fix: Support multiple stereotypes on class diagrams (#6680)

- Modified JISON grammar to support consecutive annotations like <<interface>><<injected>>
- Updated addAnnotation method to create classes if they don't exist
- Added comprehensive tests for multiple annotation scenarios
- Maintains backward compatibility with existing single annotation syntax

Fixes #6680

packages/mermaid/src/diagrams/class/classDb.ts

@@ -237,6 +237,7 @@ export class ClassDB implements DiagramDB {
    * @public
    */
   public addAnnotation(className: string, annotation: string) {
+    this.addClass(className);
     const validatedClassName = this.splitClassNameAndType(className).className;
     this.classes.get(validatedClassName)!.annotations.push(annotation);
   }

packages/mermaid/src/diagrams/class/classDiagram.spec.ts

@@ -922,6 +922,28 @@ foo()
       expect(actual.methods.length).toBe(1);
       expect(actual.annotations[0]).toBe('interface');
     });
+
+    it('should handle multiple consecutive annotations on a single class', function () {
+      const str = 'classDiagram\n' + '<<interface>><<injected>> Class1';
+
+      parser.parse(str);
+
+      const actual = parser.yy.getClass('Class1');
+      expect(actual.annotations.length).toBe(2);
+      expect(actual.annotations).toContain('interface');
+      expect(actual.annotations).toContain('injected');
+    });
+
+    it('should handle multiple separate annotations on a single class', function () {
+      const str = 'classDiagram\n' + '<<interface>> Class1\n' + '<<injected>> Class1';
+
+      parser.parse(str);
+
+      const actual = parser.yy.getClass('Class1');
+      expect(actual.annotations.length).toBe(2);
+      expect(actual.annotations).toContain('interface');
+      expect(actual.annotations).toContain('injected');
+    });
   });
 });
 

packages/mermaid/src/diagrams/class/parser/classDiagram.jison

@@ -310,7 +310,12 @@ emptyBody
     ;
 
 annotationStatement
-    : ANNOTATION_START alphaNumToken ANNOTATION_END className  { yy.addAnnotation($4,$2); }
+    : annotationList className  { for(const annotation of $1) { yy.addAnnotation($2, annotation); } }
+    ;
+
+annotationList
+    : ANNOTATION_START alphaNumToken ANNOTATION_END { $$ = [$2]; }
+    | annotationList ANNOTATION_START alphaNumToken ANNOTATION_END { $1.push($3); $$ = $1; }
     ;
 
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