ClickHouse/dbms/src/Interpreters/evaluateConstantExpression.h
2017-12-18 04:11:48 +03:00

37 lines
980 B
C++

#pragma once
#include <memory>
#include <Core/Field.h>
#include <Parsers/IAST.h>
#include <Parsers/IParser.h>
namespace DB
{
class Context;
class IDataType;
/** Evaluate constant expression and its type.
* Used in rare cases - for elements of set for IN, for data to INSERT.
* Quite suboptimal.
*/
std::pair<Field, std::shared_ptr<const IDataType>> evaluateConstantExpression(const ASTPtr & node, const Context & context);
/** Evaluate constant expression
* and returns ASTLiteral with its value.
*/
ASTPtr evaluateConstantExpressionAsLiteral(const ASTPtr & node, const Context & context);
/** Evaluate constant expression
* and returns ASTLiteral with its value.
* Also, if AST is identifier, then return string literal with its name.
* Useful in places where some name may be specified as identifier, or as result of a constant expression.
*/
ASTPtr evaluateConstantExpressionOrIdentifierAsLiteral(const ASTPtr & node, const Context & context);
}