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298 lines (261 loc) · 9.31 KB
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#ifndef _A2_H
#define _A2_H
// Author: Mathew Rodley
// SID: 305126180
// Ename: mrod5488
// Email: mrod5488@usyd.edu.au
// Purpose:
// Defines _1 to be used for lambda expressions
// For ostream
#include <iostream>
// for ostream manip funcs
typedef std::ostream&(*iomanipfunc)(std::ostream&);
#define MAKE_TRAITS_1(TYPE1, TYPE2, RESULTTYPE) \
template<> \
struct LambdaTrait<TYPE1, TYPE2> { \
typedef RESULTTYPE Type; \
};
#define MAKE_TRAITS_2(TYPE1, TYPE2, RESULTTYPE) \
template<> \
struct LambdaTrait<TYPE1, TYPE2> { \
typedef RESULTTYPE Type; \
}; \
template<> \
struct LambdaTrait<TYPE2, TYPE1> { \
typedef RESULTTYPE Type; \
};
// Taits - default, use LHS (T1)
template <class T1, class T2>
struct LambdaTrait {
typedef T1 Type; // use T1 as default
};
// Make additional Traits
MAKE_TRAITS_1(int,int,int); // int + int = int
MAKE_TRAITS_2(int,float,float); // int + float = float && float + int = float
MAKE_TRAITS_2(int,double,double); // etc..
MAKE_TRAITS_2(float,double,double); // etc..
// Special cases for ostreams
template <class T2>
struct LambdaTrait<std::ostream, T2> {
typedef std::ostream& Type;
};
template <class T2>
struct LambdaTrait<T2, std::ostream> {
typedef std::ostream& Type;
};
template <>
struct LambdaTrait<std::ostream, std::ostream> {
typedef std::ostream& Type;
};
//
// The operator we call for an expression
// operator() cant be static inline so use doOp
//
template <class T1, class T2>
class LambdaAssignOP {
public:
typedef typename LambdaTrait<T1, T2>::Type Type;
static inline Type doOp(T1& a, T2& b) { a = (T1)b; return a; }
static inline Type doOp(T1& a, T2 b) { a = (T1)b; return a; }
};
template <class T1, class T2>
class LambdaSumOP {
public:
typedef typename LambdaTrait<T1, T2>::Type Type;
static inline Type doOp(T1 a, T2 b) { return a + b; }
};
template <class T1, class T2>
class LambdaMinusOP {
public:
typedef typename LambdaTrait<T1, T2>::Type Type;
static inline Type doOp(T1 a, T2 b) { return a - b; }
};
template <class T1, class T2>
class LambdaMultOP {
public:
typedef typename LambdaTrait<T1, T2>::Type Type;
static inline Type doOp(T1 a, T2 b) { return a * b; }
};
template <class T1, class T2>
class LambdaDivOP {
public:
typedef typename LambdaTrait<T1, T2>::Type Type;
static inline Type doOp(T1 a, T2 b) { return a / b; }
};
template <class T2>
class LambdaOStreamOP {
public:
typedef typename LambdaTrait<std::ostream, T2>::Type Type;
static inline Type doOp(std::ostream& os, T2 b) {
os << b;
return os;
}
};
// Holds a the _1 variable
class LambdaVariable {
public:
typedef int Type;
Type& operator()(Type& x) {
return x;
}
};
//
// Class remembers a literal in the expression, i.e the 1 in _1 + 1
//
template <class T1>
class LambdaLiteral {
private:
T1 _l;
public:
typedef T1 Type;
LambdaLiteral(const T1 x)
: _l(x) { }
T1 operator()(int) {
return _l;
}
};
// holds ostream
class LambdaStream {
private:
std::ostream& _o;
public:
typedef std::ostream& Type;
LambdaStream(std::ostream& o) : _o(o) { }
std::ostream& operator()(int) {
return _o;
}
};
//
// Binary Expression
//
template <class L, class R, class OP>
class LambdaBinaryExpression {
private:
L _l;
R _r;
public:
typedef typename LambdaTrait<typename L::Type, typename R::Type>::Type Type;
LambdaBinaryExpression (const L& l, const R& r)
: _l(l), _r(r) { }
Type operator()(int& x) {
return OP::doOp(_l(x), _r(x));
}
};
//
// Contains an expression (Wrapped)
//
template <class E>
class LambdaExpression {
private:
E _expr;
public:
typedef typename E::Type Type;
LambdaExpression(const E& e)
: _expr(e) { }
Type operator()(int& x) {
return _expr(x);
}
};
// Special Case for LambdaVariable where operator() wants to return a reference
// Also LambdaVariable can have an assignment operator on the LHS
// i.e
// _1 = 2
// _1 = <expr>
template <>
class LambdaExpression<LambdaVariable> {
private:
LambdaVariable _expr;
public:
typedef LambdaVariable::Type Type;
LambdaExpression(const LambdaVariable& e)
: _expr(e) { }
Type& operator()(int& x) {
return _expr(x);
}
// The assign operator for LambdaExpression
template <class R>
