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#include <Functions/FunctionFactory.h>
#include <Functions/FunctionsStringSearchToString.h>
#include <base/find_symbols.h>
namespace DB
{
struct ExtractURLParameterImpl
{
static void vector(const ColumnString::Chars & data,
const ColumnString::Offsets & offsets,
std::string pattern,
ColumnString::Chars & res_data, ColumnString::Offsets & res_offsets)
{
res_data.reserve(data.size() / 5);
res_offsets.resize(offsets.size());
pattern += '=';
const char * param_str = pattern.c_str();
size_t param_len = pattern.size();
ColumnString::Offset prev_offset = 0;
ColumnString::Offset res_offset = 0;
for (size_t i = 0; i < offsets.size(); ++i)
{
ColumnString::Offset cur_offset = offsets[i];
const char * str = reinterpret_cast<const char *>(&data[prev_offset]);
const char * end = reinterpret_cast<const char *>(&data[cur_offset]);
/// Find query string or fragment identifier.
/// Note that we support parameters in fragment identifier in the same way as in query string.
const char * const query_string_begin = find_first_symbols<'?', '#'>(str, end);
/// Will point to the beginning of "name=value" pair. Then it will be reassigned to the beginning of "value".
const char * param_begin = nullptr;
if (query_string_begin + 1 < end)
{
param_begin = query_string_begin + 1;
while (true)
{
param_begin = static_cast<const char *>(memmem(param_begin, end - param_begin, param_str, param_len));
if (!param_begin)
break;
if (param_begin[-1] != '?' && param_begin[-1] != '#' && param_begin[-1] != '&')
{
/// Parameter name is different but has the same suffix.
param_begin += param_len;
continue;
}
else
{
param_begin += param_len;
break;
}
}
}
if (param_begin)
{
const char * param_end = find_first_symbols<'&', '#'>(param_begin, end);
if (param_end == end)
param_end = param_begin + strlen(param_begin);
size_t param_size = param_end - param_begin;
res_data.resize(res_offset + param_size + 1);
memcpySmallAllowReadWriteOverflow15(&res_data[res_offset], param_begin, param_size);
res_offset += param_size;
}
else
{
/// No parameter found, put empty string in result.
res_data.resize(res_offset + 1);
}
res_data[res_offset] = 0;
++res_offset;
res_offsets[i] = res_offset;
prev_offset = cur_offset;
}
}
};
struct NameExtractURLParameter { static constexpr auto name = "extractURLParameter"; };
using FunctionExtractURLParameter = FunctionsStringSearchToString<ExtractURLParameterImpl, NameExtractURLParameter>;
REGISTER_FUNCTION(ExtractURLParameter)
{
factory.registerFunction<FunctionExtractURLParameter>();
}
}
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