Properly link flecs library

engine/libs/flecs/examples/cpp/relationships/enum_relations/src/main.cpp

@@ -0,0 +1,90 @@
+#include <enum_relations.h>
+#include <stdio.h>
+
+// When an enumeration constant is added to an entity, it is added as a relationship
+// pair where the relationship is the enum type, and the target is the constant. For
+// example, this statement:
+//   e.add(Color::Red)
+//
+// adds this relationship:
+//   (Color, Color::Red)
+//
+// Enums are registered as exclusive relationships, which means that adding an
+// enum constant will replace the previous constant for that enumeration:
+//   e.add(Color::Green)
+//
+//  will replace Color::Red with Color::Green
+
+// Regular enumerations are supported
+enum Tile {
+    Grass, 
+    Sand, 
+    Stone
+};
+
+// Enum classes are supported
+enum class TileStatus {
+    Free,
+    Occupied,
+};
+
+int main(int, char *[]) {
+    flecs::world ecs;
+
+    // Create an entity with (Tile, Stone) and (TileStatus, Free) relationships
+    flecs::entity tile = ecs.entity()
+        .add(Tile::Stone)
+        .add(TileStatus::Free);
+
+    // (Tile, Tile.Stone), (TileStatus, TileStatus.Free)
+    printf("%s\n", tile.type().str().c_str());
+
+    // Replace (TileStatus, Free) with (TileStatus, Occupied)
+    tile.add(TileStatus::Occupied);
+
+    // (Tile, Tile.Stone), (TileStatus, TileStatus.Occupied)
+    printf("%s\n", tile.type().str().c_str());
+
+    // Check if the entity has the Tile relationship and the Tile::Stone pair
+    printf("%s\n", tile.has<Tile>() ? "true" : "false"); // true
+    printf("%s\n", tile.has(Tile::Stone) ? "true" : "false"); // true
+
+    // Get the current value of the enum
+    const Tile* v = tile.get<Tile>();
+    printf("%s\n", (v[0] == Tile::Stone) ? "true" : "false"); // true
+
+    // Create a few more entities that we can query
+    ecs.entity().add(Tile::Grass).add(TileStatus::Free);
+    ecs.entity().add(Tile::Sand).add(TileStatus::Occupied);
+
+    // Iterate all entities with a Tile relationship
+    ecs.filter_builder()
+        .with<Tile>(flecs::Wildcard)
+        .build()
+        .each([&](flecs::iter& it, size_t) {
+            flecs::entity tile_constant = it.pair(1).second();
+            printf("%s\n", tile_constant.path().c_str());
+        });
+
+    // Outputs:
+    //  ::Tile::Stone
+    //  ::Tile::Grass
+    //  ::Tile::Sand
+
+    // Iterate only occupied tiles
+    ecs.filter_builder()
+        .with<Tile>(flecs::Wildcard)
+        .with(TileStatus::Occupied)
+        .build()
+        .each([&](flecs::iter& it, size_t) {
+            flecs::entity tile_constant = it.pair(1).second();
+            printf("%s\n", tile_constant.path().c_str());
+        });
+
+    // Outputs:
+    //  ::Tile::Stone
+    //  ::Tile::Sand
+
+    // Remove any instance of the TileStatus relationship
+    tile.remove<TileStatus>();
+}