2014-02-04 22:45:58 -08:00
|
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
2000-07-27 14:27:00 +00:00
|
|
|
<html>
|
2014-02-04 22:45:58 -08:00
|
|
|
<head>
|
|
|
|
|
<title>shared_array</title>
|
|
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
|
|
|
|
|
</head>
|
|
|
|
|
<body text="#000000" bgcolor="#ffffff" link="#0000ff" vlink="#0000ff">
|
|
|
|
|
<h1><img height="86" alt="boost.png (6897 bytes)" src="../../boost.png"
|
|
|
|
|
width="277" align="middle" border="0">shared_array class template</h1>
|
|
|
|
|
<p>The <b>shared_array</b> class template stores a pointer to a dynamically
|
|
|
|
|
allocated array. (Dynamically allocated array are allocated with the C++ <b>new[]</b>
|
|
|
|
|
expression.) The object pointed to is guaranteed to be deleted when the last <b>shared_array</b>
|
|
|
|
|
pointing to it is destroyed or reset.</p>
|
|
|
|
|
<p>Every <b>shared_array</b> meets the <b>CopyConstructible</b> and <b>Assignable</b>
|
|
|
|
|
requirements of the C++ Standard Library, and so can be used in standard
|
|
|
|
|
library containers. Comparison operators are supplied so that <b>shared_array</b>
|
|
|
|
|
works with the standard library's associative containers.</p>
|
|
|
|
|
<p>Normally, a <b>shared_array</b> cannot correctly hold a pointer to an object
|
|
|
|
|
that has been allocated with the non-array form of <STRONG>new</STRONG>. See <a href="shared_ptr.htm">
|
|
|
|
|
<b>shared_ptr</b></a> for that usage.</p>
|
|
|
|
|
<p>Because the implementation uses reference counting, cycles of <b>shared_array</b>
|
|
|
|
|
instances will not be reclaimed. For example, if <b>main()</b> holds a <b>shared_array</b>
|
|
|
|
|
to <b>A</b>, which directly or indirectly holds a <b>shared_array</b> back to <b>A</b>,
|
|
|
|
|
<b>A</b>'s use count will be 2. Destruction of the original <b>shared_array</b>
|
|
|
|
|
will leave <b>A</b> dangling with a use count of 1.</p>
|
|
|
|
|
<p>A <b>shared_ptr</b> to a <b>std::vector</b> is an alternative to a <b>shared_array</b>
|
|
|
|
|
that is a bit heavier duty but far more flexible.</p>
|
|
|
|
|
<p>The class template is parameterized on <b>T</b>, the type of the object pointed
|
|
|
|
|
to. <b>T</b> must meet the smart pointer <a href="smart_ptr.htm#common_requirements">
|
|
|
|
|
common requirements</a>.</p>
|
|
|
|
|
<h2>Synopsis</h2>
|
|
|
|
|
<pre>namespace boost {
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T> class shared_array {
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-02-02 18:36:12 +00:00
|
|
|
public:
|
|
|
|
|
typedef T <a href="#element_type">element_type</a>;
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-02-02 18:36:12 +00:00
|
|
|
explicit <a href="#constructors">shared_array</a>(T * p = 0);
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class D> <a href="#constructors">shared_array</a>(T * p, D d);
|
2002-02-02 18:36:12 +00:00
|
|
|
<a href="#destructor">~shared_array</a>(); // never throws
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-02-02 18:36:12 +00:00
|
|
|
<a href="#constructors">shared_array</a>(shared_array const & r); // never throws
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-02-08 20:45:04 +00:00
|
|
|
shared_array & <a href="#assignment">operator=</a>(shared_array const & r); // never throws
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2002-02-08 20:45:04 +00:00
|
|
|
void <a href="#reset">reset</a>(T * p = 0);
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class D> void <a href="#reset">reset</a>(T * p, D d);
|
2000-07-27 14:27:00 +00:00
|
|
|
|
