bslmf_ispointer.h

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/// @file bslmf_ispointer.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmf_ispointer.h                                                  -*-C++-*-
#ifndef INCLUDED_BSLMF_ISPOINTER
#define INCLUDED_BSLMF_ISPOINTER
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmf_ispointer bslmf_ispointer
/// @brief  Provide a compile-time check for pointer types.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmf
/// @{
/// @addtogroup bslmf_ispointer
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmf_ispointer-purpose"> Purpose</a>
/// * <a href="#bslmf_ispointer-classes"> Classes </a>
/// * <a href="#bslmf_ispointer-description"> Description </a>
///   * <a href="#bslmf_ispointer-usage"> Usage </a>
///     * <a href="#bslmf_ispointer-example-1-verify-pointer-types"> Example 1: Verify Pointer Types </a>
///
/// # Purpose {#bslmf_ispointer-purpose}
/// Provide a compile-time check for pointer types.
///
/// # Classes {#bslmf_ispointer-classes}
///
/// -  bsl::is_pointer: standard meta-function for determining pointer types
/// -  bsl::is_pointer_v: the result value of the `bsl::is_pointer` meta-function
/// -  bsl::IsPointer: meta-function for determining pointer types
///
/// @see  bslmf_integralconstant
///
/// # Description {#bslmf_ispointer-description}
/// This component defines two meta-functions, `bsl::is_pointer`
/// and `BloombergLP::bslmf::IsPointer` and a template variable
/// `bsl::is_pointer_v`, that represents the result value of the
/// `bsl::is_pointer` meta-function.  All these meta-functions may be used to
/// query whether or not a type is a pointer type.
///
/// `bsl::is_pointer` meets the requirements of the `is_pointer` template
/// defined in the C++11 standard [meta.unary.cat], while `bslmf::IsPointer` was
/// devised before `is_pointer` was standardized.
///
/// The two meta-functions are functionally equivalent.  The major difference
/// between them is that the result for `bsl::is_pointer` is indicated by the
/// class member `value`, while the result for `bslmf::IsPointer` is indicated
/// by the class member `value`.
///
/// Note that `bsl::is_pointer` should be preferred over `bslmf::IsPointer`, and
/// in general, should be used by new components.
///
/// Also note that the template variable `is_pointer_v` is defined in the C++17
/// standard as an inline variable.  If the current compiler supports the inline
/// variable C++17 compiler feature, `bsl::is_pointer_v` is defined as an
/// `inline constexpr bool` variable.  Otherwise, if the compiler supports the
/// variable templates C++14 compiler feature, `bsl::is_pointer_v` is
/// defined as a non-inline `constexpr bool` variable.  See
/// `BSLS_COMPILERFEATURES_SUPPORT_INLINE_VARIABLES` and
/// `BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES` macros in
/// bsls_compilerfeatures component for details.
///
/// ## Usage {#bslmf_ispointer-usage}
///
///
/// In this section we show intended use of this component.
///
/// ### Example 1: Verify Pointer Types {#bslmf_ispointer-example-1-verify-pointer-types}
///
///
/// Suppose that we want to assert whether a particular type is a pointer type.
///
/// First, we create two `typedef`s -- a pointer type and a non-pointer type:
/// @code
/// typedef int  MyType;
/// typedef int *MyPtrType;
/// @endcode
/// Now, we instantiate the `bsl::is_pointer` template for each of the
/// `typedef`s and assert the `value` static data member of each instantiation:
/// @code
/// assert(false == bsl::is_pointer<MyType>::value);
/// assert(true  == bsl::is_pointer<MyPtrType>::value);
/// @endcode
/// Note that if the current compiler supports the variable templates C++14
/// feature then we can re-write the snippet of code above using the
/// `bsl::is_pointer_v` variable as follows:
/// @code
/// #ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
///   assert(false == bsl::is_pointer_v<MyType>);
///   assert(true  == bsl::is_pointer_v<MyPtrType>);
/// #endif
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslmf
 * @{
 */
/** @addtogroup bslmf_ispointer
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslmf_integralconstant.h>
 
#include <bsls_compilerfeatures.h>
#include <bsls_keyword.h>
#include <bsls_platform.h>
 
#ifndef BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
#include <bslmf_removecv.h>
#endif // BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
 
namespace bsl {
 
                         // =================
                         // struct is_pointer
                         // =================
 
