SanderMertens#1550 Support C++ enum reflection without meta addon

SanderMertens · web-flow · commit 2fcb2f690c5d · 2025-02-04T17:39:47.000-08:00
diff --git a/distr/flecs.c b/distr/flecs.c
@@ -4356,6 +4356,14 @@ void flecs_bootstrap(
     /* Run bootstrap functions for other parts of the code */
     flecs_bootstrap_hierarchy(world);
 
+    /* Register constant tag */
+    ecs_component(world, {
+        .entity = ecs_entity(world, { .id = EcsConstant,
+            .name = "constant", .symbol = "EcsConstant",
+            .add = ecs_ids(ecs_pair(EcsOnInstantiate, EcsDontInherit))
+        })
+    });
+
     ecs_set_scope(world, 0);
     ecs_set_name_prefix(world, NULL);
 
@@ -18500,10 +18508,11 @@ const ecs_entity_t ecs_id(EcsVector) =              FLECS_HI_COMPONENT_ID + 107;
 const ecs_entity_t ecs_id(EcsOpaque) =              FLECS_HI_COMPONENT_ID + 108;
 const ecs_entity_t ecs_id(EcsUnit) =                FLECS_HI_COMPONENT_ID + 109;
 const ecs_entity_t ecs_id(EcsUnitPrefix) =          FLECS_HI_COMPONENT_ID + 110;
-const ecs_entity_t EcsConstant =                    FLECS_HI_COMPONENT_ID + 111;
 const ecs_entity_t EcsQuantity =                    FLECS_HI_COMPONENT_ID + 112;
 #endif
 
+const ecs_entity_t EcsConstant =                    FLECS_HI_COMPONENT_ID + 111;
+
 /* Doc module components */
 #ifdef FLECS_DOC
 const ecs_entity_t ecs_id(EcsDocDescription) =      FLECS_HI_COMPONENT_ID + 113;
@@ -22344,7 +22353,6 @@ ecs_entity_t ecs_cpp_enum_constant_register(
     ecs_entity_t value_type,
     size_t value_size)
 {
-#ifdef FLECS_META
     ecs_suspend_readonly_state_t readonly_state;
     world = flecs_suspend_readonly(world, &readonly_state);
 
@@ -22374,6 +22382,7 @@ ecs_entity_t ecs_cpp_enum_constant_register(
 
     flecs_resume_readonly(world, &readonly_state);
 
+#ifdef FLECS_META
     if (ecs_should_log(0)) {
         ecs_value_t v = { .type = value_type, .ptr = value };
         char *str = NULL;
@@ -22384,19 +22393,9 @@ ecs_entity_t ecs_cpp_enum_constant_register(
             ecs_get_name(world, parent), name, str);
         ecs_os_free(str);
     }
+#endif
 
     return id;
-#else
-    (void)world;
-    (void)parent;
-    (void)id;
-    (void)name;
-    (void)value;
-    (void)value_type;
-    (void)value_size;
-    ecs_err("enum reflection not supported without FLECS_META addon");
-    return 0;
-#endif
 }
 
 #ifdef FLECS_META
@@ -51983,13 +51982,6 @@ void FlecsMetaImport(
         .type.alignment = ECS_ALIGNOF(EcsPrimitive)
     });
 
-    ecs_component(world, {
-        .entity = ecs_entity(world, { .id = EcsConstant,
-            .name = "constant", .symbol = "EcsConstant",
-            .add = ecs_ids(ecs_pair(EcsOnInstantiate, EcsDontInherit))
-        })
-    });
-
     ecs_component(world, {
         .entity = ecs_entity(world, { .id = ecs_id(EcsEnum),
             .name = "enum", .symbol = "EcsEnum",
diff --git a/distr/flecs.h b/distr/flecs.h
@@ -5157,6 +5157,8 @@ FLECS_API extern const ecs_entity_t EcsOnStore;     /**< OnStore pipeline phase.
 FLECS_API extern const ecs_entity_t EcsPostFrame;   /**< PostFrame pipeline phase. */
 FLECS_API extern const ecs_entity_t EcsPhase;       /**< Phase pipeline phase. */
 