LambdaExpression<LambdaBinaryExpression<LambdaExpression<LambdaVariable>, LambdaExpression<R>, LambdaAssignOP<Type, typename R::Type> > >
operator=(const LambdaExpression<R>& r) {
typedef LambdaBinaryExpression<LambdaExpression<LambdaVariable>, LambdaExpression<R>, LambdaAssignOP<Type, typename R::Type> > LambdaExpression_t;
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(*this, r));
}
// The assign operator for literal
template <class R>
LambdaExpression<LambdaBinaryExpression<LambdaExpression<LambdaVariable>, LambdaExpression<LambdaLiteral<R> >, LambdaAssignOP<Type, R> > >
operator=(const R x) {
typedef LambdaBinaryExpression<LambdaExpression<LambdaVariable>, LambdaExpression<LambdaLiteral<R> >, LambdaAssignOP<Type, R > > LambdaExpression_t;
LambdaLiteral<R> r(x);
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(*this, r));
}
};
// Special case for lambda stream
template <>
class LambdaExpression<LambdaStream> {
private:
LambdaStream _expr;
public:
typedef LambdaStream::Type Type;
LambdaExpression(const LambdaStream& e)
: _expr(e) { }
std::ostream& operator()(int& x) {
return _expr(x);
}
};
// cout << EXPR
template <class R>
LambdaExpression<LambdaBinaryExpression<LambdaExpression<LambdaStream>, LambdaExpression<R>, LambdaOStreamOP<typename R::Type> > >
operator<<(std::ostream& o, const LambdaExpression<R>& r) {
typedef LambdaBinaryExpression<LambdaExpression<LambdaStream>, LambdaExpression<R>, LambdaOStreamOP<typename R::Type> > LambdaExpression_t;
LambdaStream l(o);
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r));
};
// EXPR << literal
template <class L, class R>
LambdaExpression<LambdaBinaryExpression<LambdaExpression<L>, LambdaLiteral<R>, LambdaOStreamOP<R> > >
operator<<(const LambdaExpression<L>& l, R x) {
typedef LambdaBinaryExpression<LambdaExpression<L>, LambdaLiteral<R>, LambdaOStreamOP<R> > LambdaExpression_t;
LambdaLiteral<R> r(x);
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r));
};
// EXPT << ManipFunc
template <class L>
LambdaExpression<LambdaBinaryExpression<LambdaExpression<L>, LambdaLiteral<iomanipfunc>, LambdaOStreamOP<iomanipfunc> > >
operator<<(const LambdaExpression<L>& l, iomanipfunc x) {
typedef LambdaBinaryExpression<LambdaExpression<L>, LambdaLiteral<iomanipfunc>, LambdaOStreamOP<iomanipfunc> > LambdaExpression_t;
LambdaLiteral<iomanipfunc> r(x);
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r));
};
/*
* Creating an operation is standard bar which operator to overload
* and which evaluation object to use
*/
#define CREATE_OP(LAMBDAOP, OP) \
template <class L, class R> \
LambdaExpression<LambdaBinaryExpression<LambdaExpression<L>, LambdaExpression<R>, LAMBDAOP<typename L::Type, typename R::Type> > > \
OP(const LambdaExpression<L>& l, const LambdaExpression<R>& r) { \
typedef LambdaBinaryExpression<LambdaExpression<L>, LambdaExpression<R>, LAMBDAOP<typename L::Type, typename R::Type> > LambdaExpression_t; \
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r)); \
}; \
\
template <class L, class R> \
LambdaExpression<LambdaBinaryExpression<LambdaExpression<L>, LambdaExpression<LambdaLiteral<R> >, LAMBDAOP<typename L::Type, R> > > \
OP(const LambdaExpression<L>& l, const R x) { \
typedef LambdaBinaryExpression<LambdaExpression<L>, LambdaExpression<LambdaLiteral<R> >, LAMBDAOP<typename L::Type, R> > LambdaExpression_t; \
LambdaLiteral<R> r(x); \
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r)); \
}; \
template <class L, class R> \
LambdaExpression<LambdaBinaryExpression<LambdaExpression<LambdaLiteral<L> >, LambdaExpression<R>, LAMBDAOP<L, typename R::Type> > > \
OP(const L x, const LambdaExpression<R>& r) { \
typedef LambdaBinaryExpression<LambdaExpression<LambdaLiteral<L> >, LambdaExpression<R>, LAMBDAOP<L, typename R::Type> > LambdaExpression_t; \
LambdaLiteral<L> l(x); \
return LambdaExpression<LambdaExpression_t>(LambdaExpression_t(l, r)); \
};
CREATE_OP(LambdaSumOP, operator+)
CREATE_OP(LambdaMinusOP, operator-)
CREATE_OP(LambdaMultOP, operator*)
CREATE_OP(LambdaDivOP, operator/)
// Initialize out _1 Object, it should act like a variable
LambdaVariable __1;
LambdaExpression<LambdaVariable> _1(__1);
#endif
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