// bslmf_isarray.h -*-C++-*-
#ifndef INCLUDED_BSLMF_ISARRAY
#define INCLUDED_BSLMF_ISARRAY
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
//@PURPOSE: Provide a compile-time check for array types.
//
//@CLASSES:
// bsl::is_array: standard meta-function for detecting array types
// bsl::is_array_v: the result value of the 'bsl::is_array' meta-function
// bslmf::IsArray: meta-function for detecting array types
//
//@DESCRIPTION: This component defines two meta-functions, 'bsl::is_array' and
// 'BloombergLP::bslmf::IsArray' and a template variable 'bsl::is_array_v',
// that represents the result value of the 'bsl::is_array' meta-function. All
// these meta-functions may be used to query whether a type is an array type.
//
// 'bsl::is_array' meets the requirements of the 'is_array' template defined in
// the C++11 standard [meta.unary.cat], while 'bslmf::IsArray' was devised
// before 'is_array' was standardized.
//
// The two meta-functions are functionally equivalent. The major difference
// between them is that the result for 'bsl::is_array' is indicated by the
// class member 'value', while the result for 'bslmf::IsArray' is indicated by
// the class member 'VALUE'.
//
// Note that 'bsl::is_array' should be preferred over 'bslmf::IsArray', and in
// general, should be used by new components.
//
// Also note that the template variable 'is_array_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_array_v' is defined as
// 'inline constexpr bool' variable. Otherwise, if the compiler supports the
// variable templates C++14 compiler feature, 'bsl::is_array_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 Array Types
///- - - - - - - - - - - - - - -
// Suppose that we want to assert whether a particular type is an array type.
//
// First, we create two 'typedef's -- an array type and a non-array type:
//..
// typedef int MyType;
// typedef int MyArrayType[]
//..
// Now, we instantiate the 'bsl::is_array' template for each of the 'typedef's
// and assert the 'value' static data member of each instantiation:
//..
// assert(false == bsl::is_array<MyType>::value);
// assert(true == bsl::is_array<MyArrayType>::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_array_v' variable as follows:
//..
//#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
// assert(false == bsl::is_array_v<MyType>);
// assert(true == bsl::is_array_v<MyArrayType>);
//#endif
//..
#include <bslscm_version.h>
#include <bslmf_integralconstant.h>
#include <bsls_compilerfeatures.h>
#include <bsls_keyword.h>
#include <cstddef> // 'std::size_t'
#ifndef BDE_DONT_ALLOW_TRANSITIVE_INCLUDES
#include <cstdlib>
#endif
namespace bsl {
// ===============
// struct is_array
// ===============
template <class t_TYPE>
struct is_array : false_type {
// This 'struct' template implements the 'is_array' meta-function defined
// in the C++11 standard [meta.unary.cat] to determine if the (template
// parameter) 't_TYPE' is an array type. This 'struct' derives from
// 'bsl::true_type' if the 't_TYPE' is an array type, and 'bsl::false_type'
// otherwise.
};
// ========================================
// struct is_array<t_TYPE [t_NUM_ELEMENTS]>
// ========================================
template <class t_TYPE, std::size_t t_NUM_ELEMENTS>
struct is_array<t_TYPE[t_NUM_ELEMENTS]> : true_type {
// This specialization of 'is_array', for when the (template parameter)
// 't_TYPE' is an array type of known bound, derives from 'bsl::true_type'.
};
// ==========================
// struct is_array<t_TYPE []>
// ==========================
template <class t_TYPE>
struct is_array<t_TYPE[]> : true_type {
// This specialization of 'is_array', for when the (template parameter)
// 't_TYPE' is an array type of unknown bound, derives from
// 'bsl::true_type'.
};
#ifdef BSLS_COMPILERFEATURES_SUPPORT_VARIABLE_TEMPLATES
template <class t_TYPE>
BSLS_KEYWORD_INLINE_VARIABLE constexpr bool is_array_v =
is_array<t_TYPE>::value;
// This template variable represents the result value of the
// 'bsl::is_array' meta-function.
#endif
} // close namespace bsl
namespace BloombergLP {
namespace bslmf {
// ==============
// struct IsArray
// ==============
template <class t_TYPE>
struct IsArray : bsl::is_array<t_TYPE>::type {
// This 'struct' template implements a meta-function to determine if the
// (template parameter) 't_TYPE' is an array type. This 'struct' derives
// from 'bsl::true_type' if the 't_TYPE' is an array type, and
// 'bsl::false_type' otherwise.
//
// Note that although this 'struct' is functionally equivalent to
// 'bsl::is_array', the use of 'bsl::is_array' should be preferred.
};
} // close package namespace
} // close enterprise namespace
#ifndef BDE_OPENSOURCE_PUBLICATION // BACKWARD_COMPATIBILITY
// ============================================================================
// BACKWARD COMPATIBILITY
// ============================================================================
#ifdef bslmf_IsArray
#undef bslmf_IsArray
#endif
#define bslmf_IsArray bslmf::IsArray
// This alias is defined for backward compatibility.
#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 ----------------------------------