['move constructor] is called.
* [*Exception Safety:] In the event of an exception, the initialization state of
`*this` is unchanged and its value unspecified as far as optional is concerned
(it is up to `T`'s `operator=()`). If `*this` is initially uninitialized and
`T`'s ['move constructor] fails, `*this` is left properly uninitialized.
* [*Exception Safety:] If any exception is thrown, the initialization state of `*this` and `rhs` remain unchanged. If an exception is
thrown during the call to `T`'s move constructor, the state of `*rhs` is determined by the exception safety guarantee
of `T`'s move constructor. If an exception is thrown during the call to T's move-assignment, the state of `**this` and `*rhs` is determined by the exception safety guarantee of T's move assignment.
* [*Example:]
``
optional<T> opt(T(2)) ;
@ -751,6 +749,8 @@ optional<T> opt0(v);
optional<U> opt1;
opt1 = std::move(opt0) ;
assert ( opt0 );
assert ( opt1 )
assert ( *opt1 == static_cast<U>(v) ) ;
``
@ -1144,38 +1144,28 @@ __SPACE__
[: `bool operator == ( optional<T> const& x, optional<T> const& y );`]
* [*Requires:] `T` shall meet requirements of `EqualityComparable`.
* [*Requires:] `T` shall meet requirements of __SGI_EQUALITY_COMPARABLE__.
* [*Returns:] If both `x` and `y` are initialized, `(*x == *y)`. If only
`x` or `y` is initialized, `false`. If both are uninitialized, `true`.
* [*Throws:] Nothing.
* [*Notes:] Pointers have shallow relational operators while `optional` has
deep relational operators. Do not use `operator ==` directly in generic
deep relational operators. Do not use `operator==` directly in generic
code which expect to be given either an `optional<T>` or a pointer; use
__FUNCTION_EQUAL_POINTEES__ instead
* [*Example:]
``
T x(12);
T y(12);
T z(21);
optional<T> def0 ;
optional<T> def1 ;
optional<T> optX(x);
optional<T> optY(y);
optional<T> optZ(z);
optional<T> oN, oN_;
optional<T> o1(T(1)), o1_(T(1));
optional<T> o2(T(2));
// Identity always hold
assert ( def0 == def0 );
assert ( optX == optX );
assert ( oN == oN ); // Identity implies equality
assert ( o1 == o1 ); //
// Both uninitialized compare equal
assert ( def0 == def1 );
assert ( oN == oN_ ); // Both uninitialized compare equal
// Only one initialized compare unequal.
assert ( def0 != optX );
assert ( oN != o1 ); // Initialized unequal to initialized.
// Both initialized compare as (*lhs == *rhs)
assert ( optX == optY ) ;
assert ( optX != optZ ) ;
assert ( o1 == o1_ ); // Both initialized compare as (*lhs == *rhs)
assert ( o1 != o2 ); //
``
__SPACE__
@ -1184,35 +1174,29 @@ __SPACE__
[: `bool operator < ( optional<T> const& x, optional<T> const& y );`]
* [*Requires:] `T` shall meet requirements of `LessThanComparable`.
* [*Returns:] If `y` is not initialized, `false`. If `y` is initialized
and `x` is not initialized, `true`. If both `x` and `y` are initialized,
`(*x < *y)`.
* [*Throws:] Nothing.
* [*Requires:] Expression `*x < *y` shall be well-formed and its result shall be convertible to `bool`.
* [*Returns:] `(!y) ? false : (!x) ? true : *x < *y`.
* [*Notes:] Pointers have shallow relational operators while `optional` has
deep relational operators. Do not use `operator <` directly in generic code
which expect to be given either an `optional<T>` or a pointer; use __FUNCTION_LESS_POINTEES__ instead.
deep relational operators. Do not use `operator<` directly in generic code
which expect to be given either an `optional<T>` or a pointer; use __FUNCTION_LESS_POINTEES__ instead. `T` need not be __SGI_LESS_THAN_COMPARABLE__. Only single `operator<` is required. Other relational operations are defined in terms of this one. If `T`'s `operator<` satisfies the axioms of __SGI_LESS_THAN_COMPARABLE__ (transitivity, antisymmetry and irreflexivity), `optinal<T>` is __SGI_LESS_THAN_COMPARABLE__.
