Initial import

tool/build/lib/interner.c

@@ -0,0 +1,134 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ This program is free software; you can redistribute it and/or modify         │
+│ it under the terms of the GNU General Public License as published by         │
+│ the Free Software Foundation; version 2 of the License.                      │
+│                                                                              │
+│ 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 GNU             │
+│ General Public License for more details.                                     │
+│                                                                              │
+│ You should have received a copy of the GNU General Public License            │
+│ along with this program; if not, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/alg/arraylist.h"
+#include "libc/bits/safemacros.h"
+#include "libc/mem/mem.h"
+#include "libc/str/knuthmultiplicativehash.h"
+#include "libc/str/str.h"
+#include "libc/x/x.h"
+#include "tool/build/lib/interner.h"
+
+#define kInitialItems 16
+
+struct InternerObject {
+  struct Interner pool;
+  size_t i, n;
+  struct InternerHash {
+    unsigned hash; /* 0 means empty */
+    unsigned index;
+  } * p;
+};
+
+static void rehash(struct InternerObject *it) {
+  size_t i, j, n, step;
+  struct InternerHash *p;
+  n = it->n;
+  p = it->p;
+  it->p = xcalloc((it->n <<= 1), sizeof(struct InternerHash));
+  for (i = 0; i < n; ++i) {
+    if (!p[i].hash) continue;
+    step = 0;
+    do {
+      j = (p[i].hash + step * (step + 1) / 2) & (it->n - 1);
+      step++;
+    } while (it->p[j].hash);
+    memcpy(&it->p[j], &p[i], sizeof(p[i]));
+  }
+  free_s(&p);
+}
+
+/**
+ * Creates new interner.
+ */
+struct Interner *newinterner(void) {
+  struct InternerObject *it;
+  it = xcalloc(1, sizeof(*it));
+  it->p = xcalloc((it->n = kInitialItems), sizeof(*it->p));
+  it->pool.p = xcalloc((it->pool.n = kInitialItems), sizeof(*it->pool.p));
+  return &it->pool;
+}
+
+/**
+ * Destroys interner.
+ */
+void freeinterner(struct Interner *t) {
+  struct InternerObject *it = (struct InternerObject *)t;
+  if (it) {
+    free(it->pool.p);
+    free(it->p);
+    free(it);
+  }
+}
+
+/**
+ * Returns number of unique items interned.
+ */
+size_t interncount(const struct Interner *t) {
+  struct InternerObject *it = (struct InternerObject *)t;
+  return it->i;
+}
+
+/**
+ * Interns object.
+ *
+ * @return index into 𝑡→𝑝 holding equal item
+ * @note use consistent size w/ non-string items
+ */
+size_t internobj(struct Interner *t, const void *data, size_t size) {
+  struct InternerObject *it = (struct InternerObject *)t;
+  unsigned hash;
+  size_t i, step;
+  unsigned char *item;
+  step = 0;
+  item = data;
+  hash = max(1, KnuthMultiplicativeHash32(data, size));
+  do {
+    /* it is written that triangle probe halts iff i<n/2 && popcount(n)==1 */
+    i = (hash + step * (step + 1) / 2) & (it->n - 1);
+    if (it->p[i].hash == hash && it->p[i].index + size <= it->pool.n &&
+        memcmp(item, &it->pool.p[it->p[i].index], size) == 0) {
+      return it->p[i].index;
+    }
+    step++;
+  } while (it->p[i].hash);
+  if (++it->i == (it->n >> 1)) {
+    rehash(it);
+    step = 0;
+    do {
+      i = (hash + step * (step + 1) / 2) & (it->n - 1);
+      step++;
+    } while (it->p[i].hash);
+  }
+  it->p[i].hash = hash;
+  return (it->p[i].index = concat(&it->pool, item, size));
+}
+
+/**
+ * Interns string.
+ *
+ * The NUL-terminated string 𝑠 is concatenated to the relocatable
+ * double-NUL terminated string list 𝑡→𝑝 with de-duplication and
+ * preservation of insertion order.
+ *
+ * @return index into 𝑡→𝑝 holding string equal to 𝑠
+ */
+size_t intern(struct Interner *t, const char *s) {
+  return internobj(t, s, strlen(s) + 1);
+}