bslma_constructionutil.h

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/// @file bslma_constructionutil.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslma_constructionutil.h                                           -*-C++-*-
#ifndef INCLUDED_BSLMA_CONSTRUCTIONUTIL
#define INCLUDED_BSLMA_CONSTRUCTIONUTIL
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslma_constructionutil bslma_constructionutil
/// @brief  Provide methods to construct arbitrarily-typed objects uniformly.
/// @addtogroup bsl
/// @{
/// @addtogroup bslma
/// @{
/// @addtogroup bslma_constructionutil
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslma_constructionutil-purpose"> Purpose</a>
/// * <a href="#bslma_constructionutil-classes"> Classes </a>
/// * <a href="#bslma_constructionutil-description"> Description </a>
///   * <a href="#bslma_constructionutil-type-traits"> Type Traits </a>
///   * <a href="#bslma_constructionutil-usage"> Usage </a>
///     * <a href="#bslma_constructionutil-example-1-using-bslma-constructionutil-to-implement-a-container"> Example 1: Using bslma::ConstructionUtil to Implement a Container </a>
///     * <a href="#bslma_constructionutil-example-2-bslma-allocator-propagation"> Example 2: bslma Allocator Propagation </a>
///     * <a href="#bslma_constructionutil-example-3-constructing-into-non-heap-memory"> Example 3: Constructing into Non-heap Memory </a>
///
/// # Purpose {#bslma_constructionutil-purpose}
/// Provide methods to construct arbitrarily-typed objects uniformly.
///
/// # Classes {#bslma_constructionutil-classes}
///
/// -  bslma::ConstructionUtil: namespace for methods to construct objects
///
/// @see  bslma_allocator, bslma_bslallocator, bslma_destructionutil
///
/// # Description {#bslma_constructionutil-description}
/// This component provides a `struct`, `bslma::ConstructionUtil`,
/// that serves as a namespace for utility functions to construct objects of an
/// arbitrary (template parameter) type, given an allocator and an arbitrary
/// number of arguments.  These functions are useful for uniformly constructing
/// an object without concern for whether the object's type is allocator-aware
/// (AA) and, if so, whether the allocator is passed at the end of the argument
/// list (trailing allocator-argument convention) or at the start of the
/// argument list, preceeded by `bsl::allocator_arg` (leading allocator-argument
/// convention).  If the type being constructed is not AA or if a non-allocator
/// scalar such as an `int` or `void *` is passed to these methods, the
/// allocator argument is discarded and a non-allocator constructor is invoked.
///
/// An additional `destructiveMove` method moves an object to a new address and
/// destroys the object at the original address, often doing so as an efficient
/// `memcpy` rather than separate move-destroy operations.
///
/// *Legacy-AA* (types with constructors having a parameter of type
/// `bslma::Allocator *`) and *bsl-AA* types (types with constructors having a
/// parameter of type `bsl::allocator<>`) are handled interchangeably by the
/// functions in this component, accepting either a `bslma::Allocator*` or a
/// `bsl::allocator` argument and then passing the appropriate type to the
/// constructed type.  Thus *bsl-AA* code can work seamlessly with *legacy-AA*
/// code, allowing for a smooth transition from the old model to the new one.
/// Note that this component does not directly use `bsl::allocator` or
/// `bsl::polymorphic_allocator` because such use would cause a circular
/// dependancy; an allocator is considered bsl-like if it is implicitly
/// convertible from `bslma::Allocator *` and has a `mechanism` method that
/// returns a `bslma::Allocator *` and an allocator is considered pmr-like if it
/// is convertible from `bsl::memory_resource *` (and therefore also convertible
/// from `bslma::Allocator *`.
///
/// The `construct` method provided here has roughly the same functionality as
/// the C++20 library function `std::uninitialized_construct_using_allocator`
/// and the `make` method has roughly the same functionality as
/// `std::make_obj_using_allocator`, with the following differences:
///
/// * As described above, *Legacy-AA* types are treated as interchangle with
///   *bsl-AA* types and `bslma::Allocator *` is treated as interchangeable
///   with `bsl::allocator`.
/// * The methods in this component accept a non-allocator scalar (e.g., `int`
///   or `void *`) instead of an allocator to indicate that no allocator should
///   be supplied to the object constructor, even if it is AA.
/// * The `std` functions will ignore the allocator if it is incompatible with
///   the object type being constructed.  The methods in this component,
///   conversely, will ignore the allocator only for *non-AA* and *stl-AA*
///   types.  For *legacy-AA*, *bsl-AA*, and *pmr-AA* types, an incompatible
///   allocator will result in a compilation failure.  This special case exists
///   to avoid subtle errors in the Bloomberg code base where a bad allocator
///   argument is used in a situation where allocator propagation is expected.
/// * This component does not provide special handling for `std::pair`.
///
/// ## Type Traits {#bslma_constructionutil-type-traits}
///
///
/// The facilities in this component query several type traits of the `TYPE`
/// being constructed, using that information as follows:
/// @code
/// Trait                       How Used
/// --------------------------- -----------------------------------------------
/// bslma::UsesBslmaAllocator   If true, the allocator being passed in must be
///                             either convertible to `bslma::Allocator *` or
///                             else have a `mechanism` accessor.  If false,
///                             the allocator argument must be convertible to
///                             the `TYPE::allocator_type`.
///
/// bslma::HasAllocatorType     If true, `TYPE::allocator_type` is assumed to
///                             the type of allocator accepted by `TYPE`'s
///                             constructors.
///
/// bsl::uses_allocator<TYPE,A> If true, then `A` can be used as an allocator
///                             to construct `TYPE`.
///
/// bslmf::UsesAllocatorArgT    If true, an allocator argument is passed as the
///                             second argument to the constructor, preceeded
///                             by a `bsl::allocator_arg` tag; otherwise the
///                             allocator is passed as the last argument to the
///                             constructor.
///
/// bslmf::IsBitwiseMoveable    If true, `destructiveMove` is implemented as a
///                             simple `memcpy`, rather than as a move-destroy
///                             sequence.
/// @endcode
///
/// ## Usage {#bslma_constructionutil-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Using bslma::ConstructionUtil to Implement a Container {#bslma_constructionutil-example-1-using-bslma-constructionutil-to-implement-a-container}
///
///
/// This example demonstrates the intended use of `bslma::ConstructionUtil` to
/// implement a simple container class that uses an instance of `bsl::allocator`
/// for memory management.
///
/// First, because allocation and construction are done in two separate steps,
/// we need to define a proctor type that will deallocate the allocated memory
/// in case the constructor throws an exception:
/// @code
/// #include <bslma_bslallocator.h>
///
/// /// This class implements a proctor to release memory allocated during
/// /// the construction of a `MyContainer` object if the constructor for
/// /// the container's data element throws an exception.  Such a proctor
/// /// should be `release`d once the element is safely constructed.
/// template <class TYPE>
/// class MyContainerProctor {
///
///     // DATA
///     bsl::allocator<TYPE>  d_allocator;
///     TYPE                 *d_address_p;    // proctored memory
///
///   private:
///     // NOT IMPLEMENTED
///     MyContainerProctor(const MyContainerProctor&);             // = delete
///     MyContainerProctor& operator=(const MyContainerProctor&);  // = delete
///
///   public:
///     // CREATORS
///
///     /// Create a proctor that conditionally manages the memory at the
///     /// specified `address`, and that uses the specified `allocator` to
///     /// deallocate the block of memory (if not released -- see
///     /// `release`) upon destruction.  The behavior is undefined unless
///     /// `allocator` is non-zero and supplied the memory at `address`.
///     MyContainerProctor(const bsl::allocator<TYPE> allocator, TYPE *address)
///     : d_allocator(allocator)
///     , d_address_p(address)
///     {
///     }
///
///     /// Destroy this proctor, and deallocate the block of memory it
///     /// manages (if any) by invoking the `deallocate` method of the
///     /// allocator that was supplied at construction of this proctor.  If
