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Comparing deliantra/server/include/shstr.h (file contents):
Revision 1.1 by root, Fri Feb 3 07:12:50 2006 UTC vs.
Revision 1.20 by root, Thu Nov 8 19:43:25 2007 UTC

1/* The size of the shared strings hashtable. This must be smaller than 1/*
2 * 32767, but 947 ought to be plenty enough. 2 * This file is part of Deliantra, the Roguelike Realtime MMORPG.
3 *
4 * Copyright (©) 2005,2006,2007 Marc Alexander Lehmann / Robin Redeker / the Deliantra team
5 *
6 * Deliantra is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 *
19 * The authors can be reached via e-mail to <support@deliantra.net>
3 */ 20 */
4#define TABLESIZE 4133
5 21
6/* This specifies how many characters the hashing routine should look at. 22#ifndef SHSTR_H__
7 * You may actually save CPU by increasing this number if the typical string 23#define SHSTR_H__
8 * is large. 24
9 */ 25#include <sstream>
10#ifndef MAXSTRING 26
11#define MAXSTRING 20 27#include "util.h"
28
29extern size_t shstr_alloc;
30
31extern int buf_overflow (const char *buf1, const char *buf2, int bufsize);
32
33struct shstr
34{
35 static const char *null;
36
37 const char *s;
38
39 static int &refcnt (const char *s)
40 {
41 return *((int *)s - 1);
42 }
43
44 static int &length (const char *s)
45 {
46 return *((int *)s - 2);
47 }
48
49 int &refcnt () const
50 {
51 return refcnt (s);
52 }
53
54 int length () const
55 {
56 return length (s);
57 }
58
59 // returns wether this shared string begins with the given prefix,
60 // used mainly for searched when users give only the start of a name.
61 bool begins_with (const char *prefix) const
62 {
63 int plen = strlen (prefix);
64 return !strncasecmp (s, prefix, plen) && length () >= plen;
65 }
66
67 static const char *find (const char *s);
68 static const char *intern (const char *s);
69
70 static void gc (); // garbage collect a few strings
71
72 // this is used for informational messages and the like
73 const char *operator &() const { return s; }
74
75 const char &operator [](int i) const { return s[i]; }
76 operator const char *() const { return s == null ? 0 : s; }
77
78 shstr ()
79 : s (null)
80 {
81 }
82
83 shstr (const shstr &sh)
84 : s (sh.s)
85 {
86 ++refcnt ();
87 }
88
89 explicit shstr (const char *s)
90 : s (intern (s))
91 {
92 }
93
94 ~shstr ()
95 {
96 --refcnt ();
97 }
98
99 const shstr &operator =(const shstr &sh)
100 {
101 --refcnt ();
102 s = sh.s;
103 ++refcnt ();
104
105 return *this;
106 }
107
108 const shstr &operator =(const char *str)
109 {
110 --refcnt ();
111
112 // this optimises the important case of str == constant 0
113 if (is_constant (str))
114 s = str ? intern (str) : null;
115 else
116 s = intern (str);
117
118 return *this;
119 }
120
121 bool operator ==(const shstr &b)
122 {
123 return s == b.s;
124 }
125
126 bool operator !=(const shstr &b)
127 {
128 return !(*this == b);
129 }
130};
131
132inline int strlen (const shstr &sh)
133{
134 return sh.length ();
135}
136
137inline int strcmp (const shstr &a, const shstr &b)
138{
139 // TODO: use this to find all the occurences of people using strcmp
140 // all uses should be bogus, as we should be never interested in
141 // comparing shstr's alphabetically
142#if 0
143 extern void do_not_use_strcmp_to_compare_shstr_values ();
144 do_not_use_strcmp_to_compare_shstr_values ();
145#endif
146 return a != b;
147}
148
149static std::ostream &operator <<(std::ostream &o, const shstr &sh)
150{
151 o.write (sh.s, sh.length ());
152 return o;
153}
154
155// only good for mass comparisons to shstr objects
156struct shstr_cmp
157{
158 const char *s;
159
160 explicit shstr_cmp (const char *s)
161 : s (shstr::find (s))
162 {
163 }
164
165 shstr_cmp (const shstr_cmp &sh)
166 : s (sh.s)
167 {
168 }
169
170 shstr_cmp &operator =(const shstr_cmp sh) { s = sh.s; return *this; }
171 operator const char *() const { return s; }
172};
173
174inline bool operator ==(const shstr_cmp &a, const shstr &b)
175{
176 return a.s == b.s;
177}
178
179inline bool operator ==(const shstr &a, const shstr_cmp &b)
180{
181 return b == a;
182}
183
184#define def(str) extern const shstr shstr_ ## str;
185# include "shstrinc.h"
186#undef def
187
12#endif 188#endif
13 189
14/* In the unlikely occurence that 16383 references to a string are too
15 * few, you can modify the below type to something bigger.
16 * (The top bit of "refcount" is used to signify that "u.array" points
17 * at the array entry.)
18 */
19#define REFCOUNT_TYPE int
20
21/* The offsetof macro is part of ANSI C, but many compilers lack it, for
22 * example "gcc -ansi"
23 */
24#if !defined (offsetof)
25#define offsetof(type, member) (int)&(((type *)0)->member)
26#endif
27
28/* SS(string) will return the address of the shared_string struct which
29 * contains "string".
30 */
31#define SS(x) ((shared_string *) ((x) - offsetof(shared_string, string)))
32
33#define SS_STATISTICS
34
35#define SS_DUMP_TABLE 1
36#define SS_DUMP_TOTALS 2
37
38#ifdef SS_STATISTICS
39static struct statistics {
40 int calls;
41 int hashed;
42 int strcmps;
43 int search;
44 int linked;
45} add_stats, add_ref_stats, free_stats, find_stats, hash_stats;
46#define GATHER(n) (++n)
47#else /* !SS_STATISTICS */
48#define GATHER(n)
49#endif /* SS_STATISTICS */
50
51#define TOPBIT ((unsigned REFCOUNT_TYPE) 1 << (sizeof(REFCOUNT_TYPE) * CHAR_BIT - 1))
52
53#define PADDING ((2 * sizeof(long) - sizeof(REFCOUNT_TYPE)) % sizeof(long)) + 1
54
55typedef struct _shared_string {
56 union {
57 struct _shared_string **array;
58 struct _shared_string *previous;
59 } u;
60 struct _shared_string *next;
61 /* The top bit of "refcount" is used to signify that "u.array" points
62 * at the array entry.
63 */
64 unsigned REFCOUNT_TYPE refcount;
65 /* Padding will be unused memory, since we can't know how large
66 * the padding when allocating memory. We assume here that
67 * sizeof(long) is a good boundary.
68 */
69 char string[PADDING];
70} shared_string;

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