[gtk/wip/otte/sortlistmodel: 32/33] Add a timsort() implementation
- From: Benjamin Otte <otte src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gtk/wip/otte/sortlistmodel: 32/33] Add a timsort() implementation
- Date: Sat, 11 Jul 2020 03:49:57 +0000 (UTC)
commit 0d87d7849d772922538fc6c95b5a06b6a7916b60
Author: Benjamin Otte <otte redhat com>
Date: Sat Jul 11 05:37:31 2020 +0200
Add a timsort() implementation
gtk/gtktimsort-impl.c | 944 ++++++++++++++++++++++++++++++++++++++++++++++
gtk/gtktimsort.c | 204 ++++++++++
gtk/gtktimsortprivate.h | 106 ++++++
gtk/meson.build | 1 +
testsuite/gtk/meson.build | 1 +
testsuite/gtk/timsort.c | 159 ++++++++
6 files changed, 1415 insertions(+)
---
diff --git a/gtk/gtktimsort-impl.c b/gtk/gtktimsort-impl.c
new file mode 100644
index 0000000000..e6f9f3bba6
--- /dev/null
+++ b/gtk/gtktimsort-impl.c
@@ -0,0 +1,944 @@
+/*
+ * Copyright (C) 2020 Benjamin Otte
+ * Copyright (C) 2011 Patrick O. Perry
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef NAME
+#define NAME WIDTH
+#endif
+
+#define DEFINE_TEMP(temp) gpointer temp = g_alloca (WIDTH)
+#define ASSIGN(x, y) memcpy (x, y, WIDTH)
+#define INCPTR(x) ((gpointer) ((char *) (x) + WIDTH))
+#define DECPTR(x) ((gpointer) ((char *) (x) - WIDTH))
+#define ELEM(a, i) ((char *) (a) + (i) * WIDTH)
+#define LEN(n) ((n) * WIDTH)
+
+#define CONCAT(x, y) gtk_tim_sort_ ## x ## _ ## y
+#define MAKE_STR(x, y) CONCAT (x, y)
+#define gtk_tim_sort(x) MAKE_STR (x, NAME)
+
+/*
+ * Reverse the specified range of the specified array.
+ *
+ * @param a the array in which a range is to be reversed
+ * @param hi the index after the last element in the range to be reversed
+ */
+static void gtk_tim_sort(reverse_range) (GtkTimSort *self,
+ gpointer a,
+ gsize hi)
+{
+ DEFINE_TEMP (t);
+ char *front = a;
+ char *back = ELEM (a, hi - 1);
+
+ g_assert (hi > 0);
+
+ while (front < back)
+ {
+ ASSIGN (t, front);
+ ASSIGN (front, back);
+ ASSIGN (back, t);
+ front = INCPTR (front);
+ back = DECPTR (back);
+ }
+}
+
+/*
+ * Returns the length of the run beginning at the specified position in
+ * the specified array and reverses the run if it is descending (ensuring
+ * that the run will always be ascending when the method returns).
+ *
+ * A run is the longest ascending sequence with:
+ *
+ * a[0] <= a[1] <= a[2] <= ...
+ *
+ * or the longest descending sequence with:
+ *
+ * a[0] > a[1] > a[2] > ...
+ *
+ * For its intended use in a stable mergesort, the strictness of the
+ * definition of "descending" is needed so that the call can safely
+ * reverse a descending sequence without violating stability.
+ *
+ * @param a the array in which a run is to be counted and possibly reversed
+ * @param hi index after the last element that may be contained in the run.
+ * It is required that {@code 0 < hi}.
+ * @param compare the comparator to used for the sort
+ * @return the length of the run beginning at the specified position in
+ * the specified array
+ */
+static gsize
+gtk_tim_sort(prepare_run) (GtkTimSort *self)
+{
+ gsize run_hi = 1;
+ char *cur;
+ char *next;
+
+ if (self->size <= run_hi)
+ return self->size;
+
+ cur = INCPTR (self->base);
+ next = INCPTR (cur);
+ run_hi++;
+
+ /* Find end of run, and reverse range if descending */
+ if (gtk_tim_sort_compare (self, cur, self->base) < 0) /* Descending */
+ {
+ while (run_hi < self->size && gtk_tim_sort_compare (self, next, cur) < 0)
+ {
+ run_hi++;
+ cur = next;
+ next = INCPTR (next);
+ }
+ gtk_tim_sort(reverse_range) (self, self->base, run_hi);
+ }
+ else /* Ascending */
+ {
+ while (run_hi < self->size && gtk_tim_sort_compare (self, next, cur) >= 0)
+ {
+ run_hi++;
+ cur = next;
+ next = INCPTR (next);
+ }
+ }
+
+ return run_hi;
+}
+
+/*
+ * Sorts the specified portion of the specified array using a binary
+ * insertion sort. This is the best method for sorting small numbers
+ * of elements. It requires O(n log n) compares, but O(n^2) data
+ * movement (worst case).
+ *
+ * If the initial part of the specified range is already sorted,
+ * this method can take advantage of it: the method assumes that the
+ * elements from index {@code lo}, inclusive, to {@code start},
+ * exclusive are already sorted.
+ *
+ * @param a the array in which a range is to be sorted
+ * @param hi the index after the last element in the range to be sorted
+ * @param start the index of the first element in the range that is
+ * not already known to be sorted ({@code lo <= start <= hi})
+ */
+static void gtk_tim_sort(binary_sort) (GtkTimSort *self,
+ gpointer a,
+ gsize hi,
+ gsize start)
+{
+ DEFINE_TEMP (pivot);
+ char *startp;
+
+ g_assert (start <= hi);
+
+ if (start == 0)
+ start++;
+
+ startp = ELEM (a, start);
+
+ for (; start < hi; start++, startp = INCPTR (startp))
+ {
+ /* Set left (and right) to the index where a[start] (pivot) belongs */
+ char *leftp = a;
+ gsize right = start;
+ gsize n;
+
+ /*
+ * Invariants:
+ * pivot >= all in [0, left).
+ * pivot < all in [right, start).
