1 files changed, 27 insertions, 0 deletions
diff --git a/Source/Dafny/BigIntegerParser.cs b/Source/Dafny/BigIntegerParser.cs
new file mode 100644
index 00000000..cd2cf314
--- /dev/null
+++ b/Source/Dafny/BigIntegerParser.cs
@@ -0,0 +1,27 @@
+using System;
+using System.Numerics;
+using System.Globalization;
+
+namespace Microsoft.Dafny {
+    internal static class BigIntegerParser {
+        /// <summary>
+        ///   Mono does not support the BigInteger.TryParse method. In practice,
+        ///   we seldom actually need to parse huge integers, so it makes sense
+        ///   to support most real-life cases by simply trying to parse using
+        ///   Int64, and only falling back if needed.
+        /// </summary>
+        internal static BigInteger Parse(string str, NumberStyles style) {
+            UInt64 parsed;
+            if (UInt64.TryParse(str, style, NumberFormatInfo.CurrentInfo, out parsed)) {
+                return new BigInteger(parsed);
+            } else {
+                // Throws on Mono 3.2.8
+                return BigInteger.Parse(str, style);
+            }
+        }
+
+        internal static BigInteger Parse(string str) {
+            return BigIntegerParser.Parse(str, NumberStyles.Integer);
+        }
+    }
+}
+\ No newline at end of file