Merge pull request #63 from danez/performance-regression

Fix performance regression introduced in 6.8.2

src/plugins/flow.js

@@ -732,18 +732,24 @@ export default function (instance) {
 
   instance.extend("parseConditional", function (inner) {
     return function (expr, noIn, startPos, startLoc, refNeedsArrowPos) {
-      const state = this.state.clone();
+      // only do the expensive clone if there is a question mark
-      try {
+      // and if we come from inside parens
-        return inner.call(this, expr, noIn, startPos, startLoc);
+      if (refNeedsArrowPos && this.match(tt.question)) {
-      } catch (err) {
+        const state = this.state.clone();
-        if (refNeedsArrowPos && err instanceof SyntaxError) {
+        try {
-          this.state = state;
+          return inner.call(this, expr, noIn, startPos, startLoc);
-          refNeedsArrowPos.start = this.state.start;
+        } catch (err) {
-          return expr;
+          if (err instanceof SyntaxError) {
-        } else {
+            this.state = state;
-          throw err;
+            refNeedsArrowPos.start = err.pos || this.state.start;
+            return expr;
+          } else {
+            throw err;
+          }
         }
       }
+
+      return inner.call(this, expr, noIn, startPos, startLoc);
     };
   });
 

test/fixtures/flow/optional-type/2/options.json

@@ -1,3 +1,3 @@
 {
-  "throws": "Unexpected token (1:12)"
+  "throws": "Unexpected token (1:13)"
 }