diff options
Diffstat (limited to 'Objects/stringobject.c')
| -rw-r--r-- | Objects/stringobject.c | 136 |
1 files changed, 116 insertions, 20 deletions
diff --git a/Objects/stringobject.c b/Objects/stringobject.c index a3043d4..f66a82c 100644 --- a/Objects/stringobject.c +++ b/Objects/stringobject.c @@ -26,21 +26,76 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. #include "allobjects.h" +#ifdef COUNT_ALLOCS +int null_strings, one_strings; +#endif + +#ifdef __STDC__ +#include <limits.h> +#else +#ifndef UCHAR_MAX +#define UCHAR_MAX 255 +#endif +#endif + +static stringobject *characters[UCHAR_MAX + 1]; +static stringobject *nullstring; + +/* + Newsizedstringobject() and newstringobject() try in certain cases + to share string objects. When the size of the string is zero, + these routines always return a pointer to the same string object; + when the size is one, they return a pointer to an already existing + object if the contents of the string is known. For + newstringobject() this is always the case, for + newsizedstringobject() this is the case when the first argument in + not NULL. + A common practice to allocate a string and then fill it in or + change it must be done carefully. It is only allowed to change the + contents of the string if the obect was gotten from + newsizedstringobject() with a NULL first argument, because in the + future these routines may try to do even more sharing of objects. +*/ object * newsizedstringobject(str, size) char *str; int size; { - register stringobject *op = (stringobject *) + register stringobject *op; + if (size == 0 && (op = nullstring) != NULL) { +#ifdef COUNT_ALLOCS + null_strings++; +#endif + INCREF(op); + return op; + } + if (size == 1 && str != NULL && (op = characters[*str & UCHAR_MAX]) != NULL) { +#ifdef COUNT_ALLOCS + one_strings++; +#endif + INCREF(op); + return op; + } + op = (stringobject *) malloc(sizeof(stringobject) + size * sizeof(char)); if (op == NULL) return err_nomem(); op->ob_type = &Stringtype; op->ob_size = size; +#ifdef CACHE_HASH + op->ob_shash = -1; +#endif NEWREF(op); if (str != NULL) memcpy(op->ob_sval, str, size); op->ob_sval[size] = '\0'; + if (size == 0) { + nullstring = op; + INCREF(op); + } else if (size == 1 && str != NULL) { + characters[*str & UCHAR_MAX] = op; + INCREF(op); + } return (object *) op; } @@ -49,14 +104,39 @@ newstringobject(str) char *str; { register unsigned int size = strlen(str); - register stringobject *op = (stringobject *) + register stringobject *op; + if (size == 0 && (op = nullstring) != NULL) { +#ifdef COUNT_ALLOCS + null_strings++; +#endif + INCREF(op); + return op; + } + if (size == 1 && (op = characters[*str & UCHAR_MAX]) != NULL) { +#ifdef COUNT_ALLOCS + one_strings++; +#endif + INCREF(op); + return op; + } + op = (stringobject *) malloc(sizeof(stringobject) + size * sizeof(char)); if (op == NULL) return err_nomem(); op->ob_type = &Stringtype; op->ob_size = size; +#ifdef CACHE_HASH + op->ob_shash = -1; +#endif NEWREF(op); strcpy(op->ob_sval, str); + if (size == 0) { + nullstring = op; + INCREF(op); + } else if (size == 1) { + characters[*str & UCHAR_MAX] = op; + INCREF(op); + } return (object *) op; } @@ -189,6 +269,9 @@ string_concat(a, bb) return err_nomem(); op->ob_type = &Stringtype; op->ob_size = size; +#ifdef CACHE_HASH + op->ob_shash = -1; +#endif NEWREF(op); memcpy(op->ob_sval, a->ob_sval, (int) a->ob_size); memcpy(op->ob_sval + a->ob_size, b->ob_sval, (int) b->ob_size); @@ -218,6 +301,9 @@ string_repeat(a, n) return err_nomem(); op->ob_type = &Stringtype; op->ob_size = size; +#ifdef CACHE_HASH + op->ob_shash = -1; +#endif NEWREF(op); for (i = 0; i < size; i += a->ob_size) memcpy(op->ob_sval+i, a->ob_sval, (int) a->ob_size); @@ -247,16 +333,6 @@ string_slice(a, i, j) return newsizedstringobject(a->ob_sval + i, (int) (j-i)); } -#ifdef __STDC__ -#include <limits.h> -#else -#ifndef UCHAR_MAX -#define UCHAR_MAX 255 -#endif -#endif - -static object *characters[UCHAR_MAX + 1]; - static object * string_item(a, i) stringobject *a; @@ -269,12 +345,16 @@ string_item(a, i) return NULL; } c = a->ob_sval[i] & UCHAR_MAX; - v = characters[c]; + v = (object *) characters[c]; +#ifdef COUNT_ALLOCS + if (v != NULL) + one_strings++; +#endif if (v == NULL) { v = newsizedstringobject((char *)NULL, 1); if (v == NULL) return NULL; - characters[c] = v; + characters[c] = (stringobject *) v; ((stringobject *)v)->ob_sval[0] = c; } INCREF(v); @@ -287,9 +367,14 @@ string_compare(a, b) { int len_a = a->ob_size, len_b = b->ob_size; int min_len = (len_a < len_b) ? len_a : len_b; - int cmp = memcmp(a->ob_sval, b->ob_sval, min_len); - if (cmp != 0) - return cmp; + int cmp; + if (min_len > 0) { + cmp = *a->ob_sval - *b->ob_sval; + if (cmp == 0) + cmp = memcmp(a->ob_sval, b->ob_sval, min_len); + if (cmp != 0) + return cmp; + } return (len_a < len_b) ? -1 : (len_a > len_b) ? 1 : 0; } @@ -297,14 +382,25 @@ static long string_hash(a) stringobject *a; { - register int len = a->ob_size; - register unsigned char *p = (unsigned char *) a->ob_sval; - register long x = *p << 7; + register int len; + register unsigned char *p; + register long x; + +#ifdef CACHE_HASH + if (a->ob_shash != -1) + return a->ob_shash; +#endif + len = a->ob_size; + p = (unsigned char *) a->ob_sval; + x = *p << 7; while (--len >= 0) x = (x + x + x) ^ *p++; x ^= a->ob_size; if (x == -1) x = -2; +#ifdef CACHE_HASH + a->ob_shash = x; +#endif return x; } |