+FLECS_API extern const ecs_entity_t EcsConstant;    /**< Tag added to enum/bitmask constants. */
+
 /** Value used to quickly check if component is builtin. This is used to quickly
  * filter out tables with builtin components (for example for ecs_delete()) */
 #define EcsLastInternalComponentId (ecs_id(EcsPoly))
@@ -15634,7 +15636,6 @@ FLECS_API extern const ecs_entity_t ecs_id(EcsVector);          /**< Id for comp
 FLECS_API extern const ecs_entity_t ecs_id(EcsOpaque);          /**< Id for component that stores reflection data for an opaque type. */
 FLECS_API extern const ecs_entity_t ecs_id(EcsUnit);            /**< Id for component that stores unit data. */
 FLECS_API extern const ecs_entity_t ecs_id(EcsUnitPrefix);      /**< Id for component that stores unit prefix data. */
-FLECS_API extern const ecs_entity_t EcsConstant;                /**< Tag added to enum/bitmask constants. */
 FLECS_API extern const ecs_entity_t EcsQuantity;                /**< Tag added to unit quantities. */
 
 /* Primitive type component ids */
@@ -17332,6 +17333,7 @@ static const flecs::entity_t Monitor = EcsMonitor;
 static const flecs::entity_t System = EcsSystem;
 static const flecs::entity_t Pipeline = ecs_id(EcsPipeline);
 static const flecs::entity_t Phase = EcsPhase;
+static const flecs::entity_t Constant = EcsConstant;
 
 /* Builtin event tags */
 static const flecs::entity_t OnAdd = EcsOnAdd;
@@ -19230,7 +19232,6 @@ static const flecs::entity_t F32 = ecs_id(ecs_f32_t);
 static const flecs::entity_t F64 = ecs_id(ecs_f64_t);
 static const flecs::entity_t String = ecs_id(ecs_string_t);
 static const flecs::entity_t Entity = ecs_id(ecs_entity_t);
-static const flecs::entity_t Constant = EcsConstant;
 static const flecs::entity_t Quantity = EcsQuantity;
 
 namespace meta {
diff --git a/include/flecs.h b/include/flecs.h
@@ -1859,6 +1859,8 @@ FLECS_API extern const ecs_entity_t EcsOnStore;     /**< OnStore pipeline phase.
 FLECS_API extern const ecs_entity_t EcsPostFrame;   /**< PostFrame pipeline phase. */
 FLECS_API extern const ecs_entity_t EcsPhase;       /**< Phase pipeline phase. */
 
+FLECS_API extern const ecs_entity_t EcsConstant;    /**< Tag added to enum/bitmask constants. */
+
 /** Value used to quickly check if component is builtin. This is used to quickly
  * filter out tables with builtin components (for example for ecs_delete()) */
 #define EcsLastInternalComponentId (ecs_id(EcsPoly))
diff --git a/include/flecs/addons/cpp/c_types.hpp b/include/flecs/addons/cpp/c_types.hpp
@@ -84,6 +84,7 @@ static const flecs::entity_t Monitor = EcsMonitor;
 static const flecs::entity_t System = EcsSystem;
 static const flecs::entity_t Pipeline = ecs_id(EcsPipeline);
 static const flecs::entity_t Phase = EcsPhase;
+static const flecs::entity_t Constant = EcsConstant;
 
 /* Builtin event tags */
 static const flecs::entity_t OnAdd = EcsOnAdd;
diff --git a/include/flecs/addons/cpp/mixins/meta/decl.hpp b/include/flecs/addons/cpp/mixins/meta/decl.hpp
@@ -72,7 +72,6 @@ static const flecs::entity_t F32 = ecs_id(ecs_f32_t);
 static const flecs::entity_t F64 = ecs_id(ecs_f64_t);
 static const flecs::entity_t String = ecs_id(ecs_string_t);
 static const flecs::entity_t Entity = ecs_id(ecs_entity_t);
-static const flecs::entity_t Constant = EcsConstant;
 static const flecs::entity_t Quantity = EcsQuantity;
 
 namespace meta {
diff --git a/include/flecs/addons/meta.h b/include/flecs/addons/meta.h
@@ -125,7 +125,6 @@ FLECS_API extern const ecs_entity_t ecs_id(EcsVector);          /**< Id for comp
 FLECS_API extern const ecs_entity_t ecs_id(EcsOpaque);          /**< Id for component that stores reflection data for an opaque type. */
 FLECS_API extern const ecs_entity_t ecs_id(EcsUnit);            /**< Id for component that stores unit data. */
 FLECS_API extern const ecs_entity_t ecs_id(EcsUnitPrefix);      /**< Id for component that stores unit prefix data. */
-FLECS_API extern const ecs_entity_t EcsConstant;                /**< Tag added to enum/bitmask constants. */
 FLECS_API extern const ecs_entity_t EcsQuantity;                /**< Tag added to unit quantities. */
 
