Rename and move things about

src/Discord.Net.Commands/Attributes/PermissionAttribute.cs

@@ -5,8 +5,8 @@ using System.Threading.Tasks;
 
 namespace Discord.Commands
 {
-    public abstract class FilterAttribute : Attribute
+    public abstract class PermissionAttribute : Attribute
     {
-        public abstract void OnCommandExecuting(CommandExecutionContext context);
+        public abstract void CheckPermissions(PermissionsContext context);
     }
 }

src/Discord.Net.Commands/Command.cs

@@ -19,7 +19,7 @@ namespace Discord.Commands
         public string Text { get; }
         public Module Module { get; }
         public IReadOnlyList<CommandParameter> Parameters { get; }
-        public IReadOnlyList<FilterAttribute> Filters { get; }
+        public IReadOnlyList<PermissionAttribute> Permissions { get; }
 
         internal Command(Module module, object instance, CommandAttribute attribute, MethodInfo methodInfo, string groupPrefix)
         {
@@ -38,10 +38,24 @@ namespace Discord.Commands
                 Synopsis = synopsis.Text;
 
             Parameters = BuildParameters(methodInfo);
-            Filters = BuildFilters(methodInfo);
+            Permissions = BuildPermissions(methodInfo);
             _action = BuildAction(methodInfo);
         }
 
+        public bool CanExecute(IMessage message)
+        {
+            var context = new PermissionsContext(this, message);
+
+            foreach (PermissionAttribute permission in Permissions)
+            {
+                permission.CheckPermissions(context);
+                if (context.Handled)
+                    return false;
+            }
+
+            return true;
+        }
+
         public async Task<ParseResult> Parse(IMessage msg, SearchResult searchResult)
         {
             if (!searchResult.IsSuccess)
@@ -54,13 +68,8 @@ namespace Discord.Commands
             if (!parseResult.IsSuccess)
                 return ExecuteResult.FromError(parseResult);
 
-            var context = new CommandExecutionContext(this, parseResult, msg);
-            foreach (FilterAttribute filter in Filters)
-            {
-                filter.OnCommandExecuting(context);
-                if (context.Handled)
-                    return ExecuteResult.FromError(CommandError.InvalidPermissions, $"Permission check for {filter.GetType().FullName} failed");
-            }
+            if (!CanExecute(msg)) // TODO: should we have to check this here, or leave it entirely to the bot dev?
+                return ExecuteResult.FromError(CommandError.InvalidPermissions, "Permissions check failed");
 
             try
             {
@@ -73,9 +82,9 @@ namespace Discord.Commands
             }
         }
 
-        private IReadOnlyList<FilterAttribute> BuildFilters(MethodInfo methodInfo)
+        private IReadOnlyList<PermissionAttribute> BuildPermissions(MethodInfo methodInfo)
         {
-            return methodInfo.GetCustomAttributes<FilterAttribute>().ToImmutableArray();
+            return methodInfo.GetCustomAttributes<PermissionAttribute>().ToImmutableArray();
         }
 
         private IReadOnlyList<CommandParameter> BuildParameters(MethodInfo methodInfo)

src/Discord.Net.Commands/Context/PermissionsContext.cs

@@ -5,18 +5,16 @@ using System.Threading.Tasks;
 
 namespace Discord.Commands
 {
-    public class CommandExecutionContext
+    public class PermissionsContext
     {
         public Command ExecutingCommand { get; internal set; }
-        public ParseResult ParseResult { get; internal set; }
         public IMessage Message { get; internal set; }
 
         public bool Handled { get; set; }
 
-        internal CommandExecutionContext(Command command, ParseResult parseResult, IMessage message)
+        internal PermissionsContext(Command command, IMessage message)
         {
             ExecutingCommand = command;
-            ParseResult = parseResult;
             Message = message;
 
             Handled = false;