// bslmf_removevolatile.h -*-C++-*-
#ifndef INCLUDED_BSLMF_REMOVEVOLATILE
#define INCLUDED_BSLMF_REMOVEVOLATILE
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
//@PURPOSE: Provide a meta-function for removing 'volatile'-qualifier.
//
//@CLASSES:
// bsl::remove_volatile: meta-function for removing 'volatile'-qualifier
// bsl::remove_volatile_t: alias to the return type of the meta-function
//
//@SEE_ALSO: bslmf_addvolatile
//
//@DESCRIPTION: This component defines a meta-function, 'bsl::remove_volatile'
// and declares an 'bsl::remove_volatile_t' alias to the return type of the
// 'bsl::remove_volatile', that may be used to remove any top-level
// 'volatile'-qualifier from a type.
//
// 'bsl::remove_volatile' and 'bsl::remove_volatile_t' meet the requirements of
// the 'remove_volatile' template defined in the C++11 standard
// [meta.trans.cv].
//
///Usage
///-----
// In this section we show intended use of this component.
//
///Example 1: Removing the 'volatile'-Qualifier of a Type
/// - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Suppose that we want to remove any 'volatile'-qualifier from a particular
// type.
//
// First, we create two 'typedef's -- a 'volatile'-qualified type
// ('MyVolatileType') and the same type without the 'volatile'-qualifier
// ('MyType'):
//..
// typedef int MyType;
// typedef volatile int MyVolatileType;
//..
// Now, we remove the 'volatile'-qualifier from 'MyVolatileType' using
// 'bsl::remove_volatile' and verify that the resulting type is the same as
// 'MyType':
//..
// assert(true == (bsl::is_same<bsl::remove_volatile<MyVolatileType>::type,
// MyType>::value));
//..
// Finally, if the current compiler supports alias templates C++11 feature, we
// remove a 'volatile'-qualifier from 'MyVolatileType' using
//'bsl::remove_volatile_t' and verify that the resulting type is the same as
// 'MyType':
//..
//#ifdef BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
// assert(true ==
// (bsl::is_same<bsl::remove_volatile_t<MyVolatileType>, MyType>::value));
//#endif
//..
// Note, that the 'bsl::remove_volatile_t' avoids the '::type' suffix and
// 'typename' prefix when we want to use the result of the 'bsl::remove_const'
// meta-function in templates.
#include <bslscm_version.h>
#include <bsls_compilerfeatures.h>
#include <bsls_platform.h>
#include <stddef.h>
// Several compiler tool-chains have problems removing the 'volatile'
// qualifiers from arrays.
#if defined(BSLS_PLATFORM_CMP_IBM)
# define BSLS_REMOVEVOLATILE_WORKAROUND_VOLATILE_MULTIDIMENSIONAL_ARRAY 1
// The IBM xlC compiler has an odd issue trying to remove 'volatile'
// qualifiers from multidimensional arrays. This workaround was last
// verified as required for the xlC 12.1 compiler - more recent compilers
// still need testing.
#elif (defined(BSLS_PLATFORM_CMP_SUN) && BSLS_PLATFORM_CMP_VERSION < 0x5130) \
|| (defined(BSLS_PLATFORM_CMP_MSVC) \
&& BSLS_PLATFORM_CMP_VERSION <= 1900 \
&& _MSC_FULL_VER < 190023918)
# define BSLS_REMOVEVOLATILE_WORKAROUND_VOLATILE_ARRAY 1
// The Microsoft compiler does not recognize array-types as cv-qualified
// when the element type is cv-qualified when performing matching for
// partial template specialization, but does get the correct result when
// performing overload resolution for functions (taking arrays by
// reference). Given the function dispatch behavior being correct, we
// choose to work around this compiler bug, rather than try to report
// compiler behavior, as the compiler itself is inconsistent depending on
// how the trait might be used. This also corresponds to how Microsoft
// itself implements the trait in VC2010 and later. Note that Microsoft
// fixed this bug in Update 2 for MSVC2015, which requires checking the
// '_MSC_FULL_VER' macro; the workaround below would be ambiguous when
// trying to remove 'volatile' from an array of 'volatile' elements with a
// conforming compiler.