* [*Example:]
``
T x(12);
T y(34);
optional<T> def ;
optional<T> optX(x);
optional<T> optY(y);
optional<T> oN, oN_;
optional<T> o0(T(0));
optional<T> o1(T(1));
// Identity always hold
assert ( !(def < def) );
assert ( optX == optX );
assert ( !(oN < oN) ); // Identity implies equivalence
assert ( !(o1 < o1) );
// Both uninitialized compare equal
assert ( def0 == def1 );
assert ( !(oN < oN_) ); // Two uninitialized are equivalent
assert ( !(oN_ < oN) );
// Only one initialized compare unequal.
assert ( def0 != optX );
assert ( oN < o0 ); // Uninitialized is less than initialized
assert ( !(o0 < oN) );
// Both initialized compare as (*lhs == *rhs)
assert ( optX == optY ) ;
assert ( optX != optZ ) ;
assert ( o1 < o2 ) ; // Two initialized compare as (*lhs < *rhs)
assert ( !(o2 < o1) ) ;
assert ( !(o2 < o2) ) ;
``
__SPACE__
@ -1222,7 +1206,6 @@ __SPACE__
[: `bool operator != ( optional<T> const& x, optional<T> const& y );`]
* [*Returns: ] `!( x == y );`
* [*Throws:] Nothing.
__SPACE__
@ -1231,7 +1214,6 @@ __SPACE__
[: `bool operator > ( optional<T> const& x, optional<T> const& y );`]
* [*Returns: ] `( y < x );`
* [*Throws:] Nothing.
__SPACE__
@ -1240,7 +1222,6 @@ __SPACE__
[: `bool operator <= ( optional<T> const& x, optional<T> const& y );`]
* [*Returns: ] `!( y < x );`
* [*Throws:] Nothing.
__SPACE__
@ -1248,15 +1229,17 @@ __SPACE__
[: `bool operator >= ( optional<T> const& x, optional<T> const& y );`]
* [*Returns: ] `!( x<y );`
* [*Throws:] Nothing.
* [*Returns: ] `!( x < y );`
__SPACE__
[#reference_operator_compare_equal_optional_none]
[: `bool operator == ( optional<T> const& x, none_t ) noexcept;`]
[: `bool operator == ( none_t, optional<T> const& x ) noexcept;`]
* [*Returns:] `!x`.
* [*Notes:] `T` need not meet requirements of `EqualityComparable`.
* [*Notes:] `T` need not meet requirements of __SGI_EQUALITY_COMPARABLE__.
__SPACE__
@ -1264,6 +1247,7 @@ __SPACE__
[#reference_operator_compare_not_equal_optional_none]
[: `bool operator != ( optional<T> const& x, none_t ) noexcept;`]
[: `bool operator != ( none_t, optional<T> const& x ) noexcept;`]
* [*Returns: ] `!( x == y );`
@ -1274,19 +1258,15 @@ __SPACE__
[: `void swap ( optional<T>& x, optional<T>& y ) ;`]
* [*Effect:] If both `x` and `y` are initialized, calls `swap(*x,*y)`
using `std::swap`. If only one is initialized, say `x`, calls:
`y.reset(*x); x.reset();` If none is initialized, does nothing.
* [*Requires:] Lvalues of type `T` shall be swappable and `T` shall be __MOVE_CONSTRUCTIBLE__.
* [*Effects:]
* If `!*this && !rhs`, no effect, otherwise
* if `bool(*this) && !rhs`, initializes the contained value of `rhs` as if direct-initializing an object of type `T` with the expression `std::move(*(*this))`, followed by `val->T::~T()`, `*this` does not contain a value and `rhs` contains a value, otherwise
* if `!*this && bool(rhs)`, initializes the contained value of `*this` as if direct-initializing an object of type `T` with the expression `std::move(*rhs)`, followed by `rhs.val->T::~T()`, `*this` contains a value and `rhs` does not contain a value, otherwise
* (if `bool(*this) && bool(rhs)`) calls `swap(*(*this), *rhs)`.
* [*Postconditions:] The states of `x` and `y` interchanged.
* [*Throws:] If both are initialized, whatever `swap(T&,T&)` throws. If only
one is initialized, whatever `T::T ( T&& )` throws.
* [*Notes:] If both are initialized, `swap(T&,T&)` is used unqualified but
with `std::swap` introduced in scope.
If only one is initialized, `T::~T()` and `T::T( T&& )` is called.
* [*Exception Safety:] If both are initialized, this operation has the
exception safety guarantees of `swap(T&,T&)`.
If only one is initialized, it has the same basic guarantee as
`optional<T>::operator= ( T&& )`.
* [*Example:]
``
T x(12);

4
doc/Jamfile.v2
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@ -24,7 +24,8 @@ boostbook standalone
:
optional
:
<xsl:param>boost.root=../../../..
<format>html:<xsl:param>boost.root=../../../..
<format>html:<xsl:param>boost.libraries=../../../../libs/libraries.htm
<xsl:param>chapter.autolabel=0
<xsl:param>chunk.section.depth=8
<xsl:param>toc.section.depth=2
@ -32,6 +33,7 @@ boostbook standalone
<xsl:param>generate.section.toc.level=1
<format>pdf:<xsl:param>img.src.path=$(images)/
<format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/libs/optional/doc/html
<format>docbook:<auto-index-internal>on
;

21
doc/html/boost_optional/quick_start.html
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@ -53,7 +53,7 @@
is possible. A natural signature for this function can be:
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">optional</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">);</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">);</span>
</pre>
<p>
All necessary functionality can be included with one header <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">optional</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>.