///     /// no memory is currently being managed, this method has no effect.
///     ~MyContainerProctor()
///     {
///         if (d_address_p) {
///             d_allocator.deallocate(d_address_p, 1);
///         }
///     }
///
///     // MANIPULATORS
///
///     /// Release from management the block of memory currently managed by
///     /// this proctor.  If no memory is currently being managed, this
///     /// method has no effect.
///     void release()
///     {
///         d_address_p = 0;
///     }
/// };
/// @endcode
/// Then, we create a container class that holds a single element and uses
/// `bsl::allocator` to supply memory:
/// @code
/// #include <bslma_constructionutil.h>
///
/// /// This class provides a container that always holds exactly one
/// /// element, dynamically allocated using the specified `bslma`
/// /// allocator.
/// template <class TYPE>
/// class MyContainer {
///
///     // DATA
///     bsl::allocator<TYPE>  d_allocator;
///     TYPE                 *d_value_p;
///
///     /// Return the address of a new element that was allocated from this
///     /// container's allocator and initialized with the optionally
///     /// specified `value`, or default-initialized if `value` is not
///     /// specified.  If `TYPE` is AA, this container's allocator is used
///     /// to construct the new element.
///     TYPE *createElement();
///     TYPE *createElement(const TYPE& value);
///
///   public:
///     typedef bsl::allocator<TYPE>  allocator_type;
///
///     // CREATORS
///
///     /// Create a container with a default-constructed element.
///     /// Optionally specify a `allocator` used to supply memory.
///     explicit
///     MyContainer(const allocator_type& allocator = allocator_type())
///         : d_allocator(allocator), d_value_p(createElement()) { }
///
///     /// Create a container having an element constructed from the
///     /// specified `value`.  Optionally specify an `allocator` to supply
///     /// memory both for the container and for the contained element.
///     explicit
///     MyContainer(const TYPE&           value,
///                 const allocator_type& allocator = allocator_type())
///         : d_allocator(allocator), d_value_p(createElement(value)) { }
///
///     /// Create a container having the same value as the specified
///     /// `original` object.  Optionally specify a `allocator` used
///     /// to supply memory.  If `allocator` is 0, the currently
///     /// installed default allocator is used.
///     MyContainer(const MyContainer&    original,
///                 const allocator_type& allocator = allocator_type())
///         : d_allocator(allocator)
///         , d_value_p(createElement(*original.d_value_p)) { }
///
///     /// Destroy this object.
///     ~MyContainer();
///
///     // MANIPULATORS
///
///     /// Assign to this object the value of the specified `rhs` object,
///     /// and return a reference providing modifiable access to this
///     /// object.
///     MyContainer& operator=(const TYPE& rhs);
///     MyContainer& operator=(const MyContainer& rhs);
///
///     /// Return a non-`const` reference to the element contained in this
///     /// object.
///     TYPE& front()
///     {
///         return *d_value_p;
///     }
///
///     // ACCESSORS
///
///     /// Return a `const` reference to the element contained in this
///     /// object.
///     const TYPE& front() const
///     {
///         return *d_value_p;
///     }
///
///     /// Return the allocator used by this object to supply memory.
///     allocator_type get_allocator() const
///     {
///         return d_allocator;
///     }
///
///     // etc.
/// };
/// @endcode
/// Next, we implement the private `createElement` members that allocate memory
/// and construct a `TYPE` object in the allocated memory.  We perform the
/// allocation using the `allocate` method of `bsl::allocator` and the
/// construction using the `construct` method of `ConstructionUtil` that
/// provides the correct semantics for passing the allocator to the constructed
/// object when appropriate:
/// @code
/// template <class TYPE>
/// TYPE *MyContainer<TYPE>::createElement()
/// {
///     TYPE *value_p = d_allocator.allocate(1);
///     MyContainerProctor<TYPE> proctor(d_allocator, value_p);
///
///     // Call 'construct' passing the allocator but no constructor
///     // arguments.
///
///     bslma::ConstructionUtil::construct(value_p, d_allocator);
///     proctor.release();
///
///     return value_p;
/// }
///
/// template <class TYPE>
/// TYPE *MyContainer<TYPE>::createElement(const TYPE& value)
/// {
///     TYPE *value_p = d_allocator.allocate(1);
///     MyContainerProctor<TYPE> proctor(d_allocator, value_p);
///
///     // Call 'construct' passing the allocator and 'value' arguments.
///
///     bslma::ConstructionUtil::construct(value_p, d_allocator, value);
///     proctor.release();
///
///     return value_p;
/// }
/// @endcode
/// Now, the destructor destroys the object and deallocates the memory used to
/// hold the element using the allocator:
/// @code
/// template <class TYPE>
/// MyContainer<TYPE>::~MyContainer()
/// {
///     d_value_p->~TYPE();
///     d_allocator.deallocate(d_value_p, 1);
/// }
/// @endcode
/// Next, the assignment operator needs to assign the value without modifying
/// the allocator.
/// @code
/// template <class TYPE>
/// MyContainer<TYPE>& MyContainer<TYPE>::operator=(const TYPE& rhs)
/// {
///     if (&rhs != d_value_p) {
///         *d_value_p = rhs;
///     }
///     return *this;
/// }
///
/// template <class TYPE>
/// MyContainer<TYPE>& MyContainer<TYPE>::operator=(const MyContainer& rhs)
/// {
///     return operator=(*rhs.d_value_p);
/// }
/// @endcode
/// Finally, we perform a simple test of `MyContainer`, instantiating it with
/// element type `int`:
/// @code
/// int main()
/// {
///     bslma::TestAllocator testAlloc;
///     MyContainer<int>     C1(123, &testAlloc);
///     assert(C1.get_allocator() == &testAlloc);
///     assert(C1.front()         == 123);
///
///     MyContainer<int> C2(C1);
///     assert(C2.get_allocator() == bslma::Default::defaultAllocator());
///     assert(C2.front()         == 123);
///
///     return 0;
/// }
/// @endcode
///
/// ### Example 2: bslma Allocator Propagation {#bslma_constructionutil-example-2-bslma-allocator-propagation}
///
///
/// This example demonstrates that `MyContainer` does indeed propagate the
/// allocator to its contained element.
///
/// First, we create a representative element class, `MyType`.  Unlike the
/// `MyContainer` template, `MyType` allocates memory using the
/// `bslma::Allocator *` (legacy) allocator model instead of the
/// `bsl::allocator` (bsl) allocator model:
/// @code
/// #include <bslma_default.h>
///
/// class MyType {
///
///     // DATA
///     bslma::Allocator *d_allocator_p;
///     int               d_value;
///     // ...
///
///   public:
///     // TRAITS
///     BSLMF_NESTED_TRAIT_DECLARATION(MyType, bslma::UsesBslmaAllocator);
///
///     // CREATORS
///
///     /// Create a `MyType` object having the default value.  Optionally
///     /// specify a `basicAllocator` used to supply memory.  If
///     /// `basicAllocator` is 0, the currently installed default allocator
///     /// is used.
///     explicit MyType(bslma::Allocator *basicAllocator = 0)
///         : d_allocator_p(bslma::Default::allocator(basicAllocator))
///         , d_value()
///     {
///         // ...
///     }
///
///     /// Create a `MyType` object having the specified `value`.
///     /// Optionally specify a `basicAllocator` used to supply memory.  If
///     /// `basicAllocator` is 0, the currently installed default allocator
///     /// is used.
///     explicit MyType(int               value,
///                     bslma::Allocator *basicAllocator = 0)
///         : d_allocator_p(bslma::Default::allocator(basicAllocator))
///         , d_value(value)
///     {
///         // ...
///     }
///
///     /// Create a `MyType` object having the same value as the specified
///     /// `original` object.  Optionally specify a `basicAllocator` used
///     /// to supply memory.  If `basicAllocator` is 0, the currently
///     /// installed default allocator is used.
///     MyType(const MyType& original, bslma::Allocator *basicAllocator = 0)
///     : d_allocator_p(bslma::Default::allocator(basicAllocator))
///     , d_value(original.value())
///     {
///         // ...
///     }
///
///     // ...
///
///     // ACCESSORS
///
///     /// Return the allocator used by this object to supply memory.
///     bslma::Allocator *allocator() const
///     {
///         return d_allocator_p;
///     }
///
///     /// Return the value of this object.
///     int value() const
///     {
///         return d_value;
///     }
///
///     // ...
/// };
/// @endcode
/// Finally, we instantiate `MyContainer` using `MyType` and verify that, when
/// we provide an allocator to the constructor of the container, the same
