expression.h

/* Copyright (c) 2021 OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
See the Mulan PSL v2 for more details. */
 
//
// Created by Wangyunlai on 2022/07/05.
//
 
#pragma once
 
#include <string.h>
#include <memory>
#include <string>
 
#include "storage/field/field.h"
#include "sql/parser/value.h"
#include "common/log/log.h"
 
class Tuple;
 
enum class ExprType 
{
  NONE,
  STAR,         
  FIELD,        
  VALUE,        
  CAST,         
  COMPARISON,   
  CONJUNCTION,  
  ARITHMETIC,   
};
 
class Expression 
{
public:
  Expression() = default;
  virtual ~Expression() = default;
 
  virtual RC get_value(const Tuple &tuple, Value &value) const = 0;
 
  virtual RC try_get_value(Value &value) const
  {
    return RC::UNIMPLENMENT;
  }
 
  virtual ExprType type() const = 0;
 
  virtual AttrType value_type() const = 0;
 
  virtual std::string name() const { return name_; }
  virtual void set_name(std::string name) { name_ = name; }
 
private:
  std::string  name_;
};
 
class FieldExpr : public Expression 
{
public:
  FieldExpr() = default;
  FieldExpr(const Table *table, const FieldMeta *field) : field_(table, field)
  {}
  FieldExpr(const Field &field) : field_(field)
  {}
 
  virtual ~FieldExpr() = default;
 
  ExprType type() const override { return ExprType::FIELD; }
  AttrType value_type() const override { return field_.attr_type(); }
 
  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, Value &value) const override;
 
private:
  Field field_;
};
 
class ValueExpr : public Expression 
{
public:
  ValueExpr() = default;
  explicit ValueExpr(const Value &value) : value_(value)
  {}
 
  virtual ~ValueExpr() = default;
 
  RC get_value(const Tuple &tuple, Value &value) const override;
  RC try_get_value(Value &value) const override { value = value_; return RC::SUCCESS; }
 
  ExprType type() const override { return ExprType::VALUE; }
 
  AttrType value_type() const override { return value_.attr_type(); }
 
  void get_value(Value &value) const { value = value_; }
 
  const Value &get_value() const { return value_; }
 
private:
  Value value_;
};
 
class CastExpr : public Expression 
{
public:
  CastExpr(std::unique_ptr<Expression> child, AttrType cast_type);
  virtual ~CastExpr();
 
  ExprType type() const override
  {
    return ExprType::CAST;
  }
  RC get_value(const Tuple &tuple, Value &value) const override;
 
  RC try_get_value(Value &value) const override;
 
  AttrType value_type() const override { return cast_type_; }
 
  std::unique_ptr<Expression> &child() { return child_; }
 
private:
  RC cast(const Value &value, Value &cast_value) const;
 
private:
  std::unique_ptr<Expression> child_;  
  AttrType cast_type_;  
};
 
class ComparisonExpr : public Expression 
{
public:
  ComparisonExpr(CompOp comp, std::unique_ptr<Expression> left, std::unique_ptr<Expression> right);
  virtual ~ComparisonExpr();
 
  ExprType type() const override { return ExprType::COMPARISON; }
 
  RC get_value(const Tuple &tuple, Value &value) const override;
 
  AttrType value_type() const override { return BOOLEANS; }
 
  CompOp comp() const { return comp_; }
 
  std::unique_ptr<Expression> &left()  { return left_;  }
  std::unique_ptr<Expression> &right() { return right_; }
 
  RC try_get_value(Value &value) const override;
 
  RC compare_value(const Value &left, const Value &right, bool &value) const;
 
private:
  CompOp comp_;
  std::unique_ptr<Expression> left_;
  std::unique_ptr<Expression> right_;
};
 
class ConjunctionExpr : public Expression 
{
public:
  enum class Type {
    AND,
    OR,
  };
 
public:
  ConjunctionExpr(Type type, std::vector<std::unique_ptr<Expression>> &children);
  virtual ~ConjunctionExpr() = default;
 
  ExprType type() const override { return ExprType::CONJUNCTION; }
 
  AttrType value_type() const override { return BOOLEANS; }
 
  RC get_value(const Tuple &tuple, Value &value) const override;
 
  Type conjunction_type() const { return conjunction_type_; }
 
  std::vector<std::unique_ptr<Expression>> &children() { return children_; }
 
private:
  Type conjunction_type_;
  std::vector<std::unique_ptr<Expression>> children_;
};
 
class ArithmeticExpr : public Expression 
{
public:
  enum class Type {
    ADD,
    SUB,
    MUL,
    DIV,
    NEGATIVE,
  };
 
public:
  ArithmeticExpr(Type type, Expression *left, Expression *right);
  ArithmeticExpr(Type type, std::unique_ptr<Expression> left, std::unique_ptr<Expression> right);
  virtual ~ArithmeticExpr() = default;
 
  ExprType type() const override { return ExprType::ARITHMETIC; }
 
  AttrType value_type() const override;
 
  RC get_value(const Tuple &tuple, Value &value) const override;
  RC try_get_value(Value &value) const override;
 
  Type arithmetic_type() const { return arithmetic_type_; }
 
  std::unique_ptr<Expression> &left() { return left_; }
  std::unique_ptr<Expression> &right() { return right_; }
 
private:
  RC calc_value(const Value &left_value, const Value &right_value, Value &value) const;
  
private:
  Type arithmetic_type_;
  std::unique_ptr<Expression> left_;
  std::unique_ptr<Expression> right_;
};