Convert local function to an instance one to allow compilation with mcs. (#78)

* Convert local function to an instance one to allow compilation with mcs.

* Workaround missing mcs C# 7 features.

3 files changed, 38 insertions, 25 deletions

diff --git a/src/Common/src/System/Security/Cryptography/AsnReader.cs b/src/Common/src/System/Security/Cryptography/AsnReader.cs
index 54601ff321..52ea683e14 100644
--- a/src/Common/src/System/Security/Cryptography/AsnReader.cs
+++ b/src/Common/src/System/Security/Cryptography/AsnReader.cs
@@ -2462,6 +2462,25 @@ namespace System.Security.Cryptography.Asn1
             return value;
         }
 
+        const byte HmsState = 0;
+        const byte FracState = 1;
+        const byte SuffixState = 2;
+
+        private static byte? ParseGeneralizedTime_GetNextState(byte octet)
+        {
+            if (octet == 'Z' || octet == '-' || octet == '+')
+            {
+                return SuffixState;
+            }
+
+            if (octet == '.' || octet == ',')
+            {
+                return FracState;
+            }
+
+            return null;
+        }
+
         private static DateTimeOffset ParseGeneralizedTime(
             AsnEncodingRules ruleSet,
             ReadOnlySpan<byte> contentOctets,
@@ -2524,32 +2543,14 @@ namespace System.Security.Cryptography.Asn1
             TimeSpan? timeOffset = null;
             bool isZulu = false;
 
-            const byte HmsState = 0;
-            const byte FracState = 1;
-            const byte SuffixState = 2;
             byte state = HmsState;
 
-            byte? GetNextState(byte octet)
-            {
-                if (octet == 'Z' || octet == '-' || octet == '+')
-                {
-                    return SuffixState;
-                }
-
-                if (octet == '.' || octet == ',')
-                {
-                    return FracState;
-                }
-
-                return null;
-            }
-
             // This while loop could be rewritten to include the FracState and Suffix
             // processing steps.  But since there's a forward flow to the state machine
             // the loop body then needs to account for that.
             while (state == HmsState && contents.Length != 0)
             {
-                byte? nextState = GetNextState(contents[0]);
+                byte? nextState = ParseGeneralizedTime_GetNextState(contents[0]);
 
                 if (nextState == null)
                 {
@@ -2581,7 +2582,7 @@ namespace System.Security.Cryptography.Asn1
 
                 Debug.Assert(!contents.IsEmpty);
                 byte octet = contents[0];
-                Debug.Assert(state == GetNextState(octet));
+                Debug.Assert(state == ParseGeneralizedTime_GetNextState(octet));
 
                 if (octet == '.')
                 {
@@ -2639,7 +2640,7 @@ namespace System.Security.Cryptography.Asn1
 
                 if (contents.Length != 0)
                 {
-                    byte? nextState = GetNextState(contents[0]);
+                    byte? nextState = ParseGeneralizedTime_GetNextState(contents[0]);
 
                     if (nextState == null)
                     {
@@ -2655,7 +2656,7 @@ namespace System.Security.Cryptography.Asn1
             {
                 Debug.Assert(!contents.IsEmpty);
                 byte octet = contents[0];
-                Debug.Assert(state == GetNextState(octet));
+                Debug.Assert(state == ParseGeneralizedTime_GetNextState(octet));
                 contents = contents.Slice(1);
 
                 if (octet == 'Z')
diff --git a/src/Common/src/System/Security/Cryptography/AsnWriter.cs b/src/Common/src/System/Security/Cryptography/AsnWriter.cs
index cff5cddab2..e6de600cb4 100644
--- a/src/Common/src/System/Security/Cryptography/AsnWriter.cs
+++ b/src/Common/src/System/Security/Cryptography/AsnWriter.cs
@@ -1194,7 +1194,11 @@ namespace System.Security.Cryptography.Asn1
                     // We're only loading in sub-second ticks.
                     // Ticks are defined as 1e-7 seconds, so their printed form
                     // is at the longest "0.1234567", or 9 bytes.
+#if __MonoCS__
+                    fraction = new byte[9];
+#else
                     fraction = stackalloc byte[9];
+#endif
 
                     decimal decimalTicks = floatingTicks;
                     decimalTicks /= TimeSpan.TicksPerSecond;
@@ -1562,8 +1566,10 @@ namespace System.Security.Cryptography.Asn1
 
             pos = 0;
 
-            foreach ((int offset, int length) in positions)
+            foreach (var position in positions)
             {
+                var offset = position.Item1;
+                var length = position.Item2;
                 Buffer.BlockCopy(buffer, offset, tmp, pos, length);
                 pos += length;
             }
@@ -1612,8 +1618,10 @@ namespace System.Security.Cryptography.Asn1
 
             public int Compare((int, int) x, (int, int) y)
             {
-                (int xOffset, int xLength) = x;
-                (int yOffset, int yLength) = y;
+                int xOffset = x.Item1;
+                int xLength = x.Item2;
+                int yOffset = y.Item1;
+                int yLength = y.Item2;
 
                 int value =
                     SetOfValueComparer.Instance.Compare(
diff --git a/src/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/AnyOS/ManagedPal.Asn.cs b/src/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/AnyOS/ManagedPal.Asn.cs
index bd7463c3b1..046a114f96 100644
--- a/src/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/AnyOS/ManagedPal.Asn.cs
+++ b/src/System.Security.Cryptography.Pkcs/src/Internal/Cryptography/Pal/AnyOS/ManagedPal.Asn.cs
@@ -33,7 +33,11 @@ namespace Internal.Cryptography.Pal.AnyOS
             const int ArbitraryStackLimit = 256;
             Span<byte> tmp = stackalloc byte[ArbitraryStackLimit];
             // Use stackalloc 0 so data can later hold a slice of tmp.
+#if __MonoCS__
+            ReadOnlySpan<byte> data = new byte[0];
+#else
             ReadOnlySpan<byte> data = stackalloc byte[0];
+#endif            
             byte[] poolBytes = null;
 
             try