ExpressionEvaluatorTemplates.h

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#ifndef CommonToolsUtilsExpressionEvaluatorTemplates_H
#define CommonToolsUtilsExpressionEvaluatorTemplates_H
#include <vector>
#include <algorithm>
#include <numeric>
#include <limits>
#include <memory>
#include <tuple>

namespace reco {

  template <typename Ret, typename... Args>
  struct genericExpression {
    virtual Ret operator()(Args...) const = 0;
    virtual ~genericExpression(){};
  };

  template <typename Object>
  struct CutOnObject {
    virtual bool eval(Object const&) const = 0;
    virtual ~CutOnObject(){};
  };

  template <typename Object>
  struct ValueOnObject {
    virtual double eval(Object const&) const = 0;
    virtual ~ValueOnObject(){};
  };

  template <typename Object>
  struct MaskCollection {
    using Collection = std::vector<Object const*>;
    using Mask = std::vector<bool>;
    template <typename F>
    void mask(Collection const& cands, Mask& mask, F f) const {
      mask.resize(cands.size());
      std::transform(
          cands.begin(), cands.end(), mask.begin(), [&](typename Collection::value_type const& c) { return f(*c); });
    }
    virtual void eval(Collection const&, Mask&) const = 0;
    virtual ~MaskCollection(){};
  };

  template <typename Object>
  struct SelectInCollection {
    using Collection = std::vector<Object const*>;
    template <typename F>
    void select(Collection& cands, F f) const {
      cands.erase(
          std::remove_if(cands.begin(), cands.end(), [&](typename Collection::value_type const& c) { return !f(*c); }),
          cands.end());
    }
    virtual void eval(Collection&) const = 0;
    virtual ~SelectInCollection(){};
  };

  template <typename Object>
  struct SelectIndecesInCollection {
    using Collection = std::vector<Object const*>;
    using Indices = std::vector<unsigned int>;
    template <typename F>
    void select(Collection const& cands, Indices& inds, F f) const {
      unsigned int i = 0;
      for (auto const& c : cands) {
        if (f(*c))
          inds.push_back(i);
        ++i;
      }
    }
    virtual void eval(Collection const&, Indices&) const = 0;
    virtual ~SelectIndecesInCollection(){};
  };

}  // namespace reco

#endif  // CommonToolsUtilsExpressionEvaluatorTemplates_H