ClickHouse/src/Storages/ReplaceAliasByExpressionVisitor.cpp
2023-11-27 03:50:34 +00:00

33 lines
793 B
C++

#include <Storages/ReplaceAliasByExpressionVisitor.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTLiteral.h>
#include <Storages/ColumnsDescription.h>
#include <Common/typeid_cast.h>
namespace DB
{
void ReplaceAliasByExpressionMatcher::visit(ASTPtr & ast, Data & data)
{
if (auto * identifier = ast->as<ASTIdentifier>())
{
visit(*identifier, ast, data);
}
}
void ReplaceAliasByExpressionMatcher::visit(const ASTIdentifier & column, ASTPtr & ast, Data & data)
{
const auto & column_name = column.name();
if (data.columns.hasAlias(column_name))
{
/// Alias expr is saved in default expr.
if (auto col_default = data.columns.getDefault(column_name))
{
ast = col_default->expression->clone();
}
}
}
}