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#pragma once
#include <base/types.h>
#include <Parsers/TokenIterator.h>
#include <map>
#include <memory>
#include <Common/SipHash.h>
namespace DB
{
struct StringRange
{
const char * first = nullptr;
const char * second = nullptr;
StringRange() = default;
StringRange(const char * begin, const char * end) : first(begin), second(end) {}
explicit StringRange(TokenIterator token) : first(token->begin), second(token->end) {}
StringRange(TokenIterator token_begin, TokenIterator token_end)
{
/// Empty range.
if (token_begin == token_end)
{
first = token_begin->begin;
second = token_begin->begin;
return;
}
TokenIterator token_last = token_end;
--token_last;
first = token_begin->begin;
second = token_last->end;
}
};
using StringPtr = std::shared_ptr<String>;
inline String toString(const StringRange & range)
{
return range.first ? String(range.first, range.second) : String();
}
/// Hashes only the values of pointers in StringRange. Is used with StringRangePointersEqualTo comparator.
struct StringRangePointersHash
{
UInt64 operator()(const StringRange & range) const
{
SipHash hash;
hash.update(range.first);
hash.update(range.second);
return hash.get64();
}
};
/// Ranges are equal only when they point to the same memory region.
/// It may be used when it's enough to compare substrings by their position in the same string.
struct StringRangePointersEqualTo
{
constexpr bool operator()(const StringRange &lhs, const StringRange &rhs) const
{
return std::tie(lhs.first, lhs.second) == std::tie(rhs.first, rhs.second);
}
};
}
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