//===----------------------------------------------------------------------===//
//                         DuckDB
//
// duckdb/parser/base_expression.hpp
//
//
//===----------------------------------------------------------------------===//

#pragma once

#include "duckdb/common/common.hpp"
#include "duckdb/common/enums/expression_type.hpp"

namespace duckdb {

//!  The BaseExpression class is a base class that can represent any expression
//!  part of a SQL statement.
class BaseExpression {
public:
	//! Create an Expression
	BaseExpression(ExpressionType type, ExpressionClass expression_class)
	    : type(type), expression_class(expression_class) {
	}
	virtual ~BaseExpression() {
	}

	//! Returns the type of the expression
	ExpressionType GetExpressionType() const {
		return type;
	}
	//! Returns the class of the expression
	ExpressionClass GetExpressionClass() const {
		return expression_class;
	}

	//! Type of the expression
	ExpressionType type;
	//! The expression class of the node
	ExpressionClass expression_class;
	//! The alias of the expression,
	string alias;

public:
	//! Returns true if this expression is an aggregate or not.
	/*!
	 Examples:

	 (1) SUM(a) + 1 -- True

	 (2) a + 1 -- False
	 */
	virtual bool IsAggregate() const = 0;
	//! Returns true if the expression has a window function or not
	virtual bool IsWindow() const = 0;
	//! Returns true if the query contains a subquery
	virtual bool HasSubquery() const = 0;
	//! Returns true if expression does not contain a group ref or col ref or parameter
	virtual bool IsScalar() const = 0;
	//! Returns true if the expression has a parameter
	virtual bool HasParameter() const = 0;

	//! Get the name of the expression
	virtual string GetName() const;
	//! Convert the Expression to a String
	virtual string ToString() const = 0;
	//! Print the expression to stdout
	void Print() const;

	//! Creates a hash value of this expression. It is important that if two expressions are identical (i.e.
	//! Expression::Equals() returns true), that their hash value is identical as well.
	virtual hash_t Hash() const = 0;
	//! Returns true if this expression is equal to another expression
	virtual bool Equals(const BaseExpression *other) const;

	static bool Equals(BaseExpression *left, BaseExpression *right) {
		if (left == right) {
			return true;
		}
		if (!left || !right) {
			return false;
		}
		return left->Equals(right);
	}
	bool operator==(const BaseExpression &rhs) {
		return this->Equals(&rhs);
	}

	virtual void Verify() const;
};

} // namespace duckdb