@ -65,16 +65,16 @@
can use our function:
</p>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span> <span class="special">=</span> <span class="comment">/*... */</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">oi</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">);</span> <span class="comment">// move-construct</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">oi</span><span class="special">)</span> <span class="comment">// contextual conversion to bool</span>
<span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">*</span><span class="identifier">oi</span><span class="special">;</span> <span class="comment">// operator*</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">oi</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">);</span> <span class="comment">// move-construct</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">oi</span><span class="special">)</span> <span class="comment">// contextual conversion to bool</span>
<span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">*</span><span class="identifier">oi</span><span class="special">;</span> <span class="comment">// operator*</span>
</pre>
<p>
In order to test if <code class="computeroutput"><span class="identifier">optional</span></code>
contains a value, we use the contextual conversion to type <code class="computeroutput"><span class="keyword">bool</span></code>. Because of this we can combine the initialization
of the optional object and the test into one instruction:
</p>
<pre class="programlisting"><span class="keyword">if</span> <span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">oi</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">))</span>
<pre class="programlisting"><span class="keyword">if</span> <span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">oi</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">))</span>
<span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="special">*</span><span class="identifier">oi</span><span class="special">;</span>
</pre>
<p>
@ -114,10 +114,13 @@
Finally, you can provide a callback to be called when trying to access the
contained value fails:
</p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">l</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">).</span><span class="identifier">value_or_eval</span><span class="special">([]()</span> <span class="special">-&gt;</span> <span class="keyword">int</span> <span class="special">{</span>
<span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"could not convert; using -1 instead"</span> <span class="special">&lt;&lt;</span> <span class="identifier">endl</span><span class="special">;</span>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">fallback_to_default</span><span class="special">()</span>
<span class="special">{</span>
<span class="identifier">cerr</span> <span class="special">&lt;&lt;</span> <span class="string">"could not convert; using -1 instead"</span> <span class="special">&lt;&lt;</span> <span class="identifier">endl</span><span class="special">;</span>
<span class="keyword">return</span> <span class="special">-</span><span class="number">1</span><span class="special">;</span>
<span class="special">});</span>
<span class="special">}</span>
<span class="keyword">int</span> <span class="identifier">l</span> <span class="special">=</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">text</span><span class="special">).</span><span class="identifier">value_or_eval</span><span class="special">(</span><span class="identifier">fallback_to_default</span><span class="special">);</span>
</pre>
<p>
This will call the provided callback and return whatever the callback returns.
@ -128,7 +131,7 @@
Now, let's consider how function <code class="computeroutput"><span class="identifier">convert</span></code>
can be implemented.
</p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">)</span>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span> <span class="identifier">s</span><span class="special">(</span><span class="identifier">text</span><span class="special">);</span>
<span class="keyword">int</span> <span class="identifier">i</span><span class="special">;</span>

4
doc/html/boost_optional/quick_start/optional_automatic_variables.html
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@ -31,9 +31,9 @@
We could write function <code class="computeroutput"><span class="identifier">convert</span></code>
in a slightly different manner, so that it has a single <code class="computeroutput"><span class="keyword">return</span></code>-statement:
</p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">)</span>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">convert</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&amp;</span> <span class="identifier">text</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optionl</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">ans</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">optional</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">ans</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span> <span class="identifier">s</span><span class="special">(</span><span class="identifier">text</span><span class="special">);</span>
<span class="keyword">int</span> <span class="identifier">i</span><span class="special">;</span>
<span class="keyword">if</span> <span class="special">((</span><span class="identifier">s</span> <span class="special">&gt;&gt;</span> <span class="identifier">i</span><span class="special">)</span> <span class="special">&amp;&amp;</span> <span class="identifier">s</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">==</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">char_traits</span><span class="special">&lt;</span><span class="keyword">char</span><span class="special">&gt;::</span><span class="identifier">eof</span><span class="special">())</span>

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@ -902,40 +902,52 @@
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<span class="bold"><strong>Effect:</strong></span> Move-assigns another <code class="computeroutput"><span class="identifier">optional</span></code> to an <code class="computeroutput"><span class="identifier">optional</span></code>.
<span class="bold"><strong>Requires:</strong></span> <code class="computeroutput"><span class="identifier">T</span></code>
is <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>
and <code class="computeroutput"><span class="identifier">MoveAssignable</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Postconditions:</strong></span> If <code class="computeroutput"><span class="identifier">rhs</span></code>
is initialized, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
is initialized and its value is moved from <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>, <code class="computeroutput"><span class="identifier">rhs</span></code>
remains initialized; else <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is uninitialized.
