[script] Add support for mut variables

distr/flecs_no_addons.c

@@ -4541,20 +4541,6 @@ void flecs_on_component(ecs_iter_t *it) {
             "component id must be smaller than %u", ECS_MAX_COMPONENT_ID);
         (void)component_id;
 
-        if (it->event != EcsOnRemove) {
-            ecs_entity_t parent = ecs_get_parent(world, e);
-            if (parent) {
-                ecs_record_t *parent_record = flecs_entities_get(world, parent);
-                ecs_table_t *parent_table = parent_record->table;
-                if (!ecs_table_has_id(world, parent_table, EcsModule)) {
-                    if (!ecs_table_has_id(world, parent_table, ecs_id(EcsComponent))) {
-                        ecs_add_id(world, parent, EcsModule);
-                    }
-                }
-
-            }
-        }
-
         if (it->event == EcsOnSet) {
             if (flecs_type_info_init_id(
                 world, e, c[i].size, c[i].alignment, NULL))
@@ -38982,7 +38968,7 @@ void flecs_add_with_property(
             ecs_id_t id = ids[i];
             ecs_assert(ECS_PAIR_FIRST(id) == EcsWith, ECS_INTERNAL_ERROR, NULL);
             ecs_id_t ra = ECS_PAIR_SECOND(id);
-            ecs_id_t a = ra;
+            ecs_id_t a = ecs_get_alive(world, ra);
             if (o) {
                 a = ecs_pair(ra, o);
             }
@@ -39638,6 +39624,7 @@ typedef enum ecs_token_kind_t {
     EcsTokKeywordInclude = 138,
     EcsTokKeywordFn = 139,
     EcsTokArrow = 140,
+    EcsTokKeywordMut = 141,
     EcsTokAddAssign = 136,
     EcsTokMulAssign = 137,
 } ecs_token_kind_t;

docs/FlecsScript.md

@@ -1182,7 +1182,7 @@ Templates are commonly used in combination with the kind syntax:
 Square my_entity
 ```
 
-Templates can be parameterized with properties. Properties are variables that are exposed as component members. To create a property, use the `prop` keyword. Example:
+Templates can be parameterized with properties. Properties are variables that are exposed as component members. When the component is updated with a new value, the template is reevaluated. To create a property, use the `prop` keyword. Example:
 
 ```cpp
 template Square {
@@ -1198,6 +1198,17 @@ Square my_entity(size: 20, color: {38, 25, 13})
 
 Just like `const` variables, `prop` variables can explicitly specify a type or implicitly derive their type from the assigned (default) value.
 