2008-09-17 22:59:07 +00:00
|
|
|
T & <a href="#indexing">operator[]</a>(std::ptrdiff_t i) const; // never throws
|
2002-02-02 18:36:12 +00:00
|
|
|
T * <a href="#get">get</a>() const; // never throws
|
|
|
|
|
|
|
|
|
|
bool <a href="#unique">unique</a>() const; // never throws
|
|
|
|
|
long <a href="#use_count">use_count</a>() const; // never throws
|
|
|
|
|
|
2005-09-25 21:49:08 +00:00
|
|
|
operator <A href="#conversions" ><i>unspecified-bool-type</i></A>() const; // never throws
|
|
|
|
|
|
2002-02-02 18:36:12 +00:00
|
|
|
void <a href="#swap">swap</a>(shared_array<T> & b); // never throws
|
2000-07-27 14:27:00 +00:00
|
|
|
};
|
|
|
|
|
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool <a href="#comparison">operator==</a>(shared_array<T> const & a, shared_array<T> const & b); // never throws
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool <a href="#comparison">operator!=</a>(shared_array<T> const & a, shared_array<T> const & b); // never throws
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool <a href="#comparison">operator<</a>(shared_array<T> const & a, shared_array<T> const & b); // never throws
|
2002-02-02 18:36:12 +00:00
|
|
|
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T> void <a href="#free-swap">swap</a>(shared_array<T> & a, shared_array<T> & b); // never throws
|
2002-02-02 18:36:12 +00:00
|
|
|
|
|
|
|
|
}</pre>
|
2014-02-04 22:45:58 -08:00
|
|
|
<h2>Members</h2>
|
|
|
|
|
<h3><a name="element_type">element_type</a></h3>
|
|
|
|
|
<pre>typedef T element_type;</pre>
|
|
|
|
|
<p>Provides the type of the stored pointer.</p>
|
|
|
|
|
<h3><a name="constructors">constructors</a></h3>
|
|
|
|
|
<pre>explicit shared_array(T * p = 0);</pre>
|
|
|
|
|
<p>Constructs a <b>shared_array</b>, storing a copy of <b>p</b>, which must be a
|
|
|
|
|
pointer to an array that was allocated via a C++ <b>new[]</b> expression or be
|
|
|
|
|
0. Afterwards, the <a href="#use_count">use count</a> is 1 (even if p == 0; see <a href="#destructor">
|
|
|
|
|
~shared_array</a>). The only exception which may be thrown by this
|
|
|
|
|
constructor is <b>std::bad_alloc</b>. If an exception is thrown, <b>delete[] p</b>
|
|
|
|
|
is called.</p>
|
|
|
|
|
<pre>template<class D> shared_array(T * p, D d);</pre>
|
|
|
|
|
<p>Constructs a <b>shared_array</b>, storing a copy of <b>p</b> and of <b>d</b>.
|
|
|
|
|
Afterwards, the <a href="#use_count">use count</a> is 1. <b>D</b>'s copy
|
|
|
|
|
constructor and destructor must not throw. When the the time comes to delete
|
|
|
|
|
the array pointed to by <b>p</b>, the object <b>d</b> is used in the statement <b>d(p)</b>.
|
|
|
|
|
Invoking the object <b>d</b> with parameter <b>p</b> in this way must not
|
|
|
|
|
throw. The only exception which may be thrown by this constructor is <b>std::bad_alloc</b>.
|
|
|
|
|
If an exception is thrown, <b>d(p)</b> is called.</p>
|
|
|
|
|
<pre>shared_array(shared_array const & r); // never throws</pre>
|
|
|
|
|
<p>Constructs a <b>shared_array</b>, as if by storing a copy of the pointer stored
|
|
|
|
|
in <b>r</b>. Afterwards, the <a href="#use_count">use count</a> for all copies
|
|
|
|
|
is 1 more than the initial use count.</p>
|
|
|
|
|
<h3><a name="destructor">destructor</a></h3>
|
|
|
|
|
<pre>~shared_array(); // never throws</pre>
|
|
|
|
|
<p>Decrements the <a href="#use_count">use count</a>. Then, if the use count is 0,
|
|
|
|
|
deletes the array pointed to by the stored pointer. Note that <b>delete[]</b> on
|
|
|
|
|
a pointer with a value of 0 is harmless. <b>T</b> need not be a complete type.