+ */
+ while (0 < right)
+ {
+ gsize mid = right >> 1;
+ gpointer midp = ELEM (leftp, mid);
+ if (gtk_tim_sort_compare (self, startp, midp) < 0)
+ {
+ right = mid;
+ }
+ else
+ {
+ leftp = INCPTR (midp);
+ right -= (mid + 1);
+ }
+ }
+ g_assert (0 == right);
+
+ /*
+ * The invariants still hold: pivot >= all in [lo, left) and
+ * pivot < all in [left, start), so pivot belongs at left. Note
+ * that if there are elements equal to pivot, left points to the
+ * first slot after them -- that's why this sort is stable.
+ * Slide elements over to make room to make room for pivot.
+ */
+ n = startp - leftp; /* The number of bytes to move */
+
+ ASSIGN (pivot, startp);
+ memmove (INCPTR (leftp), leftp, n); /* POP: overlaps */
+
+ /* a[left] = pivot; */
+ ASSIGN (leftp, pivot);
+ }
+}
+
+static gboolean
+gtk_tim_sort(merge_append) (GtkTimSort *self)
+{
+ /* Identify next run */
+ gsize run_len;
+
+ run_len = gtk_tim_sort(prepare_run) (self);
+ if (run_len == 0)
+ return FALSE;
+
+ /* If run is short, extend to min(self->min_run, self->size) */
+ if (run_len < self->min_run)
+ {
+ gsize force = MIN (self->size, self->min_run);
+ gtk_tim_sort(binary_sort) (self, self->base, force, run_len);
+ run_len = force;
+ }
+ /* Push run onto pending-run stack, and maybe merge */
+ gtk_tim_sort_push_run (self, self->base, run_len);
+
+ /* Advance to find next run */
+ self->base = ELEM (self->base, run_len);
+ self->size -= run_len;
+
+ return TRUE;
+}
+
+#if 0
+static int gtk_tim_sort(timsort) (void *a, gsize nel)
+{
+ int err = SUCCESS;
+ GtkTimSort self;
+ gsize self->min_run;
+
+ g_assert (a || !nel || !width);
+ g_assert (c);
+
+ if (nel < 2 || !width)
+ return err; /* Arrays of size 0 and 1 are always sorted */
+
+ /* If array is small, do a "mini-TimSort" with no merges */
+ if (nel < MIN_MERGE)
+ {
+ gsize initRunLen =
+ gtk_tim_sort(prepare_run) (a, nel, CMPARGS (c, carg));
+ gtk_tim_sort(binary_sort) (self, a, nel, initRunLen, CMPARGS (c, carg));
+ return err;
+ }
+
+ /*
+ * March over the array once, left to right, finding natural runs,
+ * extending short natural runs to self->min_run elements, and merging runs
+ * to maintain stack invariant.
+ */
+ if ((err = timsort_init (&self, a, nel, CMPARGS (c, carg))))
+ return err;
+
+ do
+ {
+ /* Identify next run */
+ gsize run_len =
+ gtk_tim_sort(prepare_run) (a, nel, CMPARGS (c, carg));
+
+ /* If run is short, extend to min(self->min_run, nel) */
+ if (run_len < self->min_run)
+ {
+ gsize force = nel <= self->min_run ? nel : self->min_run;
+ gtk_tim_sort(binary_sort) (a, force, run_len, CMPARGS (c, carg));
+ run_len = force;
+ }
+ /* Push run onto pending-run stack, and maybe merge */
+ gtk_tim_sort_push_run (&self, a, run_len);
+ if ((err = gtk_tim_sort(mergeCollapse) (&self)))
+ goto out;
+
+ /* Advance to find next run */
+ a = ELEM (a, run_len);
+ nel -= run_len;
+ }
+ while (nel != 0);
+
+ /* Merge all remaining runs to complete sort */
+ if ((err = gtk_tim_sort(merge_force_collapse) (&self)))
+ goto out;
+
+ g_assert (self.pending_runs == 1);
+out:
+ timsort_deinit (&self);
+ return err;
+}
+#endif
+
+/*
+ * Locates the position at which to insert the specified key into the
+ * specified sorted range; if the range contains an element equal to key,
+ * returns the index of the leftmost equal element.
+ *
+ * @param key the key whose insertion point to search for
+ * @param base the array in which to search
+ * @param len the length of the range; must be > 0
+ * @param hint the index at which to begin the search, 0 <= hint < n.
+ * The closer hint is to the result, the faster this method will run.
+ * @param c the comparator used to order the range, and to search
+ * @return the int k, 0 <= k <= n such that a[b + k - 1] < key <= a[b + k],
+ * pretending that a[b - 1] is minus infinity and a[b + n] is infinity.
+ * In other words, key belongs at index b + k; or in other words,
+ * the first k elements of a should precede key, and the last n - k
+ * should follow it.
+ */
+static gsize
+gtk_tim_sort(gallop_left) (GtkTimSort *self,
+ gpointer key,
+ gpointer base,
+ gsize len,
+ gsize hint)
+{
+ char *hintp = ELEM (base, hint);
+ gsize last_ofs = 0;
+ gsize ofs = 1;
+
+ g_assert (len > 0 && hint < len);
+ if (gtk_tim_sort_compare (self, key, hintp) > 0)
+ {
+ /* Gallop right until a[hint+last_ofs] < key <= a[hint+ofs] */
+ gsize max_ofs = len - hint;
+ while (ofs < max_ofs
+ && gtk_tim_sort_compare (self, key, ELEM (hintp, ofs)) > 0)
+ {
+ last_ofs = ofs;
+ ofs = (ofs << 1) + 1; /* eventually this becomes SIZE_MAX */
+ }
+ if (ofs > max_ofs)
+ ofs = max_ofs;
+
+ /* Make offsets relative to base */
+ last_ofs += hint + 1; /* POP: we add 1 here so last_ofs stays non-negative */
+ ofs += hint;
+ }
+ else /* key <= a[hint] */
+ /* Gallop left until a[hint-ofs] < key <= a[hint-last_ofs] */
+ {
+ const gsize max_ofs = hint + 1;
+ gsize tmp;
+ while (ofs < max_ofs
+ && gtk_tim_sort_compare (self, key, ELEM (hintp, -ofs)) <= 0)
+ {
+ last_ofs = ofs;
+ ofs = (ofs << 1) + 1; /* no need to check for overflow */
+ }
+ if (ofs > max_ofs)
+ ofs = max_ofs;
+
+ /* Make offsets relative to base */
+ tmp = last_ofs;
+ last_ofs = hint + 1 - ofs; /* POP: we add 1 here so last_ofs stays non-negative */
+ ofs = hint - tmp;
+ }
+ g_assert (last_ofs <= ofs && ofs <= len);
+
+ /*
+ * Now a[last_ofs-1] < key <= a[ofs], so key belongs somewhere
+ * to the right of last_ofs but no farther right than ofs. Do a binary
+ * search, with invariant a[last_ofs - 1] < key <= a[ofs].
