expression.h

#pragma once

#include "storage/common/field.h"
#include "sql/expr/tuple_cell.h"

class Tuple;

class Expression
{
public: 
  Expression() = default;
  virtual ~Expression() = default;
  
  virtual RC get_value(const Tuple &tuple, TupleCell &cell) const = 0;
};

class FieldExpr : public Expression
{
public:
  FieldExpr() = default;
  FieldExpr(const Table *table, const FieldMeta *field) : field_(table, field)
  {}

  virtual ~FieldExpr() = default;

  Field &field()
  {
    return field_;
  }

  const Field &field() const
  {
    return field_;
  }

  const char *table_name() const
  {
    return field_.table_name();
  }

  const char *field_name() const
  {
    return field_.field_name();
  }

  RC get_value(const Tuple &tuple, TupleCell &cell) const override;
private:
  Field field_;
};

class ValueExpr : public Expression
{
public:
  ValueExpr() = default;
  ValueExpr(const Value &value) : tuple_cell(value.type, (char *)value.data)
  {}

  virtual ~ValueExpr() = default;

  RC get_value(const Tuple &tuple, TupleCell & cell) const override;

private:
  TupleCell tuple_cell;
};