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taiyang-li committed Jun 26, 2024
1 parent cb2720c commit 48f57cc
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71 changes: 71 additions & 0 deletions cpp-ch/local-engine/Parser/scalar_function_parser/chr.cpp
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <Parser/FunctionParser.h>
#include <DataTypes/IDataType.h>
#include <Common/CHUtil.h>
#include <Core/Field.h>

namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}
}

namespace local_engine
{
class FunctionParserChr : public FunctionParser
{
public:
explicit FunctionParserChr(SerializedPlanParser * plan_parser_) : FunctionParser(plan_parser_) { }
~FunctionParserChr() override = default;
static constexpr auto name = "chr";
String getName() const override { return name; }

const ActionsDAG::Node * parse(
const substrait::Expression_ScalarFunction & substrait_func,
ActionsDAGPtr & actions_dag) const override
{
auto parsed_args = parseFunctionArguments(substrait_func, "", actions_dag);
if (parsed_args.size() != 1)
throw Exception(DB::ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Function {} requires two or three arguments", getName());

/*
parse chr(number) as if(number < 0, '', char(0, number), 'unicode', 'utf-8'))
*/
const auto & num_arg = parsed_args[0];
const auto * const_zero_node = addColumnToActionsDAG(actions_dag, std::make_shared<DataTypeInt32>(), 0);
const auto * const_empty_node = addColumnToActionsDAG(actions_dag, std::make_shared<DataTypeString>(), "");
const auto * const_four_node = addColumnToActionsDAG(actions_dag, std::make_shared<DataTypeInt32>(), 4);
const auto * const_unicode_node = addColumnToActionsDAG(actions_dag, std::make_shared<DataTypeString>(), "unicode");
const auto * const_utf8_node = addColumnToActionsDAG(actions_dag, std::make_shared<DataTypeString>(), "utf-8");

const auto * less_node = toFunctionNode(actions_dag, "less", {num_arg, const_zero_node});

const auto * char_node = toFunctionNode(actions_dag, "char", {const_zero_node, num_arg});
const auto * convert_charset_node = toFunctionNode(actions_dag, "convertCharset", {char_node, const_unicode_node, const_utf8_node});

const auto * if_node = toFunctionNode(actions_dag, "if", {less_node, const_empty_node, convert_charset_node});
const auto * result_node = convertNodeTypeIfNeeded(substrait_func, if_node, actions_dag);
return result_node;
}
};

static FunctionParserRegister<FunctionParserChr> register_chr;
}

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