ClickHouse/dbms/src/Functions/FunctionsVisitParam.h
2019-01-04 15:10:00 +03:00

288 lines
8.9 KiB
C++

#pragma once
#include <Poco/UTF8Encoding.h>
#include <Poco/Unicode.h>
#include <DataTypes/DataTypesNumber.h>
#include <DataTypes/DataTypeString.h>
#include <DataTypes/DataTypeFixedString.h>
#include <DataTypes/DataTypeArray.h>
#include <Columns/ColumnString.h>
#include <Columns/ColumnArray.h>
#include <Columns/ColumnFixedString.h>
#include <Common/hex.h>
#include <Common/Volnitsky.h>
#include <Functions/IFunction.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
{
struct HasParam
{
using ResultType = UInt8;
static UInt8 extract(const UInt8 *, const UInt8 *)
{
return true;
}
};
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;
}
};
struct ExtractBool
{
using ResultType = UInt8;
static UInt8 extract(const UInt8 * begin, const UInt8 * end)
{
return begin + 4 <= end && 0 == strncmp(reinterpret_cast<const char *>(begin), "true", 4);
}
};
struct ExtractRaw
{
static constexpr size_t bytes_on_stack = 64;
using ExpectChars = PODArray<char, bytes_on_stack, AllocatorWithStackMemory<Allocator<false>, bytes_on_stack>>;
static void extract(const UInt8 * pos, const UInt8 * end, ColumnString::Chars & res_data)
{
ExpectChars expects_end;
UInt8 current_expect_end = 0;
for (auto extract_begin = pos; pos != end; ++pos)
{
if (*pos == current_expect_end)
{
expects_end.pop_back();
current_expect_end = expects_end.empty() ? 0 : expects_end.back();
}
else
{
switch (*pos)
{
case '[':
current_expect_end = ']';
expects_end.push_back(current_expect_end);
break;
case '{':
current_expect_end = '}';
expects_end.push_back(current_expect_end);
break;
case '"' :
current_expect_end = '"';
expects_end.push_back(current_expect_end);
break;
case '\\':
/// skip backslash
if (pos + 1 < end && pos[1] == '"')
pos++;
break;
default:
if (!current_expect_end && (*pos == ',' || *pos == '}'))
{
res_data.insert(extract_begin, pos);
return;
}
}
}
}
}
};
struct ExtractString
{
static void extract(const UInt8 * pos, const UInt8 * end, ColumnString::Chars & res_data)
{
size_t old_size = res_data.size();
ReadBufferFromMemory in(pos, end - pos);
if (!tryReadJSONStringInto(res_data, in))
res_data.resize(old_size);
}
};
/** 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;
/// It is assumed that `res` is the correct size and initialized with zeros.
static void vector_constant(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]);
else
res[i] = 0;
pos = begin + offsets[i];
++i;
}
if (res.size() > i)
memset(&res[i], 0, (res.size() - i) * sizeof(res[0]));
}
static void constant_constant(const std::string & data, std::string needle, ResultType & res)
{
needle = "\"" + needle + "\":";
size_t pos = data.find(needle);
if (pos == std::string::npos)
res = 0;
else
res = ParamExtractor::extract(
reinterpret_cast<const UInt8 *>(data.data() + pos + needle.size()),
reinterpret_cast<const UInt8 *>(data.data() + data.size())
);
}
template <typename... Args> static void vector_vector(Args &&...)
{
throw Exception("Functions 'visitParamHas' and 'visitParamExtract*' doesn't support non-constant needle argument", ErrorCodes::ILLEGAL_COLUMN);
}
template <typename... Args> static void constant_vector(Args &&...)
{
throw Exception("Functions 'visitParamHas' and 'visitParamExtract*' doesn't support non-constant needle 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;
}
}
};
}