expression.h

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#ifndef MSHADOW_EXPRESSION_H_
#define MSHADOW_EXPRESSION_H_
#include "./base.h"

namespace mshadow {
namespace expr {
namespace type {
// type expression type are defined as bitmask
// subtype relationshop kRValue < kMapper < kPull < kComplex
const int kRValue = 0;
const int kMapper = 1;
const int kChainer = 3;
const int kComplex = 7;
}  // namespace type
template<typename Saver, typename RValue, typename DType>
struct ExpEngine;
// template<typename EType>
// inline static void Eval(RValue *dst, const EType &exp);
template<typename SubType, typename DType, int exp_type>
struct Exp {
 public:
  inline const SubType& self(void) const {
    return *static_cast<const SubType*>(this);
  }
  inline SubType* ptrself(void) {
    return static_cast<SubType*>(this);
  }
};
template<typename DType>
struct ScalarExp: public Exp<ScalarExp<DType>, DType, type::kMapper> {
  DType scalar_;
  ScalarExp(DType scalar) : scalar_(scalar) {}  // NOLINT(*)
};
template<typename DType>
inline ScalarExp<DType> scalar(DType s) {
  return ScalarExp<DType>(s);
}
template<typename DstDType, typename SrcDType, typename EType, int etype>
struct TypecastExp:
      public Exp<TypecastExp<DstDType, SrcDType, EType, etype>,
                 DstDType, etype> {
  const EType &exp;
  explicit TypecastExp(const EType &e) : exp(e) {}
};
template<typename DstDType, typename SrcDType,
         typename EType, int etype>
inline TypecastExp<DstDType, SrcDType, EType, (etype|type::kMapper)>
tcast(const Exp<EType, SrcDType, etype> &exp) {
  return TypecastExp<DstDType, SrcDType, EType, (etype|type::kMapper)>(exp.self());
}
template<typename EType, typename DType>
struct TransposeExp: public Exp<TransposeExp<EType, DType>,
                                DType, type::kChainer> {
  const EType &exp;
  explicit TransposeExp(const EType &e) : exp(e) {}
  inline const EType &T(void) const {
    return exp;
  }
};
template<typename Container, typename DType>
class RValueExp: public Exp<Container, DType, type::kRValue> {
 public:
  inline const TransposeExp<Container, DType> T(void) const {
    return TransposeExp<Container, DType>(this->self());
  }
  inline Container &operator+=(DType s) {
    ExpEngine<sv::plusto, Container, DType>::Eval(this->ptrself(), scalar<DType>(s));
    return *(this->ptrself());
  }
  inline Container &operator-=(DType s) {
    ExpEngine<sv::minusto, Container, DType>::Eval(this->ptrself(), scalar<DType>(s));
    return *(this->ptrself());
  }
  inline Container &operator*=(DType s) {
    ExpEngine<sv::multo, Container, DType>::Eval(this->ptrself(), scalar<DType>(s));
    return *(this->ptrself());
  }
  inline Container &operator/=(DType s) {
    ExpEngine<sv::divto, Container, DType>::Eval(this->ptrself(), scalar<DType>(s));
    return *(this->ptrself());
  }
  inline Container &__assign(DType s) {
    ExpEngine<sv::saveto, Container, DType>::Eval(this->ptrself(), scalar<DType>(s));
    return *(this->ptrself());
  }
  template<typename E, int etype>
  inline Container &__assign(const Exp<E, DType, etype> &exp) {
    ExpEngine<sv::saveto, Container, DType>::Eval(this->ptrself(), exp.self());
    return *(this->ptrself());
  }
  inline Container &__assign(const Exp<Container, DType, type::kRValue> &exp);
  template<typename E, int etype>
  inline Container &operator+=(const Exp<E, DType, etype> &exp) {
    ExpEngine<sv::plusto, Container, DType>::Eval(this->ptrself(), exp.self());
    return *(this->ptrself());
  }
  template<typename E, int etype>
  inline Container &operator-=(const Exp<E, DType, etype> &exp) {
    ExpEngine<sv::minusto, Container, DType>::Eval(this->ptrself(), exp.self());
    return *(this->ptrself());
  }
  template<typename E, int etype>
  inline Container &operator*=(const Exp<E, DType, etype> &exp) {
    ExpEngine<sv::multo, Container, DType>::Eval(this->ptrself(), exp.self());
    return *(this->ptrself());
  }
  template<typename E, int etype>
  inline Container &operator/=(const Exp<E, DType, etype> &exp) {
    ExpEngine<sv::divto, Container, DType>::Eval(this->ptrself(), exp.self());
    return *(this->ptrself());
  }
};
template<typename TA, typename TB, bool ltrans, bool rtrans, typename DType>
struct DotExp: public Exp<DotExp<TA, TB, ltrans, rtrans, DType>,
                          DType, type::kComplex> {
  const TA &lhs_;
  const TB &rhs_;
  DType scale_;
  explicit DotExp(const TA &lhs, const TB &rhs, DType scale)
      : lhs_(lhs), rhs_(rhs), scale_(scale) {}
};
// definition of dot expression
template<typename TA, typename TB, typename DType>
inline DotExp<TA, TB, false, false, DType>
dot(const RValueExp<TA, DType> &lhs, const RValueExp<TB, DType> &rhs) {
  return DotExp<TA, TB, false, false, DType>(lhs.self(), rhs.self(), DType(1.0f));
}
template<typename TA, typename TB, typename DType>
inline DotExp<TA, TB, true, false, DType>
dot(const TransposeExp<TA, DType> &lhs, const RValueExp<TB, DType> &rhs) {
  return DotExp<TA, TB, true, false, DType>(lhs.exp, rhs.self(), DType(1.0f));
}
template<typename TA, typename TB, typename DType>
inline DotExp<TA, TB, false, true, DType>
dot(const RValueExp<TA, DType> &lhs, const TransposeExp<TB, DType> &rhs) {
  return DotExp<TA, TB, false, true, DType>(lhs.self(), rhs.exp, DType(1.0f));
}
template<typename TA, typename TB, typename DType>
inline DotExp<TA, TB, true, true, DType>
dot(const TransposeExp<TA, DType> &lhs, const TransposeExp<TB, DType> &rhs) {
  return DotExp<TA, TB, true, true, DType>(lhs.exp, rhs.exp, DType(1.0f));
}
template<bool transpose_left, bool transpose_right, typename TA, typename TB, typename DType>
inline DotExp<TA, TB, transpose_left, transpose_right, DType>
batch_dot(const RValueExp<TA, DType> &lhs, const RValueExp<TB, DType> &rhs) {
  return DotExp<TA, TB, transpose_left, transpose_right, DType>(
    lhs.self(), rhs.self(), DType(1.0f));
}
//---------------
// TernaryMapExp
// --------------
template<typename OP, typename TA, typename TB, typename TC, typename DType, int etype>
struct TernaryMapExp: public Exp<TernaryMapExp<OP, TA, TB, TC, DType, etype>,
                                DType, etype> {
  const TA &item1_;
  const TB &item2_;
  const TC &item3_;
  explicit TernaryMapExp(const TA &item1, const TB &item2, const TC &item3)
      :item1_(item1), item2_(item2), item3_(item3) {}
};

