Aryadev Chavali
865ab22fdc
Since most use cases require indexing the data directly, and the macro implies you're retrieving data from it, may as well take the index. If you wanted a pointer to that data, &VEC_GET(vec, index, type) works just fine.
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/* Copyright (C) 2025 Aryadev Chavali
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the Unlicense for details.
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* You may distribute and modify this code under the terms of the Unlicense,
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* which you should have received a copy of along with this program. If not,
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* please go to <https://unlicense.org/>.
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* Created: 2025-08-19
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* Description: Symbol Table implementation
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*/
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#include "../alisp.h"
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#include <malloc.h>
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#include <string.h>
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u64 djb2(sv_t string)
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{
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u64 hash = 5381;
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for (u64 i = 0; i < string.size; ++i)
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hash = string.data[i] + (hash + (hash << 5));
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return hash;
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}
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void sym_table_init(sym_table_t *table)
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{
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table->capacity = MAX(table->capacity, SYM_TABLE_INIT_SIZE);
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table->count = 0;
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vec_init(&table->entries, table->capacity * sizeof(sv_t));
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}
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char *sym_table_find(sym_table_t *table, sv_t sv)
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{
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// Initialise the table if it's not done already
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if (table->entries.capacity == 0)
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sym_table_init(table);
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// TODO: Deal with resizing this when table->count > table->size / 2
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u64 index = djb2(sv) & (table->capacity - 1);
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for (sv_t comp = VEC_GET(&table->entries, index, sv_t); comp.data; index += 1,
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index = index & (table->capacity - 1),
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comp = VEC_GET(&table->entries, index, sv_t))
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// Is it present in the table?
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if (sv.size == comp.size && strncmp(sv.data, comp.data, sv.size) == 0)
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break;
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// we couldn't find it in our linear search (worst case scenario)
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if (!VEC_GET(&table->entries, index, sv_t).data)
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{
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sv_t newsv = sv_copy(sv);
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VEC_GET(&table->entries, index, sv_t) = newsv;
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++table->count;
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}
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return VEC_GET(&table->entries, index, sv_t).data;
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}
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void sym_table_cleanup(sym_table_t *table)
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{
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// kill the data
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sv_t current = {0};
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for (u64 i = 0; i < table->capacity; ++i)
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{
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current = VEC_GET(&table->entries, i, sv_t);
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if (current.data)
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free(current.data);
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}
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// kill the container
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vec_free(&table->entries);
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memset(table, 0, sizeof(*table));
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}
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