 /* Primitive type component ids */
diff --git a/src/addons/flecs_cpp.c b/src/addons/flecs_cpp.c
@@ -394,7 +394,6 @@ ecs_entity_t ecs_cpp_enum_constant_register(
     ecs_entity_t value_type,
     size_t value_size)
 {
-#ifdef FLECS_META
     ecs_suspend_readonly_state_t readonly_state;
     world = flecs_suspend_readonly(world, &readonly_state);
 
@@ -424,6 +423,7 @@ ecs_entity_t ecs_cpp_enum_constant_register(
 
     flecs_resume_readonly(world, &readonly_state);
 
+#ifdef FLECS_META
     if (ecs_should_log(0)) {
         ecs_value_t v = { .type = value_type, .ptr = value };
         char *str = NULL;
@@ -434,19 +434,9 @@ ecs_entity_t ecs_cpp_enum_constant_register(
             ecs_get_name(world, parent), name, str);
         ecs_os_free(str);
     }
+#endif
 
     return id;
-#else
-    (void)world;
-    (void)parent;
-    (void)id;
-    (void)name;
-    (void)value;
-    (void)value_type;
-    (void)value_size;
-    ecs_err("enum reflection not supported without FLECS_META addon");
-    return 0;
-#endif
 }
 
 #ifdef FLECS_META
diff --git a/src/addons/meta/meta.c b/src/addons/meta/meta.c
@@ -1257,13 +1257,6 @@ void FlecsMetaImport(
         .type.alignment = ECS_ALIGNOF(EcsPrimitive)
     });
 
-    ecs_component(world, {
-        .entity = ecs_entity(world, { .id = EcsConstant,
-            .name = "constant", .symbol = "EcsConstant",
-            .add = ecs_ids(ecs_pair(EcsOnInstantiate, EcsDontInherit))
-        })
-    });
-
     ecs_component(world, {
         .entity = ecs_entity(world, { .id = ecs_id(EcsEnum),
             .name = "enum", .symbol = "EcsEnum",
diff --git a/src/bootstrap.c b/src/bootstrap.c
@@ -1104,6 +1104,14 @@ void flecs_bootstrap(
     /* Run bootstrap functions for other parts of the code */
     flecs_bootstrap_hierarchy(world);
 
+    /* Register constant tag */
+    ecs_component(world, {
+        .entity = ecs_entity(world, { .id = EcsConstant,
+            .name = "constant", .symbol = "EcsConstant",
+            .add = ecs_ids(ecs_pair(EcsOnInstantiate, EcsDontInherit))
+        })
+    });
+
     ecs_set_scope(world, 0);
     ecs_set_name_prefix(world, NULL);
 
diff --git a/src/world.c b/src/world.c
@@ -156,10 +156,11 @@ const ecs_entity_t ecs_id(EcsVector) =              FLECS_HI_COMPONENT_ID + 107;
 const ecs_entity_t ecs_id(EcsOpaque) =              FLECS_HI_COMPONENT_ID + 108;
 const ecs_entity_t ecs_id(EcsUnit) =                FLECS_HI_COMPONENT_ID + 109;
 const ecs_entity_t ecs_id(EcsUnitPrefix) =          FLECS_HI_COMPONENT_ID + 110;
-const ecs_entity_t EcsConstant =                    FLECS_HI_COMPONENT_ID + 111;
 const ecs_entity_t EcsQuantity =                    FLECS_HI_COMPONENT_ID + 112;
 #endif
 
