Fix duplicate recursion check

Author: slevithan

spec/recursion-spec.js

@@ -33,7 +33,6 @@ describe('recursion', () => {
   });
 
   it('should throw for multiple direct, nonoverlapping recursions', () => {
-    // TODO: Has a bug and lets invalid JS syntax through
     expect(() => regex({plugins: [recursion]})`(?<r1>a\g<r1&R=2>?)(?<r2>a\g<r2&R=2>?)`).toThrow();
   });
 

src/index.js

@@ -43,32 +43,32 @@ export function recursion(expression) {
 
       if (captureName) {
         groupContentsStartPos.set(captureName, token.lastIndex);
-      // (?R=N)
+      // `(?R=N)`
       } else if (rDepth) {
         assertMaxInBounds(rDepth);
         const maxDepth = +rDepth;
         const pre = expression.slice(0, match.index);
         const post = expression.slice(token.lastIndex);
         assertNoFollowingRecursion(post);
         return makeRecursive(pre, post, maxDepth, false);
-      // \g<name&R=N>
+      // `\g<name&R=N>`
       } else if (gRName) {
         assertMaxInBounds(gRDepth);
         const maxDepth = +gRDepth;
         const outsideOwnGroupMsg = `Recursion via \\g<${gRName}&R=${gRDepth}> must be used within the referenced group`;
-        // Appears before/outside the referenced group
+        // Appears before (outside) the referenced group
         if (!groupContentsStartPos.has(gRName)) {
           throw new Error(outsideOwnGroupMsg);
         }
         const startPos = groupContentsStartPos.get(gRName);
         const recursiveGroupContents = getGroupContents(expression, startPos);
-        // Appears after/outside the referenced group
+        // Appears after (outside) the referenced group
         if (!hasUnescaped(recursiveGroupContents, gRToken, Context.DEFAULT)) {
           throw new Error(outsideOwnGroupMsg)
         }
         const pre = expression.slice(startPos, match.index);
         const post = recursiveGroupContents.slice(pre.length + m.length);
-        assertNoFollowingRecursion(post);
+        assertNoFollowingRecursion(expression.slice(token.lastIndex));
         return expression.slice(0, startPos) +
           makeRecursive(pre, post, maxDepth, true) +
           expression.slice(startPos + recursiveGroupContents.length);