mainly theoratical work on semi, add regex sample

test/SingleFile/regex.cs

@@ -53,3 +53,72 @@ static void Match_Dot(ReadOnlySpan<char> input)
     ptr += 1;
     region_end = ptr;
 }
+
+//a{3,5}
+
+static void Match_A_3_5(ReadOnlySpan<char> input)
+{
+    int ptr = 0;
+    int region_start = ptr;
+    int region_end = region_start;
+
+    do
+    {
+        if(input[ptr..].StartsWith("aaa"))
+        {
+            ptr += 3;
+            region_end = ptr;
+        }
+        else
+        {
+            break;
+        }
+        for(int i = 0; i < 2; i++)
+        {
+            if(input[ptr] == 'a')
+            {
+                ptr += 1;
+                region_end = ptr;
+            }
+            else
+            {
+                break;
+            }
+        }
+
+    } while(false);
+}
+
+//(ab){2,3}
+static void Match_AB_2_3(ReadOnlySpan<char> input)
+{
+    int ptr = 0;
+    int region_start = ptr;
+    int region_end = region_start;
+
+    do
+    {
+        if(input[ptr..].StartsWith("abab"))
+        {
+            ptr += 4;
+            region_end = ptr;
+        }
+        else
+        {
+            break;
+        }
+        for(int i = 0; i < 1; i++)
+        {
+            if(input[ptr..].StartsWith("ab"))
+            {
+                ptr += 2;
+                region_end = ptr;
+            }
+            else
+            {
+                break;
+            }
+        }
+
+    } while(false);
+}