+ */
+ /* last_ofs++; POP: we added 1 above to keep last_ofs non-negative */
+ while (last_ofs < ofs)
+ {
+ /*gsize m = last_ofs + ((ofs - last_ofs) >> 1); */
+ /* http://stackoverflow.com/questions/4844165/safe-integer-middle-value-formula */
+ gsize m = (last_ofs & ofs) + ((last_ofs ^ ofs) >> 1);
+
+ if (gtk_tim_sort_compare (self, key, ELEM (base, m)) > 0)
+ last_ofs = m + 1; /* a[m] < key */
+ else
+ ofs = m; /* key <= a[m] */
+ }
+ g_assert (last_ofs == ofs); /* so a[ofs - 1] < key <= a[ofs] */
+ return ofs;
+}
+
+/*
+ * Like gallop_left, except that if the range contains an element equal to
+ * key, gallop_right returns the index after the rightmost equal element.
+ *
+ * @param key the key whose insertion point to search for
+ * @param base the array in which to search
+ * @param len the length of the range; must be > 0
+ * @param hint the index at which to begin the search, 0 <= hint < n.
+ * The closer hint is to the result, the faster this method will run.
+ * @param c the comparator used to order the range, and to search
+ * @return the int k, 0 <= k <= n such that a[b + k - 1] <= key < a[b + k]
+ */
+static gsize
+gtk_tim_sort(gallop_right) (GtkTimSort *self,
+ gpointer key,
+ gpointer base,
+ gsize len,
+ gsize hint)
+{
+ char *hintp = ELEM (base, hint);
+ gsize ofs = 1;
+ gsize last_ofs = 0;
+
+ g_assert (len > 0 && hint < len);
+
+ if (gtk_tim_sort_compare (self, key, hintp) < 0)
+ {
+ /* Gallop left until a[hint - ofs] <= key < a[hint - last_ofs] */
+ gsize max_ofs = hint + 1;
+ gsize tmp;
+ while (ofs < max_ofs
+ && gtk_tim_sort_compare (self, key, ELEM (hintp, -ofs)) < 0)
+ {
+ last_ofs = ofs;
+ ofs = (ofs << 1) + 1; /* no need to check for overflow */
+ }
+ if (ofs > max_ofs)
+ ofs = max_ofs;
+
+ /* Make offsets relative to base */
+ tmp = last_ofs;
+ last_ofs = hint + 1 - ofs;
+ ofs = hint - tmp;
+ }
+ else /* a[hint] <= key */
+ /* Gallop right until a[hint + last_ofs] <= key < a[hint + ofs] */
+ {
+ gsize max_ofs = len - hint;
+ while (ofs < max_ofs
+ && gtk_tim_sort_compare (self, key, ELEM (hintp, ofs)) >= 0)
+ {
+ last_ofs = ofs;
+ ofs = (ofs << 1) + 1; /* no need to check for overflow */
+ }
+ if (ofs > max_ofs)
+ ofs = max_ofs;
+
+ /* Make offsets relative to base */
+ last_ofs += hint + 1;
+ ofs += hint;
+ }
+ g_assert (last_ofs <= ofs && ofs <= len);
+
+ /*
+ * Now a[last_ofs - 1] <= key < a[ofs], so key belongs somewhere to
+ * the right of last_ofs but no farther right than ofs. Do a binary
+ * search, with invariant a[last_ofs - 1] <= key < a[ofs].
+ */
+ while (last_ofs < ofs)
+ {
+ /* gsize m = last_ofs + ((ofs - last_ofs) >> 1); */
+ gsize m = (last_ofs & ofs) + ((last_ofs ^ ofs) >> 1);
+
+ if (gtk_tim_sort_compare (self, key, ELEM (base, m)) < 0)
+ ofs = m; /* key < a[m] */
+ else
+ last_ofs = m + 1; /* a[m] <= key */
+ }
+ g_assert (last_ofs == ofs); /* so a[ofs - 1] <= key < a[ofs] */
+ return ofs;
+}
+
+/*
+ * Merges two adjacent runs in place, in a stable fashion. The first
+ * element of the first run must be greater than the first element of the
+ * second run (a[base1] > a[base2]), and the last element of the first run
+ * (a[base1 + len1-1]) must be greater than all elements of the second run.
+ *
+ * For performance, this method should be called only when len1 <= len2;
+ * its twin, merge_hi should be called if len1 >= len2. (Either method
+ * may be called if len1 == len2.)