#endif
namespace bsl {
// ======================
// struct remove_volatile
// ======================
template <class t_TYPE>
struct remove_volatile {
// This 'struct' template implements the 'remove_volatile' meta-function
// defined in the C++11 standard [meta.trans.cv], providing an alias,
// 'type', that returns the result. 'type' has the same type as the
// (template parameter) 't_TYPE' except that any top-level
// 'volatile'-qualifier has been removed. Note that this generic default
// template provides a 'type' that is an alias to 't_TYPE' for when
// 't_TYPE' is not 'volatile'-qualified. A template specialization is
// provided (below) that removes the 'volatile'-qualifier for when 't_TYPE'
// is 'volatile'-qualified.
// PUBLIC TYPES
typedef t_TYPE type;
// This 'typedef' is an alias to the (template parameter) 't_TYPE'.
};
// =======================================
// struct remove_volatile<t_TYPE volatile>
// =======================================
template <class t_TYPE>
struct remove_volatile<t_TYPE volatile> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is 'volatile'-qualified, provides a
// 'typedef', 'type', that has the 'volatile'-qualifier removed.
// PUBLIC TYPES
typedef t_TYPE type;
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE' except with the 'volatile'-qualifier removed.
};
#if defined(BSLS_REMOVEVOLATILE_WORKAROUND_VOLATILE_MULTIDIMENSIONAL_ARRAY)
template <class t_TYPE, size_t t_N>
struct remove_volatile<t_TYPE[t_N]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On IBM compilers, it is
// necessary to separately 'remove_volatile' on the element type, and then
// reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<t_TYPE>::type type[t_N];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[t_N]' except with the 'volatile'-qualifier
// removed.
};
template <class t_TYPE, size_t t_N>
struct remove_volatile<volatile t_TYPE[t_N]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On IBM compilers, it is
// necessary to separately 'remove_volatile' on the element type, and then
// reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<volatile t_TYPE>::type type[t_N];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[t_N]' except with the 'volatile'-qualifier
// removed.
};
template <class t_TYPE>
struct remove_volatile<t_TYPE[]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On IBM compilers, it is
// necessary to separately 'remove_volatile' on the element type, and then
// reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<t_TYPE>::type type[];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[]' except with the 'volatile'-qualifier removed.
};
template <class t_TYPE>
struct remove_volatile<volatile t_TYPE[]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On IBM compilers, it is
// necessary to separately 'remove_volatile' on the element type, and then
// reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<volatile t_TYPE>::type type[];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[]' except with the 'volatile'-qualifier removed.
};
#elif defined(BSLS_REMOVEVOLATILE_WORKAROUND_VOLATILE_ARRAY)
template <class t_TYPE>
struct remove_volatile<t_TYPE[]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On Microsoft compilers,
// it is necessary to separately 'remove_volatile' on the element type, and
// then reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<t_TYPE>::type type[];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[]' except with the 'volatile'-qualifier removed.
};
template <class t_TYPE, size_t t_LENGTH>
struct remove_volatile<t_TYPE[t_LENGTH]> {
// This partial specialization of 'bsl::remove_volatile', for when the
// (template parameter) 't_TYPE' is an array type. On Microsoft compilers,
// it is necessary to separately 'remove_volatile' on the element type, and
// then reconstruct the array dimensions.
// PUBLIC TYPES
typedef typename remove_volatile<t_TYPE>::type type[t_LENGTH];
// This 'typedef' is an alias to the same type as the (template
// parameter) 't_TYPE[t_N]' except with the 'volatile'-qualifier
// removed.
};
#endif
#ifdef BSLS_COMPILERFEATURES_SUPPORT_ALIAS_TEMPLATES
// ALIASES
template <class t_TYPE>
using remove_volatile_t = typename remove_volatile<t_TYPE>::type;
// 'remove_volatile_t' is an alias to the return type of the
// 'bsl::remove_volatile' meta-function. Note, that the
// 'remove_volatile_t' avoids the '::type' suffix and 'typename' prefix
// when we want to use the result of the meta-function in templates.
#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 ----------------------------------