bslmf_removepointer.h

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/// @file bslmf_removepointer.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmf_removepointer.h                                              -*-C++-*-
#ifndef INCLUDED_BSLMF_REMOVEPOINTER
#define INCLUDED_BSLMF_REMOVEPOINTER
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmf_removepointer bslmf_removepointer
/// @brief  Provide a meta-function to transform pointer type to referent type.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmf
/// @{
/// @addtogroup bslmf_removepointer
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmf_removepointer-purpose"> Purpose</a>
/// * <a href="#bslmf_removepointer-classes"> Classes </a>
/// * <a href="#bslmf_removepointer-description"> Description </a>
///   * <a href="#bslmf_removepointer-usage"> Usage </a>
///     * <a href="#bslmf_removepointer-example-1-get-the-type-pointed-to-by-a-pointer-type"> Example 1: Get the Type Pointed to by a Pointer Type </a>
///
/// # Purpose {#bslmf_removepointer-purpose}
/// Provide a meta-function to transform pointer type to referent type.
///
/// # Classes {#bslmf_removepointer-classes}
///
/// -  bsl::remove_pointer: transform a pointer type to its referent pointer
/// -  bsl::remove_pointer_t: alias to the return type of the meta-function
///
/// @see  bslmf_addpointer
///
/// # Description {#bslmf_removepointer-description}
/// This component defines a meta-function, `bsl::remove_pointer`,
/// that may be used to obtain the type pointed to by a pointer type.
///
/// `bsl::remove_pointer` and `bsl::remove_pointer_t` meet the requirements of
/// the @ref remove_pointer  template defined in the C++11 standard
/// [meta.trans.ptr].
///
/// ## Usage {#bslmf_removepointer-usage}
///
///
/// In this section we show intended use of this component.
///
/// ### Example 1: Get the Type Pointed to by a Pointer Type {#bslmf_removepointer-example-1-get-the-type-pointed-to-by-a-pointer-type}
///
///
/// Suppose that we want to get the type pointed to by a pointer type.
///
/// First, we create two `typedef`s -- a pointer type (`MyPtrType`) and the type
/// pointed to by the pointer type (`MyType`):
/// @code
/// typedef int  MyType;
/// typedef int *MyPtrType;
/// @endcode
/// Now, we get the type pointed to by `MyPtrType` using `bsl::remove_pointer`
/// and verify that the resulting type is the same as `MyType`:
/// @code
/// assert((bsl::is_same<bsl::remove_pointer<MyPtrType>::type,
///                      MyType>::value));
/// @endcode
/// Finally, if the current compiler supports alias templates C++11 feature, we
/// get the type pointed to by `MyPtrType` using `bsl::remove_pointer_t` and
/// verify that the resulting type is the same as `MyType`:
/// @code
/// #ifdef BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
///   assert((bsl::is_same<bsl::remove_pointer_t<MyPtrType>, MyType>::value));
/// #endif
/// @endcode
/// Note, that the `bsl::remove_pointer_t` avoids the `::type` suffix and
/// `typename` prefix when we want to use the result of the
/// `bsl::remove_pointer` meta-function in templates.
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslmf
 * @{
 */
/** @addtogroup bslmf_removepointer
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslmf_functionpointertraits.h>
 
#include <bsls_compilerfeatures.h>
#include <bsls_platform.h>
 
#ifndef BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
    // Permit reliance on transitive includes within robo.
#include <bslmf_removecvq.h>
#endif // BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
 
 
namespace bslmf {
 
                         // ========================
                         // struct RemovePointer_Imp
                         // ========================
 
/// This `struct` template provides an alias `Type` that refers to the type
/// pointed to by the (template parameter) `t_TYPE` if `t_TYPE` is a
/// (non-cv-qualified) pointer type; otherwise, `Type` refers to `t_TYPE`.
/// This generic default template's `Type` always refers to `t_TYPE`.  A
/// template specialization (below) handles the case where `t_TYPE` is a
/// pointer type.
template <class t_TYPE>
struct RemovePointer_Imp {
 
    // PUBLIC TYPES
 
    /// This `typedef` is an alias to the (template parameter) `t_TYPE`.
    typedef t_TYPE Type;
};
 
                     // ==================================
                     // struct RemovePointer_Imp<t_TYPE *>
                     // ==================================
 
/// This partial specialization of `RemovePointer_Imp`, for when the
/// (template parameter) `t_TYPE` is a pointer type, provides an alias
/// `Type` that refers to the type pointed to by `t_TYPE`.
template <class t_TYPE>
struct RemovePointer_Imp<t_TYPE *> {
 
    // PUBLIC TYPES
 
    /// This `typedef` is an alias to the type pointed to by the (template
    /// parameter) `t_TYPE`.
    typedef t_TYPE Type;
};
 
/// This partial specialization of `RemovePointer_Imp`, for when the
/// (template parameter) `t_TYPE` is a `const`-qualified pointer type,
/// provides an alias `Type` that refers to the type pointed to by `t_TYPE`.
/// Note that this is specifically for `const`-qualified pointers, and not
/// for pointers-to-`const`-type.
template <class t_TYPE>
struct RemovePointer_Imp<t_TYPE *const> {
 
    // PUBLIC TYPES
 
    /// This `typedef` is an alias to the type pointed to by the (template
    /// parameter) `t_TYPE`.
    typedef t_TYPE Type;
};
 
