forked from Public-Mirror/Textractor
56 lines
1.1 KiB
C++
56 lines
1.1 KiB
C++
#ifndef HASHSTR_H
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#define HASHSTR_H
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// hashstr.h
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// 8/1/2011
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// See: http://www.cse.yorku.ca/~oz/hash.html
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#include "hashutil/hashutil.h"
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#include <cstdint>
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HASHUTIL_BEGIN_NAMESPACE
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enum : uint64_t { djb2_hash0 = 5381 };
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/// djb2: h = h*33 + c
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template <typename charT>
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inline uint64_t djb2(const charT *str, uint64_t hash = djb2_hash0)
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{
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charT c;
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while ((c = *str++))
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hash = ((hash << 5) + hash) + c; // hash * 33 + c
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return hash;
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}
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/// n: length
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template <typename charT>
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inline uint64_t djb2_n(const charT *str, size_t len, uint64_t hash = djb2_hash0)
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{
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while (len--)
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hash = ((hash << 5) + hash) + (*str++); // hash * 33 + c
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return hash;
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}
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/// sdbm: hash(i) = hash(i - 1) * 65599 + str[i];
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template <typename charT>
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inline uint64_t sdbm(const charT *str, uint64_t hash = 0)
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{
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charT c;
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while ((c = *str++))
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hash = c + (hash << 6) + (hash << 16) - hash;
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return hash;
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}
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template <typename charT>
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inline uint64_t loselose(const charT *str, uint64_t hash = 0)
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{
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charT c;
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while ((c = *str++))
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hash += c;
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return hash;
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}
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HASHUTIL_END_NAMESPACE
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#endif // HASHSTR_H
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