+ *
+ * @param base1 first element in first run to be merged
+ * @param len1 length of first run to be merged (must be > 0)
+ * @param base2 first element in second run to be merged
+ * (must be aBase + aLen)
+ * @param len2 length of second run to be merged (must be > 0)
+ */
+static void
+gtk_tim_sort(merge_lo) (GtkTimSort *self,
+ gpointer base1,
+ gsize len1,
+ gpointer base2,
+ gsize len2)
+{
+ /* Copy first run into temp array */
+ gpointer tmp = gtk_tim_sort_ensure_capacity (self, len1);
+ char *cursor1;
+ char *cursor2;
+ char *dest;
+ gsize min_gallop;
+
+ g_assert (len1 > 0 && len2 > 0 && ELEM (base1, len1) == base2);
+
+ /* System.arraycopy(a, base1, tmp, 0, len1); */
+ memcpy (tmp, base1, LEN (len1)); /* POP: can't overlap */
+
+ cursor1 = tmp; /* Indexes into tmp array */
+ cursor2 = base2; /* Indexes int a */
+ dest = base1; /* Indexes int a */
+
+ /* Move first element of second run and deal with degenerate cases */
+ /* a[dest++] = a[cursor2++]; */
+ ASSIGN (dest, cursor2);
+ dest = INCPTR (dest);
+ cursor2 = INCPTR (cursor2);
+
+ if (--len2 == 0)
+ {
+ memcpy (dest, cursor1, LEN (len1)); /* POP: can't overlap */
+ return;
+ }
+ if (len1 == 1)
+ {
+ memmove (dest, cursor2, LEN (len2)); /* POP: overlaps */
+
+ /* a[dest + len2] = tmp[cursor1]; // Last elt of run 1 to end of merge */
+ ASSIGN (ELEM (dest, len2), cursor1);
+ return;
+ }
+
+ /* Use local variable for performance */
+ min_gallop = self->min_gallop;
+
+ while (TRUE)
+ {
+ gsize count1 = 0; /* Number of times in a row that first run won */
+ gsize count2 = 0; /* Number of times in a row that second run won */
+
+ /*
+ * Do the straightforward thing until (if ever) one run starts
+ * winning consistently.
+ */
+ do
+ {
+ g_assert (len1 > 1 && len2 > 0);
+ if (gtk_tim_sort_compare (self, cursor2, cursor1) < 0)
+ {
+ ASSIGN (dest, cursor2);
+ dest = INCPTR (dest);
+ cursor2 = INCPTR (cursor2);
+ count2++;
+ count1 = 0;
+ if (--len2 == 0)
+ goto outer;
+ if (count2 >= min_gallop)
+ break;
+ }
+ else
+ {
+ ASSIGN (dest, cursor1);
+ dest = INCPTR (dest);
+ cursor1 = INCPTR (cursor1);
+ count1++;
+ count2 = 0;
+ if (--len1 == 1)
+ goto outer;
+ if (count1 >= min_gallop)
+ break;
+ }
+ }
+ while (TRUE); /* (count1 | count2) < min_gallop); */
+
+ /*
+ * One run is winning so consistently that galloping may be a
+ * huge win. So try that, and continue galloping until (if ever)
+ * neither run appears to be winning consistently anymore.
+ */
+ do
+ {
+ g_assert (len1 > 1 && len2 > 0);
+ count1 = gtk_tim_sort(gallop_right) (self, cursor2, cursor1, len1, 0);
+ if (count1 != 0)
+ {
+ memcpy (dest, cursor1, LEN (count1)); /* POP: can't overlap */
+ dest = ELEM (dest, count1);
+ cursor1 = ELEM (cursor1, count1);
+ len1 -= count1;
+ if (len1 <= 1) /* len1 == 1 || len1 == 0 */
+ goto outer;
+ }
+ ASSIGN (dest, cursor2);
+ dest = INCPTR (dest);
+ cursor2 = INCPTR (cursor2);
+ if (--len2 == 0)
+ goto outer;
+
+ count2 = gtk_tim_sort(gallop_left) (self, cursor1, cursor2, len2, 0);
+ if (count2 != 0)
+ {
+ memmove (dest, cursor2, LEN (count2)); /* POP: might overlap */
+ dest = ELEM (dest, count2);
+ cursor2 = ELEM (cursor2, count2);
+ len2 -= count2;
+ if (len2 == 0)
+ goto outer;
+ }
+ ASSIGN (dest, cursor1);
+ dest = INCPTR (dest);
+ cursor1 = INCPTR (cursor1);
+ if (--len1 == 1)
+ goto outer;
+ if (min_gallop > 0)
+ min_gallop--;
+ }
+ while (count1 >= MIN_GALLOP || count2 >= MIN_GALLOP);
+ min_gallop += 2; /* Penalize for leaving gallop mode */
+ } /* End of "outer" loop */
+outer:
+ self->min_gallop = min_gallop < 1 ? 1 : min_gallop; /* Write back to field */
+
+ if (len1 == 1)
+ {
+ g_assert (len2 > 0);
+ memmove (dest, cursor2, LEN (len2)); /* POP: might overlap */
+ ASSIGN (ELEM (dest, len2), cursor1); /* Last elt of run 1 to end of merge */
+ }
+ else if (len1 == 0)
+ {
+ g_critical ("Comparison method violates its general contract");
+ return;
+ }
+ else
+ {
+ g_assert (len2 == 0);
+ g_assert (len1 > 1);
+ memcpy (dest, cursor1, LEN (len1)); /* POP: can't overlap */
+ }
+}
+
+/*
+ * Like merge_lo, except that this method should be called only if
+ * len1 >= len2; merge_lo should be called if len1 <= len2. (Either method
+ * may be called if len1 == len2.)
