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