fexpr_cumminmax.cc

//------------------------------------------------------------------------------
// Copyright 2022 H2O.ai
//
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// copy of this software and associated documentation files (the "Software"),
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// IN THE SOFTWARE.
//------------------------------------------------------------------------------
#include "column/const.h"
#include "column/cumminmax.h"
#include "column/latent.h"
#include "documentation.h"
#include "expr/fexpr_func.h"
#include "expr/eval_context.h"
#include "expr/workframe.h"
#include "python/xargs.h"
#include "stype.h"


namespace dt {
namespace expr {

template <bool MIN>
class FExpr_CumMinMax : public FExpr_Func {
  private:
    ptrExpr arg_;

  public:
    FExpr_CumMinMax(ptrExpr&& arg)
      : arg_(std::move(arg)) {}

    std::string repr() const override {
      std::string out = MIN? "cummin" : "cummax";
      out += '(';
      out += arg_->repr();
      out += ')';
      return out;
    }


    Workframe evaluate_n(EvalContext& ctx) const override {
      Workframe wf = arg_->evaluate_n(ctx);
      Groupby gby = Groupby::single_group(wf.nrows());

      if (ctx.has_groupby()) {
        wf.increase_grouping_mode(Grouping::GtoALL);
        gby = ctx.get_groupby();
      }

      for (size_t i = 0; i < wf.ncols(); ++i) {
        Column coli = evaluate1(wf.retrieve_column(i), gby);
        wf.replace_column(i, std::move(coli));
      }
      return wf;
    }


    Column evaluate1(Column&& col, const Groupby& gby) const {
      SType stype = col.stype();
      switch (stype) {
        case SType::VOID:    return Column(new ConstNa_ColumnImpl(col.nrows()));
        case SType::BOOL:
        case SType::INT8:    return make<int8_t>(std::move(col), gby);
        case SType::INT16:   return make<int16_t>(std::move(col), gby);
        case SType::DATE32:
        case SType::INT32:   return make<int32_t>(std::move(col), gby);
        case SType::TIME64:
        case SType::INT64:   return make<int64_t>(std::move(col), gby);
        case SType::FLOAT32: return make<float>(std::move(col), gby);
        case SType::FLOAT64: return make<double>(std::move(col), gby);
        default: throw TypeError()
          << "Invalid column of type `" << stype << "` in " << repr();
      }
    }


    template <typename T>
    Column make(Column&& col, const Groupby& gby) const {
      return Column(new Latent_ColumnImpl(
        new CumMinMax_ColumnImpl<T, MIN>(std::move(col), gby)
      ));
    }
};


static py::oobj pyfn_cummax(const py::XArgs& args) {
  auto cummax = args[0].to_oobj();
  return PyFExpr::make(new FExpr_CumMinMax<false>(as_fexpr(cummax)));
}


static py::oobj pyfn_cummin(const py::XArgs& args) {
  auto cummin = args[0].to_oobj();
  return PyFExpr::make(new FExpr_CumMinMax<true>(as_fexpr(cummin)));
}


DECLARE_PYFN(&pyfn_cummax)
    ->name("cummax")
    ->docs(doc_dt_cummax)
    ->arg_names({"cummax"})
    ->n_positional_args(1)
    ->n_required_args(1);


DECLARE_PYFN(&pyfn_cummin)
    ->name("cummin")
    ->docs(doc_dt_cummin)
    ->arg_names({"cummin"})
    ->n_positional_args(1)
    ->n_required_args(1);


}}  // dt::expr