using System;
using System.Runtime.InteropServices;
using System.Text;
namespace Python.Runtime.Native
{
[StructLayout(LayoutKind.Sequential)]
struct StrPtr : IDisposable
{
public IntPtr RawPointer { get; set; }
unsafe byte* Bytes => (byte*)this.RawPointer;
public unsafe StrPtr(string value) : this(value, Encodings.UTF8) {}
public unsafe StrPtr(string value, Encoding encoding)
{
if (value is null) throw new ArgumentNullException(nameof(value));
if (encoding is null) throw new ArgumentNullException(nameof(encoding));
var bytes = encoding.GetBytes(value);
this.RawPointer = Marshal.AllocHGlobal(checked(bytes.Length + 1));
try
{
Marshal.Copy(bytes, 0, this.RawPointer, bytes.Length);
this.Bytes[bytes.Length] = 0;
}
catch
{
this.Dispose();
throw;
}
}
public unsafe string? ToString(Encoding encoding)
{
if (encoding is null) throw new ArgumentNullException(nameof(encoding));
if (this.RawPointer == IntPtr.Zero) return null;
return encoding.GetString((byte*)this.RawPointer, byteCount: checked((int)this.ByteCount));
}
public unsafe nuint ByteCount
{
get
{
if (this.RawPointer == IntPtr.Zero) throw new NullReferenceException();
nuint zeroIndex = 0;
while (this.Bytes[zeroIndex] != 0)
{
zeroIndex++;
}
return zeroIndex;
}
}
public void Dispose()
{
if (this.RawPointer == IntPtr.Zero)
return;
Marshal.FreeHGlobal(this.RawPointer);
this.RawPointer = IntPtr.Zero;
}
internal static Encoding GetEncodingByPythonName(string pyEncodingName)
{
// https://stackoverflow.com/a/7798749/231238
if (pyEncodingName == "mbcs") return Encoding.Default;
return Encoding.GetEncoding(pyEncodingName);
}
}
}