|
|
|
|
|
The guarantee that this does not throw exceptions depends on the requirement
|
|
|
|
|
that the deleted object's destructor does not throw exceptions. See the smart
|
|
|
|
|
pointer <a href="smart_ptr.htm#common_requirements">common requirements</a>.</p>
|
|
|
|
|
<h3><a name="assignment">assignment</a></h3>
|
|
|
|
|
<pre>shared_array & operator=(shared_array const & r); // never throws</pre>
|
|
|
|
|
<p>Constructs a new <b>shared_array</b> as described <a href="#constructors">above</a>,
|
|
|
|
|
then replaces this <b>shared_array</b> with the new one, destroying the
|
|
|
|
|
replaced object.</p>
|
|
|
|
|
<h3><a name="reset">reset</a></h3>
|
|
|
|
|
<pre>void reset(T * p = 0);</pre>
|
|
|
|
|
<p>Constructs a new <b>shared_array</b> as described <a href="#constructors">above</a>,
|
|
|
|
|
then replaces this <b>shared_array</b> with the new one, destroying the
|
|
|
|
|
replaced object. The only exception which may be thrown is <b>std::bad_alloc</b>.
|
|
|
|
|
If an exception is thrown, <b>delete[] p</b> is called.</p>
|
|
|
|
|
<pre>template<class D> void reset(T * p, D d);</pre>
|
|
|
|
|
<p>Constructs a new <b>shared_array</b> as described <a href="#constructors">above</a>,
|
|
|
|
|
then replaces this <b>shared_array</b> with the new one, destroying the
|
|
|
|
|
replaced object. <b>D</b>'s copy constructor must not throw. The only exception
|
|
|
|
|
which may be thrown is <b>std::bad_alloc</b>. If an exception is thrown, <b>d(p)</b>
|
|
|
|
|
is called.</p>
|
|
|
|
|
<h3><a name="indexing">indexing</a></h3>
|
|
|
|
|
<pre>T & operator[](std::ptrdiff_t i) const; // never throws</pre>
|
|
|
|
|
<p>Returns a reference to element <b>i</b> of the array pointed to by the stored
|
|
|
|
|
pointer. Behavior is undefined and almost certainly undesirable if the stored
|
|
|
|
|
pointer is 0, or if <b>i</b> is less than 0 or is greater than or equal to the
|
|
|
|
|
number of elements in the array.</p>
|
|
|
|
|
<h3><a name="get">get</a></h3>
|
|
|
|
|
<pre>T * get() const; // never throws</pre>
|
|
|
|
|
<p>Returns the stored pointer. <b>T</b> need not be a complete type. See the smart
|
|
|
|
|
pointer <a href="smart_ptr.htm#common_requirements">common requirements</a>.</p>
|
|
|
|
|
<h3><a name="unique">unique</a></h3>
|
|
|
|
|
<pre>bool unique() const; // never throws</pre>
|
|
|
|
|
<p>Returns true if no other <b>shared_array</b> is sharing ownership of the stored
|
|
|
|
|
pointer, false otherwise. <b>T</b> need not be a complete type. See the smart
|
|
|
|
|
pointer <a href="smart_ptr.htm#common_requirements">common requirements</a>.</p>
|
|
|
|
|
<h3><a name="use_count">use_count</a></h3>
|
|
|
|
|
<pre>long use_count() const; // never throws</pre>
|
|
|
|
|
<p>Returns the number of <b>shared_array</b> objects sharing ownership of the
|
|
|
|
|
stored pointer. <b>T</b> need not be a complete type. See the smart pointer <a href="smart_ptr.htm#common_requirements">
|
|
|
|
|
common requirements</a>.</p>
|
|
|
|
|
<p>Because <b>use_count</b> is not necessarily efficient to implement for
|
|
|
|
|
