epics::pvData::AnyScalar Class Reference

#include "anyscalar.h"

Classes
struct	bad_cast

Public Member Functions
	AnyScalar ()
template<typename T >
	AnyScalar (T v)
	Construct from provided value. More...
	AnyScalar (ScalarType type, const void *buf)
	AnyScalar (const AnyScalar &o)
	~AnyScalar ()
AnyScalar &	operator= (const AnyScalar &o)
template<typename T >
AnyScalar &	operator= (T v)
void	clear ()
void	swap (AnyScalar &o)
ScalarType	type () const
	Type code of contained value. Or (ScalarType)-1 is empty. More...
void *	unsafe ()
const void *	unsafe () const
bool	empty () const
	operator bool_type () const
const void *	bufferUnsafe () const
template<typename T >
detail::any_storage_type< typename meta::strip_const< T >::type >::type &	ref ()
template<typename T >
meta::decorate_const< typename detail::any_storage_type< typename meta::strip_const< T >::type >::type >::type &	ref () const
template<typename T >
T	as () const

Friends
epicsShareFunc std::ostream &	operator<< (std::ostream &strm, const AnyScalar &v)

Detailed Description

A type-safe variant union capable of holding any of the PVD scalar types (POD or string)

AnyScalar A(5);
assert(A.type()==pvInt);
assert(A.ref<int32>()==5);
assert(A.as<int32>()==5);
assert(A.as<double>()==5.0);
assert(A.ref<double>()==5.0); // throws AnyScalar::bad_cast

Definition at line 51 of file anyscalar.h.

Constructor & Destructor Documentation

epics::pvData::AnyScalar::AnyScalar ( )

inline

Construct empty

Postcondition

empty()==true

Definition at line 100 of file anyscalar.h.

: _stype((ScalarType)-1) {}

template<typename T >

epics::pvData::AnyScalar::AnyScalar ( T  v )

inlineexplicit

Construct from provided value.

Definition at line 104 of file anyscalar.h.

    {
        typedef typename meta::strip_const<T>::type T2;
        typedef typename detail::any_storage_type<T2>::type TT;

        STATIC_ASSERT(sizeof(TT)<=sizeof(_wrap.blob));

        new (_wrap.blob) TT(v);

        // this line fails to compile when type T can't be mapped to one of
        // the PVD scalar types.
        _stype = (ScalarType)ScalarTypeID<TT>::value;
    }

epics::pvData::AnyScalar::AnyScalar	(	ScalarType	type,
		const void *	buf
	)

Construct from un-typed pointer. Caller is responsible to ensure that buf actually points to the provided type

Version

Added after 7.0.0

Definition at line 11 of file anyscalar.cpp.

{
    if(type==pvString) {
        new (_wrap.blob) std::string(*static_cast<const std::string*>(buf));

    } else {
        memcpy(_wrap.blob, buf, ScalarTypeFunc::elementSize(type));
    }

    _stype = type;
}

epics::pvData::AnyScalar::AnyScalar

(

const AnyScalar &

o

)

Definition at line 23 of file anyscalar.cpp.

    :_stype(o._stype)
{
    if(o._stype==pvString) {
        new (_wrap.blob) std::string(o._as<std::string>());
    } else if(o._stype!=(ScalarType)-1) {
        memcpy(_wrap.blob, o._wrap.blob, sizeof(_largest_blob));
    }
}

epics::pvData::AnyScalar::~AnyScalar ( )

inline

Definition at line 129 of file anyscalar.h.

{clear();}

Member Function Documentation

template<typename T >

T epics::pvData::AnyScalar::as ( ) const

inline

copy out wrapped value, with a value conversion.

Exceptions

bad_cast

when empty()==true

Definition at line 230 of file anyscalar.h.

                 {
        typedef typename meta::strip_const<T>::type T2;
        typedef typename detail::any_storage_type<T2>::type TT;

        if(_stype==(ScalarType)-1)
            throw bad_cast();
        TT ret;
        castUnsafeV(1, (ScalarType)ScalarTypeID<T2>::value, &ret,
                                   _stype, _wrap.blob);
        return ret;
    }

const void * epics::pvData::AnyScalar::bufferUnsafe

(

)

const

Provide read-only access to underlying buffer. For a string this is std::string::c_str().

Version

Added after 7.0.0

Definition at line 137 of file anyscalar.cpp.

                                          {
    if(_stype==pvString) {
        return as<std::string>().c_str();
    } else {
        return _wrap.blob;
    }
}

void epics::pvData::AnyScalar::clear

(

)

Reset internal state.

Version

Added after 7.0.0

Postcondition

empty()==true

Definition at line 49 of file anyscalar.cpp.

                      {
    if(_stype==pvString) {
        typedef std::string string;
        _as<string>().~string();
    }
    // other types need no cleanup
    _stype = (ScalarType)-1;
}

bool epics::pvData::AnyScalar::empty ( ) const

inline

Definition at line 165 of file anyscalar.h.

{ return _stype==(ScalarType)-1; }

epics::pvData::AnyScalar::operator bool_type ( ) const

inline

Definition at line 173 of file anyscalar.h.

{ return !empty() ? &AnyScalar::swap : 0; }

AnyScalar& epics::pvData::AnyScalar::operator= ( const AnyScalar &  o )

inline

Definition at line 131 of file anyscalar.h.

