// bslmf_isfloatingpoint.h                                            -*-C++-*-
#ifndef INCLUDED_BSLMF_ISFLOATINGPOINT
#define INCLUDED_BSLMF_ISFLOATINGPOINT

#include <bsls_ident.h>
BSLS_IDENT("$Id: $")

//@PURPOSE: Provide a compile-time check for floating-point types.
//
//@CLASSES:
//  bsl::is_floating_point: meta-function for determining floating-point types
//  bsl::is_floating_point_v: the result value of `bsl::is_floating_point`
//
//@SEE_ALSO: bslmf_integralconstant
//
//@DESCRIPTION: This component defines a meta-function,
// `bsl::is_floating_point` and a template variable `bsl::is_floating_point_v`,
// that represents the result value of the `bsl::is_floating_point`
// meta-function, that may be used to query whether a type is a (possibly
// cv-qualified) floating-point type as defined in section 3.9.1.8 of the C++11
// standard [basic.fundamental].
//
// `bsl::is_floating_point` meets the requirements of the `is_floating_point`
// template defined in the C++11 standard [meta.unary.cat].
//
// Note that the template variable `is_floating_point_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_floating_point_v` is
// defined as an `inline constexpr bool` variable.  Otherwise, if the compiler
// supports the variable templates C++14 compiler feature,
// `bsl::is_floating_point_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
///-----
// In this section we show intended use of this component.
//
///Example 1: Verify Floating-Point Types
/// - - - - - - - - - - - - - - - - - - -
// Suppose that we want to assert whether a particular type is a floating-point
// type.
//
// First, we create two `typedef`s -- a floating-point type and a
// non-floating-point type:
// ```
// typedef void  MyType;
// typedef float MyFloatingPointType;
// ```
// Now, we instantiate the `bsl::is_floating_point` template for each of the
// `typedef`s and assert the `value` static data member of each instantiation:
// ```
// assert(false == bsl::is_floating_point<MyType>::value);
// assert(true  == bsl::is_floating_point<MyFloatingPointType>::value);
// ```
// 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_floating_point_v<T> as follows:
// ```
// #ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
//   assert(false == bsl::is_floating_point_v<MyType>);
//   assert(true  == bsl::is_floating_point_v<MyFloatingPointType>);
// #endif
// ```

#include <bslscm_version.h>

#include <bslmf_integralconstant.h>

#include <bsls_compilerfeatures.h>
#include <bsls_keyword.h>
#include <bsls_libraryfeatures.h>

#ifndef BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
#include <bslmf_removecv.h>
#endif // BDE_DONT_ALLOW_TRANSITIVE_INCLUDES

#ifdef BSLS_LIBRARYFEATURES_HAS_CPP11_BASELINE_LIBRARY
#include <type_traits> // 'std::is_floating_point' and
                       // 'std::is_floating_point_v' (C++17)
#endif

                         // ========================
                         // struct is_floating_point
                         // ========================

namespace bsl {
#ifdef BSLS_LIBRARYFEATURES_HAS_CPP11_BASELINE_LIBRARY
template <class t_TYPE>
struct is_floating_point : bsl::integral_constant<
                                         bool,
                                         std::is_floating_point<t_TYPE>::value>
{};

#else

/// This `struct` template implements the `is_floating_point` meta-function
/// defined in the C++11 standard [meta.unary.cat] to determine if the
/// (template parameter) `t_TYPE` is a floating-point type.  This `struct`
/// derives from `bsl::true_type` if the `t_TYPE` is a floating-point type,
/// and `bsl::false_type` otherwise.
template <class t_TYPE>
struct is_floating_point : bsl::false_type {
};

/// This explicit specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `float`, derives from `bsl::true_type`.
template <>
struct is_floating_point<float> : bsl::true_type {
};

/// This explicit specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `double`, derives from
/// `bsl::true_type`.
template <>
struct is_floating_point<double> : bsl::true_type {
};

/// This explicit specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `long double`, derives from
/// `bsl::true_type`.
template <>
struct is_floating_point<long double> : bsl::true_type {
};

/// This partial specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `const`-qualified delegates to the
/// non-cv-qualified primary template.
template <class t_TYPE>
struct is_floating_point<const t_TYPE> : is_floating_point<t_TYPE>::type {
};

/// This partial specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `volatile`-qualified delegates to the
/// non-cv-qualified primary template.
template <class t_TYPE>
struct is_floating_point<volatile t_TYPE> : is_floating_point<t_TYPE>::type {
};

/// This partial specialization of `is_floating_point`, for when the
/// (template parameter) `t_TYPE` is `const volatile`-qualified delegates to
/// the non-cv-qualified primary template.
template <class t_TYPE>
struct is_floating_point<const volatile t_TYPE>
: is_floating_point<t_TYPE>::type {
};
#endif // BSLS_LIBRARYFEATURES_HAS_CPP11_BASELINE_LIBRARY

#ifdef BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY
using std::is_floating_point_v;
#else
#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
template <class t_TYPE>
BSLS_KEYWORD_INLINE_VARIABLE constexpr bool is_floating_point_v =
                                            is_floating_point<t_TYPE>::value;
    // This template variable represents the result value of the
    // 'bsl::is_floating_point' meta-function.
#endif
#endif // BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY
}  // 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 ----------------------------------