<span class="bold"><strong>Effects:</strong></span>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
If <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
<span class="special">&amp;&amp;</span> <span class="special">!</span><span class="identifier">rhs</span></code> no effect, otherwise
</li>
<li class="listitem">
if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
<span class="special">&amp;&amp;</span> <span class="special">!</span><span class="identifier">rhs</span></code>, destroys the contained value
by calling <code class="computeroutput"><span class="identifier">val</span><span class="special">-&gt;</span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, otherwise
</li>
<li class="listitem">
if <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
<span class="special">&amp;&amp;</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>, initializes the contained value
as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
with <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>,
otherwise
</li>
<li class="listitem">
(if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
<span class="special">&amp;&amp;</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>) assigns <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code> to the contained value.
</li>
</ul></div>
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Whatever <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">(</span> <span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="special">)</span></code>
or <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="identifier">T</span><span class="special">(</span> <span class="identifier">T</span> <span class="special">&amp;&amp;</span>
<span class="special">)</span></code> throws.
<span class="bold"><strong>Postconditions:</strong></span> <code class="computeroutput"><span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span> <span class="special">==</span> <span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Remarks:</strong></span> The expression inside <code class="computeroutput"><span class="keyword">noexcept</span></code> is equivalent to <code class="computeroutput"><span class="identifier">is_nothrow_move_constructible</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">value</span> <span class="special">&amp;&amp;</span>
<span class="identifier">is_nothrow_move_assignable</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">value</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Notes:</strong></span> If both <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and <code class="computeroutput"><span class="identifier">rhs</span></code>
are initially initialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
<span class="emphasis"><em>move assignment operator</em></span> is used. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
is initially initialized but <code class="computeroutput"><span class="identifier">rhs</span></code>
is uninitialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
[destructor] is called. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is initially uninitialized but <code class="computeroutput"><span class="identifier">rhs</span></code> is initialized, <code class="computeroutput"><span class="identifier">T</span></code>'s
<span class="emphasis"><em>move constructor</em></span> is called.
</li>
<li class="listitem">
<span class="bold"><strong>Exception Safety:</strong></span> In the event of an
exception, the initialization state of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is unchanged and its value unspecified
as far as optional is concerned (it is up to <code class="computeroutput"><span class="identifier">T</span></code>'s
<code class="computeroutput"><span class="keyword">operator</span><span class="special">=()</span></code>).
If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
is initially uninitialized and <code class="computeroutput"><span class="identifier">T</span></code>'s
<span class="emphasis"><em>move constructor</em></span> fails, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is left properly uninitialized.
<span class="bold"><strong>Exception Safety:</strong></span> If any exception is
thrown, the initialization state of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and <code class="computeroutput"><span class="identifier">rhs</span></code>
remain unchanged. If an exception is thrown during the call to <code class="computeroutput"><span class="identifier">T</span></code>'s move constructor, the state of
<code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
is determined by the exception safety guarantee of <code class="computeroutput"><span class="identifier">T</span></code>'s
move constructor. If an exception is thrown during the call to T's move-assignment,
the state of <code class="computeroutput"><span class="special">**</span><span class="keyword">this</span></code>
and <code class="computeroutput"><span class="special">*</span><span class="identifier">rhs</span></code>
is determined by the exception safety guarantee of T's move assignment.
</li>
<li class="listitem">
<span class="bold"><strong>Example:</strong></span>
@ -1064,6 +1076,8 @@
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">U</span><span class="special">&gt;</span> <span class="identifier">opt1</span><span class="special">;</span>
<span class="identifier">opt1</span> <span class="special">=</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">opt0</span><span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">opt0</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">opt1</span> <span class="special">)</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">*</span><span class="identifier">opt1</span> <span class="special">==</span> <span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">U</span><span class="special">&gt;(</span><span class="identifier">v</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
</pre>
</li>
@ -1823,7 +1837,7 @@
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<span class="bold"><strong>Requires:</strong></span> <code class="computeroutput"><span class="identifier">T</span></code>
shall meet requirements of <code class="computeroutput"><span class="identifier">EqualityComparable</span></code>.
shall meet requirements of <a href="http://www.sgi.com/tech/stl/EqualityComparable.html" target="_top"><code class="computeroutput"><span class="identifier">EqualityComparable</span></code></a>.
</li>
<li class="listitem">
<span class="bold"><strong>Returns:</strong></span> If both <code class="computeroutput"><span class="identifier">x</span></code>
@ -1833,41 +1847,28 @@
If only <code class="computeroutput"><span class="identifier">x</span></code> or <code class="computeroutput"><span class="identifier">y</span></code> is initialized, <code class="computeroutput"><span class="keyword">false</span></code>.
