Minor
diff --git a/src/hb-shaper.cc b/src/hb-shaper.cc
new file mode 100644
index 0000000..a16ffc8
--- /dev/null
+++ b/src/hb-shaper.cc
@@ -0,0 +1,109 @@
+/*
+ * Copyright © 2012 Google, Inc.
+ *
+ * This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#include "hb-private.hh"
+
+#include "hb-shaper-private.hh"
+
+
+static const hb_shaper_pair_t all_shapers[] = {
+#define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},
+#include "hb-shaper-list.hh"
+#undef HB_SHAPER_IMPLEMENT
+};
+
+
+/* Thread-safe, lock-free, shapers */
+
+static const hb_shaper_pair_t *static_shapers;
+
+static
+void free_static_shapers (void)
+{
+ if (unlikely (static_shapers != all_shapers))
+ free ((void *) static_shapers);
+}
+
+const hb_shaper_pair_t *
+_hb_shapers_get (void)
+{
+retry:
+ hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);
+
+ if (unlikely (!shapers))
+ {
+ char *env = getenv ("HB_SHAPER_LIST");
+ if (!env || !*env) {
+ (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
+ return (const hb_shaper_pair_t *) all_shapers;
+ }
+
+ /* Not found; allocate one. */
+ shapers = (hb_shaper_pair_t *) malloc (sizeof (all_shapers));
+ if (unlikely (!shapers)) {
+ (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
+ return (const hb_shaper_pair_t *) all_shapers;
+ }
+
+ memcpy (shapers, all_shapers, sizeof (all_shapers));
+
+ /* Reorder shaper list to prefer requested shapers. */
+ unsigned int i = 0;
+ char *end, *p = env;
+ for (;;) {
+ end = strchr (p, ',');
+ if (!end)
+ end = p + strlen (p);
+
+ for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
+ if (end - p == (int) strlen (shapers[j].name) &&
+ 0 == strncmp (shapers[j].name, p, end - p))
+ {
+ /* Reorder this shaper to position i */
+ struct hb_shaper_pair_t t = shapers[j];
+ memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
+ shapers[i] = t;
+ i++;
+ }
+
+ if (!*end)
+ break;
+ else
+ p = end + 1;
+ }
+
+ if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {
+ free (shapers);
+ goto retry;
+ }
+
+#ifdef HAVE_ATEXIT
+ atexit (free_static_shapers); /* First person registers atexit() callback. */
+#endif
+ }
+
+ return shapers;
+}