template<typename OP, typename TA, typename TB, typename TC, typename DType, int ta, int tb, int tc>
inline TernaryMapExp<OP, TA, TB, TC, DType, (ta|tb|tc|type::kMapper)>
MakeExp(const Exp<TA, DType, ta> &item1, const Exp<TB, DType, tb> &item2,
 const Exp<TC, DType, tc> &item3) {
  return TernaryMapExp<OP, TA, TB, TC, DType,
                      (ta|tb|tc|type::kMapper)>(item1.self(), item2.self(), item3.self());
}
// Ternary
template<typename OP, typename TA, typename TB, typename TC, typename DType, int ta, int tb, int tc>
inline TernaryMapExp<OP, TA, TB, TC, DType, (ta|tb|tc|type::kMapper)>
F(const Exp<TA, DType, ta> &item1, const Exp<TB, DType, tb> &item2,
 const Exp<TC, DType, tc> &item3) {
  return MakeExp<OP>(item1, item2, item3);
}
//---------------
// BinaryMapExp
// --------------
template<typename OP, typename TA, typename TB, typename DType, int etype>
struct BinaryMapExp: public Exp<BinaryMapExp<OP, TA, TB, DType, etype>,
                                DType, etype> {
  const TA &lhs_;
  const TB &rhs_;
  explicit BinaryMapExp(const TA &lhs, const TB &rhs)
      :lhs_(lhs), rhs_(rhs) {}
};

template<typename OP, typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<OP, TA, TB, DType, (ta|tb|type::kMapper)>
MakeExp(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return BinaryMapExp<OP, TA, TB, DType,
                      (ta|tb|type::kMapper)>(lhs.self(), rhs.self());
}
template<typename OP, typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<OP, TA, TB, DType, (ta|tb|type::kMapper)>
F(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return MakeExp<OP>(lhs, rhs);
}
// operator rules
template<typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<op::plus, TA, TB, DType, (ta|tb|type::kMapper)>
operator+(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return MakeExp<op::plus>(lhs, rhs);
}
template<typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<op::minus, TA, TB, DType, (ta|tb|type::kMapper)>
operator-(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return MakeExp<op::minus>(lhs, rhs);
}
template<typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<op::mul, TA, TB, DType, (ta|tb|type::kMapper)>
operator*(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return MakeExp<op::mul>(lhs, rhs);
}
template<typename TA, typename TB, typename DType, int ta, int tb>
inline BinaryMapExp<op::div, TA, TB, DType, (ta|tb|type::kMapper)>
operator/(const Exp<TA, DType, ta> &lhs, const Exp<TB, DType, tb> &rhs) {
  return MakeExp<op::div>(lhs, rhs);
}
//---------------
// UnaryMapExp
// --------------
template<typename OP, typename TA, typename DType, int etype>
struct UnaryMapExp: public Exp<UnaryMapExp<OP, TA, DType, etype>,
                               DType, etype> {
  const TA &src_;
  explicit UnaryMapExp(const TA &src) : src_(src) {}
};

template<typename OP, typename TA, typename DType, int ta>
inline UnaryMapExp<OP, TA, DType, (ta|type::kMapper)>
MakeExp(const Exp<TA, DType, ta> &src) {
  return UnaryMapExp<OP, TA, DType, (ta|type::kMapper)>(src.self());
}
template<typename OP, typename TA, typename DType, int ta>
inline UnaryMapExp<OP, TA, DType, (ta|type::kMapper)>
F(const Exp<TA, DType, ta> &src) {
  return MakeExp<OP>(src);
}
}  // namespace expr
}  // namespace mshadow
#endif  // MSHADOW_EXPRESSION_H_