If both are uninitialized, <code class="computeroutput"><span class="keyword">true</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
</li>
<li class="listitem">
<span class="bold"><strong>Notes:</strong></span> Pointers have shallow relational
operators while <code class="computeroutput"><span class="identifier">optional</span></code>
has deep relational operators. Do not use <code class="computeroutput"><span class="keyword">operator</span>
<span class="special">==</span></code> directly in generic code which
expect to be given either an <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> or a pointer; use <a href="../../../../../utility/OptionalPointee.html#equal" target="_top"><code class="computeroutput"><span class="identifier">equal_pointees</span><span class="special">()</span></code></a>
has deep relational operators. Do not use <code class="computeroutput"><span class="keyword">operator</span><span class="special">==</span></code> directly in generic code which expect
to be given either an <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> or a pointer; use <a href="../../../../../utility/OptionalPointee.html#equal" target="_top"><code class="computeroutput"><span class="identifier">equal_pointees</span><span class="special">()</span></code></a>
instead
</li>
<li class="listitem">
<span class="bold"><strong>Example:</strong></span>
<pre class="programlisting"><span class="identifier">T</span> <span class="identifier">x</span><span class="special">(</span><span class="number">12</span><span class="special">);</span>
<span class="identifier">T</span> <span class="identifier">y</span><span class="special">(</span><span class="number">12</span><span class="special">);</span>
<span class="identifier">T</span> <span class="identifier">z</span><span class="special">(</span><span class="number">21</span><span class="special">);</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">def0</span> <span class="special">;</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">def1</span> <span class="special">;</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">optX</span><span class="special">(</span><span class="identifier">x</span><span class="special">);</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">optY</span><span class="special">(</span><span class="identifier">y</span><span class="special">);</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">optZ</span><span class="special">(</span><span class="identifier">z</span><span class="special">);</span>
<pre class="programlisting"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">oN</span><span class="special">,</span> <span class="identifier">oN_</span><span class="special">;</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">o1</span><span class="special">(</span><span class="identifier">T</span><span class="special">(</span><span class="number">1</span><span class="special">)),</span> <span class="identifier">o1_</span><span class="special">(</span><span class="identifier">T</span><span class="special">(</span><span class="number">1</span><span class="special">));</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">o2</span><span class="special">(</span><span class="identifier">T</span><span class="special">(</span><span class="number">2</span><span class="special">));</span>
<span class="comment">// Identity always hold</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">def0</span> <span class="special">==</span> <span class="identifier">def0</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">==</span> <span class="identifier">optX</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">oN</span> <span class="special">==</span> <span class="identifier">oN</span> <span class="special">);</span> <span class="comment">// Identity implies equality</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">o1</span> <span class="special">==</span> <span class="identifier">o1</span> <span class="special">);</span> <span class="comment">//</span>
<span class="comment">// Both uninitialized compare equal</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">def0</span> <span class="special">==</span> <span class="identifier">def1</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">oN</span> <span class="special">==</span> <span class="identifier">oN_</span> <span class="special">);</span> <span class="comment">// Both uninitialized compare equal</span>
<span class="comment">// Only one initialized compare unequal.</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">def0</span> <span class="special">!=</span> <span class="identifier">optX</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">oN</span> <span class="special">!=</span> <span class="identifier">o1</span> <span class="special">);</span> <span class="comment">// Initialized unequal to initialized.</span>
<span class="comment">// Both initialized compare as (*lhs == *rhs)</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">==</span> <span class="identifier">optY</span> <span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">!=</span> <span class="identifier">optZ</span> <span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">o1</span> <span class="special">==</span> <span class="identifier">o1_</span> <span class="special">);</span> <span class="comment">// Both initialized compare as (*lhs == *rhs)</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">o1</span> <span class="special">!=</span> <span class="identifier">o2</span> <span class="special">);</span> <span class="comment">//</span>
</pre>
</li>
</ul></div>
@ -1881,50 +1882,44 @@
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<span class="bold"><strong>Requires:</strong></span> <code class="computeroutput"><span class="identifier">T</span></code>
shall meet requirements of <code class="computeroutput"><span class="identifier">LessThanComparable</span></code>.
<span class="bold"><strong>Requires:</strong></span> Expression <code class="computeroutput"><span class="special">*</span><span class="identifier">x</span> <span class="special">&lt;</span> <span class="special">*</span><span class="identifier">y</span></code>
shall be well-formed and its result shall be convertible to <code class="computeroutput"><span class="keyword">bool</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Returns:</strong></span> If <code class="computeroutput"><span class="identifier">y</span></code>
is not initialized, <code class="computeroutput"><span class="keyword">false</span></code>.
