Re: "Reusable" operator overloading for enum?
On Dec 27, 9:36 am, nick <nick...@fastmail.fm> wrote:
I'm sort of rusty at C++, so this may be silly, but here's my
situation:
I have an enum like this:
enum ParserMode
{
PM_NONE = 0,
PM_READY = 1, // ready for next col or row, or EOF
PM_EMPTY = 2, // empty cell
PM_CELL = 4, // cell
PM_QCELL = 8, // quoted cell
PM_HEAD = 16, // header cell
};
And elsewhere I want to write something like:
void DoStuff(ParserMode m)
{
if (m & PM_HEAD)
...
else if (m & PM_QCELL)
...
}
...
DoStuff(PM_CELL | PM_EMPTY | PM_HEAD);
But this will not work, because the compiler complains about not being
able to cast between int and ParserMode. So some operator overloading
clears that up:
inline ParserMode operator|(ParserMode p1, ParserMode p2)
{
return (ParserMode)((int)p1 | (int)p2);
};
inline ParserMode operator&(ParserMode p1, ParserMode p2)
{
return (ParserMode)((int)p1 & (int)p2);
};
inline ParserMode operator~(ParserMode p1)
{
return (ParserMode)(~(int)p1);
};
inline ParserMode& operator&=(ParserMode& p1, ParserMode p2) {
p1 = p1 & p2;
return p1;
}
...
...And everything works fine. But, now I need to add another enum, and
I don't want to copy all of these overloaded operators for this other
enum. Is there some way I can share one set of operator overloads
between many enums using templates, macros, or some other trick, or am
I just going about this wrong altogether?
Thanks in advance for any help.
-- Nick
Hi Nick
I think the following code helps you
enum ParserMode {
PM_NONE = 0,
PM_READY = 1, // ready for next col or row, or EOF
PM_EMPTY = 2, // empty cell
PM_CELL = 4, // cell
PM_QCELL = 8, // quoted cell
PM_HEAD = 16, // header cell
};
enum ScannerMode { // another enum
SM_NONE = 0,
SM_READY = 1,
SM_EMPTY = 2,
SM_CELL = 4,
SM_QCELL = 8,
SM_HEAD = 16,
};
template<class ENUM_TYPE>
ENUM_TYPE operator|(ENUM_TYPE e1, ENUM_TYPE e2)
{
int i1 = e1; // implicit type conversion
int i2 = e2;
return ENUM_TYPE(i1 | i2);
}
template<class ENUM_TYPE>
ENUM_TYPE operator&(ENUM_TYPE e1, ENUM_TYPE e2)
{
int i1 = e1; // implicit type conversion
int i2 = e2;
return ENUM_TYPE(i1 & i2);
}
template<class ENUM_TYPE>
ENUM_TYPE operator~(ENUM_TYPE e)
{
int i = e; // implicit type conversion
return ENUM_TYPE(~i);
}
int main()
{
ScannerMode s1 = SM_NONE, s2 = SM_HEAD;
s1 = s1 | s2;
ParserMode p1 = PM_NONE, p2 = p1;
p1 = ~p1;
p2 = ~(p2 & p1);
return 0;
}
Regards,
-- Saeed Amrollahi