refactor: turn MermaidUtil.isMermaidId() to more general isMermaidEqualIds()

refs #318

src/prebarrage/pre_barrage.ts

@@ -134,7 +134,7 @@ export class PreBarrage extends Nub {
         if (uid !== undefined) {
             let pos = 0;
             for (const c of this.children) {
-                if (MermaidUtil.isMermaidId(c.uid, uid)) {
+                if (MermaidUtil.isMermaidEqualIds(c.uid, uid)) {
                     res.child = c;
                     res.position = pos;
                     break;

src/util/mermaid.ts

@@ -3,16 +3,25 @@
  */
 export class MermaidUtil {
     /**
-     * check if an id is a Mermaid generated id
-     * @param id to check. Can be equal to the original,graph provided id or Mermaid transformed (ie. flowchart-id-xx)
-     * @param ref reference id
+     * check if two ids are equal in a Mermaid way
+     * @param id1 first id to compare. Can be equal to the original,graph provided id or Mermaid transformed (ie. flowchart-id-xx)
+     * @param id2 second  to compare (same remarks)
      */
-    public static isMermaidId(id: string, ref: string): boolean {
-        if (id === ref) {
+    public static isMermaidEqualIds(id1: string, id2: string): boolean {
+        if (id1 === id2) {
             return true;
         }
-        const mid = "flowchart-" + id + "-"; // Mermaid generated element id
-        return ref.startsWith(mid);
+        const mid = "flowchart-" + id1 + "-"; // Mermaid generated element id
+        if (id2.startsWith(mid)) {
+            return true;
+        }
+
+        const mid2 = "flowchart-" + id2 + "-"; // so the same in reverse order
+        if (mid2.startsWith(id1)) {
+            return true;
+        }
+
+        return false;
     }
 
     /**