/// This partial specialization of `RemovePointer_Imp`, for when the
/// (template parameter) `t_TYPE` is a `volatile`-qualified pointer type,
/// provides an alias `Type` that refers to the type pointed to by `t_TYPE`.
/// Note that this is specifically for `volatile`-qualified pointers, and
/// not for pointers-to-`volatile`-type.
template <class t_TYPE>
struct RemovePointer_Imp<t_TYPE *volatile> {
 
    // PUBLIC TYPES
 
    /// This `typedef` is an alias to the type pointed to by the (template
    /// parameter) `t_TYPE`.
    typedef t_TYPE Type;
};
 
/// This partial specialization of `RemovePointer_Imp`, for when the
/// (template parameter) `t_TYPE` is a `const volatile`-qualified pointer
/// type, provides an alias `Type` that refers to the type pointed to by
/// `t_TYPE`.  Note that this is specifically for `const volatile`-qualified
/// pointers, and not for pointers-to-`const volatile`-type.
template <class t_TYPE>
struct RemovePointer_Imp<t_TYPE *const volatile> {
 
    // PUBLIC TYPES
 
    /// This `typedef` is an alias to the type pointed to by the (template
    /// parameter) `t_TYPE`.
    typedef t_TYPE Type;
};
 
#if defined(BSLS_PLATFORM_CMP_IBM)
template <class t_TYPE, bool isFunctionPtr>
struct RemovePointer_Aix : RemovePointer_Imp<t_TYPE> {
    // The implementation of the 'RemovePointer_Imp' for the AIX xlC 11
    // compiler uses the generic mechanism for non-function types, but see
    // below for a specialization for pointer-to-function types.
};
 
template <class t_TYPE>
struct RemovePointer_Aix<t_TYPE, true> {
    // The implementation of the 'RemovePointer_Imp' for the AIX xlC 11
    // compiler when 't_TYPE' is a pointer-to-function.  xlC 11 has a bug
    // specializing on 't_TYPE*' where 't_TYPE' is was deduced from the address
    // of a function with default arguments. To workaround the bug, this
    // specialization uses 'FunctionPointerTraits' to obtain the function type
    // by somewhat more complicated means.
 
    typedef typename FunctionPointerTraits<t_TYPE>::FuncType Type;
};
#endif
 
#if defined(BSLS_PLATFORM_CMP_MSVC)
template <class t_TYPE, bool isFunctionPtr = IsFunctionPointer<t_TYPE>::value>
struct RemovePointer_Msvc : RemovePointer_Imp<t_TYPE> {
    // The implementation of the 'RemovePointer_Imp' for the Microsoft Visual
    // C++ compiler which has a bug matching a 'T * const' template parameter
    // with a cv-qualified function pointer type.  To workaround the bug, we
    // provide additional partial specializations predicated on 't_TYPE' being
    // a function pointer type to first strip the cv-qualifier, and then
    // delegate to the regular 'RemovePointer_Imp'.  This yields the correct
    // result withough accidentally stripping the cv-qualifier from non-pointer
    // types.
};
 
template <class t_TYPE>
struct RemovePointer_Msvc<t_TYPE const, true> : RemovePointer_Imp<t_TYPE> {
};
 
template <class t_TYPE>
struct RemovePointer_Msvc<t_TYPE volatile, true> : RemovePointer_Imp<t_TYPE> {
};
 
template <class t_TYPE>
struct RemovePointer_Msvc<t_TYPE const volatile, true>
: RemovePointer_Imp<t_TYPE> {
};
#endif
 
}  // close package namespace
 
 
namespace bsl {
 
                         // =====================
                         // struct remove_pointer
                         // =====================
 
/// This `struct` template implements the @ref remove_pointer  meta-function
/// defined in the C++11 standard [meta.trans.ptr], providing an alias,
/// `type`, that returns the result.  If the (template parameter) `t_TYPE`
/// is a (possibly cv-qualified) pointer type, then `type` is an alias to
/// the type pointed to by `t_TYPE`; otherwise, `type` is an alias to
/// `t_TYPE`.
template <class t_TYPE>
struct remove_pointer {
 
#if defined(BSLS_PLATFORM_CMP_IBM)
    typedef typename BloombergLP::bslmf::RemovePointer_Aix<
        t_TYPE,
        BloombergLP::bslmf::IsFunctionPointer<t_TYPE>::value>::Type type;
#elif defined(BSLS_PLATFORM_CMP_MSVC)
    typedef typename BloombergLP::bslmf::RemovePointer_Msvc<t_TYPE>::Type type;
#else
    /// This `typedef` is an alias to the type pointed to by the (template
    /// parameter) `t_TYPE` if `t_TYPE` is a (possibly cv-qualified) pointer
    /// type; otherwise, `type` is an alias to `t_TYPE`.
    typedef typename BloombergLP::bslmf::RemovePointer_Imp<t_TYPE>::Type type;
 
#endif
};
 
#ifdef BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
 
// ALIASES
 
/// `remove_pointer_t` is an alias to the return type of the
/// `bsl::remove_pointer` meta-function.  Note, that the `remove_pointer_t`
/// avoids the `::type` suffix and `typename` prefix when we want to use the
/// result of the meta-function in templates.
template <class t_TYPE>
using remove_pointer_t = typename remove_pointer<t_TYPE>::type;
 
#endif  // BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
 
}  // close namespace bsl
 
#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 ----------------------------------
 
/** @} */
/** @} */
/** @} */