| 1 | /* The size of the shared strings hashtable. This must be smaller than |
1 | #ifndef SHSTR_H__ |
| 2 | * 32767, but 947 ought to be plenty enough. |
2 | #define SHSTR_H__ |
| 3 | */ |
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| 4 | #define TABLESIZE 4133 |
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| 5 | |
3 | |
| 6 | /* This specifies how many characters the hashing routine should look at. |
4 | extern int buf_overflow(const char *buf1, const char *buf2, int bufsize); |
| 7 | * You may actually save CPU by increasing this number if the typical string |
5 | |
| 8 | * is large. |
6 | struct shstr |
| 9 | */ |
7 | { |
| 10 | #ifndef MAXSTRING |
8 | const char *s; |
| 11 | #define MAXSTRING 20 |
9 | |
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10 | static int &refcnt (const char *s) |
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11 | { |
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12 | return *((int *)s - 1); |
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13 | } |
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14 | |
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15 | static int &length (const char *s) |
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16 | { |
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17 | return *((int *)s - 2); |
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18 | } |
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19 | |
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20 | int &refcnt () const |
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21 | { |
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22 | return refcnt (s); |
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23 | } |
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24 | |
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25 | int length () const |
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26 | { |
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27 | return s ? length (s) : 0; |
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28 | } |
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29 | |
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30 | static const char *find (const char *s); |
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31 | static const char *intern (const char *s); |
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32 | |
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33 | static void gc (); // garbage collect a few strings |
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34 | |
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35 | // this is used for informational messages and the like |
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36 | const char *operator &() const { return s ? s : "<nil>"; } |
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37 | |
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38 | const char &operator [](int i) const { return s[i]; } |
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39 | operator const char *() const { return s; } |
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40 | |
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41 | shstr () |
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42 | : s (0) |
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43 | { |
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44 | } |
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45 | |
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46 | shstr (const shstr &sh) |
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47 | : s (sh.s) |
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48 | { |
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49 | if (s) ++refcnt (); |
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50 | } |
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51 | |
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52 | explicit shstr (const char *s) |
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53 | : s (intern (s)) |
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54 | { |
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55 | } |
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56 | |
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57 | ~shstr () |
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58 | { |
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59 | if (s) --refcnt (); |
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60 | } |
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61 | |
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62 | const shstr &operator =(const shstr &sh) |
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63 | { |
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64 | if (s) --refcnt (); |
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65 | s = sh.s; |
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66 | if (s) ++refcnt (); |
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67 | |
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68 | return *this; |
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69 | } |
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70 | |
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71 | const shstr &operator =(const char *str) |
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72 | { |
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73 | if (s) --refcnt (); |
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74 | s = intern (str); |
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75 | |
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76 | return *this; |
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77 | } |
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78 | }; |
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79 | |
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80 | inline int strlen (const shstr &sh) |
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81 | { |
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82 | return sh.length (); |
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83 | } |
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84 | |
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85 | inline bool operator ==(const shstr &a, const shstr &b) |
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86 | { |
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87 | return a.s == b.s; |
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88 | } |
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89 | |
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90 | inline bool operator !=(const shstr &a, const shstr &b) |
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91 | { |
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92 | return !(a == b); |
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93 | } |
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94 | |
| 12 | #endif |
95 | #endif |
| 13 | |
96 | |
| 14 | /* In the unlikely occurence that 16383 references to a string are too |
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| 15 | * few, you can modify the below type to something bigger. |
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| 16 | * (The top bit of "refcount" is used to signify that "u.array" points |
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| 17 | * at the array entry.) |
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| 18 | */ |
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| 19 | #define REFCOUNT_TYPE int |
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| 20 | |
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| 21 | /* The offsetof macro is part of ANSI C, but many compilers lack it, for |
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| 22 | * example "gcc -ansi" |
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| 23 | */ |
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| 24 | #if !defined (offsetof) |
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| 25 | #define offsetof(type, member) (int)&(((type *)0)->member) |
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| 26 | #endif |
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| 27 | |
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| 28 | /* SS(string) will return the address of the shared_string struct which |
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| 29 | * contains "string". |
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| 30 | */ |
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| 31 | #define SS(x) ((shared_string *) ((x) - offsetof(shared_string, string))) |
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| 32 | |
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| 33 | #define SS_STATISTICS |
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| 34 | |
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| 35 | #define SS_DUMP_TABLE 1 |
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| 36 | #define SS_DUMP_TOTALS 2 |
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| 37 | |
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| 38 | #ifdef SS_STATISTICS |
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| 39 | static struct statistics { |
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| 40 | int calls; |
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| 41 | int hashed; |
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| 42 | int strcmps; |
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| 43 | int search; |
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| 44 | int linked; |
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| 45 | } add_stats, add_ref_stats, free_stats, find_stats, hash_stats; |
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| 46 | #define GATHER(n) (++n) |
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| 47 | #else /* !SS_STATISTICS */ |
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| 48 | #define GATHER(n) |
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| 49 | #endif /* SS_STATISTICS */ |
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| 50 | |
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| 51 | #define TOPBIT ((unsigned REFCOUNT_TYPE) 1 << (sizeof(REFCOUNT_TYPE) * CHAR_BIT - 1)) |
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| 52 | |
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| 53 | #define PADDING ((2 * sizeof(long) - sizeof(REFCOUNT_TYPE)) % sizeof(long)) + 1 |
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| 54 | |
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| 55 | typedef struct _shared_string { |
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| 56 | union { |
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| 57 | struct _shared_string **array; |
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| 58 | struct _shared_string *previous; |
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| 59 | } u; |
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| 60 | struct _shared_string *next; |
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| 61 | /* The top bit of "refcount" is used to signify that "u.array" points |
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| 62 | * at the array entry. |
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| 63 | */ |
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| 64 | unsigned REFCOUNT_TYPE refcount; |
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| 65 | /* Padding will be unused memory, since we can't know how large |
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| 66 | * the padding when allocating memory. We assume here that |
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| 67 | * sizeof(long) is a good boundary. |
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| 68 | */ |
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| 69 | char string[PADDING]; |
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| 70 | } shared_string; |
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