                                                    {
        AnyScalar(o).swap(*this);
        return *this;
    }

template<typename T >

AnyScalar& epics::pvData::AnyScalar::operator= ( T  v )

inline

Definition at line 137 of file anyscalar.h.

                                     {
        AnyScalar(v).swap(*this);
        return *this;
    }

template<typename T >

detail::any_storage_type<typename meta::strip_const<T>::type>::type& epics::pvData::AnyScalar::ref ( )

inline

Return typed reference to wrapped value. Non-const reference allows value modification

Exceptions

bad_cast

when the requested type does not match the stored type AnyScalar v(42); v.ref<uint32>() = 43; assert(v.ref<uint32>() == 43);

Definition at line 194 of file anyscalar.h.

          {
        typedef typename meta::strip_const<T>::type T2;
        typedef typename detail::any_storage_type<T2>::type TT;

        if(_stype!=(ScalarType)ScalarTypeID<TT>::value)
            throw bad_cast();
        return reinterpret_cast<TT&>(_wrap.blob);
    }

template<typename T >

meta::decorate_const<typename detail::any_storage_type<typename meta::strip_const<T>::type>::type>::type& epics::pvData::AnyScalar::ref ( ) const

inline

Return typed reference to wrapped value. Const reference does not allow modification.

Exceptions

bad_cast

when the requested type does not match the stored type const AnyScalar v(42); assert(v.ref<uint32>() == 42);

Definition at line 215 of file anyscalar.h.

                {
        typedef typename meta::strip_const<T>::type T2;
        typedef typename detail::any_storage_type<T2>::type TT;

        if(_stype!=(ScalarType)ScalarTypeID<TT>::value)
            throw bad_cast();
        return reinterpret_cast<typename meta::decorate_const<TT>::type&>(_wrap.blob);
    }

void epics::pvData::AnyScalar::swap

(

AnyScalar &

o

)

Definition at line 58 of file anyscalar.cpp.

                                 {
    typedef std::string string;
    switch((int)_stype) {
    case -1:
        switch((int)o._stype) {
        case -1:
            // nil <-> nil
            break;
        case pvString:
            // nil <-> string
            new (_wrap.blob) std::string();
            _as<std::string>().swap(o._as<std::string>());
            o._as<std::string>().~string();
            break;
        default:
            // nil <-> non-string
            memcpy(_wrap.blob, o._wrap.blob, sizeof(_largest_blob));
            break;
        }
        break;
    case pvString:
        switch((int)o._stype) {
        case -1:
            // string <-> nil
            new (o._wrap.blob) std::string();
            _as<std::string>().swap(o._as<std::string>());
            _as<std::string>().~string();
            break;
        case pvString:
            // string <-> string
            _as<std::string>().swap(o._as<std::string>());
            break;
        default: {
            // string <-> non-string
            std::string temp;
            temp.swap(_as<std::string>());

            _as<std::string>().~string();

            memcpy(_wrap.blob, o._wrap.blob, sizeof(_largest_blob));

            new (o._wrap.blob) std::string();
            temp.swap(o._as<std::string>());
        }
            break;
        }
        break;
    default:
        switch((int)o._stype) {
        case -1:
            // non-string <-> nil
            memcpy(o._wrap.blob, _wrap.blob, sizeof(_largest_blob));
            break;
        case pvString: {
            // non-string <-> string
            std::string temp;
            temp.swap(o._as<std::string>());

            o._as<std::string>().~string();

            memcpy(o._wrap.blob, _wrap.blob, sizeof(_largest_blob));

            new (_wrap.blob) std::string();
            temp.swap(_as<std::string>());
        }
            break;
        default:
            // non-string <-> non-string
            _largest_blob temp;
            memcpy(&temp, _wrap.blob, sizeof(_largest_blob));
            memcpy(_wrap.blob, o._wrap.blob, sizeof(_largest_blob));
            memcpy(o._wrap.blob, &temp, sizeof(_largest_blob));
            // std::swap(o._wrap.blob, _wrap.blob); // gcc <=4.3 doesn't like this
            break;
        }
        break;
    }
    std::swap(_stype, o._stype);
}

ScalarType epics::pvData::AnyScalar::type ( ) const

inline

Type code of contained value. Or (ScalarType)-1 is empty.

Definition at line 158 of file anyscalar.h.

                                   {
        return _stype;
    }

void* epics::pvData::AnyScalar::unsafe ( )

inline

Definition at line 162 of file anyscalar.h.

{ return _wrap.blob; }

const void* epics::pvData::AnyScalar::unsafe ( ) const

inline

Definition at line 163 of file anyscalar.h.

{ return _wrap.blob; }

Friends And Related Function Documentation

epicsShareFunc std::ostream& operator<< ( std::ostream &  strm, const AnyScalar &  v  )

friend

Definition at line 145 of file anyscalar.cpp.

{
    switch(v.type()) {
#define CASE(BASETYPE, PVATYPE, DBFTYPE, PVACODE) case pv ## PVACODE: strm<<v._as<PVATYPE>(); break;
#define CASE_REAL_INT64
#define CASE_STRING
#include "pv/typemap.h"
#undef CASE
#undef CASE_REAL_INT64
#undef CASE_STRING
    default:
        strm<<"(nil)"; break;
    }
    return strm;
}

---

The documentation for this class was generated from the following files:

• modules/pvData/src/misc/pv/anyscalar.h
• modules/pvData/src/misc/anyscalar.cpp