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Add hash.lookup module

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Eugen Wissner 2018-03-15 19:10:24 +01:00
parent 8faccbada4
commit 1adc4cd868
3 changed files with 90 additions and 1 deletions
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3
README.md
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@ -26,12 +26,13 @@ Tanya consists of the following packages and (top-level) modules:
* `algorithm`: Collection of generic algorithms.
* `async`: Event loop (epoll, kqueue and IOCP).
* `container`: Queue, Array, Singly and doubly linked lists, Buffers, UTF-8
string, Hash set.
string, Hash table.
* `conv`: This module provides functions for converting between different
types.
* `encoding`: This package provides tools to work with text encodings.
* `exception`: Common exceptions and errors.
* `format`: Formatting and conversion functions.
* `hash`: Hash algorithms.
* `math`: Arbitrary precision integer and a set of functions.
* `memory`: Tools for manual memory management (allocators, smart pointers).
* `meta`: Template metaprogramming. This package contains utilities to acquire

73
source/tanya/hash/lookup.d Normal file
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@ -0,0 +1,73 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Non-cryptographic, lookup hash functions.
*
* Copyright: Eugene Wissner 2018.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/hash/lookup.d,
* tanya/hash/lookup.d)
*/
module tanya.hash.lookup;
import tanya.meta.trait;
/**
* FNV-1a (Fowler-Noll-Vo) hash function.
*
* See_Also: $(LINK http://www.isthe.com/chongo/tech/comp/fnv/).
*/
size_t fnv(const ubyte[] key) @nogc nothrow pure @safe
{
static if (size_t.sizeof == 4)
{
enum uint offsetBasis = 2166136261;
enum uint fnvPrime = 16777619;
}
else static if (size_t.sizeof == 8)
{
enum ulong offsetBasis = 14695981039346656037UL;
enum ulong fnvPrime = 1099511628211UL;
}
else
{
static assert(false, "FNV requires at least 32-bit hash length");
}
size_t h = offsetBasis;
foreach (c; key)
{
h = (h ^ c) * fnvPrime;
}
return h;
}
static if (size_t.sizeof == 4) @nogc nothrow pure @safe unittest
{
assert(fnv(null) == 2166136261);
ubyte[1] given = [0];
assert(fnv(given) == 84696351);
}
static if (size_t.sizeof == 8) @nogc nothrow pure @safe unittest
{
assert(fnv(null) == 14695981039346656037UL);
ubyte[1] given = [0];
assert(fnv(given) == (14695981039346656037UL * 1099511628211UL));
}
size_t hash(T)(auto ref const T key)
{
static if (isScalarType!T)
{
return (() @trusted => fnv(cast(const ubyte[]) (&key)[0 .. T.sizeof]))();
}
}

15
source/tanya/hash/package.d Normal file
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@ -0,0 +1,15 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Copyright: Eugene Wissner 2018.
* License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
* Mozilla Public License, v. 2.0).
* Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
* Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/hash/package.d,
* tanya/hash/package.d)
*/
module tanya.hash;
public import tanya.hash.lookup;