+ *
+ * @param base1 first element in first run to be merged
+ * @param len1 length of first run to be merged (must be > 0)
+ * @param base2 first element in second run to be merged
+ * (must be aBase + aLen)
+ * @param len2 length of second run to be merged (must be > 0)
+ */
+static void
+gtk_tim_sort(merge_hi) (GtkTimSort *self,
+ gpointer base1,
+ gsize len1,
+ gpointer base2,
+ gsize len2)
+{
+ /* Copy second run into temp array */
+ gpointer tmp = gtk_tim_sort_ensure_capacity (self, len2);
+ char *cursor1; /* Indexes into a */
+ char *cursor2; /* Indexes into tmp array */
+ char *dest; /* Indexes into a */
+ gsize min_gallop;
+
+ g_assert (len1 > 0 && len2 > 0 && ELEM (base1, len1) == base2);
+
+ memcpy (tmp, base2, LEN (len2)); /* POP: can't overlap */
+
+ cursor1 = ELEM (base1, len1 - 1); /* Indexes into a */
+ cursor2 = ELEM (tmp, len2 - 1); /* Indexes into tmp array */
+ dest = ELEM (base2, len2 - 1); /* Indexes into a */
+
+ /* Move last element of first run and deal with degenerate cases */
+ /* a[dest--] = a[cursor1--]; */
+ ASSIGN (dest, cursor1);
+ dest = DECPTR (dest);
+ cursor1 = DECPTR (cursor1);
+ if (--len1 == 0)
+ {
+ memcpy (ELEM (dest, -(len2 - 1)), tmp, LEN (len2)); /* POP: can't overlap */
+ return;
+ }
+ if (len2 == 1)
+ {
+ dest = ELEM (dest, -len1);
+ cursor1 = ELEM (cursor1, -len1);
+ memmove (ELEM (dest, 1), ELEM (cursor1, 1), LEN (len1)); /* POP: overlaps */
+ /* a[dest] = tmp[cursor2]; */
+ ASSIGN (dest, cursor2);
+ return;
+ }
+
+ /* Use local variable for performance */
+ min_gallop = self->min_gallop;
+
+ while (TRUE)
+ {
+ gsize count1 = 0; /* Number of times in a row that first run won */
+ gsize count2 = 0; /* Number of times in a row that second run won */
+
+ /*
+ * Do the straightforward thing until (if ever) one run
+ * appears to win consistently.
+ */
+ do
+ {
+ g_assert (len1 > 0 && len2 > 1);
+ if (gtk_tim_sort_compare (self, cursor2, cursor1) < 0)
+ {
+ ASSIGN (dest, cursor1);
+ dest = DECPTR (dest);
+ cursor1 = DECPTR (cursor1);
+ count1++;
+ count2 = 0;
+ if (--len1 == 0)
+ goto outer;
+ }
+ else
+ {
+ ASSIGN (dest, cursor2);
+ dest = DECPTR (dest);
+ cursor2 = DECPTR (cursor2);
+ count2++;
+ count1 = 0;
+ if (--len2 == 1)
+ goto outer;
+ }
+ }
+ while ((count1 | count2) < min_gallop);
+
+ /*
+ * One run is winning so consistently that galloping may be a
+ * huge win. So try that, and continue galloping until (if ever)
+ * neither run appears to be winning consistently anymore.
+ */
+ do
+ {
+ g_assert (len1 > 0 && len2 > 1);
+ count1 = len1 - gtk_tim_sort(gallop_right) (self, cursor2, base1, len1, len1 - 1);
+ if (count1 != 0)
+ {
+ dest = ELEM (dest, -count1);
+ cursor1 = ELEM (cursor1, -count1);
+ len1 -= count1;
+ memmove (INCPTR (dest), INCPTR (cursor1),
+ LEN (count1)); /* POP: might overlap */
+ if (len1 == 0)
+ goto outer;
+ }
+ ASSIGN (dest, cursor2);
+ dest = DECPTR (dest);
+ cursor2 = DECPTR (cursor2);
+ if (--len2 == 1)
+ goto outer;
+
+ count2 = len2 - gtk_tim_sort(gallop_left) (self, cursor1, tmp, len2, len2 - 1);
+ if (count2 != 0)
+ {
+ dest = ELEM (dest, -count2);
+ cursor2 = ELEM (cursor2, -count2);
+ len2 -= count2;
+ memcpy (INCPTR (dest), INCPTR (cursor2), LEN (count2)); /* POP: can't overlap */
+ if (len2 <= 1) /* len2 == 1 || len2 == 0 */
+ goto outer;
+ }
+ ASSIGN (dest, cursor1);
+ dest = DECPTR (dest);
+ cursor1 = DECPTR (cursor1);
+ if (--len1 == 0)
+ goto outer;
+ if (min_gallop > 0)
+ min_gallop--;
+ }
+ while (count1 >= MIN_GALLOP || count2 >= MIN_GALLOP);
+ min_gallop += 2; /* Penalize for leaving gallop mode */
+ } /* End of "outer" loop */
+outer:
+ self->min_gallop = min_gallop < 1 ? 1 : min_gallop; /* Write back to field */
+
+ if (len2 == 1)
+ {
+ g_assert (len1 > 0);
+ dest = ELEM (dest, -len1);
+ cursor1 = ELEM (cursor1, -len1);
+ memmove (INCPTR (dest), INCPTR (cursor1), LEN (len1)); /* POP: might overlap */
+ /* a[dest] = tmp[cursor2]; // Move first elt of run2 to front of merge */
+ ASSIGN (dest, cursor2);
+ }
+ else if (len2 == 0)
+ {
+ g_critical ("Comparison method violates its general contract");
+ return;
+ }
+ else
+ {
+ g_assert (len1 == 0);
+ g_assert (len2 > 0);
+ memcpy (ELEM (dest, -(len2 - 1)), tmp, LEN (len2)); /* POP: can't overlap */
+ }
+}
+
+/*
+ * Merges the two runs at stack indices i and i+1. Run i must be
+ * the penultimate or antepenultimate run on the stack. In other words,
+ * i must be equal to pending_runs-2 or pending_runs-3.
+ *
+ * @param i stack index of the first of the two runs to merge
+ */
+static void
+gtk_tim_sort(merge_at) (GtkTimSort *self,
+ gsize i)
+{
+ gpointer base1 = self->run[i].base;
+ gsize len1 = self->run[i].len;
+ gpointer base2 = self->run[i + 1].base;
+ gsize len2 = self->run[i + 1].len;
+ gsize k;
+
+ g_assert (self->pending_runs >= 2);
+ g_assert (i == self->pending_runs - 2 || i == self->pending_runs - 3);
+ g_assert (len1 > 0 && len2 > 0);
+ g_assert (ELEM (base1, len1) == base2);
+
+ /*
+ * Record the length of the combined runs; if i is the 3rd-last
+ * run now, also slide over the last run (which isn't involved
+ * in this merge). The current run (i+1) goes away in any case.
