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#include <iostream>
#include <vector>
#include <functional>
using namespace std;
enum
{
ADD,
SUB,
};
template<typename LHS, typename RHS, int operation>
struct BinExpr
{
template<typename Type>
struct BasicType;
template<typename LH, typename RH, int oper>
struct BasicType<BinExpr<LH, RH, oper>>;
typedef typename BasicType<RHS>::ObjType ObjType;
typedef typename ObjType::value_type value_type;
LHS const &d_lhs;
RHS const &d_rhs;
BinExpr(LHS const &lhs, RHS const &rhs)
:
d_lhs(lhs),
d_rhs(rhs)
{}
size_t size() const
{
return d_lhs.size();
}
template <typename LH, typename RH, int oper>
struct Operation;
value_type operator[](size_t ix) const
{
return Operation<LHS, RHS, operation>::cpt(d_lhs[ix], d_rhs[ix]);
// *************** this causes
// calling
// the proper
// cpt ****************
}
operator ObjType() const
{
ObjType retVal;
retVal.reserve(size());
for (size_t ix = 0, end = size(); ix != end; ++ix)
new(&retVal[ix]) value_type{ (*this)[ix] };
return retVal;
}
};
template<typename LHS, typename RHS, int operation>
template<typename Type>
struct BinExpr<LHS, RHS, operation>::BasicType
{
typedef Type ObjType;
};
template<typename LHS, typename RHS, int operation>
template<typename LH, typename RH, int oper>
struct BinExpr<LHS, RHS, operation>::BasicType<BinExpr<LH, RH, oper>>
{
typedef typename BinExpr<LH, RH, oper>::ObjType ObjType;
};
template<typename LHS, typename RHS, int operation>
template <typename LH, typename RH>
struct BinExpr<LHS, RHS, operation>::Operation<LH, RH, ADD>
{
static value_type cpt(value_type const &lhs, value_type const &rhs)
{
return lhs + rhs;
};
};
template<typename LHS, typename RHS, int operation>
template <typename LH, typename RH>
struct BinExpr<LHS, RHS, operation>::Operation<LH, RH, SUB>
{
static value_type cpt(value_type const &lhs, value_type const &rhs)
{
return lhs - rhs;
};
};
template<typename LHS, typename RHS>
BinExpr<LHS, RHS, ADD> operator+(LHS const &lhs, RHS const &rhs)
{
return BinExpr<LHS, RHS, ADD>(lhs, rhs);
}
template<typename LHS, typename RHS>
BinExpr<LHS, RHS, SUB> operator-(LHS const &lhs, RHS const &rhs)
{
return BinExpr<LHS, RHS, SUB>(lhs, rhs);
}
struct VI: public vector<int> // define the data structure to
{ // operate on
static size_t const s_max = 1;//0000;
VI()
:
vector<int>(s_max, 1)
{}
};
int main()
{
// vector<int> one {1, 2, 3};
// vector<int> two {4, 5, 6};
//
// vector<int> three = one + two + (one + two);
//
// auto four = one + two + (one + two);
//
// auto z = "hello world";
//
// cout << z << '\n';
//
// cout << three[0] << ' ' << three[2] << '\n';
// cout << four[0] << ' ' << four[2] << '\n';
VI a, b, c, d;
d = a + b;
// d = a - b - c - d - (a - b - c - d);
//
// d = a + b - (c + d) - (a + b - c + d);
//
// d = VI{};
//
// d = a + b + c + d + (a + b + c + d);
//
cout << d.front() << ", " << d.back() << '\n';
}
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