Lazy detect Set, use internal flag in tests

jneen · Jul 8, 2020 · 1514352 · 1514352
1 parent 08ec6fc
commit 1514352
Show file tree

Hide file tree

Showing 3 changed files with 18 additions and 34 deletions.
diff --git a/src/parsimmon.js b/src/parsimmon.js
@@ -97,6 +97,15 @@ function bufferExists() {
   return typeof Buffer !== "undefined";
 }
 
+function setExists() {
+  if (Parsimmon._supportsSet !== undefined) {
+    return Parsimmon._supportsSet;
+  }
+  var exists = typeof Set !== "undefined";
+  Parsimmon._supportsSet = exists;
+  return exists;
+}
+
 function ensureBuffer() {
   if (!bufferExists()) {
     throw new Error(
@@ -379,9 +388,9 @@ function makeLineColumnIndex(input, i) {
 function union(xs, ys) {
   // for newer browsers/node we can improve performance by using
   // modern JS
-  if (Parsimmon.Set && Array.from) {
+  if (setExists() && Array.from) {
     // eslint-disable-next-line no-undef
-    var set = new Parsimmon.Set(xs);
+    var set = new Set(xs);
     for (var y = 0; y < ys.length; y++) {
       set.add(ys[y]);
     }
@@ -1397,8 +1406,4 @@ Parsimmon.Binary = {
   doubleLE: doubleLE()
 };
 
-// For use later, we set Set if it is available
-// eslint-disable-next-line no-undef
-Parsimmon.Set = typeof Set !== "undefined" ? Set : undefined;
-
 module.exports = Parsimmon;
diff --git a/test/core/startup.test.js b/test/core/startup.test.js
diff --git a/test/setup.js b/test/setup.js
@@ -31,18 +31,18 @@ globalThis.equivalentParsers = function equivalentParsers(p1, p2, inputs) {
 
 globalThis.testSetScenario = function testSetScenario(fn) {
   describe("", function() {
-    var origSet = Parsimmon.Set;
-    after(function() {
-      Parsimmon.Set = origSet;
-    });
-
     fn();
 
     if (typeof Set !== "undefined") {
       describe("no Set", function() {
-        beforeEach(function() {
-          Parsimmon.Set = undefined;
+        before(function() {
+          Parsimmon._supportsSet = false;
+        });
+
+        after(function() {
+          Parsimmon._supportsSet = undefined;
         });
+
         fn();
       });
     }