implementations of <b>shared_array</b> that do not use an explicit reference
|
|
|
|
|
count, it might be removed from some future version. Thus it should be used for
|
|
|
|
|
debugging purposes only, and not production code.</p>
|
|
|
|
|
<h3><a name="conversions">conversions</a></h3>
|
|
|
|
|
<pre>operator <i>unspecified-bool-type</i> () const; // never throws</pre>
|
|
|
|
|
<p>Returns an unspecified value that, when used in boolean contexts, is equivalent
|
|
|
|
|
to <code>get() != 0</code>.</p>
|
|
|
|
|
<h3><a name="swap">swap</a></h3>
|
|
|
|
|
<pre>void swap(shared_ptr & b); // never throws</pre>
|
|
|
|
|
<p>Exchanges the contents of the two smart pointers. <b>T</b> need not be a
|
|
|
|
|
complete type. See the smart pointer <a href="smart_ptr.htm#common_requirements">common
|
|
|
|
|
requirements</a>.</p>
|
|
|
|
|
<h2><a name="functions">Free Functions</a></h2>
|
|
|
|
|
<h3><a name="comparison">comparison</a></h3>
|
|
|
|
|
<pre>template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool operator==(shared_array<T> const & a, shared_array<T> const & b); // never throws
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool operator!=(shared_array<T> const & a, shared_array<T> const & b); // never throws
|
2002-10-23 13:55:18 +00:00
|
|
|
template<class T>
|
2002-02-09 01:18:00 +00:00
|
|
|
bool operator<(shared_array<T> const & a, shared_array<T> const & b); // never throws</pre>
|
2014-02-04 22:45:58 -08:00
|
|
|
<p>Compares the stored pointers of the two smart pointers. <b>T</b> need not be a
|
|
|
|
|
complete type. See the smart pointer <a href="smart_ptr.htm#common_requirements">common
|
|
|
|
|
requirements</a>.</p>
|
|
|
|
|
<p>The <b>operator<</b> overload is provided to define an ordering so that <b>shared_array</b>
|
|
|
|
|
objects can be used in associative containers such as <b>std::map</b>. The
|
|
|
|
|
implementation uses <b>std::less<T *></b> to perform the comparison. This
|
|
|
|
|
ensures that the comparison is handled correctly, since the standard mandates
|
|
|
|
|
that relational operations on pointers are unspecified (5.9 [expr.rel]
|
|
|
|
|
paragraph 2) but <b>std::less<></b> on pointers is well-defined (20.3.3
|
|
|
|
|
[lib.comparisons] paragraph 8).</p>
|
|
|
|
|
<h3><a name="free-swap">swap</a></h3>
|
|
|
|
|
<pre>template<class T>
|
2002-02-02 18:36:12 +00:00
|
|
|
void swap(shared_array<T> & a, shared_array<T> & b) // never throws</pre>
|
2014-02-04 22:45:58 -08:00
|
|
|
<p>Equivalent to <b>a.swap(b)</b>. Matches the interface of <b>std::swap</b>.
|
|
|
|
|
Provided as an aid to generic programming.</p>
|
|
|
|
|
<hr>
|
2014-02-06 01:40:46 -08:00
|
|
|
<p>$Date$</p>
|
2014-02-04 22:45:58 -08:00
|
|
|
<p><small>Copyright 1999 Greg Colvin and Beman Dawes. Copyright 2002 Darin Adler.
|
|
|
|
|
Copyright 2002-2005 Peter Dimov. Distributed under the Boost Software License, Version
|
|
|
|
|
1.0. See accompanying file <A href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</A> or
|
|
|
|
|
copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>.</small></p>
|
|
|
|
|
</body>
|
2003-01-25 17:58:01 +00:00
|
|
|
</html>
|
