ClickHouse/src/Common/parseRemoteDescription.cpp
2020-04-03 18:14:31 +03:00

171 lines
6.8 KiB
C++

#include "parseRemoteDescription.h"
#include <Common/Exception.h>
#include <IO/WriteHelpers.h>
namespace DB
{
namespace ErrorCodes
{
extern const int BAD_ARGUMENTS;
}
/// The Cartesian product of two sets of rows, the result is written in place of the first argument
static void append(std::vector<String> & to, const std::vector<String> & what, size_t max_addresses)
{
if (what.empty())
return;
if (to.empty())
{
to = what;
return;
}
if (what.size() * to.size() > max_addresses)
throw Exception("Table function 'remote': first argument generates too many result addresses",
ErrorCodes::BAD_ARGUMENTS);
std::vector<String> res;
for (const auto & elem_to : to)
for (const auto & elem_what : what)
res.push_back(elem_to + elem_what);
to.swap(res);
}
/// Parse number from substring
static bool parseNumber(const String & description, size_t l, size_t r, size_t & res)
{
res = 0;
for (size_t pos = l; pos < r; pos ++)
{
if (!isNumericASCII(description[pos]))
return false;
res = res * 10 + description[pos] - '0';
if (res > 1e15)
return false;
}
return true;
}
/* Parse a string that generates shards and replicas. Separator - one of two characters | or ,
* depending on whether shards or replicas are generated.
* For example:
* host1,host2,... - generates set of shards from host1, host2, ...
* host1|host2|... - generates set of replicas from host1, host2, ...
* abc{8..10}def - generates set of shards abc8def, abc9def, abc10def.
* abc{08..10}def - generates set of shards abc08def, abc09def, abc10def.
* abc{x,yy,z}def - generates set of shards abcxdef, abcyydef, abczdef.
* abc{x|yy|z} def - generates set of replicas abcxdef, abcyydef, abczdef.
* abc{1..9}de{f,g,h} - is a direct product, 27 shards.
* abc{1..9}de{0|1} - is a direct product, 9 shards, in each 2 replicas.
*/
std::vector<String> parseRemoteDescription(const String & description, size_t l, size_t r, char separator, size_t max_addresses)
{
std::vector<String> res;
std::vector<String> cur;
/// An empty substring means a set of an empty string
if (l >= r)
{
res.push_back("");
return res;
}
for (size_t i = l; i < r; ++i)
{
/// Either the numeric interval (8..10) or equivalent expression in brackets
if (description[i] == '{')
{
int cnt = 1;
int last_dot = -1; /// The rightmost pair of points, remember the index of the right of the two
size_t m;
std::vector<String> buffer;
bool have_splitter = false;
/// Look for the corresponding closing bracket
for (m = i + 1; m < r; ++m)
{
if (description[m] == '{') ++cnt;
if (description[m] == '}') --cnt;
if (description[m] == '.' && description[m-1] == '.') last_dot = m;
if (description[m] == separator) have_splitter = true;
if (cnt == 0) break;
}
if (cnt != 0)
throw Exception("Table function 'remote': incorrect brace sequence in first argument",
ErrorCodes::BAD_ARGUMENTS);
/// The presence of a dot - numeric interval
if (last_dot != -1)
{
size_t left, right;
if (description[last_dot - 1] != '.')
throw Exception("Table function 'remote': incorrect argument in braces (only one dot): " + description.substr(i, m - i + 1),
ErrorCodes::BAD_ARGUMENTS);
if (!parseNumber(description, i + 1, last_dot - 1, left))
throw Exception("Table function 'remote': incorrect argument in braces (Incorrect left number): "
+ description.substr(i, m - i + 1),
ErrorCodes::BAD_ARGUMENTS);
if (!parseNumber(description, last_dot + 1, m, right))
throw Exception("Table function 'remote': incorrect argument in braces (Incorrect right number): "
+ description.substr(i, m - i + 1),
ErrorCodes::BAD_ARGUMENTS);
if (left > right)
throw Exception("Table function 'remote': incorrect argument in braces (left number is greater then right): "
+ description.substr(i, m - i + 1),
ErrorCodes::BAD_ARGUMENTS);
if (right - left + 1 > max_addresses)
throw Exception("Table function 'remote': first argument generates too many result addresses",
ErrorCodes::BAD_ARGUMENTS);
bool add_leading_zeroes = false;
size_t len = last_dot - 1 - (i + 1);
/// If the left and right borders have equal numbers, then you must add leading zeros.
/// TODO The code is somewhat awful.
if (last_dot - 1 - (i + 1) == m - (last_dot + 1))
add_leading_zeroes = true;
for (size_t id = left; id <= right; ++id)
{
String id_str = toString<UInt64>(id);
if (add_leading_zeroes)
{
while (id_str.size() < len)
id_str = "0" + id_str;
}
buffer.push_back(id_str);
}
}
else if (have_splitter) /// If there is a current delimiter inside, then generate a set of resulting rows
buffer = parseRemoteDescription(description, i + 1, m, separator, max_addresses);
else /// Otherwise just copy, spawn will occur when you call with the correct delimiter
buffer.push_back(description.substr(i, m - i + 1));
/// Add all possible received extensions to the current set of lines
append(cur, buffer, max_addresses);
i = m;
}
else if (description[i] == separator)
{
/// If the delimiter, then add found rows
res.insert(res.end(), cur.begin(), cur.end());
cur.clear();
}
else
{
/// Otherwise, simply append the character to current lines
std::vector<String> buffer;
buffer.push_back(description.substr(i, 1));
append(cur, buffer, max_addresses);
}
}
res.insert(res.end(), cur.begin(), cur.end());
if (res.size() > max_addresses)
throw Exception("Table function 'remote': first argument generates too many result addresses",
ErrorCodes::BAD_ARGUMENTS);
return res;
}
}