+const ecs_entity_t EcsConstant =                    FLECS_HI_COMPONENT_ID + 111;
+
 /* Doc module components */
 #ifdef FLECS_DOC
 const ecs_entity_t ecs_id(EcsDocDescription) =      FLECS_HI_COMPONENT_ID + 113;
diff --git a/test/custom_builds/cpp/enum_reflection_no_meta/include/enum_reflection_no_meta.h b/test/custom_builds/cpp/enum_reflection_no_meta/include/enum_reflection_no_meta.h
@@ -0,0 +1,16 @@
+#ifndef ENUM_REFLECTION_NO_META_H
+#define ENUM_REFLECTION_NO_META_H
+
+/* This generated file contains includes for project dependencies */
+#include "enum_reflection_no_meta/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
diff --git a/test/custom_builds/cpp/enum_reflection_no_meta/include/enum_reflection_no_meta/bake_config.h b/test/custom_builds/cpp/enum_reflection_no_meta/include/enum_reflection_no_meta/bake_config.h
@@ -0,0 +1,24 @@
+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef ENUM_REFLECTION_NO_META_BAKE_CONFIG_H
+#define ENUM_REFLECTION_NO_META_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include "../../deps/flecs.h"
+
+#endif
+
diff --git a/test/custom_builds/cpp/enum_reflection_no_meta/project.json b/test/custom_builds/cpp/enum_reflection_no_meta/project.json
@@ -0,0 +1,15 @@
+{
+    "id": "enum_reflection_no_meta",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "language": "c++",
+        "public": false,
+        "standalone": true
+    },
+    "lang.cpp": {
+        "defines": ["FLECS_CUSTOM_BUILD", "FLECS_CPP"]
+    }
+}
diff --git a/test/custom_builds/cpp/enum_reflection_no_meta/src/main.cpp b/test/custom_builds/cpp/enum_reflection_no_meta/src/main.cpp
@@ -0,0 +1,84 @@
+#include <enum_reflection_no_meta.h>
+#include <iostream>
+
+// Test if enum reflection works without the meta addon
+
+enum Color {
+    Red, Green, Blue
+};
+
+int main(int argc, char *argv[]) {
+    flecs::world world(argc, argv);
+
+    flecs::entity c = world.component<Color>();
+
+    if (!world.is_alive(flecs::Constant)) {
+        std::cout << "Constant tag is not alive\n";
+        return -1;
+    }
+
+    {
+        flecs::entity constant = c.lookup("Red");
+        if (!constant) {
+            std::cout << "Constant not found\n";
+            return -1;
+        }
+
+        using U = std::underlying_type<Color>::type;
+
+        if (!constant.has(flecs::Constant, world.id<U>())) {
+            std::cout << "Constant pair not found on constant\n";
+            return -1;
+        }
+
+        const U *v = constant.get_second<U>(flecs::Constant);
+        if (*v != Red) {
+            std::cout << "Constant has wrong value\n";
+            return -1;
+        }
+    }
+
+    {
+        flecs::entity constant = c.lookup("Green");
+        if (!constant) {
+            std::cout << "Constant not found\n";
+            return -1;
+        }
+
+        using U = std::underlying_type<Color>::type;
+
+        if (!constant.has(flecs::Constant, world.id<U>())) {
+            std::cout << "Constant pair not found on constant\n";
+            return -1;
+        }
+
+        const U *v = constant.get_second<U>(flecs::Constant);
+        if (*v != Green) {
+            std::cout << "Constant has wrong value\n";
+            return -1;
+        }
+    }
+
+    {
+        flecs::entity constant = c.lookup("Blue");
+        if (!constant) {
+            std::cout << "Constant not found\n";
+            return -1;
+        }
+
+        using U = std::underlying_type<Color>::type;
+
+        if (!constant.has(flecs::Constant, world.id<U>())) {
+            std::cout << "Constant pair not found on constant\n";
+            return -1;
+        }
+
+        const U *v = constant.get_second<U>(flecs::Constant);
+        if (*v != Blue) {
+            std::cout << "Constant has wrong value\n";
+            return -1;
+        }
+    }
+
+    return 0;
+}
diff --git a/test/script/src/Error.c b/test/script/src/Error.c
@@ -173,9 +173,9 @@ void Error_invalid_oneof(void) {
 
     const char *expr =
     HEAD "flecs.meta.enum Color {"
-    LINE "  flecs.meta.constant Red"
-    LINE "  flecs.meta.constant Green"
-    LINE "  flecs.meta.constant Blue"
+    LINE "  flecs.core.constant Red"
+    LINE "  flecs.core.constant Green"
+    LINE "  flecs.core.constant Blue"
     LINE "}"
     LINE "e { (Color, Foo) }";
 
diff --git a/test/script/src/Eval.c b/test/script/src/Eval.c