+ */
+ self->run[i].len = len1 + len2;
+ if (i == self->pending_runs - 3)
+ {
+ self->run[i + 1] = self->run[i + 2];
+ }
+ self->pending_runs--;
+
+ /*
+ * Find where the first element of run2 goes in run1. Prior elements
+ * in run1 can be ignored (because they're already in place).
+ */
+ k = gtk_tim_sort(gallop_right) (self, base2, base1, len1, 0);
+ base1 = ELEM (base1, k);
+ len1 -= k;
+ if (len1 == 0)
+ return;
+
+ /*
+ * Find where the last element of run1 goes in run2. Subsequent elements
+ * in run2 can be ignored (because they're already in place).
+ */
+ len2 = gtk_tim_sort(gallop_left) (self,
+ ELEM (base1, len1 - 1),
+ base2, len2, len2 - 1);
+ if (len2 == 0)
+ return;
+
+ /* Merge remaining runs, using tmp array with min(len1, len2) elements */
+ if (len1 <= len2)
+ gtk_tim_sort(merge_lo) (self, base1, len1, base2, len2);
+ else
+ gtk_tim_sort(merge_hi) (self, base1, len1, base2, len2);
+}
+
+
+/*
+ * Examines the stack of runs waiting to be merged and merges adjacent runs
+ * until the stack invariants are reestablished:
+ *
+ * 1. run_len[i - 3] > run_len[i - 2] + run_len[i - 1]
+ * 2. run_len[i - 2] > run_len[i - 1]
+ *
+ * This method is called each time a new run is pushed onto the stack,
+ * so the invariants are guaranteed to hold for i < pending_runs upon
+ * entry to the method.
+ *
+ * POP:
+ * Modified according to http://envisage-project.eu/wp-content/uploads/2015/02/sorting.pdf
+ *
+ * and
+ *
+ * https://bugs.openjdk.java.net/browse/JDK-8072909 (suggestion 2)
+ *
+ */
+static gboolean
+gtk_tim_sort(merge_collapse) (GtkTimSort *self)
+{
+ GtkTimSortRun *run = self->run;
+ gsize n;
+
+ if (self->pending_runs <= 1)
+ return FALSE;
+
+ n = self->pending_runs - 2;
+ if ((n > 0 && run[n - 1].len <= run[n].len + run[n + 1].len) ||
+ (n > 1 && run[n - 2].len <= run[n].len + run[n - 1].len))
+ {
+ if (run[n - 1].len < run[n + 1].len)
+ n--;
+ }
+ else if (run[n].len > run[n + 1].len)
+ {
+ return FALSE; /* Invariant is established */
+ }
+
+ gtk_tim_sort(merge_at) (self, n);
+ return TRUE;
+}
+
+/*
+ * Merges all runs on the stack until only one remains. This method is
+ * called once, to complete the sort.
+ */
+static gboolean
+gtk_tim_sort(merge_force_collapse) (GtkTimSort *self)
+{
+ gsize n;
+
+ if (self->pending_runs <= 1)
+ return FALSE;
+
+ n = self->pending_runs - 2;
+ if (n > 0 && self->run[n - 1].len < self->run[n + 1].len)
+ n--;
+ gtk_tim_sort(merge_at) (self, n);
+ return TRUE;
+}
+
+static gboolean
+gtk_tim_sort(step) (GtkTimSort * self)
+{
+ g_assert (self);
+
+ if (gtk_tim_sort(merge_collapse) (self))
+ return TRUE;
+
+ if (gtk_tim_sort(merge_append) (self))
+ return TRUE;
+
+ if (gtk_tim_sort(merge_force_collapse) (self))
+ return TRUE;
+
+ return FALSE;
+}
+
+#undef DEFINE_TEMP
+#undef ASSIGN
+#undef INCPTR
+#undef DECPTR
+#undef ELEM
+#undef LEN
+
+#undef CONCAT
+#undef MAKE_STR
+#undef gtk_tim_sort
+
+#undef WIDTH
+#undef NAME
diff --git a/gtk/gtktimsort.c b/gtk/gtktimsort.c
new file mode 100644
index 0000000000..451a63a902
--- /dev/null
+++ b/gtk/gtktimsort.c
@@ -0,0 +1,204 @@
+/* Lots of code for an adaptive, stable, natural mergesort. There are many
+ * pieces to this algorithm; read listsort.txt for overviews and details.
+ */
+
+#include "config.h"
+
+#include "gtktimsortprivate.h"
+
+/*
+ * This is the minimum sized sequence that will be merged. Shorter
+ * sequences will be lengthened by calling binarySort. If the entire
+ * array is less than this length, no merges will be performed.
+ *
+ * This constant should be a power of two. It was 64 in Tim Peter's C
+ * implementation, but 32 was empirically determined to work better in
+ * [Android's Java] implementation. In the unlikely event that you set
+ * this constant to be a number that's not a power of two, you'll need
+ * to change the compute_min_run() computation.
+ *
+ * If you decrease this constant, you must change the
+ * GTK_TIM_SORT_MAX_PENDING value, or you risk running out of space.
+ * See Python's listsort.txt for a discussion of the minimum stack
+ * length required as a function of the length of the array being sorted and
+ * the minimum merge sequence length.
+ */
+#define MIN_MERGE 32
+
+
+/*
+ * When we get into galloping mode, we stay there until both runs win less
+ * often than MIN_GALLOP consecutive times.
+ */
+#define MIN_GALLOP 7
+
+/*
+ * Returns the minimum acceptable run length for an array of the specified
+ * length. Natural runs shorter than this will be extended with binary sort.
+ *
+ * Roughly speaking, the computation is:
+ *
+ * If n < MIN_MERGE, return n (it's too small to bother with fancy stuff).
+ * Else if n is an exact power of 2, return MIN_MERGE/2.
+ * Else return an int k, MIN_MERGE/2 <= k <= MIN_MERGE, such that n/k
+ * is close to, but strictly less than, an exact power of 2.
+ *
+ * For the rationale, see listsort.txt.
