Merge 0577c93 into 8894cd9

src/parsimmon.js

@@ -694,8 +694,17 @@ function formatError(input, error) {
 }
 
 function flags(re) {
-  var s = "" + re;
-  return s.slice(s.lastIndexOf("/") + 1);
+  if (re.flags !== undefined) {
+    return re.flags;
+  }
+  // legacy browser support
+  return [
+    re.global ? "g" : "",
+    re.ignoreCase ? "i" : "",
+    re.multiline ? "m" : "",
+    re.unicode ? "u" : "",
+    re.sticky ? "y" : ""
+  ].join("");
 }
 
 function anchoredRegexp(re) {
@@ -1356,6 +1365,7 @@ Parsimmon.empty = empty;
 Parsimmon.end = end;
 Parsimmon.eof = eof;
 Parsimmon.fail = fail;
+Parsimmon.flags = flags;
 Parsimmon.formatError = formatError;
 Parsimmon.index = index;
 Parsimmon.isParser = isParser;

test/.eslintrc

@@ -7,5 +7,8 @@
     "Parsimmon": true,
     "assert": true,
     "testSetScenario": true
+  },
+  "rules": {
+    "no-invalid-regexp": ["error", {"allowConstructorFlags": ["u", "y"]}]
   }
 }

test/core/flags.test.js

@@ -0,0 +1,35 @@
+"use strict";
+
+testSetScenario(function() {
+  describe("Parsimmon.flags()", function() {
+    it("works in modern browsers", function() {
+      // eslint-disable-next-line no-invalid-regexp
+      var flags = Parsimmon.flags(new RegExp("a", "gimuy"));
+      assert.strictEqual(flags, "gimuy");
+    });
+
+    it("works on legacy browsers without Regexp.flags property with flags", function() {
+      // eslint-disable-next-line no-invalid-regexp
+      var oldRegExp = new RegExp("a", "gimuy");
+
+      // Simulate old RegExp without the flags property
+      Object.defineProperty(oldRegExp, "flags", { value: undefined });
+      assert.strictEqual(oldRegExp.flags, undefined);
+
+      var flags = Parsimmon.flags(oldRegExp);
+      assert.strictEqual(flags, "gimuy");
+    });
+
+    it("works on legacy browsers without Regexp.flags property without flags", function() {
+      // eslint-disable-next-line no-invalid-regexp
+      var oldRegExp = new RegExp("a", "");
+
+      // Simulate old RegExp without the flags property
+      Object.defineProperty(oldRegExp, "flags", { value: undefined });
+      assert.strictEqual(oldRegExp.flags, undefined);
+
+      var flags = Parsimmon.flags(oldRegExp);
+      assert.strictEqual(flags, "");
+    });
+  });
+});