#region License
//
// The Open Toolkit Library License
//
// Copyright (c) 2006 - 2009 the Open Toolkit library.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
#endregion

using System;
using System.Runtime.InteropServices;

namespace OpenTK {
	
	/// <summary>
	/// Provides a common foundation for all flat API bindings and implements the extension loading interface.
	/// </summary>
	public abstract class BindingsBase {

		protected abstract IntPtr GetAddress(string funcname);
		
		public static bool IsInvalidAddress(IntPtr address) {
			return address == IntPtr.Zero || address == new IntPtr(1) ||
				address == new IntPtr(2) || address == new IntPtr(-1);
		}

		// Creates a System.Delegate that can be used to call a dynamically exported OpenGL function.
		protected internal void LoadDelegate<T>(string name, out T del) where T : class {
			IntPtr address = GetAddress(name);
			del = IsInvalidAddress(address) ? null :
				(T)(object)Marshal.GetDelegateForFunctionPointer(address, typeof(T));
		}
	}
}