90 lines
1.8 KiB
C
90 lines
1.8 KiB
C
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#include "hashtable.h"
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#include <stdlib.h>
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#include <string.h>
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#define INIT_SIZE 64
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static
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unsigned long hash(const char *s)
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{
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unsigned long h = 0;
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while (*s)
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h = (h << 5) + h + (unsigned char)*s++;
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return h;
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}
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NAMED *lookup(HASH_TABLE *table, const char *name, size_t createSize)
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{
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size_t i;
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if (table->size == 0) {
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if (!createSize)
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return 0;
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table->v = calloc(INIT_SIZE, sizeof(NAMED *));
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if (!table->v)
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return 0;
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table->size = INIT_SIZE;
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table->usedLim = INIT_SIZE / 2;
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i = hash(name) & (table->size - 1);
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}
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else {
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unsigned long h = hash(name);
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for (i = h & (table->size - 1);
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table->v[i];
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i == 0 ? i = table->size - 1 : --i) {
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if (strcmp(name, table->v[i]->name) == 0)
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return table->v[i];
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}
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if (!createSize)
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return 0;
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if (table->used == table->usedLim) {
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/* check for overflow */
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size_t newSize = table->size * 2;
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NAMED **newV = calloc(newSize, sizeof(NAMED *));
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if (!newV)
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return 0;
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for (i = 0; i < table->size; i++)
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if (table->v[i]) {
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size_t j;
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for (j = hash(table->v[i]->name) & (newSize - 1);
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newV[j];
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j == 0 ? j = newSize - 1 : --j)
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;
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newV[j] = table->v[i];
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}
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free(table->v);
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table->v = newV;
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table->size = newSize;
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table->usedLim = newSize/2;
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for (i = h & (table->size - 1);
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table->v[i];
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i == 0 ? i = table->size - 1 : --i)
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;
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}
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}
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table->v[i] = calloc(1, createSize);
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if (!table->v[i])
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return 0;
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table->v[i]->name = name;
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(table->used)++;
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return table->v[i];
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}
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void hashTableDestroy(HASH_TABLE *table)
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{
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size_t i;
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for (i = 0; i < table->size; i++) {
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NAMED *p = table->v[i];
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if (p)
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free(p);
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}
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free(table->v);
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}
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void hashTableInit(HASH_TABLE *p)
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{
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p->size = 0;
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p->usedLim = 0;
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p->used = 0;
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p->v = 0;
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}
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