bslmf_isfundamental.h

Go to the documentation of this file.

/// @file bslmf_isfundamental.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bslmf_isfundamental.h                                              -*-C++-*-
#ifndef INCLUDED_BSLMF_ISFUNDAMENTAL
#define INCLUDED_BSLMF_ISFUNDAMENTAL
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bslmf_isfundamental bslmf_isfundamental
/// @brief  Provide a compile-time check for determining fundamental types.
/// @addtogroup bsl
/// @{
/// @addtogroup bslmf
/// @{
/// @addtogroup bslmf_isfundamental
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bslmf_isfundamental-purpose"> Purpose</a>
/// * <a href="#bslmf_isfundamental-classes"> Classes </a>
/// * <a href="#bslmf_isfundamental-description"> Description </a>
///   * <a href="#bslmf_isfundamental-usage"> Usage </a>
///     * <a href="#bslmf_isfundamental-example-1-verify-fundamental-types"> Example 1: Verify Fundamental Types </a>
///
/// # Purpose {#bslmf_isfundamental-purpose}
/// Provide a compile-time check for determining fundamental types.
///
/// # Classes {#bslmf_isfundamental-classes}
///
/// -  bsl::is_fundamental: standard meta-function for detecting fundamental types
/// -  bsl::is_fundamental_v: the result value of `bsl::is_fundamental`
/// -  bslmf::IsFundamental: meta-function for detecting fundamental types
///
/// @see  bslmf_isenum, bslmf_ispointer
///
/// # Description {#bslmf_isfundamental-description}
/// This component defines two meta-functions,
/// `bsl::is_fundamental` and `BloombergLP::bslmf::IsFundamental` and a template
/// variable `bsl::is_fundamental_v`, that represents the result value of the
/// `bsl::is_fundamental` meta-function.  All these meta-functions may be used
/// to query whether a type is a fundamental type.
///
/// `bsl::is_fundamental` meets the requirements of the `is_fundamental`
/// template defined in the C++11 standard [meta.unary.comp], while
/// `bslmf::Fundamental` was devised before `is_fundamental` was standardized.
///
/// The two meta-functions are functionally equivalent except on reference of
/// fundamental types.  Lvalue-references to fundamental types are determined as
/// fundamental types by `bslmf::IsFundamental`, but not by
/// `bsl::is_fundamental`.  Rvalue-references, on compilers that support them,
/// are not deemed to be fundamental by either trait.  In expected use, the
/// result for `bsl::is_fundamental` is indicated by the class member `value`,
/// while the result for `bslmf::Fundamental` is indicated by the class member
/// `value`.
///
/// Note that `bsl::is_fundamental` should be preferred over
/// `bslmf::Fundamental`, and in general, should be used by new components.
///
/// Also note that the template variable `is_fundamental_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_fundamental_v` is defined
/// as an `inline constexpr bool` variable.  Otherwise, if the compiler supports
/// the variable templates C++14 compiler feature, `bsl::is_fundamental_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.
///
/// The C++ fundamental types are described in the C++ standard
/// [basic.fundamental], and consist of the following distinct types, and
/// cv-qualified variations of these types:
/// @code
/// bool
/// char
/// signed char
/// unsigned char
/// wchar_t
/// char16_t
/// char32_t
/// short int                                    (also referred to as "short")
/// unsigned short int                  (also referred to as "unsigned short")
/// int
/// unsigned int
/// long int                                      (also referred to as "long")
/// unsigned long int                    (also referred to as "unsigned long")
/// long long int                            (also referred to as "long long")
/// unsigned long long int          (also referred to as "unsigned long long")
/// float
/// double
/// long double
/// void
/// nullptr_t
/// @endcode
///
/// ## Usage {#bslmf_isfundamental-usage}
///
///
/// In this section we show intended use of this component.
///
/// ### Example 1: Verify Fundamental Types {#bslmf_isfundamental-example-1-verify-fundamental-types}
///
///
/// Suppose that we want to assert whether a set of types are fundamental types.
///
/// Now, we instantiate the `bsl::is_fundamental` template for several
/// non-fundamental and fundamental types, and assert the `value` static data
/// member of each instantiation:
/// @code
/// assert(true  == bsl::is_fundamental<int>::value);
/// assert(false == bsl::is_fundamental<int&>::value);
/// assert(true  == bsl::is_fundamental<long long  >::value);
/// assert(false == bsl::is_fundamental<long long *>::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_fundamental_v` variable as follows:
/// @code
/// #ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
///   assert(true  == bsl::is_fundamental_v<int>);
///   assert(false == bsl::is_fundamental_v<int&>);
///   assert(true  == bsl::is_fundamental_v<long long  >);
///   assert(false == bsl::is_fundamental_v<long long *>);
/// #endif
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bsl
 * @{
 */
/** @addtogroup bslmf
 * @{
 */
/** @addtogroup bslmf_isfundamental
 * @{
 */
 
#include <bslscm_version.h>
 
#include <bslmf_integralconstant.h>
#include <bslmf_isarithmetic.h>
#include <bslmf_isvoid.h>
#include <bslmf_removecv.h>
 
#include <bsls_compilerfeatures.h>
#include <bsls_keyword.h>
#include <bsls_nullptr.h>
 
 
namespace bslmf {
 
                         // ========================
                         // struct IsFundamental_Imp
                         // ========================
 
