ClickHouse/dbms/Functions/FunctionsVisitParam.h
Ivan 97f2a2213e
Move all folders inside /dbms one level up (#9974)
* Move some code outside dbms/src folder
* Fix paths
2020-04-02 02:51:21 +03:00

199 lines
6.2 KiB
C++

#pragma once
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeFixedString.h>
#include <Columns/ColumnString.h>
#include <Common/Volnitsky.h>
#include <Functions/IFunctionImpl.h>
#include <Functions/FunctionHelpers.h>
#include <IO/ReadBufferFromMemory.h>
#include <IO/ReadHelpers.h>
/** Functions for retrieving "visit parameters".
* Visit parameters in Yandex.Metrika are a special kind of JSONs.
* These functions are applicable to almost any JSONs.
* Implemented via templates from FunctionsStringSearch.h.
*
* Check if there is a parameter
* visitParamHas
*
* Retrieve the numeric value of the parameter
* visitParamExtractUInt
* visitParamExtractInt
* visitParamExtractFloat
* visitParamExtractBool
*
* Retrieve the string value of the parameter
* visitParamExtractString - unescape value
* visitParamExtractRaw
*/
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_COLUMN;
}
template <typename NumericType>
struct ExtractNumericType
{
using ResultType = NumericType;
static ResultType extract(const UInt8 * begin, const UInt8 * end)
{
ReadBufferFromMemory in(begin, end - begin);
/// Read numbers in double quotes
if (!in.eof() && *in.position() == '"')
++in.position();
ResultType x = 0;
if (!in.eof())
{
if constexpr (std::is_floating_point_v<NumericType>)
tryReadFloatText(x, in);
else
tryReadIntText(x, in);
}
return x;
}
};
/** Searches for occurrences of a field in the visit parameter and calls ParamExtractor
* for each occurrence of the field, passing it a pointer to the part of the string,
* where the occurrence of the field value begins.
* ParamExtractor must parse and return the value of the desired type.
*
* If a field was not found or an incorrect value is associated with the field,
* then the default value used - 0.
*/
template <typename ParamExtractor>
struct ExtractParamImpl
{
using ResultType = typename ParamExtractor::ResultType;
static constexpr bool use_default_implementation_for_constants = true;
/// It is assumed that `res` is the correct size and initialized with zeros.
static void vectorConstant(const ColumnString::Chars & data, const ColumnString::Offsets & offsets,
std::string needle,
PaddedPODArray<ResultType> & res)
{
/// We are looking for a parameter simply as a substring of the form "name"
needle = "\"" + needle + "\":";
const UInt8 * begin = data.data();
const UInt8 * pos = begin;
const UInt8 * end = pos + data.size();
/// The current index in the string array.
size_t i = 0;
Volnitsky searcher(needle.data(), needle.size(), end - pos);
/// We will search for the next occurrence in all strings at once.
while (pos < end && end != (pos = searcher.search(pos, end - pos)))
{
/// Let's determine which index it belongs to.
while (begin + offsets[i] <= pos)
{
res[i] = 0;
++i;
}
/// We check that the entry does not pass through the boundaries of strings.
if (pos + needle.size() < begin + offsets[i])
res[i] = ParamExtractor::extract(pos + needle.size(), begin + offsets[i] - 1); /// don't include terminating zero
else
res[i] = 0;
pos = begin + offsets[i];
++i;
}
if (res.size() > i)
memset(&res[i], 0, (res.size() - i) * sizeof(res[0]));
}
template <typename... Args> static void vectorVector(Args &&...)
{
throw Exception("Functions 'visitParamHas' and 'visitParamExtract*' doesn't support non-constant needle argument", ErrorCodes::ILLEGAL_COLUMN);
}
template <typename... Args> static void constantVector(Args &&...)
{
throw Exception("Functions 'visitParamHas' and 'visitParamExtract*' doesn't support non-constant needle argument", ErrorCodes::ILLEGAL_COLUMN);
}
template <typename... Args>
static void vectorFixedConstant(Args &&...)
{
throw Exception("Functions 'visitParamHas' don't support FixedString haystack argument", ErrorCodes::ILLEGAL_COLUMN);
}
};
/** For the case where the type of field to extract is a string.
*/
template <typename ParamExtractor>
struct ExtractParamToStringImpl
{
static void vector(const ColumnString::Chars & data, const ColumnString::Offsets & offsets,
std::string needle,
ColumnString::Chars & res_data, ColumnString::Offsets & res_offsets)
{
/// Constant 5 is taken from a function that performs a similar task FunctionsStringSearch.h::ExtractImpl
res_data.reserve(data.size() / 5);
res_offsets.resize(offsets.size());
/// We are looking for a parameter simply as a substring of the form "name"
needle = "\"" + needle + "\":";
const UInt8 * begin = data.data();
const UInt8 * pos = begin;
const UInt8 * end = pos + data.size();
/// The current index in the string array.
size_t i = 0;
Volnitsky searcher(needle.data(), needle.size(), end - pos);
/// We will search for the next occurrence in all strings at once.
while (pos < end && end != (pos = searcher.search(pos, end - pos)))
{
/// Determine which index it belongs to.
while (begin + offsets[i] <= pos)
{
res_data.push_back(0);
res_offsets[i] = res_data.size();
++i;
}
/// We check that the entry does not pass through the boundaries of strings.
if (pos + needle.size() < begin + offsets[i])
ParamExtractor::extract(pos + needle.size(), begin + offsets[i], res_data);
pos = begin + offsets[i];
res_data.push_back(0);
res_offsets[i] = res_data.size();
++i;
}
while (i < res_offsets.size())
{
res_data.push_back(0);
res_offsets[i] = res_data.size();
++i;
}
}
};
}