ClickHouse/src/Functions/substring.cpp

#include <Columns/ColumnConst.h>
#include <Columns/ColumnFixedString.h>
#include <Columns/ColumnString.h>
#include <DataTypes/DataTypeEnum.h>
#include <DataTypes/DataTypeString.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionHelpers.h>
#include <Functions/GatherUtils/Algorithms.h>
#include <Functions/GatherUtils/GatherUtils.h>
#include <Functions/GatherUtils/Sinks.h>
#include <Functions/GatherUtils/Slices.h>
#include <Functions/GatherUtils/Sources.h>
#include <Functions/IFunction.h>
#include <IO/WriteHelpers.h>


namespace DB
{

using namespace GatherUtils;

namespace ErrorCodes
{
extern const int ILLEGAL_COLUMN;
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
extern const int ZERO_ARRAY_OR_TUPLE_INDEX;
}

namespace
{

/// If 'is_utf8' - measure offset and length in code points instead of bytes.
template <bool is_utf8>
class FunctionSubstring : public IFunction
{
public:
    static constexpr auto name = is_utf8 ? "substringUTF8" : "substring";

    static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionSubstring>(); }
    String getName() const override { return name; }
    bool isVariadic() const override { return true; }
    size_t getNumberOfArguments() const override { return 0; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return true; }
    bool useDefaultImplementationForConstants() const override { return true; }

    DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
    {
        const size_t number_of_arguments = arguments.size();

        if (number_of_arguments < 2 || number_of_arguments > 3)
            throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH, "Number of arguments for function {} doesn't match: "
                            "passed {}, should be 2 or 3", getName(), number_of_arguments);

        if constexpr (is_utf8)
        {
            /// UTF8 variant is not available for FixedString and Enum arguments.
            if (!isString(arguments[0]))
                throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of first argument of function {}",
                                arguments[0]->getName(), getName());
        }
        else
        {
            if (!isStringOrFixedString(arguments[0]) && !isEnum(arguments[0]))
                throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of first argument of function {}",
                                arguments[0]->getName(), getName());
        }

        if (!isNativeNumber(arguments[1]))
            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of second argument of function {}",
                            arguments[1]->getName(), getName());

        if (number_of_arguments == 3 && !isNativeNumber(arguments[2]))
            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Illegal type {} of second argument of function {}",
                            arguments[2]->getName(), getName());

        return std::make_shared<DataTypeString>();
    }

    template <typename Source>
    ColumnPtr executeForSource(const ColumnPtr & column_offset, const ColumnPtr & column_length,
                          bool column_offset_const, bool column_length_const,
                          Int64 offset, Int64 length,
                          Source && source, size_t input_rows_count) const
    {
        auto col_res = ColumnString::create();

        if (!column_length)
        {
            if (column_offset_const)
            {
                if (offset > 0)
                    sliceFromLeftConstantOffsetUnbounded(source, StringSink(*col_res, input_rows_count), static_cast<size_t>(offset - 1));
                else if (offset < 0)
                    sliceFromRightConstantOffsetUnbounded(source, StringSink(*col_res, input_rows_count), -static_cast<size_t>(offset));
                else
                    throw Exception(ErrorCodes::ZERO_ARRAY_OR_TUPLE_INDEX, "Indices in strings are 1-based");
            }
            else
                sliceDynamicOffsetUnbounded(source, StringSink(*col_res, input_rows_count), *column_offset);
        }
        else
        {
            if (column_offset_const && column_length_const)
            {
                if (offset > 0)
                    sliceFromLeftConstantOffsetBounded(source, StringSink(*col_res, input_rows_count), static_cast<size_t>(offset - 1), length);
                else if (offset < 0)
                    sliceFromRightConstantOffsetBounded(source, StringSink(*col_res, input_rows_count), -static_cast<size_t>(offset), length);
                else
                    throw Exception(ErrorCodes::ZERO_ARRAY_OR_TUPLE_INDEX, "Indices in strings are 1-based");
            }
            else
                sliceDynamicOffsetBounded(source, StringSink(*col_res, input_rows_count), *column_offset, *column_length);
        }

        return col_res;
    }

    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override
    {
        const size_t number_of_arguments = arguments.size();

        ColumnPtr column_string = arguments[0].column;
        ColumnPtr column_offset = arguments[1].column;
        ColumnPtr column_length;
        if (number_of_arguments == 3)
            column_length = arguments[2].column;

        const ColumnConst * column_offset_const = checkAndGetColumn<ColumnConst>(column_offset.get());
        const ColumnConst * column_length_const = nullptr;
        if (number_of_arguments == 3)
            column_length_const = checkAndGetColumn<ColumnConst>(column_length.get());

        Int64 offset = 0;
        Int64 length = 0;

        if (column_offset_const)
            offset = column_offset_const->getInt(0);
        if (column_length_const)
            length = column_length_const->getInt(0);

        if constexpr (is_utf8)
        {
            if (const ColumnString * col = checkAndGetColumn<ColumnString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, UTF8StringSource(*col), input_rows_count);
            if (const ColumnConst * col_const = checkAndGetColumnConst<ColumnString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, ConstSource<UTF8StringSource>(*col_const), input_rows_count);
            throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Illegal column {} of first argument of function {}", arguments[0].column->getName(), getName());
        }
        else
        {
            if (const ColumnString * col = checkAndGetColumn<ColumnString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, StringSource(*col), input_rows_count);
            if (const ColumnFixedString * col_fixed = checkAndGetColumn<ColumnFixedString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, FixedStringSource(*col_fixed), input_rows_count);
            if (const ColumnConst * col_const = checkAndGetColumnConst<ColumnString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, ConstSource<StringSource>(*col_const), input_rows_count);
            if (const ColumnConst * col_const_fixed = checkAndGetColumnConst<ColumnFixedString>(column_string.get()))
                return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, ConstSource<FixedStringSource>(*col_const_fixed), input_rows_count);
            if (isEnum(arguments[0].type))
            {
                if (const typename DataTypeEnum8::ColumnType * col_enum8 = checkAndGetColumn<typename DataTypeEnum8::ColumnType>(column_string.get()))
                {
                    const auto * type_enum8 = assert_cast<const DataTypeEnum8 *>(arguments[0].type.get());
                    return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, EnumSource<DataTypeEnum8>(*col_enum8, *type_enum8), input_rows_count);
                }
                if (const typename DataTypeEnum16::ColumnType * col_enum16 = checkAndGetColumn<typename DataTypeEnum16::ColumnType>(column_string.get()))
                {
                    const auto * type_enum16 = assert_cast<const DataTypeEnum16 *>(arguments[0].type.get());
                    return executeForSource(column_offset, column_length, column_offset_const, column_length_const, offset, length, EnumSource<DataTypeEnum16>(*col_enum16, *type_enum16), input_rows_count);
                }
            }

            throw Exception(ErrorCodes::ILLEGAL_COLUMN, "Illegal column {} of first argument of function {}", arguments[0].column->getName(), getName());
        }
    }
};

}

REGISTER_FUNCTION(Substring)
{
    factory.registerFunction<FunctionSubstring<false>>({}, FunctionFactory::CaseInsensitive);
    factory.registerAlias("substr", "substring", FunctionFactory::CaseInsensitive); // MySQL alias
    factory.registerAlias("mid", "substring", FunctionFactory::CaseInsensitive); /// MySQL alias

    factory.registerFunction<FunctionSubstring<true>>({}, FunctionFactory::CaseSensitive);
}

}