/// This `struct` template implements a meta-function to determine whether
/// the (template parameter) `t_TYPE` is a (non-cv-qualified) fundamental
/// type.  This generic default template derives from `bsl::false_type`.
/// Template specializations for fundamental types are provided (below) that
/// derive from `bsl::true_type`.
template <class t_TYPE>
struct IsFundamental_Imp : bsl::false_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `bool`.
template <> struct IsFundamental_Imp<bool> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `char`.
template <> struct IsFundamental_Imp<char> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `signed char`.
template <> struct IsFundamental_Imp<signed char> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `unsigned char`.
template <> struct IsFundamental_Imp<unsigned char> : bsl::true_type {
};
 
#if defined BSLS_COMPILERFEATURES_SUPPORT_UTF8_CHAR_TYPE
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `TYPE` is `char8_t`.
template <> struct IsFundamental_Imp<char8_t> : bsl::true_type {
};
#endif
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `wchar_t`.
template <> struct IsFundamental_Imp<wchar_t> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `short`.
template <> struct IsFundamental_Imp<short> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `unsigned short`.
template <> struct IsFundamental_Imp<unsigned short> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `int`.
template <> struct IsFundamental_Imp<int> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `unsigned int`.
template <> struct IsFundamental_Imp<unsigned int> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `long`.
template <> struct IsFundamental_Imp<long> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `unsigned long`.
template <> struct IsFundamental_Imp<unsigned long> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `long long`.
template <> struct IsFundamental_Imp<long long> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `unsigned long long`
template <> struct IsFundamental_Imp<unsigned long long> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `float`.
template <> struct IsFundamental_Imp<float> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `double`.
template <>
struct IsFundamental_Imp<double> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is
/// `long double`.
template <> struct IsFundamental_Imp<long double> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `void`.
template <> struct IsFundamental_Imp<void> : bsl::true_type {
};
 
#if defined(BSLS_COMPILERFEATURES_SUPPORT_NULLPTR)
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `void`.
template <> struct IsFundamental_Imp<bsl::nullptr_t> : bsl::true_type {
};
#endif
 
#if defined(BSLS_COMPILERFEATURES_SUPPORT_UNICODE_CHAR_TYPES)
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `void`.
template <> struct IsFundamental_Imp<char16_t> : bsl::true_type {
};
 
/// This partial specialization of `IsFundamental_Imp` derives from
/// `bsl::true_type` for when the (template parameter) `t_TYPE` is `void`.
template <> struct IsFundamental_Imp<char32_t> : bsl::true_type {
};
#endif
 
 
                         // ====================
                         // struct IsFundamental
                         // ====================
 
/// This `struct` template implements a meta-function for checking if a type
/// is fundamental, or a reference to a fundamental type.  The static
/// constant `value` member will be 1 if `t_TYPE` is fundamental and 0
/// otherwise.
template <class t_TYPE>
struct IsFundamental
: IsFundamental_Imp<typename bsl::remove_cv<t_TYPE>::type>::type {
};
 
/// This specialization of `IsFundamental` causes lvalue-references to be
/// treated as their underlying (non-reference) types.
template <class t_TYPE>
struct IsFundamental<t_TYPE&>
: IsFundamental_Imp<typename bsl::remove_cv<t_TYPE>::type>::type {
};
 
}  // close package namespace
 
 
namespace bsl {
 
                         // =====================
                         // struct is_fundamental
                         // =====================
 
/// This `struct` template implements a meta-function for checking if a type
/// is fundamental as defined in the C++11 standard [basic.fundamental]. 
/// 
/// \note Note that   this is subtly differemt from `bslmf::IsFundamental`, which
/// also returns `true_type` for references to fundamental types.
template <class t_TYPE>
struct is_fundamental
: integral_constant<bool,
                    is_arithmetic<t_TYPE>::value || is_void<t_TYPE>::value> {
};
 
#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
/// This template variable represents the result value of the
/// `bsl::is_fundamental` meta-function.
template <class t_TYPE>
BSLS_KEYWORD_INLINE_VARIABLE constexpr bool is_fundamental_v =
                                                 is_fundamental<t_TYPE>::value;
#endif
 
#if defined(BSLS_COMPILERFEATURES_SUPPORT_NULLPTR)
/// Explicit specialization to confirm that the type of `nullptr` is
/// fundamental.
template <>
struct is_fundamental<bsl::nullptr_t> : bsl::true_type {
};
 
/// Explicit specialization to confirm that the type of `const nullptr` is
/// fundamental.
template <>
struct is_fundamental<const bsl::nullptr_t> : bsl::true_type {
};
 
/// Explicit specialization to confirm that the type of `volatile nullptr`
/// is fundamental.
template <>
struct is_fundamental<volatile bsl::nullptr_t> : bsl::true_type {
};
 
/// Explicit specialization to confirm that the type of
/// `const volatile nullptr` is fundamental.
template <>
struct is_fundamental<const volatile bsl::nullptr_t> : bsl::true_type {
};
 
#endif
 
}  // close namespace bsl
 
#ifndef BDE_OPENSOURCE_PUBLICATION  // BACKWARD_COMPATIBILITY
// ============================================================================
//                           BACKWARD COMPATIBILITY
// ============================================================================
 
#ifdef bslmf_IsFundamental
#undef bslmf_IsFundamental
#endif
/// This alias is defined for backward compatibility.
#define bslmf_IsFundamental bslmf::IsFundamental
#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 ----------------------------------
 
/** @} */
/** @} */
/** @} */