+ *
+ * @param n the length of the array to be sorted
+ * @return the length of the minimum run to be merged
+ */
+static gsize
+compute_min_run (gsize n)
+{
+ gsize r = 0; // Becomes 1 if any 1 bits are shifted off
+
+ while (n >= MIN_MERGE) {
+ r |= (n & 1);
+ n >>= 1;
+ }
+ return n + r;
+}
+
+void
+gtk_tim_sort_init (GtkTimSort *self,
+ gpointer base,
+ gsize size,
+ gsize element_size,
+ GCompareDataFunc compare_func,
+ gpointer data)
+{
+ self->element_size = element_size;
+ self->base = base;
+ self->size = size;
+ self->compare_func = compare_func;
+ self->data = data;
+
+ self->min_gallop = MIN_GALLOP;
+ self->min_run = compute_min_run (size);
+
+ self->tmp = NULL;
+ self->tmp_length = 0;
+ self->pending_runs = 0;
+}
+
+void
+gtk_tim_sort_finish (GtkTimSort *self)
+{
+ g_free (self->tmp);
+}
+
+void
+gtk_tim_sort (gpointer base,
+ gsize size,
+ gsize element_size,
+ GCompareDataFunc compare_func,
+ gpointer user_data)
+{
+ GtkTimSort self;
+
+ gtk_tim_sort_init (&self, base, size, element_size, compare_func, user_data);
+
+ while (gtk_tim_sort_step (&self));
+
+ gtk_tim_sort_finish (&self);
+}
+
+static inline int
+gtk_tim_sort_compare (GtkTimSort *self,
+ gpointer a,
+ gpointer b)
+{
+ return self->compare_func (a, b, self->data);
+}
+
+
+/**
+ * Pushes the specified run onto the pending-run stack.
+ *
+ * @param runBase index of the first element in the run
+ * @param runLen the number of elements in the run
+ */
+static void
+gtk_tim_sort_push_run (GtkTimSort *self,
+ void *base,
+ gsize len)
+{
+ g_assert (self->pending_runs < GTK_TIM_SORT_MAX_PENDING);
+
+ self->run[self->pending_runs].base = base;
+ self->run[self->pending_runs].len = len;
+ self->pending_runs++;
+}
+
+/**
+ * Ensures that the external array tmp has at least the specified
+ * number of elements, increasing its size if necessary. The size
+ * increases exponentially to ensure amortized linear time complexity.
+ *
+ * @param min_capacity the minimum required capacity of the tmp array
+ * @return tmp, whether or not it grew
+ */
+static gpointer
+gtk_tim_sort_ensure_capacity (GtkTimSort *self,
+ gsize min_capacity)
+{
+ if (self->tmp_length < min_capacity)
+ {
+ /* Compute smallest power of 2 > min_capacity */
+ gsize new_size = min_capacity;
+ new_size |= new_size >> 1;
+ new_size |= new_size >> 2;
+ new_size |= new_size >> 4;
+ new_size |= new_size >> 8;
+ new_size |= new_size >> 16;
+ if (sizeof(new_size) > 4)
+ new_size |= new_size >> 32;
+
+ new_size++;
+ if (new_size == 0) /* (overflow) Not bloody likely! */
+ new_size = min_capacity;
+
+ g_free (self->tmp);
+ self->tmp_length = new_size;
+ self->tmp = g_malloc (self->tmp_length * self->element_size);
+ }
+
+ return self->tmp;
+}
+
+#if 1
+#define WIDTH 4
+#include "gtktimsort-impl.c"
+
+#define WIDTH 8
+#include "gtktimsort-impl.c"
+
+#define WIDTH 16
+#include "gtktimsort-impl.c"
+#endif
+
+#define NAME default
+#define WIDTH (self->element_size)
+#include "gtktimsort-impl.c"
+
+gboolean
+gtk_tim_sort_step (GtkTimSort *self)
+{
+ g_assert (self);
+
+ switch (self->element_size)
+ {
+#if 1
+ case 4:
+ return gtk_tim_sort_step_4 (self);
+ case 8:
+ return gtk_tim_sort_step_8 (self);
+ case 16:
+ return gtk_tim_sort_step_16 (self);
+#endif
+ default:
+ return gtk_tim_sort_step_default(self);
+ }
+}
+
diff --git a/gtk/gtktimsortprivate.h b/gtk/gtktimsortprivate.h
new file mode 100644
index 0000000000..d44c74c470
--- /dev/null
+++ b/gtk/gtktimsortprivate.h
@@ -0,0 +1,106 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __GTK_TIMSORT_PRIVATE_H__
+#define __GTK_TIMSORT_PRIVATE_H__
+
+#include <gdk/gdk.h>
+
+/* The maximum number of entries in a GtkTimState's pending-runs stack.
+ * This is enough to sort arrays of size up to about
+ * 32 * phi ** GTK_TIM_SORT_MAX_PENDING
+ * where phi ~= 1.618. 85 is ridiculously large enough, good for an array
+ * with 2**64 elements.
+ */
+#define GTK_TIM_SORT_MAX_PENDING 86
+
+typedef struct _GtkTimSort GtkTimSort;
+typedef struct _GtkTimSortRun GtkTimSortRun;
+
+struct _GtkTimSortRun
+{
+ void *base;
+ gsize len;
+};
+
+struct _GtkTimSort
+{
+ /*
+ * Size of elements. Used to decide on fast paths.
+ */
+ gsize element_size;
+
+ /* The comparator for this sort.
+ */
+ GCompareDataFunc compare_func;
+ gpointer data;
+
+ /*
+ * The array being sorted.
+ */
+ gpointer base;
+ gsize size;
+
+ /*
+ * This controls when we get *into* galloping mode. It is initialized
+ * to MIN_GALLOP. The mergeLo and mergeHi methods nudge it higher for
+ * random data, and lower for highly structured data.
+ */
+ gsize min_gallop;
+
+ /*
+ * The minimum run length. See compute_min_run() for details.
+ */
+ gsize min_run;
+
+ /*
+ * Temp storage for merges.
