add extension_list example (#281)

- Created an example of extension policy
- Added C# binding support of .NET framework 4.0 and created a Nuget
  spec for it.
- Added a pytest in python bindings to test the extension policy and the
  python binding
- Restructured the example and Csharp binding directories due to above
  changes.
- Added copyrights.
- Added a Windows workflow for .NET 4.0 build and test.

bindings/csharp/net8.0/Regorus.cs

@@ -0,0 +1,220 @@
+using System.Text;
+
+namespace Regorus
+{
+    public class Exception : System.Exception
+    {
+	public Exception(string? message) : base(message) {}
+    }
+
+    public class Engine : ICloneable
+    {
+	unsafe private RegorusFFI.RegorusEngine* E;
+	public Engine()
+	{
+	    unsafe
+	    {
+		E = RegorusFFI.API.regorus_engine_new();
+	    }
+	}
+
+	public object Clone()
+	{
+	    var clone = (Engine)this.MemberwiseClone();
+	    unsafe
+	    {
+		clone.E = RegorusFFI.API.regorus_engine_clone(E);
+	    }
+	    return clone;
+
+	}
+
+	public string AddPolicy(string path, string rego)
+	{
+	    var pathBytes = Encoding.UTF8.GetBytes(path);
+	    var regoBytes = Encoding.UTF8.GetBytes(rego);
+
+	    unsafe
+	    {
+		fixed (byte* pathPtr = pathBytes)
+		{
+		    fixed(byte* regoPtr = regoBytes)
+		    {
+			return CheckAndDropResult(RegorusFFI.API.regorus_engine_add_policy(E, pathPtr, regoPtr));
+		    }
+		}
+	    }
+	}
+
+	public string AddPolicyFromFile(string path)
+	{
+	    var pathBytes = Encoding.UTF8.GetBytes(path);
+
+	    unsafe
+	    {
+		fixed (byte* pathPtr = pathBytes)
+		{
+		    return CheckAndDropResult(RegorusFFI.API.regorus_engine_add_policy_from_file(E, pathPtr));
+		}
+	    }
+	}
+
+	public void AddDataJson(string data)
+	{
+	    var dataBytes = Encoding.UTF8.GetBytes(data);
+
+	    unsafe
+	    {
+		fixed (byte* dataPtr = dataBytes)
+		{
+		    CheckAndDropResult(RegorusFFI.API.regorus_engine_add_data_json(E, dataPtr));
+		}
+	    }
+	}
+
+	public void AddDataFromJsonFile(string path)
+	{
+	    var pathBytes = Encoding.UTF8.GetBytes(path);
+
+	    unsafe
+	    {
+		fixed (byte* pathPtr = pathBytes)
+		{
+		    CheckAndDropResult(RegorusFFI.API.regorus_engine_add_data_from_json_file(E, pathPtr));
+		}
+	    }
+	}
+
+	public void SetInputJson(string input)
+	{
+	    var inputBytes = Encoding.UTF8.GetBytes(input);
+
+	    unsafe
+	    {
+		fixed (byte* inputPtr = inputBytes)
+		{
+		    CheckAndDropResult(RegorusFFI.API.regorus_engine_set_input_json(E, inputPtr));
+		}
+	    }
+	}
+
+	public void SetInputFromJsonFile(string path)
+	{
+	    var pathBytes = Encoding.UTF8.GetBytes(path);
+
+	    unsafe
+	    {
+		fixed (byte* pathPtr = pathBytes)
+		{
+		    CheckAndDropResult(RegorusFFI.API.regorus_engine_set_input_from_json_file(E, pathPtr));
+		}
+	    }
+	}
+
+	public string EvalQuery(string query)
+	{
+	    var queryBytes = Encoding.UTF8.GetBytes(query);
+
+	    unsafe
+	    {
+		fixed (byte* queryPtr = queryBytes)
+		{
+		    return CheckAndDropResult(RegorusFFI.API.regorus_engine_eval_query(E, queryPtr));
+		}
+	    }
+	}
+
+	public string EvalRule(string rule)
+	{
+	    var ruleBytes = Encoding.UTF8.GetBytes(rule);
+
+	    unsafe
+	    {
+		fixed (byte* rulePtr = ruleBytes)
+		{
+		    return CheckAndDropResult(RegorusFFI.API.regorus_engine_eval_query(E, rulePtr));
+		}
+	    }
+	}
+	
+	public void SetEnableCoverage(bool enable)
+	{
+	    unsafe
+	    {
+		CheckAndDropResult(RegorusFFI.API.regorus_engine_set_enable_coverage(E, enable));
+	    }
+	}
+	
+	public void ClearCoverageData()
+	{
+	    unsafe
+	    {
+		CheckAndDropResult(RegorusFFI.API.regorus_engine_clear_coverage_data(E));
+	    }
+	}
+	
+	public string GetCoverageReport()
+	{
+	    unsafe
+	    {
+		return CheckAndDropResult(RegorusFFI.API.regorus_engine_get_coverage_report(E));
+	    }
+	}
+	
+	public string GetCoverageReportPretty()
+	{
+	    unsafe
+	    {
+		return CheckAndDropResult(RegorusFFI.API.regorus_engine_get_coverage_report_pretty(E));
+	    }
+	}
+	
+	public void SetGatherPrints(bool enable)
+	{
+	    unsafe
+	    {
+		CheckAndDropResult(RegorusFFI.API.regorus_engine_set_gather_prints(E, enable));
+	    }
+	}
+	
+	public string TakePrints()
+	{
+	    unsafe
+	    {
+		return CheckAndDropResult(RegorusFFI.API.regorus_engine_take_prints(E));
+	    }
+	}
+	
+	~Engine()
+	{
+	    unsafe
+	    {
+		RegorusFFI.API.regorus_engine_drop(E);
+	    }
+	}
+
+
+	string CheckAndDropResult(RegorusFFI.RegorusResult result)
+	{
+	    if (result.status != RegorusFFI.RegorusStatus.RegorusStatusOk) {
+		unsafe {
+		    var message = System.Runtime.InteropServices.Marshal.PtrToStringUTF8((IntPtr)result.error_message);
+		    var ex = new Exception(message);
+		    RegorusFFI.API.regorus_result_drop(result);
+		    throw ex;
+		}
+	    }
+
+	    var resultString = "";
+	    unsafe
+	    {
+		if (result.output is not null) {
+		    resultString = System.Runtime.InteropServices.Marshal.PtrToStringUTF8((IntPtr)result.output);
+		}
+		RegorusFFI.API.regorus_result_drop(result);
+	    }
+	    return resultString;
+	}
+
+    }
+}