tests, use just NonBacktracking instead

Author: ieviev

src/fable-library-ts/RegExp.ts

@@ -9,23 +9,16 @@ export function create(pattern: string, options = 0) {
   // * ECMAScript:  0x0100 (ignored)
   // * NonBacktracking:  0x0400
   if ((options & ~(1 ^ 2 ^ 8 ^ 16 ^ 256 ^ 1024)) !== 0) {
-    throw new Error("RegexOptions only supports: IgnoreCase, Multiline, Compiled, Singleline, ECMAScript and (NonBacktracking ||| ECMAScript)");
+    throw new Error("RegexOptions only supports: IgnoreCase, Multiline, Compiled, Singleline, ECMAScript and NonBacktracking");
   }
 
-  // Set always global and unicode flags for compatibility with dotnet, see #2925
+  // Set global and unicode flags for compatibility with dotnet, see #2925
   let flags = "g";
-  flags += options & 256 ? "" : "u"; // only add 'u' if not EcmaScript, ('l' and 'u' together are not allowed)
+  // add unicode only if not NonBacktracking, 'l' and 'u' together are not allowed
+  flags += options & 1024 ? "l" : "u";
   flags += options & 1 ? "i" : ""; // 0x0001 RegexOptions.IgnoreCase
   flags += options & 2 ? "m" : "";
   flags += options & 16 ? "s" : "";
-  if (options & 1024) {
-    if (options & 256) {
-      flags += "l";
-    }
-    else {
-      throw new Error("RegexOptions.NonBacktracking is only allowed together with ECMAScript");
-    }
-  }
   return new RegExp(pattern, flags);
 }
 // From http://stackoverflow.com/questions/3446170/escape-string-for-use-in-javascript-regex

tests/Js/Main/RegexTests.fs

@@ -37,6 +37,32 @@ let tests =
         let r = Regex("[a-z]", options)
         int r.Options |> equal 257
 
+    testCase "RegexOptions.NonBacktracking = 1024" <| fun _ ->
+        let options = RegexOptions.NonBacktracking
+        int options |> equal 1024
+
+    testCase "Nonbacktracking regex tests" <| fun _ ->
+        // Note: this is not consistent with .NET because JS linear engine
+        // does not support unicode. JS \d = 10 digits, .NET \d = 350+ digits
+        // but for these tests the behavior should be identical.
+        let none = RegexOptions.None
+        let nonb = RegexOptions.NonBacktracking
+        let multiline = RegexOptions.Multiline
+        let ignorecase = RegexOptions.IgnoreCase
+        let multilineignorecase = multiline ||| ignorecase
+        let str = "For more information, see Chapter 3.4.5.1"
+        let sameResult extraopts str pat =
+            let result1 = Regex.Match(str, pat, none ||| extraopts).Success
+            let result2 = Regex.Match(str, pat, nonb ||| extraopts).Success
+            equal result1 result2
+        sameResult none str "Chapter \d+(\.\d)*"
+        sameResult none str "chapter \d+(\.\d)*"
+        sameResult multilineignorecase "^ab" "ab\ncd"
+        sameResult multilineignorecase "^cd" "ab\ncd"
+        sameResult multilineignorecase "^AB" "ab\ncd"
+        sameResult multilineignorecase "^bc" "ab\ncd"
+
+
     testCase "Regex.IsMatch with IgnoreCase and Multiline works" <| fun _ ->
         let str = "ab\ncd"
         let option1 = RegexOptions.IgnoreCase