Add RegExp.flags function with tests

Author: jmagaram

src/Core__RegExp.res

@@ -22,3 +22,4 @@ module Result = {
 @get external source: t => string = "source"
 @get external sticky: t => bool = "sticky"
 @get external unicode: t => bool = "unicode"
+@get external flags: t => string = "flags"

src/Core__RegExp.resi

@@ -288,3 +288,20 @@ Console.log(regexp2->RegExp.unicode) // Logs `true`, since `u` is set
 */
 @get
 external unicode: t => bool = "unicode"
+
+/**
+`flags(regexp)` returns a string consisting of the flags of this `RegExp`.
+
+See [`RegExp.flags`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/flags) on MDN.
+
+## Examples
+```rescript
+let regexp1 = RegExp.fromStringWithFlags("\\w+", ~flags="gi")
+Console.log(regexp1->RegExp.flags) // Logs `"gi"`, the flags of the RegExp
+
+let regexp2 = RegExp.fromStringWithFlags("\\w+", ~flags="myu")
+Console.log(regexp2->RegExp.flags) // Logs `"muy"`, the flags sorted alphabetically
+```
+*/
+@get
+external flags: t => string = "flags"

test/RegExpTests.mjs

@@ -0,0 +1,41 @@
+// Generated by ReScript, PLEASE EDIT WITH CARE
+
+import * as Test from "./Test.mjs";
+import * as Caml_obj from "rescript/lib/es6/caml_obj.js";
+
+var eq = Caml_obj.equal;
+
+Test.run([
+      [
+        "RegExpTests.res",
+        7,
+        13,
+        33
+      ],
+      "RegExp.flags basic"
+    ], new RegExp("\\w+", "gi").flags, eq, "gi");
+
+Test.run([
+      [
+        "RegExpTests.res",
+        15,
+        13,
+        35
+      ],
+      "RegExp.flags sorting"
+    ], new RegExp("\\w+", "igd").flags, eq, "dgi");
+
+Test.run([
+      [
+        "RegExpTests.res",
+        22,
+        20,
+        40
+      ],
+      "RegExp.flags empty"
+    ], new RegExp("\\w+").flags, eq, "");
+
+export {
+  eq ,
+}
+/*  Not a pure module */

test/RegExpTests.res

@@ -0,0 +1,22 @@
+open RescriptCore
+
+let eq = (a, b) => a == b
+
+// Test for RegExp.flags
+Test.run(
+  __POS_OF__("RegExp.flags basic"),
+  RegExp.fromStringWithFlags("\\w+", ~flags="gi")->RegExp.flags,
+  eq,
+  "gi",
+)
+
+// Test for alphabetical sorting of flags
+Test.run(
+  __POS_OF__("RegExp.flags sorting"),
+  RegExp.fromStringWithFlags("\\w+", ~flags="igd")->RegExp.flags,
+  eq,
+  "dgi",
+)
+
+// Test with no flags
+Test.run(__POS_OF__("RegExp.flags empty"), RegExp.fromString("\\w+")->RegExp.flags, eq, "")

test/TestSuite.mjs

@@ -9,6 +9,7 @@ import * as ErrorTests from "./ErrorTests.mjs";
 import * as FloatTests from "./FloatTests.mjs";
 import * as ObjectTests from "./ObjectTests.mjs";
 import * as PromiseTest from "./PromiseTest.mjs";
+import * as RegExpTests from "./RegExpTests.mjs";
 import * as ResultTests from "./ResultTests.mjs";
 import * as IteratorTests from "./IteratorTests.mjs";
 import * as NullableTests from "./NullableTests.mjs";
@@ -72,8 +73,6 @@ var decodeJsonTest = JsonTests.decodeJsonTest;
 
 var shouldHandleNullableValues = NullableTests.shouldHandleNullableValues;
 
-var eq = IteratorTests.eq;
-
 var iterator = IteratorTests.iterator;
 
 var syncResult = IteratorTests.syncResult;
@@ -82,6 +81,8 @@ var asyncResult = IteratorTests.asyncResult;
 
 var asyncIterator = IteratorTests.asyncIterator;
 
+var eq = RegExpTests.eq;
+
 export {
   bign ,
   TestError ,
@@ -112,10 +113,10 @@ export {
   o ,
   decodeJsonTest ,
   shouldHandleNullableValues ,
-  eq ,
   iterator ,
   syncResult ,
   asyncResult ,
   asyncIterator ,
+  eq ,
 }
 /* IntTests Not a pure module */

test/TestSuite.res

@@ -11,3 +11,4 @@ include JsonTests
 include NullableTests
 include DictTests
 include IteratorTests
+include RegExpTests