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#include <Analyzer/Passes/IfTransformStringsToEnumPass.h>
#include <Analyzer/ConstantNode.h>
#include <Analyzer/FunctionNode.h>
#include <Analyzer/IQueryTreeNode.h>
#include <Analyzer/InDepthQueryTreeVisitor.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeEnum.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/IDataType.h>
#include <Functions/FunctionFactory.h>
namespace DB
{
namespace
{
/// We place strings in ascending order here under the assumption it could speed up String to Enum conversion.
template <typename EnumType>
auto getDataEnumType(const std::set<std::string> & string_values)
{
using EnumValues = typename EnumType::Values;
EnumValues enum_values;
enum_values.reserve(string_values.size());
size_t number = 1;
for (const auto & value : string_values)
enum_values.emplace_back(value, number++);
return std::make_shared<EnumType>(std::move(enum_values));
}
DataTypePtr getEnumType(const std::set<std::string> & string_values)
{
if (string_values.size() >= 255)
return getDataEnumType<DataTypeEnum16>(string_values);
else
return getDataEnumType<DataTypeEnum8>(string_values);
}
QueryTreeNodePtr createCastFunction(QueryTreeNodePtr from, DataTypePtr result_type, ContextPtr context)
{
auto enum_literal = std::make_shared<ConstantValue>(result_type->getName(), std::make_shared<DataTypeString>());
auto enum_literal_node = std::make_shared<ConstantNode>(std::move(enum_literal));
auto cast_function = FunctionFactory::instance().get("_CAST", std::move(context));
QueryTreeNodes arguments{ std::move(from), std::move(enum_literal_node) };
auto function_node = std::make_shared<FunctionNode>("_CAST");
function_node->getArguments().getNodes() = std::move(arguments);
function_node->resolveAsFunction(cast_function->build(function_node->getArgumentColumns()));
return function_node;
}
/// if(arg1, arg2, arg3) will be transformed to if(arg1, _CAST(arg2, Enum...), _CAST(arg3, Enum...))
/// where Enum is generated based on the possible values stored in string_values
void changeIfArguments(
FunctionNode & if_node, const std::set<std::string> & string_values, const ContextPtr & context)
{
auto result_type = getEnumType(string_values);
auto & argument_nodes = if_node.getArguments().getNodes();
argument_nodes[1] = createCastFunction(argument_nodes[1], result_type, context);
argument_nodes[2] = createCastFunction(argument_nodes[2], result_type, context);
auto if_resolver = FunctionFactory::instance().get("if", context);
if_node.resolveAsFunction(if_resolver->build(if_node.getArgumentColumns()));
}
/// transform(value, array_from, array_to, default_value) will be transformed to transform(value, array_from, _CAST(array_to, Array(Enum...)), _CAST(default_value, Enum...))
/// where Enum is generated based on the possible values stored in string_values
void changeTransformArguments(
FunctionNode & transform_node,
const std::set<std::string> & string_values,
const ContextPtr & context)
{
auto result_type = getEnumType(string_values);
auto & arguments = transform_node.getArguments().getNodes();
auto & array_to = arguments[2];
auto & default_value = arguments[3];
array_to = createCastFunction(array_to, std::make_shared<DataTypeArray>(result_type), context);
default_value = createCastFunction(default_value, std::move(result_type), context);
auto transform_resolver = FunctionFactory::instance().get("transform", context);
transform_node.resolveAsFunction(transform_resolver->build(transform_node.getArgumentColumns()));
}
void wrapIntoToString(FunctionNode & function_node, QueryTreeNodePtr arg, ContextPtr context)
{
auto to_string_function = FunctionFactory::instance().get("toString", std::move(context));
QueryTreeNodes arguments{ std::move(arg) };
function_node.getArguments().getNodes() = std::move(arguments);
function_node.resolveAsFunction(to_string_function->build(function_node.getArgumentColumns()));
assert(isString(function_node.getResultType()));
}
class ConvertStringsToEnumVisitor : public InDepthQueryTreeVisitorWithContext<ConvertStringsToEnumVisitor>
{
public:
using Base = InDepthQueryTreeVisitorWithContext<ConvertStringsToEnumVisitor>;
using Base::Base;
void enterImpl(QueryTreeNodePtr & node)
{
if (!getSettings().optimize_if_transform_strings_to_enum)
return;
auto * function_node = node->as<FunctionNode>();
if (!function_node)
return;
const auto & context = getContext();
/// to preserve return type (String) of the current function_node, we wrap the newly
/// generated function nodes into toString
std::string_view function_name = function_node->getFunctionName();
if (function_name == "if")
{
if (function_node->getArguments().getNodes().size() != 3)
return;
auto modified_if_node = function_node->clone();
auto * function_if_node = modified_if_node->as<FunctionNode>();
auto & argument_nodes = function_if_node->getArguments().getNodes();
const auto * first_literal = argument_nodes[1]->as<ConstantNode>();
const auto * second_literal = argument_nodes[2]->as<ConstantNode>();
if (!first_literal || !second_literal)
return;
if (!isString(first_literal->getResultType()) || !isString(second_literal->getResultType()))
return;
std::set<std::string> string_values;
string_values.insert(first_literal->getValue().get<std::string>());
string_values.insert(second_literal->getValue().get<std::string>());
changeIfArguments(*function_if_node, string_values, context);
wrapIntoToString(*function_node, std::move(modified_if_node), context);
return;
}
if (function_name == "transform")
{
if (function_node->getArguments().getNodes().size() != 4)
return;
auto modified_transform_node = function_node->clone();
auto * function_modified_transform_node = modified_transform_node->as<FunctionNode>();
auto & argument_nodes = function_modified_transform_node->getArguments().getNodes();
if (!isString(function_node->getResultType()))
return;
const auto * literal_to = argument_nodes[2]->as<ConstantNode>();
const auto * literal_default = argument_nodes[3]->as<ConstantNode>();
if (!literal_to || !literal_default)
return;
if (!isArray(literal_to->getResultType()) || !isString(literal_default->getResultType()))
return;
auto array_to = literal_to->getValue().get<Array>();
if (array_to.empty())
return;
if (!std::all_of(
array_to.begin(),
array_to.end(),
[](const auto & field) { return field.getType() == Field::Types::Which::String; }))
return;
/// collect possible string values
std::set<std::string> string_values;
for (const auto & value : array_to)
string_values.insert(value.get<std::string>());
string_values.insert(literal_default->getValue().get<std::string>());
changeTransformArguments(*function_modified_transform_node, string_values, context);
wrapIntoToString(*function_node, std::move(modified_transform_node), context);
return;
}
}
};
}
void IfTransformStringsToEnumPass::run(QueryTreeNodePtr query, ContextPtr context)
{
ConvertStringsToEnumVisitor visitor(std::move(context));
visitor.visit(query);
}
}
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