// bslma_destructionutil.h -*-C++-*-
#ifndef INCLUDED_BSLMA_DESTRUCTIONUTIL
#define INCLUDED_BSLMA_DESTRUCTIONUTIL
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
//@PURPOSE: Provide routines that destroy objects efficiently.
//
//@CLASSES:
// bslma::DestructionUtil: namespace for routines that destroy objects
//
//@SEE_ALSO: bslma_constructionutil
//
//@DESCRIPTION: This component provides utilities to destroy scalars with a
// uniform interface, but select a different implementation according to the
// traits possessed by the underlying type.
//
// The trait under consideration by this component is:
//..
// Trait Note
// ------------------------------- -------------------------------------
// bsl::is_trivially_copyable Expressed in English as "TYPE has the
// bit-wise copyable trait", or "TYPE is
// bit-wise copyable", this trait also
// implies that destructor calls can be
// elided with no effect on observable
// behavior.
//
//..
//
///Usage
///-----
// In this section we show intended use of this component. Note that this
// component is for use by the 'bslstl' package. Other clients should use the
// STL algorithms (in header '<algorithm>' and '<memory>').
//
///Example 1: Destroy 'int' and an Integer Wrapper
///- - - - - - - - - - - - - - - - - - - - - - - -
// In this example, we will use 'bslma::DestructionUtil' to destroy both a
// scalar integer and a 'MyInteger' type object. Calling the 'destroy' method
// on a scalar integer is a no-op while calling the 'destroy' method on an
// object of 'MyInteger' class invokes the destructor of the object.
//
// First, we define a 'MyInteger' class that represents an integer value:
//..
// class MyInteger {
// // This class represents an integer value.
//
// // DATA
// int d_intValue; // integer value
//
// public:
// // CREATORS
// MyInteger();
// // Create a 'MyInteger' object having integer value '0'.
//
// explicit MyInteger(int value);
// // Create a 'MyInteger' object having the specified 'value'.
//
// ~MyInteger();
// // Destroy this object.
//
// // ACCESSORS
// int getValue() const;
// };
//..
// Then, we create an object, 'myInteger', of type 'MyInteger':
//..
// bsls::ObjectBuffer<MyInteger> buffer;
// MyInteger *myInteger = &buffer.object();
// new (myInteger) MyInteger(1);
//..
// Notice that we use an 'ObjectBuffer' to allow us to safely invoke the
// destructor explicitly.
//
// Now, we define a primitive integer:
//..
// int scalarInteger = 2;
//..
// Finally, we use the uniform 'bslma::DestructionUtil::destroy'
// method to destroy both 'myInteger' and 'scalarInteger':
//..
// bslma::DestructionUtil::destroy(myInteger);
// bslma::DestructionUtil::destroy(&scalarInteger);
//..
#include <bslscm_version.h>
#include <bslmf_integralconstant.h>
#include <bslmf_istriviallycopyable.h>
#include <bslmf_removecv.h>
#include <bsls_assert.h>
#include <bsls_platform.h>
#include <string.h> // 'memset'
namespace BloombergLP {
namespace bslma {
// ======================
// struct DestructionUtil
// ======================
struct DestructionUtil {
// This 'struct' provides a namespace for a suite of utility functions that
// destroy elements of the parameterized type 'TYPE'. Depending on the
// traits of 'TYPE', the destructor may be invoked or not (i.e., optimized
// away as a no-op).
private:
// PRIVATE CLASS METHODS
template <class TYPE>
static void destroy(TYPE *address, bsl::true_type);
template <class TYPE>
static void destroy(const TYPE *address, bsl::true_type);
template <class TYPE>
static void destroy(TYPE *address, bsl::false_type);
// Destroy the object of the parameterized 'TYPE' at the specified
// 'address' if the second argument is of type 'bsl::false_type', and
// do nothing otherwise. This method is a no-op if the second argument
// is of type 'bsl::true_type', indicating that the object at 'address'
// is bit-wise copyable. Note that the second argument is for overload
// resolution only and its value is ignored.
public:
// CLASS METHODS
template <class TYPE>
static void destroy(TYPE *object);
// Destroy the specified 'object' of the parameterized 'TYPE', as if by
// calling the 'TYPE' destructor, but do not deallocate the memory
// occupied by 'object'. Note that the destructor may deallocate other
// memory owned by 'object'. Also note that this function is a no-op
// if the 'TYPE' has the trivial destructor trait.
};
// ============================================================================
// INLINE AND TEMPLATE FUNCTION DEFINITIONS
// ============================================================================
// ----------------------
// struct DestructionUtil
// ----------------------
// PRIVATE CLASS METHODS
template <class TYPE>
inline
void DestructionUtil::destroy(TYPE *address, bsl::true_type)
{
// No-op.
#ifdef BSLS_ASSERT_SAFE_IS_ACTIVE
memset((void *)address, 0xa5, sizeof *address);
#else
(void) address;
#endif
}
template <class TYPE>
inline
void DestructionUtil::destroy(const TYPE *address, bsl::true_type)
{
// No-op.
(void) address;
}
#ifdef BSLS_PLATFORM_CMP_MSVC
#pragma warning( push ) // For some reason, VC2008 does not detect
#pragma warning( disable : 4100 ) // that 'address' is used.
#endif
template <class TYPE>
inline
void DestructionUtil::destroy(TYPE *address, bsl::false_type)
{
#ifndef BSLS_PLATFORM_CMP_SUN
address->~TYPE();
#else
// Workaround for a bug in Sun's CC whereby destructors cannot be called on
// 'const' objects of polymorphic types.
typedef bsl::remove_cv<TYPE>::type NoCvType;
const_cast<NoCvType *>(address)->~NoCvType();
#endif
}
#ifdef BSLS_PLATFORM_CMP_MSVC
#pragma warning( pop )
#endif
// CLASS METHODS
template <class TYPE>
inline
void DestructionUtil::destroy(TYPE *object)
{
BSLS_ASSERT_SAFE(object);
destroy(object, typename bsl::is_trivially_copyable<TYPE>::type());
}
} // close package namespace
} // close enterprise namespace
#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 ----------------------------------