1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
|
// Copyright (C) 2010, Gabriel Dos Reis.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the
// distribution.
//
// - Neither the name of The Numerical Algorithms Group Ltd. nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef OPENAXIOM_HASH_TABLE_INCLUDED
#define OPENAXIOM_HASH_TABLE_INCLUDED
// --% Author: Gabriel Dos Reis.
// --% Description:
// --% Simple hash table facility. To be replaced by C++0x
// --% hash tables when C++0x compilers become common place.
#include <open-axiom/storage>
namespace OpenAxiom {
// --------------------
// -- HashTableEntry --
// --------------------
// Datatype for entries in a parameterized hash table.
// The type parameter is required to be a value-construcitble datatype.
// A table bucket entry is required to be at least 8-byte aligned
// so that an instance of it can be used directly as a VM value.
// See <open-axiom/vm> for more description.
template<typename T>
struct alignas(8) HashTableEntry : T {
HashTableEntry* chain; // previous item in the same bucket chain
size_t hash; // hash code of stored data
};
// --------------------
// -- BasicHashTable --
// --------------------
// A simple hash table data structure. Ideally, we would like to use
// standard C++ types, but hash tables were only in a C++ 2003 TR,
// officially part of C++0x standard library. We still don't have
// wide-spread C++0x compilers.
template<typename T>
struct BasicHashTable : private Memory::Arena<HashTableEntry<T> > {
typedef HashTableEntry<T> EntryType;
explicit BasicHashTable(size_t n)
: Memory::Arena<HashTableEntry<T> >(n),
buckets(this->allocate(n)), nbuckets(n) { }
EntryType* hash_chain(size_t h) const {
return buckets + (h % nbuckets);
}
EntryType* new_bucket() {
return this->allocate(1);
}
private:
HashTableEntry<T>* const buckets;
const size_t nbuckets;
};
}
#endif // OPENAXIOM_HASH_TABLE_INCLUDED
|