/// allocator is passed to the constructor of the contained element.  Because
/// the container and the element implement different allocator models, the
/// invocation of `bslma::ConstructionUtil::construct` automatically adapts the
/// `bsl::allocator` held by the container to a `bslma::Allocator` pointer
/// expected by the element.  We also verify that, when the container is
/// copy-constructed without supplying an allocator, the copy uses the default
/// allocator, not the allocator from the original object.  Moreover, we verify
/// that the element stored in the copy also uses the default allocator:
/// @code
/// int main()
/// {
///     bslma::TestAllocator testAlloc;
///     bslma::TestAllocator testAlloc2;
///
///     MyContainer<MyType>  C1(&testAlloc);  // extended default constructor
///     assert(C1.get_allocator()     == &testAlloc);
///     assert(C1.front().allocator() == &testAlloc);
///     assert(C1.front().value()     == 0);
///
///     MyContainer<MyType>  C2(MyType(22), &testAlloc);  // value constructor
///     assert(C2.get_allocator()     == &testAlloc);
///     assert(C2.front().allocator() == &testAlloc);
///     assert(C2.front().value()     == 22);
///
///     MyContainer<MyType> C3(C2);
///     assert(C3.get_allocator()     != C2.get_allocator());
///     assert(C3.get_allocator()     == bslma::Default::defaultAllocator());
///     assert(C3.front().allocator() != C1.front().allocator());
///     assert(C3.front().allocator() == bslma::Default::defaultAllocator());
///     assert(C3.front().value()     == 22);
///
///     MyContainer<MyType> C4(C2, &testAlloc2);
///     assert(C4.get_allocator()     == &testAlloc2);
///     assert(C4.front().allocator() == &testAlloc2);
///     assert(C4.front().value()     == 22);
/// }
/// @endcode
///
/// ### Example 3: Constructing into Non-heap Memory {#bslma_constructionutil-example-3-constructing-into-non-heap-memory}
///
///
/// This example demonstrates using `bslma::ConstructionUtil::make` to
/// implement a simple wrapper class that contains a single item that might or
/// might not use the `bslma` allocator protocol.
///
/// First, we define a wrapper class that holds an object and a functor.  The
/// functor (known as the *listener*) is called each time the wrapped object is
/// changes.  We store the object directly as a member variable, instead of
/// using an uninitialized buffer, to avoid a separate construction step:
/// @code
/// /// This class is a wrapper around an object of the specified `TYPE`
/// /// that triggers a call to an object, called the "listener", of the
/// /// specified `FUNC` invocable type whenever the wrapped object is
/// /// changed.
/// template <class TYPE, class FUNC>
/// class MyTriggeredWrapper {
///
///     // DATA
///     TYPE d_value;
///     FUNC d_listener;
///
///   public:
///     typedef bsl::allocator<> allocator_type;
///
///     // CREATORS
///
///     /// Create an object with the specified `f` as the listener to be
///     /// called when a change is triggered.  Optionally specify `v` as
///     /// the wrapped value; otherwise the wrapped value is default
///     /// constructed.  Optionally specify `allocator` to supply
///     /// memory; otherwise the current default allocator is used.  If
///     /// `TYPE` is not allocator aware, `allocator` is ignored.
///     explicit
///     MyTriggeredWrapper(const FUNC&           f,
///                        const allocator_type& allocator = allocator_type());
///     MyTriggeredWrapper(const TYPE&           v,
///                        const FUNC&           f,
///                        const allocator_type& allocator = allocator_type());
///
///     /// Create a copy of the specified `original`.  Optionally specify
///     /// `allocator` to supply memory; otherwise the current
///     /// default allocator is used.
///     MyTriggeredWrapper(const MyTriggeredWrapper&  original,
///                        const allocator_type& allocator = allocator_type());
///
///     /// Destroy the wrapped object and listener.
///     ~MyTriggeredWrapper()
///     {
///     }
///
///     // MANIPULATORS
///
///     /// Assign to the wrapped value the value of the specified `rhs`,
///     /// invoke the listener with the new value, and return a reference
///     /// providing modifiable access to this object.  Note that the
///     /// listener itself is not assigned.
///     MyTriggeredWrapper& operator=(const TYPE& rhs);
///     MyTriggeredWrapper& operator=(const MyTriggeredWrapper& rhs);
///
///     /// Set the wrapped value to the specified `value` and invoke the
///     /// listener with the new value.
///     void setValue(const TYPE& value);
///
///     // ACCESSORS
///
///     /// Return a reference providing read-only access to the wrapped
///     /// value.
///     const TYPE& value() const
///     {
///         return d_value;
///     }
///
///     /// Return a reference providing read-only access to the listener.
///     const FUNC& listener() const
///     {
///         return d_listener;
///     }
/// };
/// @endcode
/// Next, we define the constructors such that they initialize `d_value` using
/// the specified allocator if and only if `TYPE` accepts an allocator.  The
/// `bslma::ConstructionUtil::make` family of functions encapsulate all of the
/// metaprogramming that detects whether `TYPE` uses an allocator and, if so,
/// which construction protocol it uses (allocator at the front or at the back
/// of the argument list), making all three constructors straightforward:
/// @code
/// template <class TYPE, class FUNC>
/// MyTriggeredWrapper<TYPE, FUNC>::MyTriggeredWrapper(
///                                           const FUNC&           f,
///                                           const allocator_type& allocator)
/// : d_value(bslma::ConstructionUtil::make<TYPE>(allocator))
/// , d_listener(f)
/// {
/// }
///
/// template <class TYPE, class FUNC>
/// MyTriggeredWrapper<TYPE, FUNC>::MyTriggeredWrapper(
///                                           const TYPE&           v,
///                                           const FUNC&           f,
///                                           const allocator_type& allocator)
/// : d_value(bslma::ConstructionUtil::make<TYPE>(allocator, v))
/// , d_listener(f)
/// {
/// }
///
/// template <class TYPE, class FUNC>
/// MyTriggeredWrapper<TYPE, FUNC>::MyTriggeredWrapper(
///                                        const MyTriggeredWrapper& other,
///                                        const allocator_type&     allocator)
/// : d_value(bslma::ConstructionUtil::make<TYPE>(allocator, other.value()))
/// , d_listener(other.d_listener)
/// {
/// }
/// @endcode
/// Note that, for `d_value` to be constructed with the correct allocator, the
/// compiler must construct the result returned from `make` directly into the
/// `d_value` variable, an optimization known prior to C++17 as "copy elision".
/// This optimization is required by the C++17 standard and is optional in
/// pre-2017 standards, but is implemented in all of the C++11 compilers for
/// which this component is expected to be used at Bloomberg.
///
/// Next, we implement the assignment operators, which simply call `setValue`:
/// @code
/// template <class TYPE, class FUNC>
/// MyTriggeredWrapper<TYPE, FUNC>&
/// MyTriggeredWrapper<TYPE, FUNC>::operator=(const TYPE& rhs)
/// {
///     setValue(rhs);
///     return *this;
/// }
///
/// template <class TYPE, class FUNC>
/// MyTriggeredWrapper<TYPE, FUNC>&
/// MyTriggeredWrapper<TYPE, FUNC>::operator=(const MyTriggeredWrapper& rhs)
/// {
///     setValue(rhs.value());
///     return *this;
/// }
/// @endcode
/// Then, we implement `setValue`, which calls the listener after modifying the
/// value:
/// @code
/// template <class TYPE, class FUNC>
/// void MyTriggeredWrapper<TYPE, FUNC>::setValue(const TYPE& value)
/// {
///     d_value = value;
///     d_listener(d_value);
/// }
/// @endcode
/// Finally, we check our work by creating a listener for `MyContainer<int>`
/// that stores its last-seen value in a known location and a wrapper around
/// `MyContainer<int>` to test it:
/// @code
/// int lastSeen = 0;
/// void myListener(const MyContainer<int>& c)
/// {
///     lastSeen = c.front();
/// }
///
/// int main()
/// {
///     bslma::TestAllocator testAlloc;
///     MyTriggeredWrapper<MyContainer<int>,
///                        void (*)(const MyContainer<int>&)>
///                          wrappedContainer(myListener, &testAlloc);
///     assert(&testAlloc == wrappedContainer.value().get_allocator());
///
///     wrappedContainer = MyContainer<int>(99);
///
///     assert(99 == lastSeen);
/// }
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslma
 * @{
 */
/** @addtogroup bslma_constructionutil
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslma_allocator.h>
#include <bslma_destructionutil.h>
#include <bslma_hasallocatortype.h>
#include <bslma_usesbslmaallocator.h>
 