+In addition to property variables, templates can also contain mutables. Mutables that are exposed as component members on a `TemplateComponent::mut` component. To create a mutable, use the `mut` keyword. For example the `hover` mutable variable ends up on a `Button::mut` component:
+
+```cpp
+template Button {
+  prop text: "Howdy"
+  mut hover: false
+
+  // ...
+}
+```
+
 Template scripts can do anything a regular script can do, including creating child entities. The following example shows how to create an template that uses a nested template to create children:
 
 ```cpp

src/addons/parser/tokenizer.c

@@ -137,6 +137,7 @@ const char* flecs_token_kind_str(
     case EcsTokKeywordWith:
     case EcsTokKeywordUsing:
     case EcsTokKeywordProp:
+    case EcsTokKeywordMut:
     case EcsTokKeywordConst:
     case EcsTokKeywordIf:
     case EcsTokKeywordElse:
@@ -215,6 +216,7 @@ const char* flecs_token_str(
     case EcsTokKeywordWith: return "with";
     case EcsTokKeywordUsing: return "using";
     case EcsTokKeywordProp: return "prop";
+    case EcsTokKeywordMut: return "mut";
     case EcsTokKeywordConst: return "const";
     case EcsTokKeywordMatch: return "match";
     case EcsTokKeywordNew: return "new";
@@ -908,6 +910,7 @@ const char* flecs_token(
     Keyword           ("using",    EcsTokKeywordUsing)
     Keyword           ("template", EcsTokKeywordTemplate)
     Keyword           ("prop",     EcsTokKeywordProp)
+    Keyword           ("mut",      EcsTokKeywordMut)
     Keyword           ("const",    EcsTokKeywordConst)
     Keyword           ("if",       EcsTokKeywordIf)
     Keyword           ("else",     EcsTokKeywordElse)

src/addons/parser/tokenizer.h

@@ -65,6 +65,7 @@ typedef enum ecs_token_kind_t {
     EcsTokKeywordInclude = 138,
     EcsTokKeywordFn = 139,
     EcsTokArrow = 140,
+    EcsTokKeywordMut = 141,
     EcsTokAddAssign = 136,
     EcsTokMulAssign = 137,
 } ecs_token_kind_t;

src/addons/script/ast.h

@@ -21,6 +21,7 @@ typedef enum ecs_script_node_kind_t {
     EcsAstAnnotation,
     EcsAstTemplate,
     EcsAstProp,
+    EcsAstMut,
     EcsAstConst,
     EcsAstExportConst,
     EcsAstEntity,

src/addons/script/expr/util.c

@@ -354,6 +354,7 @@ int flecs_value_binary(
     case EcsTokKeywordNew:
     case EcsTokKeywordExport:
     case EcsTokKeywordProp:
+    case EcsTokKeywordMut:
     case EcsTokKeywordConst:
     case EcsTokKeywordInclude:
     case EcsTokKeywordFn:

src/addons/script/expr/visit_type.c

@@ -308,6 +308,7 @@ bool flecs_expr_oper_valid_for_type(
     case EcsTokKeywordExport:
     case EcsTokKeywordTemplate:
     case EcsTokKeywordProp:
+    case EcsTokKeywordMut:
     case EcsTokKeywordConst:
     case EcsTokKeywordInclude:
     case EcsTokKeywordFn:
@@ -459,6 +460,7 @@ int flecs_expr_type_for_operator(
     case EcsTokKeywordExport:
     case EcsTokKeywordTemplate:
     case EcsTokKeywordProp:
+    case EcsTokKeywordMut:
     case EcsTokKeywordConst:
     case EcsTokKeywordInclude:
     case EcsTokKeywordFn:

src/addons/script/parser.c

@@ -348,6 +348,8 @@ const char* flecs_script_parse_var(
         var->node.kind = kind;
 
         bool is_prop = kind == EcsAstProp;
+        bool is_mut = kind == EcsAstMut;
+        const char *kind_str = is_prop ? "prop" : (is_mut ? "mut" : "const");
 
         Parse(
             // const color =
@@ -391,8 +393,7 @@ const char* flecs_script_parse_var(
                 Expr('\n',
                     Warning("'%s var = expr' syntax is deprecated"
                         ", use '%s var: expr' instead", 
-                            is_prop ? "prop" : "const",
-                            is_prop ? "prop" : "const");
+                            kind_str, kind_str);
                     var->expr = EXPR;
                     EndOfRule;
                 )
@@ -421,6 +422,15 @@ const char* flecs_script_parse_const(
     return flecs_script_parse_var(parser, pos, tokenizer, EcsAstConst);
 }
 
+static
+const char* flecs_script_parse_mut(
+    ecs_parser_t *parser,
+    const char *pos,
+    ecs_tokenizer_t *tokenizer)
+{
+    return flecs_script_parse_var(parser, pos, tokenizer, EcsAstMut);
+}
+
 static
 const char* flecs_script_parse_export_const(
     ecs_parser_t *parser,
@@ -574,6 +584,7 @@ const char* flecs_script_stmt(
         case EcsTokKeywordUsing:      goto using_stmt;
         case EcsTokKeywordTemplate:   goto template_stmt;
         case EcsTokKeywordProp:       goto prop_var;
+        case EcsTokKeywordMut:        goto mut_var;
         case EcsTokKeywordConst:      goto const_var;
         case EcsTokKeywordExport:     goto export_var;
         case EcsTokKeywordIf:         goto if_stmt;
@@ -741,6 +752,11 @@ prop_var: {
     return flecs_script_parse_prop(parser, pos, tokenizer);
 }
 
+// mut
+mut_var: {
+    return flecs_script_parse_mut(parser, pos, tokenizer);
+}
+
 // export
 export_var: {
     // export const

src/addons/script/script.c

@@ -369,7 +369,7 @@ int ecs_script_update(
     const char *name = ecs_get_name(world, e);
     EcsScript *s = ecs_ensure(world, e, EcsScript);
     if (s->template_) {
-        char *template_name = ecs_get_path(world, s->template_->entity);
+        char *template_name = ecs_get_path(world, s->template_->props.type);
         ecs_err("cannot update scripts for individual templates, "
             "update parent script instead (tried to update '%s')",
                 template_name);