mirror of https://github.com/AMT-Cheif/Stylet.git
WIP towards ActionCommand using expression trees. Needs a bit more work to finish it off...
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@ -9,13 +9,16 @@ using System.Windows;
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using System.Windows.Controls.Primitives;
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using System.Windows.Input;
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using Expressions = System.Linq.Expressions;
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namespace Stylet
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{
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public class ActionCommand : ICommand
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{
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private FrameworkElement subject;
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private string methodName;
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private PropertyInfo guardPropertyInfo;
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private Func<bool> guardPropertyGetter;
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private Func<object> methodInvoker;
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private object target;
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@ -26,6 +29,7 @@ namespace Stylet
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this.UpdateGuardHandler();
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DependencyPropertyDescriptor.FromProperty(View.TargetProperty, typeof(View)).AddValueChanged(this.subject, (o, e) => this.UpdateGuardHandler());
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}
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@ -37,12 +41,18 @@ namespace Stylet
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private void UpdateGuardHandler()
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{
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var newTarget = View.GetTarget(this.subject);
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this.guardPropertyInfo = null;
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this.guardPropertyGetter = null;
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if (newTarget != null)
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{
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var guardPropertyInfo = newTarget.GetType().GetProperty(this.GuardName);
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if (guardPropertyInfo != null && guardPropertyInfo.PropertyType == typeof(bool))
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this.guardPropertyInfo = guardPropertyInfo;
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{
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var param = Expressions.Expression.Parameter(typeof(bool), "returnValue");
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var propertyAccess = Expressions.Expression.Property(param, guardPropertyInfo);
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this.guardPropertyGetter = Expressions.Expression.Lambda<Func<bool>>(propertyAccess, param).Compile();
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}
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}
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var oldTarget = this.target as INotifyPropertyChanged;
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@ -52,12 +62,43 @@ namespace Stylet
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this.target = newTarget;
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var inpc = newTarget as INotifyPropertyChanged;
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if (this.guardPropertyInfo != null && inpc != null)
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if (this.guardPropertyGetter != null && inpc != null)
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inpc.PropertyChanged += this.PropertyChangedHandler;
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this.UpdateCanExecute();
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}
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private void UpdateMethodInvoker()
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{
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if (this.target == null)
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throw new ArgumentException("Target not set");
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var methodInfo = this.target.GetType().GetMethod(this.methodName);
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if (methodInfo == null)
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throw new Exception(String.Format("Unable to find method {0} on {1}", this.methodName, this.target.GetType().Name));
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var target = Expressions.Expression.Constant(this.target);
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var param = Expressions.Expression.Parameter(typeof(object), "parameter");
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Expressions.Expression call;
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var methodParameters = methodInfo.GetParameters();
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if (methodParameters.Length == 0)
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{
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call = Expressions.Expression.Call(target, methodInfo);
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}
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else if (methodParameters.Length == 1)
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{
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var convertedParam = Expressions.Expression.Convert(param, methodParameters[0].ParameterType);
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call = Expressions.Expression.Call(target, methodInfo, convertedParam);
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}
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else
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{
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throw new Exception(String.Format("Method {0} must accept either 0 or 1 arguments", this.methodName));
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}
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this.methodInvoker = Expressions.Expression.Lambda<Func<object>>(call, param).Compile();
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}
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private void PropertyChangedHandler(object sender, PropertyChangedEventArgs e)
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{
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if (String.IsNullOrEmpty(e.PropertyName) || e.PropertyName == this.GuardName)
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@ -75,10 +116,10 @@ namespace Stylet
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public bool CanExecute(object parameter)
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{
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if (this.guardPropertyInfo == null)
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if (this.guardPropertyGetter == null)
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return true;
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return (bool)this.guardPropertyInfo.GetValue(this.target);
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return this.guardPropertyGetter();
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}
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public event EventHandler CanExecuteChanged;
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@ -86,7 +127,7 @@ namespace Stylet
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public void Execute(object parameter)
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{
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if (this.target == null)
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throw new Exception("Target not set");
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throw new ArgumentException("Target not set");
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var methodInfo = this.target.GetType().GetMethod(this.methodName);
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if (methodInfo == null)
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