#include <bslmf_allocatorargt.h>
#include <bslmf_enableif.h>
#include <bslmf_integralconstant.h>
#include <bslmf_isbitwisemoveable.h>
#include <bslmf_isclass.h>
#include <bslmf_isconvertible.h>
#include <bslmf_isfundamental.h>
#include <bslmf_ismemberpointer.h>
#include <bslmf_ispointer.h>
#include <bslmf_movableref.h>
#include <bslmf_removecv.h>
#include <bslmf_usesallocatorargt.h>
#include <bslmf_util.h>    // 'forward(V)'
#include <bslmf_voidtype.h>
 
#include <bsls_assert.h>
#include <bsls_compilerfeatures.h>
#include <bsls_libraryfeatures.h>
#include <bsls_platform.h>
#include <bsls_util.h>     // 'forward<T>(V)'
 
#include <stddef.h>
#include <string.h>
 
#include <new>          // placement 'new'
 
#if BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
// Include version that can be compiled with C++03
// Generated on Tue Oct  4 14:49:46 2022
// Command line: sim_cpp11_features.pl bslma_constructionutil.h
# define COMPILING_BSLMA_CONSTRUCTIONUTIL_H
# include <bslma_constructionutil_cpp03.h>
# undef COMPILING_BSLMA_CONSTRUCTIONUTIL_H
#else
 
 
namespace bslma {
 
// Workaround for optimization issue in xlC that mishandles pointer aliasing.
//   IV56864: ALIASING BEHAVIOUR FOR PLACEMENT NEW
//   http://www-01.ibm.com/support/docview.wss?uid=swg1IV56864
// Place this macro following each use of placement new.  Alternatively,
// compile with xlC_r -qalias=noansi, which reduces optimization opportunities
// across entire translation unit instead of simply across optimization fence.
// Update: issue is fixed in xlC 13.1 (__xlC__ >= 0x0d01).
 