+ */
+ void *tmp;
+ gsize tmp_length;
+
+ /*
+ * A stack of pending runs yet to be merged. Run i starts at
+ * address base[i] and extends for len[i] elements. It's always
+ * true (so long as the indices are in bounds) that:
+ *
+ * runBase[i] + runLen[i] == runBase[i + 1]
+ *
+ * so we could cut the storage for this, but it's a minor amount,
+ * and keeping all the info explicit simplifies the code.
+ */
+ gsize pending_runs; // Number of pending runs on stack
+ GtkTimSortRun run[GTK_TIM_SORT_MAX_PENDING];
+};
+
+void gtk_tim_sort_init (GtkTimSort *self,
+ gpointer base,
+ gsize size,
+ gsize element_size,
+ GCompareDataFunc compare_func,
+ gpointer data);
+void gtk_tim_sort_finish (GtkTimSort *self);
+
+gboolean gtk_tim_sort_step (GtkTimSort *self);
+
+void gtk_tim_sort (gpointer base,
+ gsize size,
+ gsize element_size,
+ GCompareDataFunc compare_func,
+ gpointer user_data);
+
+#endif /* __GTK_TIMSORT_PRIVATE_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index 3f386b4771..bb77ced30f 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -141,6 +141,7 @@ gtk_private_sources = files([
'gtktextbtree.c',
'gtktexthistory.c',
'gtktextviewchild.c',
+ 'gtktimsort.c',
'gtktrashmonitor.c',
'gtktreedatalist.c',
])
diff --git a/testsuite/gtk/meson.build b/testsuite/gtk/meson.build
index 44a344ffb6..4cda4fd9f9 100644
--- a/testsuite/gtk/meson.build
+++ b/testsuite/gtk/meson.build
@@ -66,6 +66,7 @@ tests = [
['textbuffer'],
['textiter'],
['theme-validate'],
+ ['timsort', ['timsort.c', '../../gtk/gtktimsort.c']],
['tooltips'],
['treelistmodel'],
['treemodel', ['treemodel.c', 'liststore.c', 'treestore.c', 'filtermodel.c',
diff --git a/testsuite/gtk/timsort.c b/testsuite/gtk/timsort.c
new file mode 100644
index 0000000000..3f9a991639
--- /dev/null
+++ b/testsuite/gtk/timsort.c
@@ -0,0 +1,159 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <locale.h>
+
+#include <gtk/gtk.h>
+
+#include "gtk/gtktimsortprivate.h"
+
+#define assert_sort_equal(a, b, size, n) \
+ g_assert_cmpmem (a, sizeof (size) * n, b, sizeof (size) * n)
+
+static int
+compare_int (gconstpointer a,
+ gconstpointer b,
+ gpointer unused)
+{
+ int ia = *(const int *) a;
+ int ib = *(const int *) b;
+
+ return ia < ib ? -1 : (ia > ib);
+}
+
+G_GNUC_UNUSED static void
+dump (int *a,
+ gsize n)
+{
+ gsize i;
+
+ for (i = 0; i < n; i++)
+ {
+ if (i)
+ g_print(", ");
+ g_print ("%d", a[i]);
+ }
+ g_print ("\n");
+}
+
+static void
+run_comparison (gpointer a,
+ gsize n,
+ gsize element_size,
+ GCompareDataFunc compare_func,
+ gpointer data)
+{
+ gint64 start, mid, end;
+ gpointer b;
+
+ b = g_memdup (a, element_size * n);
+
+ start = g_get_monotonic_time ();
+ gtk_tim_sort (a, n, element_size, compare_func, data);
+ mid = g_get_monotonic_time ();
+ g_qsort_with_data (b, n, element_size, compare_func, data);
+ end = g_get_monotonic_time ();
+
+ g_test_message ("%zu items in %ldus vs %ldus (%ld%%)", n, mid - start, end - mid, 100 * (mid - start) /
MAX (1, end - mid));
+ assert_sort_equal (a, b, int, n);
+
+ g_free (b);
+}
+
+static void
+test_integers (void)
+{
+ int *a;
+ gsize i, n, run;
+
+ a = g_new (int, 1000);
+
+ for (run = 0; run < 10; run++)
+ {
+ n = g_test_rand_int_range (0, 1000);
+ for (i = 0; i < n; i++)
+ a[i] = g_test_rand_int ();
+
+ run_comparison (a, n, sizeof (int), compare_int, NULL);
+ }
+
+ g_free (a);
+}
+
+static void
+test_integers_runs (void)
+{
+ int *a;
+ gsize i, j, n, run;
+
+ a = g_new (int, 1000);
+
+ for (run = 0; run < 10; run++)
+ {
+ n = g_test_rand_int_range (0, 1000);
+ for (i = 0; i < n; i++)
+ {
+ a[i] = g_test_rand_int ();
+ j = i + g_test_rand_int_range (0, 20);
+ j = MIN (n, j);
+ if (g_test_rand_bit ())
+ {
+ for (i++; i < j; i++)
+ a[i] = a[i - 1] + 1;
+ }
+ else
+ {
+ for (i++; i < j; i++)
+ a[i] = a[i - 1] - 1;
+ }
+ }
+
+ run_comparison (a, n, sizeof (int), compare_int, NULL);
+ }
+
+ g_free (a);
+}
+
+static void
+test_integers_huge (void)
+{
+ int *a;
+ gsize i, n;
+
+ n = g_test_rand_int_range (5 * 1000 * 1000, 10 * 1000 * 1000);
+
+ a = g_new (int, n);
+ for (i = 0; i < n; i++)
+ a[i] = g_test_rand_int ();
+
+ run_comparison (a, n, sizeof (int), compare_int, NULL);
+
+ g_free (a);
+}
+
+int
+main (int argc, char *argv[])
+{
+ g_test_init (&argc, &argv, NULL);
+ setlocale (LC_ALL, "C");
+
+ g_test_add_func ("/timsort/integers", test_integers);
+ g_test_add_func ("/timsort/integers/runs", test_integers_runs);
+ g_test_add_func ("/timsort/integers/huge", test_integers_huge);
+
+ return g_test_run ();
+}
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