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#include <Interpreters/ApplyWithAliasVisitor.h>
#include <Interpreters/misc.h>
#include <Parsers/ASTSelectQuery.h>
#include <Parsers/ASTSelectWithUnionQuery.h>
#include <Common/checkStackSize.h>
namespace DB
{
void ApplyWithAliasVisitor::visit(ASTPtr & ast, const Data & data)
{
checkStackSize();
if (auto * node_select = ast->as<ASTSelectQuery>())
{
std::optional<Data> new_data;
if (auto with = node_select->with())
{
std::set<String> current_names;
for (auto & child : with->children)
{
visit(child, new_data ? *new_data : data);
if (auto * ast_with_alias = dynamic_cast<ASTWithAlias *>(child.get()))
{
if (!new_data)
new_data = data;
new_data->exprs[ast_with_alias->alias] = child;
current_names.insert(ast_with_alias->alias);
}
}
for (const auto & with_alias : data.exprs)
{
if (!current_names.contains(with_alias.first))
with->children.push_back(with_alias.second->clone());
}
}
else if (!data.exprs.empty())
{
auto with_expression_list = std::make_shared<ASTExpressionList>();
for (const auto & with_alias : data.exprs)
with_expression_list->children.push_back(with_alias.second->clone());
node_select->setExpression(ASTSelectQuery::Expression::WITH, std::move(with_expression_list));
}
for (auto & child : node_select->children)
{
if (child != node_select->with())
visit(child, new_data ? *new_data : data);
}
}
else
for (auto & child : ast->children)
visit(child, data);
}
}
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