#if defined(BSLS_PLATFORM_CMP_IBM) && BSLS_PLATFORM_CMP_VERSION < 0x0d01
    #define BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX                     \
                             BSLS_PERFORMANCEHINT_OPTIMIZATION_FENCE
#else
    #define BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX
#endif
 
struct ConstructionUtil_Imp;
 
                          // =======================
                          // struct ConstructionUtil
                          // =======================
 
/// This `struct` provides a namespace for utility functions that construct
/// elements of (a template parameter) `TARGET_TYPE`.
struct ConstructionUtil {
 
  private:
    // PRIVATE TYPES
 
    /// This `typedef` is a convenient alias for the implementation-specific
    /// utility class defined in this component.
    typedef ConstructionUtil_Imp Imp;
 
  public:
    // CLASS METHODS
 
    /// Create a default-constructed object of (template parameter)
    /// `TARGET_TYPE` at the specified `address`.  If `allocator` is a
    /// `bslma`-compatible allocator and `TARGET_TYPE` supports
    /// `bslma`-style allocation, `allocator` is passed to the default
    /// extended constructor; otherwise, `allocator` is ignored.  If the
    /// constructor throws, the memory at `address` is left in an
    /// unspecified state.  The behavior is undefined unless `address`
    /// refers to a block that is of sufficient size and properly aligned
    /// for objects of `TARGET_TYPE`.
    template <class TARGET_TYPE, class ALLOCATOR>
    static void construct(TARGET_TYPE *address, const ALLOCATOR& allocator);
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES // $var-args=13
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
    // 'ARG1' lvalue overloaded unneeded in C++11 and hits bug in gcc < 10.2.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(TARGET_TYPE             *address,
                          const ALLOCATOR&         allocator,
                          ARG1&                    argument1,
                          ARGS&&...                arguments);
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
    /// Create an object of (template parameter) `TARGET_TYPE` at the
    /// specified `address`, constructed by forwarding the specified
    /// `argument1` and the (variable number of) additional specified
    /// `arguments` to the corresponding constructor of `TARGET_TYPE`.  If
    /// the specified `allocator` is a bslma-compatible allocator and
    /// `TARGET_TYPE` supports `bslma`-style allocation, the allocator is
    /// passed to the constructor; otherwise, `allocator` is ignored.  If
    /// the constructor throws, the memory at `address` is left in an
    /// unspecified state.  Note that, in C++03, perfect forwarding is
    /// limited such that any lvalue reference in the `arguments` parameter
    /// pack is const-qualified when forwarded to the `TARGET_TYPE`
    /// constructor; only `argument1` can be forwarded as an unqualified
    /// lvalue.  The behavior is undefined unless `address` refers to a
    /// block that is of sufficient size and properly aligned for objects of
    /// `TARGET_TYPE`.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(TARGET_TYPE                             *address,
                          const ALLOCATOR&                         allocator,
                          BSLS_COMPILERFEATURES_FORWARD_REF(ARG1)  argument1,
                          ARGS&&...                                arguments);
#endif
 
    /// Create an object of (template parameter) `TARGET_TYPE` at the
    /// specified `address` by moving from the specified `original` object,
    /// then destroy `original`.  The specified `allocator` is unused
    /// (except possibly in precondition checks).  The constructed object
    /// will have the same allocator (if any) as `original`.  If
    /// `bslmf::IsBitwiseMoveable<TARGET_TYPE>::value` is `true`, then the
    /// entire operation is a simple `memcpy` -- no constructors or
    /// destructors are invoked; otherwise, this method move-constructs an
    /// object at `address` from the object at `original` then invokes the
    /// destructor on `original`.  If the move constructor throws an
    /// exception, the memory at `address` is left in an uninitialized state
    /// and `original` is left in a valid but unspecified state.  The
    /// behavior is undefined if `original` uses an allocator other than
    /// `allocator` to supply memory.  Note that if `original` points to an
    /// object of a type derived from `TARGET_TYPE` (i.e., a slicing move)
    /// where `TARGET_TYPE` has a non-`virtual` destructor, then `original`
    /// will be only partially destroyed.
    template <class TARGET_TYPE, class ALLOCATOR>
    static void destructiveMove(TARGET_TYPE      *address,
                                const ALLOCATOR&  allocator,
                                TARGET_TYPE      *original);
 
#if defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
    /// Return, by value, an object of the specified (template parameter)
    /// `TARGET_TYPE`, having default value.  If `allocator` is a
    /// `bslma`-compatible allocator and `TARGET_TYPE` supports
    /// `bslma`-style allocation, `allocator` is passed to the extended
    /// default constructor; otherwise, `allocator` is ignored.  Note that
    /// this method is available only for compilers that reliably implement
    /// copy/move elision (i.e., RVO) on the returned object.  This
    /// copy/move elision is required starting with C++17 and is widely
    /// implemented, though optional, prior to C++17.
    template <class TARGET_TYPE, class ALLOCATOR>
    static TARGET_TYPE make(const ALLOCATOR& allocator);
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
    // 'ARG1' lvalue overloaded unneeded in C++11 and hits bug in gcc < 10.2.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(const ALLOCATOR&         allocator,
                            ARG1&                    argument1,
                            ARGS&&...                arguments);
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
    /// Return, by value, an object of the specified (template parameter)
    /// `TARGET_TYPE`, constructed by forwarding the specified `argument1`
    /// and the (variable number of) additional specified `arguments` to the
    /// corresponding constructor of `TARGET_TYPE`.  If the specified
    /// `allocator` is a bslma-compatible allocator and `TARGET_TYPE`
    /// supports `bslma`-style allocation, the allocator is passed to the
    /// constructor; otherwise, `allocator` is ignored.  Note that this
    /// method is available only for compilers that reliably implement
    /// copy/move elision (i.e., RVO) on the returned object.  This
    /// copy/move elision is required starting with C++17 and is widely
    /// implemented, though optional, prior to C++17.  Note that, in C++03,
    /// perfect forwarding is limited such that any lvalue reference in the
    /// `arguments` parameter pack is const-qualified when forwarded to the
    /// `TARGET_TYPE` constructor; only `argument1` can be forwarded as an
    /// unqualified lvalue.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(const ALLOCATOR&                        allocator,
                            BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
                            ARGS&&...                               arguments);
#endif
#endif // defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
};
 
                        // ===========================
                        // struct ConstructionUtil_Imp
                        // ===========================
 
/// This `struct` provides a namespace for a suite of utility functions that
/// are used to implement functions in `ConstructionUtil`.  In particular,
/// they provide overloads, resolved at compile-time, for various features
/// (e.g., passing down the allocator to sub-elements of `pair`-like types)
/// and optimizations (e.g., bypassing the call to the constructor for
/// classes with trivial default and copy constructors).  These functions
/// should not be used outside this component.
struct ConstructionUtil_Imp {
 