If <code class="computeroutput"><span class="identifier">y</span></code> is initialized and
<code class="computeroutput"><span class="identifier">x</span></code> is not initialized,
<code class="computeroutput"><span class="keyword">true</span></code>. If both <code class="computeroutput"><span class="identifier">x</span></code> and <code class="computeroutput"><span class="identifier">y</span></code>
are initialized, <code class="computeroutput"><span class="special">(*</span><span class="identifier">x</span>
<span class="special">&lt;</span> <span class="special">*</span><span class="identifier">y</span><span class="special">)</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">(!</span><span class="identifier">y</span><span class="special">)</span> <span class="special">?</span> <span class="keyword">false</span> <span class="special">:</span> <span class="special">(!</span><span class="identifier">x</span><span class="special">)</span> <span class="special">?</span> <span class="keyword">true</span>
<span class="special">:</span> <span class="special">*</span><span class="identifier">x</span> <span class="special">&lt;</span> <span class="special">*</span><span class="identifier">y</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Notes:</strong></span> Pointers have shallow relational
operators while <code class="computeroutput"><span class="identifier">optional</span></code>
has deep relational operators. Do not use <code class="computeroutput"><span class="keyword">operator</span>
<span class="special">&lt;</span></code> directly in generic code
which expect to be given either an <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> or a pointer; use <a href="../../../../../utility/OptionalPointee.html#less" target="_top"><code class="computeroutput"><span class="identifier">less_pointees</span><span class="special">()</span></code></a>
instead.
has deep relational operators. Do not use <code class="computeroutput"><span class="keyword">operator</span><span class="special">&lt;</span></code> directly in generic code which expect
to be given either an <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> or a pointer; use <a href="../../../../../utility/OptionalPointee.html#less" target="_top"><code class="computeroutput"><span class="identifier">less_pointees</span><span class="special">()</span></code></a>
instead. <code class="computeroutput"><span class="identifier">T</span></code> need not be
<a href="http://www.sgi.com/tech/stl/LessThanComparable.html" target="_top"><code class="computeroutput"><span class="identifier">LessThanComparable</span></code></a>. Only single
<code class="computeroutput"><span class="keyword">operator</span><span class="special">&lt;</span></code>
is required. Other relational operations are defined in terms of this
one. If <code class="computeroutput"><span class="identifier">T</span></code>'s <code class="computeroutput"><span class="keyword">operator</span><span class="special">&lt;</span></code>
satisfies the axioms of <a href="http://www.sgi.com/tech/stl/LessThanComparable.html" target="_top"><code class="computeroutput"><span class="identifier">LessThanComparable</span></code></a> (transitivity,
antisymmetry and irreflexivity), <code class="computeroutput"><span class="identifier">optinal</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> is <a href="http://www.sgi.com/tech/stl/LessThanComparable.html" target="_top"><code class="computeroutput"><span class="identifier">LessThanComparable</span></code></a>.
</li>
<li class="listitem">
<span class="bold"><strong>Example:</strong></span>
<pre class="programlisting"><span class="identifier">T</span> <span class="identifier">x</span><span class="special">(</span><span class="number">12</span><span class="special">);</span>
<span class="identifier">T</span> <span class="identifier">y</span><span class="special">(</span><span class="number">34</span><span class="special">);</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">def</span> <span class="special">;</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">optX</span><span class="special">(</span><span class="identifier">x</span><span class="special">);</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">optY</span><span class="special">(</span><span class="identifier">y</span><span class="special">);</span>
<pre class="programlisting"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">oN</span><span class="special">,</span> <span class="identifier">oN_</span><span class="special">;</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">o0</span><span class="special">(</span><span class="identifier">T</span><span class="special">(</span><span class="number">0</span><span class="special">));</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">o1</span><span class="special">(</span><span class="identifier">T</span><span class="special">(</span><span class="number">1</span><span class="special">));</span>
<span class="comment">// Identity always hold</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">def</span> <span class="special">&lt;</span> <span class="identifier">def</span><span class="special">)</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">==</span> <span class="identifier">optX</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">oN</span> <span class="special">&lt;</span> <span class="identifier">oN</span><span class="special">)</span> <span class="special">);</span> <span class="comment">// Identity implies equivalence</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">o1</span> <span class="special">&lt;</span> <span class="identifier">o1</span><span class="special">)</span> <span class="special">);</span>
<span class="comment">// Both uninitialized compare equal</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">def0</span> <span class="special">==</span> <span class="identifier">def1</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">oN</span> <span class="special">&lt;</span> <span class="identifier">oN_</span><span class="special">)</span> <span class="special">);</span> <span class="comment">// Two uninitialized are equivalent</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">oN_</span> <span class="special">&lt;</span> <span class="identifier">oN</span><span class="special">)</span> <span class="special">);</span>
