[PairPosFormat1] Use a coverage cache as well

Speeds up Arial shaping by 3%.

src/OT/Layout/GPOS/PairPosFormat1.hh

@@ -103,11 +103,50 @@ struct PairPosFormat1_3
 
   const Coverage &get_coverage () const { return this+coverage; }
 
-  bool apply (hb_ot_apply_context_t *c) const
+  unsigned cache_cost () const
+  {
+    return (this+coverage).cost ();
+  }
+  static void * cache_func (void *p, hb_ot_lookup_cache_op_t op)
+  {
+    switch (op)
+    {
+      case hb_ot_lookup_cache_op_t::CREATE:
+      {
+	hb_ot_lookup_cache_t *cache = (hb_ot_lookup_cache_t *) hb_malloc (sizeof (hb_ot_lookup_cache_t));
+	if (likely (cache))
+	  cache->clear ();
+	return cache;
+      }
+      case hb_ot_lookup_cache_op_t::ENTER:
+	return (void *) true;
+      case hb_ot_lookup_cache_op_t::LEAVE:
+	return nullptr;
+      case hb_ot_lookup_cache_op_t::DESTROY:
+	{
+	  hb_ot_lookup_cache_t *cache = (hb_ot_lookup_cache_t *) p;
+	  hb_free (cache);
+	  return nullptr;
+	}
+    }
+  }
+
+  bool apply_cached (hb_ot_apply_context_t *c) const { return _apply (c, true); }
+  bool apply (hb_ot_apply_context_t *c) const { return _apply (c, false); }
+  bool _apply (hb_ot_apply_context_t *c, bool cached) const
   {
     TRACE_APPLY (this);
+
+#ifndef HB_NO_OT_LAYOUT_LOOKUP_CACHE
+    hb_ot_lookup_cache_t *cache = cached ? (hb_ot_lookup_cache_t *) c->lookup_accel->cache : nullptr;
+#endif
+
     hb_buffer_t *buffer = c->buffer;
+#ifndef HB_NO_OT_LAYOUT_LOOKUP_CACHE
+    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint, cache);
+#else
     unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
+#endif
     if (likely (index == NOT_COVERED)) return_trace (false);
 
     hb_ot_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
@@ -156,7 +195,7 @@ struct PairPosFormat1_3
         strip = true;
       newFormats = compute_effective_value_formats (glyphset, strip, true);
     }
-    
+
     out->valueFormat[0] = newFormats.first;
     out->valueFormat[1] = newFormats.second;