138 lines
4.8 KiB
C
138 lines
4.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/alg/arraylist.internal.h"
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#include "libc/alg/arraylist2.internal.h"
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#include "libc/bits/safemacros.internal.h"
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#include "libc/mem/mem.h"
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#include "libc/str/knuthmultiplicativehash.h"
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#include "libc/str/str.h"
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#include "libc/x/x.h"
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#include "tool/build/lib/interner.h"
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#define kInitialItems 16
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struct InternerObject {
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struct Interner pool;
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size_t i, n;
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struct InternerHash {
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unsigned hash; /* 0 means empty */
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unsigned index;
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} * p;
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};
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static void rehash(struct InternerObject *it) {
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size_t i, j, n, step;
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struct InternerHash *p;
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n = it->n;
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p = it->p;
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it->p = xcalloc((it->n <<= 1), sizeof(struct InternerHash));
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for (i = 0; i < n; ++i) {
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if (!p[i].hash) continue;
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step = 0;
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do {
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j = (p[i].hash + step * (step + 1) / 2) & (it->n - 1);
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step++;
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} while (it->p[j].hash);
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memcpy(&it->p[j], &p[i], sizeof(p[i]));
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}
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free_s(&p);
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}
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/**
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* Creates new interner.
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*/
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struct Interner *newinterner(void) {
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struct InternerObject *it;
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it = xcalloc(1, sizeof(*it));
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it->p = xcalloc((it->n = kInitialItems), sizeof(*it->p));
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it->pool.p = xcalloc((it->pool.n = kInitialItems), sizeof(*it->pool.p));
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return &it->pool;
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}
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/**
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* Destroys interner.
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*/
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void freeinterner(struct Interner *t) {
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struct InternerObject *it = (struct InternerObject *)t;
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if (it) {
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free(it->pool.p);
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free(it->p);
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free(it);
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}
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}
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/**
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* Returns number of unique items interned.
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*/
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size_t interncount(const struct Interner *t) {
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struct InternerObject *it = (struct InternerObject *)t;
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return it->i;
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}
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/**
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* Interns object.
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*
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* @return index into 𝑡→𝑝 holding equal item
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* @note use consistent size w/ non-string items
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*/
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size_t internobj(struct Interner *t, const void *data, size_t size) {
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char *item;
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unsigned hash;
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size_t i, step;
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struct InternerObject *it;
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step = 0;
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item = data;
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it = (struct InternerObject *)t;
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hash = max(1, KnuthMultiplicativeHash32(data, size));
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do {
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/* it is written that triangle probe halts iff i<n/2 && popcnt(n)==1 */
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i = (hash + step * (step + 1) / 2) & (it->n - 1);
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if (it->p[i].hash == hash && it->p[i].index + size <= it->pool.n &&
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memcmp(item, &it->pool.p[it->p[i].index], size) == 0) {
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return it->p[i].index;
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}
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step++;
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} while (it->p[i].hash);
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if (++it->i == (it->n >> 1)) {
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rehash(it);
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step = 0;
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do {
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i = (hash + step * (step + 1) / 2) & (it->n - 1);
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step++;
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} while (it->p[i].hash);
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}
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it->p[i].hash = hash;
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return (it->p[i].index =
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CONCAT(&it->pool.p, &it->pool.i, &it->pool.n, item, size));
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}
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/**
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* Interns string.
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*
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* The NUL-terminated string 𝑠 is concatenated to the relocatable
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* double-NUL terminated string list 𝑡→𝑝 with de-duplication and
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* preservation of insertion order.
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*
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* @return index into 𝑡→𝑝 holding string equal to 𝑠
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*/
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size_t intern(struct Interner *t, const char *s) {
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return internobj(t, s, strlen(s) + 1);
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}
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