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#include "UserDefinedSQLFunctionVisitor.h"
#include <unordered_map>
#include <unordered_set>
#include <stack>
#include <Parsers/ASTAlterQuery.h>
#include <Parsers/ASTCreateQuery.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTCreateFunctionQuery.h>
#include <Parsers/ASTExpressionList.h>
#include <Parsers/ASTIdentifier.h>
#include <Functions/UserDefined/UserDefinedSQLFunctionFactory.h>
#include "Parsers/ASTColumnDeclaration.h"
namespace DB
{
namespace ErrorCodes
{
extern const int UNSUPPORTED_METHOD;
}
void UserDefinedSQLFunctionVisitor::visit(ASTPtr & ast)
{
if (!ast)
{
chassert(false);
return;
}
const auto visit_child_with_shared_ptr = [&](ASTPtr & child)
{
if (!child)
return;
auto * old_value = child.get();
visit(child);
// child did not change
if (old_value == child.get())
return;
// child changed, we need to modify it in the list of children of the parent also
for (auto & current_child : ast->children)
{
if (current_child.get() == old_value)
current_child = child;
}
};
if (auto * col_decl = ast->as<ASTColumnDeclaration>())
{
visit_child_with_shared_ptr(col_decl->default_expression);
visit_child_with_shared_ptr(col_decl->ttl);
return;
}
if (auto * storage = ast->as<ASTStorage>())
{
const auto visit_child = [&](IAST * & child)
{
if (!child)
return;
if (const auto * function = child->template as<ASTFunction>())
{
std::unordered_set<std::string> udf_in_replace_process;
auto replace_result = tryToReplaceFunction(*function, udf_in_replace_process);
if (replace_result)
ast->setOrReplace(child, replace_result);
}
visit(child);
};
visit_child(storage->partition_by);
visit_child(storage->primary_key);
visit_child(storage->order_by);
visit_child(storage->sample_by);
visit_child(storage->ttl_table);
return;
}
if (auto * alter = ast->as<ASTAlterCommand>())
{
visit_child_with_shared_ptr(alter->col_decl);
visit_child_with_shared_ptr(alter->column);
visit_child_with_shared_ptr(alter->partition);
visit_child_with_shared_ptr(alter->order_by);
visit_child_with_shared_ptr(alter->sample_by);
visit_child_with_shared_ptr(alter->index_decl);
visit_child_with_shared_ptr(alter->index);
visit_child_with_shared_ptr(alter->constraint_decl);
visit_child_with_shared_ptr(alter->constraint);
visit_child_with_shared_ptr(alter->projection_decl);
visit_child_with_shared_ptr(alter->projection);
visit_child_with_shared_ptr(alter->predicate);
visit_child_with_shared_ptr(alter->update_assignments);
visit_child_with_shared_ptr(alter->values);
visit_child_with_shared_ptr(alter->ttl);
visit_child_with_shared_ptr(alter->select);
return;
}
if (const auto * function = ast->template as<ASTFunction>())
{
std::unordered_set<std::string> udf_in_replace_process;
auto replace_result = tryToReplaceFunction(*function, udf_in_replace_process);
if (replace_result)
ast = replace_result;
}
for (auto & child : ast->children)
visit(child);
}
void UserDefinedSQLFunctionVisitor::visit(IAST * ast)
{
if (!ast)
return;
for (auto & child : ast->children)
visit(child);
}
ASTPtr UserDefinedSQLFunctionVisitor::tryToReplaceFunction(const ASTFunction & function, std::unordered_set<std::string> & udf_in_replace_process)
{
if (udf_in_replace_process.find(function.name) != udf_in_replace_process.end())
throw Exception(ErrorCodes::UNSUPPORTED_METHOD,
"Recursive function call detected during function call {}",
function.name);
auto user_defined_function = UserDefinedSQLFunctionFactory::instance().tryGet(function.name);
if (!user_defined_function)
return nullptr;
const auto & function_arguments_list = function.children.at(0)->as<ASTExpressionList>();
auto & function_arguments = function_arguments_list->children;
const auto & create_function_query = user_defined_function->as<ASTCreateFunctionQuery>();
auto & function_core_expression = create_function_query->function_core->children.at(0);
const auto & identifiers_expression_list = function_core_expression->children.at(0)->children.at(0)->as<ASTExpressionList>();
const auto & identifiers_raw = identifiers_expression_list->children;
if (function_arguments.size() != identifiers_raw.size())
throw Exception(ErrorCodes::UNSUPPORTED_METHOD,
"Function {} expects {} arguments actual arguments {}",
create_function_query->getFunctionName(),
identifiers_raw.size(),
function_arguments.size());
std::unordered_map<std::string, ASTPtr> identifier_name_to_function_argument;
for (size_t parameter_index = 0; parameter_index < identifiers_raw.size(); ++parameter_index)
{
const auto & identifier = identifiers_raw[parameter_index]->as<ASTIdentifier>();
const auto & function_argument = function_arguments[parameter_index];
const auto & identifier_name = identifier->name();
identifier_name_to_function_argument.emplace(identifier_name, function_argument);
}
auto [it, _] = udf_in_replace_process.emplace(function.name);
auto function_body_to_update = function_core_expression->children.at(1)->clone();
auto expression_list = std::make_shared<ASTExpressionList>();
expression_list->children.emplace_back(std::move(function_body_to_update));
std::stack<ASTPtr> ast_nodes_to_update;
ast_nodes_to_update.push(expression_list);
while (!ast_nodes_to_update.empty())
{
auto ast_node_to_update = ast_nodes_to_update.top();
ast_nodes_to_update.pop();
for (auto & child : ast_node_to_update->children)
{
if (auto * inner_function = child->as<ASTFunction>())
{
auto replace_result = tryToReplaceFunction(*inner_function, udf_in_replace_process);
if (replace_result)
child = replace_result;
}
auto identifier_name_opt = tryGetIdentifierName(child);
if (identifier_name_opt)
{
auto function_argument_it = identifier_name_to_function_argument.find(*identifier_name_opt);
if (function_argument_it == identifier_name_to_function_argument.end())
continue;
auto child_alias = child->tryGetAlias();
child = function_argument_it->second->clone();
if (!child_alias.empty())
child->setAlias(child_alias);
continue;
}
ast_nodes_to_update.push(child);
}
}
udf_in_replace_process.erase(it);
function_body_to_update = expression_list->children[0];
auto function_alias = function.tryGetAlias();
if (!function_alias.empty())
function_body_to_update->setAlias(function_alias);
return function_body_to_update;
}
}
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