    // TYPES
 
    /// These constants are used in the overloads below, when the last argument
    /// is of type `bsl::integral_constant<int, N> *`, indicating that
    /// `TARGET_TYPE` has the traits for which the enumerator equal to `N` is
    /// named.
    enum {
 
        e_NIL_TRAITS                 ,
        e_BITWISE_MOVABLE_TRAITS     ,
        e_USES_ALLOCATOR_TRAITS      ,
        e_USES_ALLOCATOR_ARG_T_TRAITS   // Implies USES_ALLOCATOR
    };
 
    // CLASS METHODS
 
    /// Construct a default instance of (template parameter) `TARGET_TYPE`
    /// at the specified `address`, passing to the constructor the specified
    /// `allocator` using the leading or trailing allocator convention,
    /// according to the specified `integral_constant` tag, or ignoring
    /// `allocator` in the `e_NIL_TRAITS` case.  If the constructor throws,
    /// the memory at `address` is left in an unspecified state.
    template <class TARGET_TYPE, class ALLOCATOR>
    static void construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>);
    template <class TARGET_TYPE, class ALLOCATOR>
    static void construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>);
    template <class TARGET_TYPE, class ALLOCATOR>
    static void construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>);
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
    // 'ARG1' lvalue overloaded unneeded in C++11 and hits bug in gcc < 10.2.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE             *address,
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE             *address,
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE             *address,
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
    /// Construct an instance of (template parameter) `TARGET_TYPE` at the
    /// specified `address` forwarding to the constructor the specified
    /// `argument1` and `arguments` arguments and passing the specified
    /// `allocator` using the leading or trailing allocator convention,
    /// according to the specified `integral_constant` tag, or ignoring
    /// `allocator` in the `e_NIL_TRAITS` case.  If the constructor throws,
    /// the memory at `address` is left in an unspecified state.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE                            *address,
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE                            *address,
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static void construct(
             TARGET_TYPE                            *address,
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
#endif
 
    /// Move the bitwise movable object of (template parameter)
    /// `TARGET_TYPE` at the specified `original` address to the specified
    /// `address`, eliding the call to the move constructor and destructor
    /// in favor of performing a bitwise copy.  The specified `allocator`
    /// argument is ignored (except possibly for precondition checks).  The
    /// behavior is undefined if `original` uses an allocator other than
    /// `allocator` to supply memory.
    template <class TARGET_TYPE, class ALLOCATOR>
    static void destructiveMove(
              TARGET_TYPE                                           *address,
              const ALLOCATOR&                                       allocator,
              bsl::integral_constant<int, e_BITWISE_MOVABLE_TRAITS>  ,
              TARGET_TYPE                                           *original);
 
    /// Create an object of (template parameter) `TARGET_TYPE` at the
    /// specified `address` by move construction from the specified
    /// `original` object, then destroy `original`.  The specified
    /// `allocator` is unused (except possibly in precondition checks).  The
    /// constructed object will have the same allocator (if any) as
    /// `original`.  If the move constructor throws an exception, the memory
    /// at `address` is left in an uninitialized state and `original` is
    /// left in a valid but unspecified state.  The behavior is undefined if
    /// `original` uses an allocator other than `allocator` to supply
    /// memory.  Note that, if `original` points to an object of a type
    /// derived from `TARGET_TYPE` (i.e., a slicing move) where
    /// `TARGET_TYPE` has a non-`virtual` destructor, then `original` will
    /// be only partially destroyed.
    template <class TARGET_TYPE, class ALLOCATOR>
    static void destructiveMove(
                          TARGET_TYPE                               *address,
                          const ALLOCATOR&                           allocator,
                          bsl::integral_constant<int, e_NIL_TRAITS>  ,
                          TARGET_TYPE                               *original);
 
#if defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
    /// Return, by value, a default-constructed object of (template
    /// parameter) `TARGET_TYPE`, passing the specified `allocator` to the
    /// constructor using the leading or trailing allocator convention,
    /// according to the specified `integral_constant` tag, or ignoring
    /// `allocator` in the `e_NIL_TRAITS` case.
    template <class TARGET_TYPE, class ALLOCATOR>
    static TARGET_TYPE make(
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>);
    template <class TARGET_TYPE, class ALLOCATOR>
    static TARGET_TYPE make(
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>);
    template <class TARGET_TYPE, class ALLOCATOR>
    static TARGET_TYPE make(
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>);
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
    // 'ARG1' lvalue overloaded unneeded in C++11 and hits bug in gcc < 10.2.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&         allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>,
             ARG1&                    argument1,
             ARGS&&...                arguments);
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
    /// Return, by value, an instance of (template parameter) `TARGET_TYPE`,
    /// forwarding to the constructor the specified `argument1` and
    /// `arguments` arguments and passing the specified `allocator` using
    /// the leading or trailing allocator convention, according to the
    /// specified `integral_constant` tag, or ignoring `allocator` in the
    /// `e_NIL_TRAITS` case.
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
    template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
    static TARGET_TYPE make(
             const ALLOCATOR&                        allocator,
             bsl::integral_constant<int, e_NIL_TRAITS>,
             BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
             ARGS&&...                               arguments);
 
#endif
#endif // defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
 
    /// Return the specified `address` cast as a pointer to `void`, even if
    /// the (template parameter) `TARGET_TYPE` is cv-qualified.
    template <class TARGET_TYPE>
    static void *voidify(TARGET_TYPE *address);
};
 
// ============================================================================
//                      TEMPLATE IMPLEMENTATIONS
// ============================================================================
 
              // -----------------------------------------------
              // struct template ConstructionUtil_IsAllocatorPtr
              // -----------------------------------------------
 
/// Metafunction that inherits from `true_type` if the `ALLOC` type is a
/// pointer to `bslma::Allocator` or a class derived from it and
/// `false_type` otherwise.
template <class ALLOC>
struct ConstructionUtil_IsAllocatorPtr;
 
/// This primary template is instantiated only for non-pointer type `ALLOC`
/// and always evaluates false.
template <class ALLOC>
struct ConstructionUtil_IsAllocatorPtr : bsl::false_type {
};
 
/// This partial specialization is for pointer type `ALLOC *` and evaulates
/// true if and only if `ALLOC` is derived from `bslma::Allocator`.
template <class ALLOC>
struct ConstructionUtil_IsAllocatorPtr<ALLOC *>
    : bsl::is_convertible<ALLOC *, bslma::Allocator *>::type {
};
 
              // ---------------------------------------------------
              // struct template ConstructionUtil_ConstructionTraits
              // ---------------------------------------------------
 