/// This `struct` template implements the `is_pointer` meta-function defined
/// in the C++11 standard [meta.unary.cat] to determine if the (template
/// parameter) `t_TYPE` is a pointer.  This `struct` derives from
/// `bsl::true_type` if the `t_TYPE` is a pointer type (but not a
/// pointer-to-non-static-member type), and `bsl::false_type` otherwise.
template <class t_TYPE>
struct is_pointer : bsl::false_type {
};
 
/// This partial specialization of `is_pointer` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is a
/// (cv-unqalified) pointer type.
template <class t_TYPE>
struct is_pointer<t_TYPE *> : bsl::true_type {
};
 
#if defined(BSLS_PLATFORM_CMP_MSVC) && BSLS_PLATFORM_CMP_VERSION < 1900
// Older Microsoft compilers do not recognize cv-qualifiers on function pointer
// types as matching a 't_TYPE *const' partial specialization, but can
// correctly strip the cv-qualifier if we take a second template instantiation
// on a more general 't_TYPE const' parameter.
 
template <class t_TYPE>
struct is_pointer<t_TYPE const> : is_pointer<t_TYPE>::type {
    // This partial specialization of 'is_pointer' derives from
    // 'bsl::true_type' for when the (template parameter) 't_TYPE' is a 'const'
    // qualified pointer type.
};
 
template <class t_TYPE>
struct is_pointer<t_TYPE volatile> : is_pointer<t_TYPE>::type {
    // This partial specialization of 'is_pointer' derives from
    // 'bsl::true_type' for when the (template parameter) 't_TYPE' is a
    // 'volatile' qualified pointer type.
};
 
template <class t_TYPE>
struct is_pointer<t_TYPE const volatile> : is_pointer<t_TYPE>::type {
    // This partial specialization of 'is_pointer' derives from
    // 'bsl::true_type' for when the (template parameter) 't_TYPE' is a 'const
    // volatile' qualified pointer type.
};
#else
// Preferred implementation avoids a second dispatch for arbitrary cv-qualified
// types.
 
/// This partial specialization of `is_pointer` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is a `const`
/// qualified pointer type.
template <class t_TYPE>
struct is_pointer<t_TYPE *const> : bsl::true_type {
};
 
/// This partial specialization of `is_pointer` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is a
/// `volatile` qualified pointer type.
template <class t_TYPE>
struct is_pointer<t_TYPE *volatile> : bsl::true_type {
};
 
/// This partial specialization of `is_pointer` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is a 'const
/// volatile' qualified pointer type.
template <class t_TYPE>
struct is_pointer<t_TYPE *const volatile> : bsl::true_type {
};
#endif
 
#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
/// This template variable represents the result value of the
/// `bsl::is_pointer` meta-function.
template <class t_TYPE>
BSLS_KEYWORD_INLINE_VARIABLE constexpr bool is_pointer_v =
                                                     is_pointer<t_TYPE>::value;
#endif
 
}  // close namespace bsl
 
 
namespace bslmf {
 
                         // ================
                         // struct IsPointer
                         // ================
 
/// This `struct` template implements a meta-function to determine if the
/// (template parameter) `t_TYPE` is a pointer type.  This `struct` derives
/// from `bsl::true_type` if the `t_TYPE` is a pointer type (but not a
/// pointer to non-static member), and `bsl::false_type` otherwise.
///
/// Note that this `struct` is functionally equivalent to `bsl::is_pointer`,
/// and the use of `bsl::is_pointer` should be preferred.
template <class t_TYPE>
struct IsPointer : bsl::is_pointer<t_TYPE>::type {
};
 
}  // close package namespace
 
 
#ifndef BDE_OPENSOURCE_PUBLICATION  // BACKWARD_COMPATIBILITY
// ============================================================================
//                           BACKWARD-COMPATIBILITY
// ============================================================================
 
#ifdef bslmf_IsPointer
#undef bslmf_IsPointer
#endif
 
/// This alias is defined for backward-compatibility.
#define bslmf_IsPointer bslmf::IsPointer
#endif  // BDE_OPENSOURCE_PUBLICATION -- BACKWARD_COMPATIBILITY
 
#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 ----------------------------------
 
/** @} */
/** @} */
/** @} */