committed

GuiWPF/DelegateCommand.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Windows.Input;
+
+namespace GuiWPF {
+    public class DelegateCommand : ICommand {
+        /// <summary>
+        /// Action to be performed when this command is executed
+        /// </summary>
+        private Action<object> executionAction;
+
+        /// <summary>
+        /// Predicate to determine if the command is valid for execution
+        /// </summary>
+        private Predicate<object> canExecutePredicate;
+
+        /// <summary>
+        /// Initializes a new instance of the DelegateCommand class.
+        /// The command will always be valid for execution.
+        /// </summary>
+        /// <param name="execute">The delegate to call on execution</param>
+        public DelegateCommand(Action<object> execute)
+            : this(execute, null)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the DelegateCommand class.
+        /// </summary>
+        /// <param name="execute">The delegate to call on execution</param>
+        /// <param name="canExecute">The predicate to determine if command is valid for execution</param>
+        public DelegateCommand(Action<object> execute, Predicate<object> canExecute)
+        {
+            if (execute == null)
+            {
+                throw new ArgumentNullException("execute");
+            }
+
+            this.executionAction = execute;
+            this.canExecutePredicate = canExecute;
+        }
+
+        /// <summary>
+        /// Raised when CanExecute is changed
+        /// </summary>
+        public event EventHandler CanExecuteChanged
+        {
+            add { CommandManager.RequerySuggested += value; }
+            remove { CommandManager.RequerySuggested -= value; }
+        }
+
+        /// <summary>
+        /// Executes the delegate backing this DelegateCommand
+        /// </summary>
+        /// <param name="parameter">parameter to pass to predicate</param>
+        /// <returns>True if command is valid for execution</returns>
+        public bool CanExecute(object parameter)
+        {
+            return this.canExecutePredicate == null ? true : this.canExecutePredicate(parameter);
+        }
+
+        /// <summary>
+        /// Executes the delegate backing this DelegateCommand
+        /// </summary>
+        /// <param name="parameter">parameter to pass to delegate</param>
+        /// <exception cref="InvalidOperationException">Thrown if CanExecute returns false</exception>
+        public void Execute(object parameter)
+        {
+            if (!this.CanExecute(parameter))
+            {
+                throw new InvalidOperationException("The command is not valid for execution, check the CanExecute method before attempting to execute.");
+            }
+            this.executionAction(parameter);
+        }
+    }
+}