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/* 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/. */
/*
* Internal package used by containers that rely on entries/nodes.
*
* Copyright: Eugene Wissner 2016-2018.
* 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/container/entry.d,
* tanya/container/entry.d)
*/
module tanya.container.entry;
import tanya.algorithm.mutation;
import tanya.container.array;
import tanya.meta.trait;
import tanya.typecons;
package struct SEntry(T)
{
// Item content.
T content;
// Next item.
SEntry* next;
}
package struct DEntry(T)
{
// Item content.
T content;
// Previous and next item.
DEntry* next, prev;
}
package enum BucketStatus : byte
{
deleted = -1,
empty = 0,
used = 1,
}
package struct Bucket(K, V = void)
{
private alias Key = K;
private alias Value = V;
@property void key(ref K key)
{
this.key_ = key;
this.status = BucketStatus.used;
}
@property ref inout(K) key() inout
{
return this.key_;
}
bool opEquals(ref K key)
{
if (this.status == BucketStatus.used && this.key == key)
{
return true;
}
return false;
}
bool opEquals(ref const K key) const
{
if (this.status == BucketStatus.used && this.key == key)
{
return true;
}
return false;
}
bool opEquals(ref typeof(this) that)
{
return key == that.key && this.status == that.status;
}
bool opEquals(ref typeof(this) that) const
{
return key == that.key && this.status == that.status;
}
void remove()
{
static if (hasElaborateDestructor!K)
{
destroy(key);
}
this.status = BucketStatus.deleted;
}
private K key_;
static if (!is(V == void))
{
V value;
}
BucketStatus status = BucketStatus.empty;
}
// Possible sizes for the hash-based containers.
package static immutable size_t[33] primes = [
0, 3, 7, 13, 23, 37, 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289,
24593, 49157, 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469,
12582917, 25165843, 50331653, 100663319, 201326611, 402653189,
805306457, 1610612741, 3221225473
];
package struct HashArray(alias hasher, K, V = void)
{
alias Bucket = .Bucket!(K, V);
alias Buckets = Array!Bucket;
Array!Bucket array;
size_t lengthIndex;
/*
* Returns bucket position for `hash`. `0` may mean the 0th position or an
* empty `buckets` array.
*/
size_t locateBucket(ref const K key) const
{
return this.array.length == 0 ? 0 : hasher(key) % this.array.length;
}
/*
* Inserts the value in an empty or deleted bucket. If the value is
* already in there, does nothing and returns InsertStatus.found. If the
* hash array is full returns InsertStatus.failed. Otherwise,
* InsertStatus.added is returned.
*/
ref Bucket insert(ref K key)
{
while (true)
{
auto bucketPosition = locateBucket(key);
foreach (ref e; this.array[bucketPosition .. $])
{
if (e == key || e.status != BucketStatus.used)
{
return e;
}
}
if (primes.length == (this.lengthIndex + 1))
{
this.array.insertBack(Bucket(key));
return this.array[$ - 1];
}
if (this.rehashToSize(this.lengthIndex + 1))
{
++this.lengthIndex;
}
}
}
// Takes an index in the primes array.
bool rehashToSize(const size_t n)
{
auto storage = typeof(this.array)(primes[n], this.array.allocator);
DataLoop: foreach (ref e1; this.array[])
{
if (e1.status == BucketStatus.used)
{
auto bucketPosition = hasher(e1.key) % storage.length;
foreach (ref e2; storage[bucketPosition .. $])
{
if (e2.status != BucketStatus.used) // Insert the value.
{
e2 = e1;
continue DataLoop;
}
}
return false; // Rehashing failed.
}
}
move(storage, this.array);
return true;
}
void rehash(const size_t n)
{
size_t lengthIndex;
for (; lengthIndex < primes.length; ++lengthIndex)
{
if (primes[lengthIndex] >= n)
{
break;
}
}
if (this.rehashToSize(lengthIndex))
{
this.lengthIndex = lengthIndex;
}
}
@property size_t capacity() const
{
return this.array.length;
}
}
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