/// Metafunction yielding one of the following three `value` constants:
///
///: e_USES_ALLOCATOR_ARG_T_TRAITS  `TARGET_TYPE` supports an allocator as
///:                                its second constructor argument, after
///:                                `bsl::allocator_arg`.
///:
///: e_USES_ALLOCATOR_TRAITS        `TARGET_TYPE` supports an allocator as
///:                                its last constructor argument.
///:
///: e_NIL_TRAITS                   `TARGET_TYPE` does not support an
///:                                allocator and/or `ALLOCATOR` is `void*`
///:                                `int`, or any other non-allocator
///:                                scalar.  The allocator argument to
///:                                `construct` will be ignored.
///
/// `ALLOCATOR` is compatible with an AA `TARGET_TYPE` if `ALLOCATOR` is
/// convertible to the allocator type expected by `TARGET_TYPE`'s
/// constructors.  There are three special cases of incompatible `ALLOCATOR`
/// types:
///
/// 1. If `TARGET_TYPE` expects an allocator of type `bslma::Allocator *`
///    this metafunction yields either `e_USES_ALLOCATOR_ARG_T_TRAITS` or
///    `e_USES_ALLOCATOR_TRAITS`, even if `ALLOCATOR` is not compatible with
///    `TARGET_TYPE`.  The `construct` method will attempt to extract the
///    `bslma::Allocator *` from the allocator using its `mechanism`
///    accessor.  If there is no `mechanism` accessor, compilation will
///    fail.
/// 2. Otherwise, if `bslma::UsesBslmaAllocator<TARGET_TYPE>::value` is
///    `true`, this metafunction yields either
///    `e_USES_ALLOCATOR_ARG_T_TRAITS` or `e_USES_ALLOCATOR_TRAITS`, even if
///    `ALLOCATOR` is not compatible with `TARGET_TYPE`, resulting in a
///    compilation error within `construct`.
/// 3. Otherwise, if `ALLOCATOR` is incompatible with `TARGET_TYPE`, then
///    `ALLOCATOR` is ignored and this metafunction yields `e_NIL_TRAITS`,
///    as though `TARGET_TYPE` were not AA.
///
/// The first two special cases allow mixing and matching between
/// `bsl::allocator` and `bslma::Allocator *` in both directions, but will
/// fail for other allocator types.  The failure is desirable to prevent
/// code accidentally passing an incorrect allocator type.
///
/// The third special case is inconsistent with the other two so as to allow
/// third-party classes that use third-party allocators to be treated as
/// non-AA within containers that use BDE allocators.
///
/// This metafunction also yields a `type` of 'bsl::integral_constant<value,
/// int>'.
template <class TARGET_TYPE, class ALLOCATOR>
struct ConstructionUtil_ConstructionTrait {
 
  private:
    // PRIVATE TYPES
    typedef ConstructionUtil_Imp Imp;
 
  public:
    // PUBLIC TYPES
    enum {
        value = ((UsesBslmaAllocator<TARGET_TYPE>::value ||
                  bsl::uses_allocator<TARGET_TYPE, ALLOCATOR>::value) &&
                 (bsl::is_class<ALLOCATOR>::value ||
                  ConstructionUtil_IsAllocatorPtr<ALLOCATOR>::value))
                ? (bslmf::UsesAllocatorArgT<TARGET_TYPE>::value
                   ? Imp::e_USES_ALLOCATOR_ARG_T_TRAITS
                   : Imp::e_USES_ALLOCATOR_TRAITS)
                : Imp::e_NIL_TRAITS
    };
 
    typedef bsl::integral_constant<int, value> type;
};
 
 
              // -------------------------------------------------
              // struct template ConstructionUtil_AllocAdaptorUtil
              // -------------------------------------------------
 
template <class TYPE,
          bool HAS_ALLOC_TYPE = HasAllocatorType<TYPE>::value,
          bool IS_BSLMA_AA    = UsesBslmaAllocator<TYPE>::value>
struct ConstructionUtil_AllocAdaptorUtil;
 
/// This utility class template provides a static `adapt` method that adapts
/// an allocator object to the type expected by `TYPE`.  This primary
/// template is instantiated only for a non-AA `TYPE`; such types do not
/// expect an allocator, so no `adapt` method is defined.
template <class TYPE>
struct ConstructionUtil_AllocAdaptorUtil<TYPE, false, false> {
};
 
/// This utility class template provides a static `adapt` method that adapts
/// an allocator object to the type expected by `TYPE`.  This partial
/// specialization is instantiated for types that expect an allocator of
/// type `bslma::Allocator *`.
template <class TYPE>
struct ConstructionUtil_AllocAdaptorUtil<TYPE, false, true> {
 
    /// Return the `bslma::Allocator` pointer held by the specified `a`
    /// object of non-pointer class.  Compilation will fail if type `ALLOC`
    /// does not provide a `mechanism()` accessor returning a pointer to
    /// type convertible to `bslma::Allocator *`.
    template <class ALLOC>
    static bslma::Allocator *adapt(const ALLOC& a) { return a.mechanism(); }
 
    /// Return the specified `alloc_p` pointer, implicitly converted to
    /// `bslma::Allocator *`.  Compilation will fail unless `ALLOC` is
    /// derived from `bslma::Allocator`.
    template <class ALLOC>
    static bslma::Allocator *adapt(ALLOC *const &alloc_p) { return alloc_p; }
};
 
/// This utility class template provides a static `adapt` method that adapts
/// an allocator object to the type expected by `TYPE`.  This partial
/// specialization is instantiated for types that expect an allocator of
/// type `TYPE::allocator_type`.
template <class TYPE, bool IS_BSLMA_AA>
struct ConstructionUtil_AllocAdaptorUtil<TYPE, true, IS_BSLMA_AA> {
 
    /// Return the specified `a` allocator, implicitly converted to
    /// `TYPE::allocator_type`.  Compilation will fail if implicit
    /// conversion to the return type is invalid.
    template <class ALLOC>
    static typename TYPE::allocator_type adapt(const ALLOC& a) { return a; }
};
 
 
                          // -----------------------
                          // struct ConstructionUtil
                          // -----------------------
 
// CLASS METHODS
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil::construct(TARGET_TYPE      *address,
                            const ALLOCATOR&  allocator)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    Imp::construct(address, allocator, Trait());
}
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil::construct(TARGET_TYPE             *address,
                            const ALLOCATOR&         allocator,
                            ARG1&                    argument1,
                            ARGS&&...                arguments)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    Imp::construct(address,
                   allocator,
                   Trait(),
                   argument1,
                   BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
# endif  // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil::construct(TARGET_TYPE                            *address,
                            const ALLOCATOR&                        allocator,
                            BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
                            ARGS&&...                               arguments)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    Imp::construct(address,
                   allocator,
                   Trait(),
                   BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
                   BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
#endif
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil::destructiveMove(TARGET_TYPE      *address,
                                  const ALLOCATOR&  allocator,
                                  TARGET_TYPE      *original)
{
    BSLS_ASSERT_SAFE(address);
    BSLS_ASSERT_SAFE(original);
 
    enum {
        k_VALUE = bslmf::IsBitwiseMoveable<TARGET_TYPE>::value
                ? Imp::e_BITWISE_MOVABLE_TRAITS
                : Imp::e_NIL_TRAITS
    };
 
