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/* Copyright (C) 2025 Aryadev Chavali
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the Unlicense for details.
* You may distribute and modify this code under the terms of the Unlicense,
* which you should have received a copy of along with this program. If not,
* please go to <https://unlicense.org/>.
* Created: 2025-08-19
* Description: Symbol Table implementation
*/
#include "./alisp.h"
#include <malloc.h>
#include <string.h>
u64 djb2(sv_t string)
{
u64 hash = 5381;
for (u64 i = 0; i < string.size; ++i)
hash = string.data[i] + (hash + (hash << 5));
return hash;
}
void sym_table_init(sym_table_t *table)
{
table->capacity = MAX(table->capacity, SYM_TABLE_INIT_SIZE);
table->count = 0;
vec_init(&table->entries, table->capacity * sizeof(sv_t));
}
char *sym_table_find(sym_table_t *table, sv_t sv)
{
// WIP: Deal with resizing this when table->count > table->size / 2
u64 index = djb2(sv) & (table->capacity - 1);
for (sv_t comp = VEC_GET(&table->entries, sv_t)[index]; comp.data; index += 1,
index = index & (table->capacity - 1),
comp = VEC_GET(&table->entries, sv_t)[index])
// Is it present in the table?
if (sv.size == comp.size && strncmp(sv.data, comp.data, sv.size) == 0)
break;
// we couldn't find it in our linear search (worst case scenario)
if (!VEC_GET(&table->entries, sv_t)[index].data)
{
sv_t newsv = sv_copy(sv);
VEC_GET(&table->entries, sv_t)[index] = newsv;
++table->count;
}
return VEC_GET(&table->entries, sv_t)[index].data;
}
void sym_table_cleanup(sym_table_t *table)
{
// kill the data
sv_t current = {0};
for (u64 i = 0; i < table->capacity; ++i)
{
current = VEC_GET(&table->entries, sv_t)[i];
if (current.data)
free(current.data);
}
// kill the container
vec_free(&table->entries);
memset(table, 0, sizeof(*table));
}
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