1 /*
2  Copyright (c) 2011, Oracle and/or its affiliates. All rights
3  reserved.
4 
5  This program is free software; you can redistribute it and/or modify
6  it under the terms of the GNU General Public License, version 2.0,
7  as published by the Free Software Foundation.
8 
9  This program is also distributed with certain software (including
10  but not limited to OpenSSL) that is licensed under separate terms,
11  as designated in a particular file or component or in included license
12  documentation.  The authors of MySQL hereby grant you an additional
13  permission to link the program and your derivative works with the
14  separately licensed software that they have included with MySQL.
15 
16  This program is distributed in the hope that it will be useful,
17  but WITHOUT ANY WARRANTY; without even the implied warranty of
18  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  GNU General Public License, version 2.0, for more details.
20 
21  You should have received a copy of the GNU General Public License
22  along with this program; if not, write to the Free Software
23  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
24  02110-1301  USA
25  */
26 
27 
28 /*  SIMPLE HASH TABLE.  Maps a null-terminated string to a pointer.
29     Creates and manages its own copy of the string.
30 */
31 #include <stdio.h>
32 #include <string.h>
33 
34 template<typename T> class LookupTable {
35 public:
36   int elements;
37   bool do_free_values;
38 
39   LookupTable(int sz = 128) :
40     elements(0),
41     do_free_values(false),
42     size(sz),
43     symtab(new Entry *[sz])
44   {
45     for(int i = 0 ; i < size ; i++)
46       symtab[i] = 0;
47   }
48 
49 
~LookupTable()50   ~LookupTable() {
51     for(int i = 0 ; i < size ; i++) {
52       Entry *sym = symtab[i];
53       while(sym) {
54         if(do_free_values) free((void *) sym->value);
55         Entry *next = sym->next;
56         delete sym;
57         sym = next;
58       }
59     }
60     delete[] symtab;
61   }
62 
63 
find(const char * name)64   T * find(const char *name) {
65     Uint32 h = do_hash(name) % size;
66     for(Entry *sym = symtab[h] ; sym != 0 ; sym = sym->next)
67       if(strcmp(name, sym->key) == 0)
68         return sym->value;
69     return 0;
70   }
71 
insert(const char * name,T * value)72   void insert(const char *name, T * value) {
73     Uint32 h = do_hash(name) % size;
74     Entry *sym = new Entry(name, value);
75     sym->next = symtab[h];
76     symtab[h] = sym;
77     elements++;
78   }
79 
80 
81 private:
82   class Entry {
83   public:
84     char *key;
85     T * value;
86     Entry *next;
87 
Entry(const char * name,T * val)88     Entry(const char *name, T * val) {
89       key = strdup(name);
90       value = val;
91     }
92 
~Entry()93     ~Entry() {
94       free(key);
95     }
96   };
97 
98   int size;
99   Entry ** symtab;
100 
do_hash(const char * string)101   Uint32 do_hash(const char *string) {
102     Uint32 h = 0;
103     for(const char *s = string; *s != 0; s++) h = 37 * h + *s;
104     return h;
105   }
106 };
107 
108