[map] Add hb_map_update()

docs/harfbuzz-sections.txt

@@ -546,6 +546,7 @@ hb_map_get_population
 hb_map_is_empty
 hb_map_is_equal
 hb_map_hash
+hb_map_update
 hb_map_next
 HB_MAP_VALUE_INVALID
 hb_map_t

src/hb-map.cc

@@ -341,6 +341,22 @@ hb_map_hash (const hb_map_t *map)
   return map->hash ();
 }
 
+/**
+ * hb_map_update:
+ * @map: A map
+ * @other: Another map
+ *
+ * Add the contents of @other to @map.
+ *
+ * Since: REPLACEME
+ **/
+HB_EXTERN void
+hb_map_update (hb_map_t *map,
+	       const hb_map_t *other)
+{
+  map->update (*other);
+}
+
 /**
  * hb_map_next:
  * @map: A map

src/hb-map.h

@@ -118,6 +118,10 @@ HB_EXTERN hb_bool_t
 hb_map_has (const hb_map_t *map,
 	    hb_codepoint_t  key);
 
+HB_EXTERN void
+hb_map_update (hb_map_t *map,
+	       const hb_map_t *other);
+
 /* Pass -1 in for idx to get started. */
 HB_EXTERN hb_bool_t
 hb_map_next (const hb_map_t *map,

src/hb-map.hh

@@ -308,6 +308,13 @@ struct hb_hashmap_t
 
   unsigned int get_population () const { return population; }
 
+  void update (const hb_hashmap_t &other)
+  {
+    if (unlikely (!successful)) return;
+
+    hb_copy (other, *this);
+  }
+
   /*
    * Iterator
    */

src/test-map.cc

@@ -314,7 +314,7 @@ main (int argc, char **argv)
     hb_codepoint_t k;
     hb_codepoint_t v;
     unsigned pop = 0;
-    for (signed i;
+    for (signed i = -1;
 	 m.next (&i, &k, &v);)
     {
       pop++;
@@ -326,7 +326,19 @@ main (int argc, char **argv)
       else if (k == 6) assert (v == 8);
       else assert (false);
     }
-    assert (pop = m.get_population ());
+    assert (pop == m.get_population ());
+  }
+  /* Test update */
+  {
+    hb_map_t m1, m2;
+    m1.set (1, 2);
+    m1.set (2, 4);
+    m2.set (1, 3);
+
+    m1.update (m2);
+    assert (m1.get_population () == 2);
+    assert (m1[1] == 3);
+    assert (m1[2] == 4);
   }
 
   return 0;