Modelunit can implement interfaces

packages/meta/src/languagedef/generator/templates/UnitTemplate.ts

@@ -21,6 +21,11 @@ export class UnitTemplate {
             .concat([Names.FreModelUnit, Names.FreParseLocation])
             .concat(hasReferences ? (Names.FreNodeReference) : null);
         const metaType = Names.metaType(language);
+        const intfaces = Array.from(
+            new Set(
+                unitDescription.interfaces.map(i => Names.interface(i.referred))
+            )
+        );
 
         // Template starts here. Note that the imports are gathered during the generation, and added later.
         const result: string = `
@@ -29,13 +34,13 @@ export class UnitTemplate {
              * It uses mobx decorators to enable parts of the language environment, e.g. the editor, to react
              * to any changes in the state of its properties.
              */
-            export class ${myName} extends ${extendsClass} implements ${Names.FreModelUnit} {
+            export class ${myName} extends ${extendsClass} implements ${Names.FreModelUnit}${intfaces.map(imp => `, ${imp}`).join("")} {
 
                 ${ConceptUtils.makeStaticCreateMethod(unitDescription, myName)}
 
                 fileExtension: string;
                 ${ConceptUtils.makeBasicProperties(metaType, myName, false)}
-                ${unitDescription.primProperties.map(p => ConceptUtils.makePrimitiveProperty(p)).join("\n")}
+                ${unitDescription.implementedPrimProperties().map(p => ConceptUtils.makePrimitiveProperty(p)).join("\n")}
                 ${unitDescription.parts().map(p => ConceptUtils.makePartProperty(p)).join("\n")}
                 ${unitDescription.references().map(p => ConceptUtils.makeReferenceProperty(p)).join("\n")}
 
@@ -56,6 +61,7 @@ export class UnitTemplate {
         return Array.from(
             new Set(
                 unitDescription.parts().map(part => Names.classifier(part.type))
+                    .concat(unitDescription.interfaces.map(intf => Names.interface((intf.referred))))
                     .concat(unitDescription.references().map(part => Names.classifier(part.type)))
                     .concat(Names.metaType(unitDescription.language))
                     .filter(name => !(name === myName))

packages/meta/src/languagedef/metalanguage/FreLanguage.ts

@@ -131,8 +131,41 @@ export class FreModelDescription extends FreClassifier {
 }
 
 export class FreUnitDescription extends FreClassifier {
+    interfaces: MetaElementReference<FreInterface>[] = []; // the interfaces that this concept implements
+
     fileExtension: string = "";
     isPublic: boolean = true;
+
+    /**
+     * Returns a list of properties that are either (1) defined in this concept or (2) in one of the interfaces
+     * that is implemented by this concept. Excluded are properties that are defined in an interface but are already
+     * included in one of the base concepts.
+     */
+    implementedPrimProperties(): FrePrimitiveProperty[] {
+        let result: FrePrimitiveProperty[] = []; // return a new array!
+        result.push(...this.primProperties);
+        for (const intf of this.interfaces) {
+            for (const intfProp of intf.referred.allPrimProperties()) {
+                let allreadyIncluded = false;
+                // if the prop from the interface is present in this concept, do not include
+                allreadyIncluded = this.primProperties.some(p => p.name === intfProp.name );
+                // TODO The next lines are only needed if units can have other units as base classes
+                // if the prop from the interface is present in the base of this concept (resursive), do not include
+                // if (!allreadyIncluded && !!this.base && !!this.base.referred) {
+                //     allreadyIncluded = this.base.referred.allPrimProperties().some(p => p.name === intfProp.name);
+                // }
+                // if the prop from the interface is present in another implemented interface, do not include
+                if (!allreadyIncluded) {
+                    allreadyIncluded = result.some(p => p.name === intfProp.name );
+                }
+                if (!allreadyIncluded) {
+                    result = result.concat(intfProp);
+                }
+            }
+        }
+        return result;
+    }
+
 }
 
 export class FreInterface extends FreClassifier {

packages/meta/src/languagedef/parser/LanguageCreators.ts

@@ -116,6 +116,12 @@ export function createUnit(data: Partial<FreUnitDescription>): FreUnitDescriptio
             prop.owningClassifier = result;
         }
     }
+    if (!!data.interfaces) {
+        result.interfaces = data.interfaces;
+        for (const intf of result.interfaces) {
+            intf.owner = result;
+        }
+    }
     if (!!data.fileExtension) {
         result.fileExtension = data.fileExtension;
     }

packages/meta/src/languagedef/parser/LanguageGrammar.part.pegjs

@@ -10,7 +10,7 @@ Language_Definition
             "concepts": langparts,
             "location": location()
         });
-    } 
+    }
 
 abstractKey     = "abstract" rws { return true; }
 modelKey        = "model" rws { return true; }
@@ -39,17 +39,24 @@ model = isModel:modelKey name:var
         });
     }
 
-unit = isUnit:unitKey name:var
-    curly_begin props:property* fileExtension:(fileExtensionKey equals_separator "\"" fileExt:var "\"" semicolon_separator {return fileExt;})? curly_end    {
+unit = isUnit:unitKey name:var ws implementedInterfaces:implementedInterfaces?
+        curly_begin
+            props:property*
+            fileExtension:(fileExtensionKey equals_separator "\"" fileExt:var "\"" semicolon_separator {return fileExt;})?
+         curly_end    {
         return create.createUnit({
             "name": name,
             "properties": props,
+            "interfaces": implementedInterfaces,
             "fileExtension": (!!fileExtension ? fileExtension : ""),
             "location": location()
         });
     }
 
-concept = abs:abstractKey? conceptKey name:var rws base:conceptbase? ws implementedInterfaces:implementedInterfaces? curly_begin props:property* curly_end
+concept = abs:abstractKey? conceptKey name:var rws base:conceptbase? ws implementedInterfaces:implementedInterfaces?
+            curly_begin
+                props:property*
+            curly_end
     {
         return create.createConcept({
             "isAbstract": (!!abs),
@@ -74,7 +81,10 @@ limited = abs:abstractKey? limitedKey ws name:var rws base:conceptbase? ws imple
         });
     }
 
-interface = interfaceKey ws name:var rws base:interfacebase? curly_begin props:property* curly_end
+interface = interfaceKey ws name:var rws base:interfacebase?
+            curly_begin
+                props:property*
+            curly_end
     {
         return create.createInterface({
             "name": name,