summary refs log tree commit diff
path: root/src/libutil/aterm-map.hh
blob: db36da377a793cb50783e652128de9c035bac29b (plain) (blame)
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
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
#ifndef __ATERM_MAP_H
#define __ATERM_MAP_H

typedef struct _ATerm * ATerm;

#include <assert.h>


namespace nix {


class ATermMap
{
public:

    struct KeyValue
    {
        ATerm key;
        ATerm value;
    };

private:

    /* Hash table for the map.  We use open addressing, i.e., all
       key/value pairs are stored directly in the table, and there are
       no pointers.  Collisions are resolved through probing. */
    KeyValue * hashTable;

    /* Current size of the hash table. */
    unsigned int capacity;

    /* Number of elements in the hash table. */
    unsigned int count;

    /* Maximum number of elements in the hash table.  If `count'
       exceeds this number, the hash table is expanded. */
    unsigned int maxCount;
    
public:

    /* Create a map.  `expectedCount' is the number of elements the
       map is expected to hold. */
    ATermMap(unsigned int expectedCount = 16);
    
    ATermMap(const ATermMap & map);
    
    ~ATermMap();

    ATermMap & operator = (const ATermMap & map);
        
    void set(ATerm key, ATerm value);

    ATerm get(ATerm key) const;

    ATerm operator [](ATerm key) const
    {
        return get(key);
    }

    void remove(ATerm key);

    unsigned int size();

    struct const_iterator
    {
        const ATermMap & map;
        unsigned int pos;
        const_iterator(const ATermMap & map, int pos) : map(map)
        {
            this->pos = pos;
        }
        bool operator !=(const const_iterator & i)
        {
            return pos != i.pos;
        }
        void operator ++()
        {
            if (pos == map.capacity) return;
            do { ++pos; 
            } while (pos < map.capacity && map.hashTable[pos].value == 0);
        }
        const KeyValue & operator *()
        {
            assert(pos < map.capacity);
            return map.hashTable[pos];
        }
        const KeyValue * operator ->()
        {
            assert(pos < map.capacity);
            return &map.hashTable[pos];
        }
    };

    friend class ATermMap::const_iterator;
    
    const_iterator begin() const
    {
        unsigned int i = 0;
        while (i < capacity && hashTable[i].value == 0) ++i;
        return const_iterator(*this, i);
    }
    
    const_iterator end() const
    {
        return const_iterator(*this, capacity);
    }

private:
    
    void init(unsigned int expectedCount);

    void free();

    void resizeTable(unsigned int expectedCount);

    void copy(KeyValue * elements, unsigned int capacity);
    
    inline unsigned long hash1(ATerm key) const;
    inline unsigned long hash2(ATerm key) const;
};


/* Hack. */
void printATermMapStats();

 
}


#endif /* !__ATERM_MAP_H */