<span class="comment">// Only one initialized compare unequal.</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">def0</span> <span class="special">!=</span> <span class="identifier">optX</span> <span class="special">);</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">oN</span> <span class="special">&lt;</span> <span class="identifier">o0</span> <span class="special">);</span> <span class="comment">// Uninitialized is less than initialized</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">o0</span> <span class="special">&lt;</span> <span class="identifier">oN</span><span class="special">)</span> <span class="special">);</span>
<span class="comment">// Both initialized compare as (*lhs == *rhs)</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">==</span> <span class="identifier">optY</span> <span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">optX</span> <span class="special">!=</span> <span class="identifier">optZ</span> <span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="identifier">o1</span> <span class="special">&lt;</span> <span class="identifier">o2</span> <span class="special">)</span> <span class="special">;</span> <span class="comment">// Two initialized compare as (*lhs &lt; *rhs)</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">o2</span> <span class="special">&lt;</span> <span class="identifier">o1</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
<span class="identifier">assert</span> <span class="special">(</span> <span class="special">!(</span><span class="identifier">o2</span> <span class="special">&lt;</span> <span class="identifier">o2</span><span class="special">)</span> <span class="special">)</span> <span class="special">;</span>
</pre>
</li>
</ul></div>
@ -1935,16 +1930,11 @@
<code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span>
<span class="special">!=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">y</span> <span class="special">);</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
<span class="bold"><strong>Returns: </strong></span> <code class="computeroutput"><span class="special">!(</span>
<span class="identifier">x</span> <span class="special">==</span>
<span class="identifier">y</span> <span class="special">);</span></code>
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
</li>
</ul></div>
</li></ul></div>
<p>
<span class="inlinemediaobject"><img src="../../images/space.png" alt="space"></span>
</p>
@ -1953,16 +1943,11 @@
<span class="special">&gt;</span> <span class="special">(</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">y</span> <span class="special">);</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
<span class="bold"><strong>Returns: </strong></span> <code class="computeroutput"><span class="special">(</span>
<span class="identifier">y</span> <span class="special">&lt;</span>
<span class="identifier">x</span> <span class="special">);</span></code>
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
</li>
</ul></div>
</li></ul></div>
<p>
<span class="inlinemediaobject"><img src="../../images/space.png" alt="space"></span>
</p>
@ -1971,16 +1956,11 @@
<span class="special">&lt;=</span> <span class="special">(</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">y</span> <span class="special">);</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
<span class="bold"><strong>Returns: </strong></span> <code class="computeroutput"><span class="special">!(</span>
<span class="identifier">y</span> <span class="special">&lt;</span>
<span class="identifier">x</span> <span class="special">);</span></code>
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
</li>
</ul></div>
</li></ul></div>
<p>
<span class="inlinemediaobject"><img src="../../images/space.png" alt="space"></span>
</p>
@ -1989,27 +1969,30 @@
<span class="special">&gt;=</span> <span class="special">(</span>
<span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">y</span> <span class="special">);</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
<span class="bold"><strong>Returns: </strong></span> <code class="computeroutput"><span class="special">!(</span>
<span class="identifier">x</span><span class="special">&lt;</span><span class="identifier">y</span> <span class="special">);</span></code>
</li>
<li class="listitem">
<span class="bold"><strong>Throws:</strong></span> Nothing.
</li>
</ul></div>
<span class="identifier">x</span> <span class="special">&lt;</span>
<span class="identifier">y</span> <span class="special">);</span></code>
</li></ul></div>
<p>
<span class="inlinemediaobject"><img src="../../images/space.png" alt="space"></span>
</p>
<a name="reference_operator_compare_equal_optional_none"></a><div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span>
<span class="special">==</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">none_t</span>
<span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></code>
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span>
<span class="special">==</span> <span class="special">(</span> <span class="identifier">none_t</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span> <span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<span class="bold"><strong>Returns:</strong></span> <code class="computeroutput"><span class="special">!</span><span class="identifier">x</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Notes:</strong></span> <code class="computeroutput"><span class="identifier">T</span></code>
need not meet requirements of <code class="computeroutput"><span class="identifier">EqualityComparable</span></code>.
need not meet requirements of <a href="http://www.sgi.com/tech/stl/EqualityComparable.html" target="_top"><code class="computeroutput"><span class="identifier">EqualityComparable</span></code></a>.