    Imp::destructiveMove(address,
                         allocator,
                         bsl::integral_constant<int, k_VALUE>(),
                         original);
}
 
#if defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
// Suppress bde_verify warnings about return-by-value in this region.
// BDE_VERIFY pragma: push
// BDE_VERIFY pragma: -AR01: Type using allocator is returned by value
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
TARGET_TYPE
ConstructionUtil::make(const ALLOCATOR&  allocator)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    return Imp::make<TARGET_TYPE>(allocator, Trait());
}
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil::make(const ALLOCATOR&         allocator,
                       ARG1&                    argument1,
                       ARGS&&...                arguments)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    return Imp::make<TARGET_TYPE>(
                          allocator,
                          Trait(),
                          argument1,
                          BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil::make(const ALLOCATOR&                        allocator,
                       BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
                       ARGS&&...                               arguments)
{
    typedef typename
        ConstructionUtil_ConstructionTrait<TARGET_TYPE, ALLOCATOR>::type Trait;
 
    return Imp::make<TARGET_TYPE>(
                          allocator,
                          Trait(),
                          BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
                          BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
#endif
 
// BDE_VERIFY pragma: pop
#endif // defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
 
                       // ---------------------------
                       // struct ConstructionUtil_Imp
                       // ---------------------------
 
// CLASS METHODS
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil_Imp::construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(bsl::allocator_arg,
                                         AllocUtil::adapt(allocator));
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil_Imp::construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(AllocUtil::adapt(allocator));
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil_Imp::construct(
             TARGET_TYPE      *address,
             const ALLOCATOR&  ,
             bsl::integral_constant<int, e_NIL_TRAITS>)
{
    ::new (voidify(address)) TARGET_TYPE();
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE             *address,
         const ALLOCATOR&         allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(
        bsl::allocator_arg,
        AllocUtil::adapt(allocator),
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE             *address,
         const ALLOCATOR&         allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...,
        AllocUtil::adapt(allocator));
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE             *address,
         const ALLOCATOR&         ,
         bsl::integral_constant<int, e_NIL_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    ::new (voidify(address)) TARGET_TYPE(
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE                            *address,
         const ALLOCATOR&                        allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(
        bsl::allocator_arg,
        AllocUtil::adapt(allocator),
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE                            *address,
         const ALLOCATOR&                        allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    ::new (voidify(address)) TARGET_TYPE(
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...,
        AllocUtil::adapt(allocator));
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
void
ConstructionUtil_Imp::construct(
         TARGET_TYPE                            *address,
         const ALLOCATOR&                        ,
         bsl::integral_constant<int, e_NIL_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    ::new (voidify(address)) TARGET_TYPE(
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
    BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
}
#endif
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil_Imp::destructiveMove(
               TARGET_TYPE                                           *address,
               const ALLOCATOR&                                       ,
               bsl::integral_constant<int, e_BITWISE_MOVABLE_TRAITS>  ,
               TARGET_TYPE                                           *original)
{
    if (bsl::is_fundamental<TARGET_TYPE>::value ||
        bsl::is_pointer<TARGET_TYPE>::value) {
        ::new (voidify(address)) TARGET_TYPE(*original);
        BSLMA_CONSTRUCTIONUTIL_XLC_PLACEMENT_NEW_FIX;
    }
    else {
        // voidify(address) is used here to suppress compiler warning
        // "-Wclass-memaccess".
        memcpy(voidify(address), original, sizeof *original);
    }
}
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
void
ConstructionUtil_Imp::destructiveMove(
                          TARGET_TYPE                               *address,
                          const ALLOCATOR&                           allocator,
                          bsl::integral_constant<int, e_NIL_TRAITS>  ,
                          TARGET_TYPE                               *original)
{
    // TBD: Eventually, we can add a precondition that 'allocator' matches
    // 'original''s allocator, but that is not universally detectable right
    // now, as not all allocator-aware types provide an 'allocator()' method.
    //..
    // BSLS_ASSERT(allocator == original->allocator());
 
    ConstructionUtil::construct(address,
                                allocator,
                                bslmf::MovableRefUtil::move(*original));
    DestructionUtil::destroy(original);
}
 
#if defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
// Suppress bde_verify warnings about return-by-value in this region.
// BDE_VERIFY pragma: push
// BDE_VERIFY pragma: -AR01: Type using allocator is returned by value
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(bsl::allocator_arg, AllocUtil::adapt(allocator));
}
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
             const ALLOCATOR&  allocator,
             bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(AllocUtil::adapt(allocator));
}
 
template <class TARGET_TYPE, class ALLOCATOR>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
             const ALLOCATOR&  ,
             bsl::integral_constant<int, e_NIL_TRAITS>)
{
    return TARGET_TYPE();
}
 
#if !BSLS_COMPILERFEATURES_SIMULATE_CPP11_FEATURES
# ifndef BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&         allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(
        bsl::allocator_arg,
        AllocUtil::adapt(allocator),
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&         allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...,
        AllocUtil::adapt(allocator));
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&         ,
         bsl::integral_constant<int, e_NIL_TRAITS>,
         ARG1&                    argument1,
         ARGS&&...                arguments)
{
    return TARGET_TYPE(
        argument1,
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
# endif // BSLS_COMPILERFEATURES_SUPPORT_RVALUE_REFERENCES
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&                        allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_ARG_T_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(
        bsl::allocator_arg,
        AllocUtil::adapt(allocator),
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&                        allocator,
         bsl::integral_constant<int, e_USES_ALLOCATOR_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    typedef ConstructionUtil_AllocAdaptorUtil<TARGET_TYPE> AllocUtil;
    return TARGET_TYPE(
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...,
        AllocUtil::adapt(allocator));
}
 
template <class TARGET_TYPE, class ALLOCATOR, class ARG1, class... ARGS>
inline
TARGET_TYPE
ConstructionUtil_Imp::make(
         const ALLOCATOR&                        ,
         bsl::integral_constant<int, e_NIL_TRAITS>,
         BSLS_COMPILERFEATURES_FORWARD_REF(ARG1) argument1,
         ARGS&&...                               arguments)
{
    return TARGET_TYPE(
        BSLS_COMPILERFEATURES_FORWARD(ARG1, argument1),
        BSLS_COMPILERFEATURES_FORWARD(ARGS, arguments)...);
}
#endif
 
// BDE_VERIFY pragma: pop
#endif // defined(BSLS_COMPILERFEATURES_GUARANTEED_COPY_ELISION)
 
template <class TARGET_TYPE>
inline
void *ConstructionUtil_Imp::voidify(TARGET_TYPE *address)
{
    return static_cast<void *>(
            const_cast<typename bsl::remove_cv<TARGET_TYPE>::type *>(address));
}
 
}  // close package namespace
 
 
#endif // End C++11 code
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2013 Bloomberg Finance L.P.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */