BLI: support checking if two maps are the same

source/blender/blenlib/BLI_map.hh

@@ -1015,6 +1015,33 @@ class Map {
     return this->count_collisions__impl(key, hash_(key));
   }
 
+  /**
+   * True if both maps have the same key-value-pairs.
+   */
+  friend bool operator==(const Map &a, const Map &b)
+  {
+    if (a.size() != b.size()) {
+      return false;
+    }
+    for (const Item item : a.items()) {
+      const Key &key = item.key;
+      const Value &value_a = item.value;
+      const Value *value_b = b.lookup_ptr(key);
+      if (value_b == nullptr) {
+        return false;
+      }
+      if (value_a != *value_b) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  friend bool operator!=(const Map &a, const Map &b)
+  {
+    return !(a == b);
+  }
+
  private:
   BLI_NOINLINE void realloc_and_reinsert(int64_t min_usable_slots)
   {

source/blender/blenlib/BLI_multi_value_map.hh

@@ -21,6 +21,7 @@
  */
 
 #include "BLI_map.hh"
+#include "BLI_struct_equality_utils.hh"
 #include "BLI_vector.hh"
 
 namespace blender {
@@ -157,6 +158,8 @@ template<typename Key, typename Value> class MultiValueMap {
   {
     map_.clear_and_shrink();
   }
+
+  BLI_STRUCT_EQUALITY_OPERATORS_1(MultiValueMap, map_)
 };
 
 }  // namespace blender

source/blender/blenlib/tests/BLI_map_test.cc

@@ -694,6 +694,22 @@ TEST(map, VectorKey)
   EXPECT_EQ(map.size(), 1);
 }
 
+TEST(map, Equality)
+{
+  Map<int, int> a;
+  Map<int, int> b;
+
+  EXPECT_EQ(a, b);
+  a.add(3, 4);
+  EXPECT_NE(a, b);
+  b.add(3, 4);
+  EXPECT_EQ(a, b);
+
+  a.add(4, 10);
+  b.add(4, 11);
+  EXPECT_NE(a, b);
+}
+
 /**
  * Set this to 1 to activate the benchmark. It is disabled by default, because it prints a lot.
  */