</li>
</ul></div>
<p>
@ -2020,6 +2003,10 @@
<span class="special">!=</span> <span class="special">(</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">none_t</span>
<span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></code>
</p></blockquote></div>
<div class="blockquote"><blockquote class="blockquote"><p>
<code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span>
<span class="special">!=</span> <span class="special">(</span> <span class="identifier">none_t</span><span class="special">,</span> <span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">x</span> <span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span></code>
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
<span class="bold"><strong>Returns: </strong></span> <code class="computeroutput"><span class="special">!(</span>
<span class="identifier">x</span> <span class="special">==</span>
@ -2035,12 +2022,37 @@
</p></blockquote></div>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<span class="bold"><strong>Effect:</strong></span> If both <code class="computeroutput"><span class="identifier">x</span></code>
and <code class="computeroutput"><span class="identifier">y</span></code> are initialized,
calls <code class="computeroutput"><span class="identifier">swap</span><span class="special">(*</span><span class="identifier">x</span><span class="special">,*</span><span class="identifier">y</span><span class="special">)</span></code>
using <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">swap</span></code>. If only one is initialized, say
<code class="computeroutput"><span class="identifier">x</span></code>, calls: <code class="computeroutput"><span class="identifier">y</span><span class="special">.</span><span class="identifier">reset</span><span class="special">(*</span><span class="identifier">x</span><span class="special">);</span> <span class="identifier">x</span><span class="special">.</span><span class="identifier">reset</span><span class="special">();</span></code>
If none is initialized, does nothing.
<span class="bold"><strong>Requires:</strong></span> Lvalues of type <code class="computeroutput"><span class="identifier">T</span></code> shall be swappable and <code class="computeroutput"><span class="identifier">T</span></code> shall be <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Effects:</strong></span>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; ">
<li class="listitem">
If <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
<span class="special">&amp;&amp;</span> <span class="special">!</span><span class="identifier">rhs</span></code>, no effect, otherwise
</li>
<li class="listitem">
if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
<span class="special">&amp;&amp;</span> <span class="special">!</span><span class="identifier">rhs</span></code>, initializes the contained
value of <code class="computeroutput"><span class="identifier">rhs</span></code> as
if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">))</span></code>, followed by <code class="computeroutput"><span class="identifier">val</span><span class="special">-&gt;</span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> does not contain a value and
<code class="computeroutput"><span class="identifier">rhs</span></code> contains a
value, otherwise
</li>
<li class="listitem">
if <code class="computeroutput"><span class="special">!*</span><span class="keyword">this</span>
<span class="special">&amp;&amp;</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>, initializes the contained value
of <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
as if direct-initializing an object of type <code class="computeroutput"><span class="identifier">T</span></code>
with the expression <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="identifier">rhs</span><span class="special">)</span></code>, followed by <code class="computeroutput"><span class="identifier">rhs</span><span class="special">.</span><span class="identifier">val</span><span class="special">-&gt;</span><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code>, <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> contains a value and <code class="computeroutput"><span class="identifier">rhs</span></code> does not contain a value,
otherwise
</li>
<li class="listitem">
(if <code class="computeroutput"><span class="keyword">bool</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
<span class="special">&amp;&amp;</span> <span class="keyword">bool</span><span class="special">(</span><span class="identifier">rhs</span><span class="special">)</span></code>) calls <code class="computeroutput"><span class="identifier">swap</span><span class="special">(*(*</span><span class="keyword">this</span><span class="special">),</span> <span class="special">*</span><span class="identifier">rhs</span><span class="special">)</span></code>.
</li>
</ul></div>
</li>
<li class="listitem">
<span class="bold"><strong>Postconditions:</strong></span> The states of <code class="computeroutput"><span class="identifier">x</span></code> and <code class="computeroutput"><span class="identifier">y</span></code>
@ -2052,17 +2064,6 @@
throws. If only one is initialized, whatever <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="identifier">T</span> <span class="special">(</span> <span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="special">)</span></code>
throws.
</li>
<li class="listitem">
<span class="bold"><strong>Notes:</strong></span> If both are initialized, <code class="computeroutput"><span class="identifier">swap</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;,</span><span class="identifier">T</span><span class="special">&amp;)</span></code>
is used unqualified but with <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">swap</span></code>
introduced in scope. If only one is initialized, <code class="computeroutput"><span class="identifier">T</span><span class="special">::~</span><span class="identifier">T</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="identifier">T</span><span class="special">(</span> <span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="special">)</span></code>
is called.
</li>
<li class="listitem">
<span class="bold"><strong>Exception Safety:</strong></span> If both are initialized,
this operation has the exception safety guarantees of <code class="computeroutput"><span class="identifier">swap</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;,</span><span class="identifier">T</span><span class="special">&amp;)</span></code>. If only one is initialized, it
has the same basic guarantee as <code class="computeroutput"><span class="identifier">optional</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="keyword">operator</span><span class="special">=</span> <span class="special">(</span> <span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="special">)</span></code>.
</li>
<li class="listitem">
<span class="bold"><strong>Example:</strong></span>
<pre class="programlisting"><span class="identifier">T</span> <span class="identifier">x</span><span class="special">(</span><span class="number">12</span><span class="special">);</span>

2
doc/html/index.html
View File

@ -133,7 +133,7 @@
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: June 20, 2014 at 09:06:52 GMT</small></p></td>
<td align="left"><p><small>Last revised: June 20, 2014 at 16:17:17 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td>
</tr></table>
<hr>