public static TestExpression <Func <T1, T2, T3, T> > Lambda <T1, T2, T3, T>(Expression <Func <T1, T2, T3, TestExpression <T> > > expression)
{
/* In order to access the TestExpression value, the expression needs
* to be evaluated and this requires that no unused parameters are
* present at the evaluation time as this results in an error.
* So to avoid this, the unused parameters are replaced with an default
* value, then everything is evaluated, and the default value is
* replaced back to a parameter
*/
UnaryExpression constant1 = Expression.Convert(Expression.Constant(default(T1)), typeof(T1));
UnaryExpression constant2 = Expression.Convert(Expression.Constant(default(T2)), typeof(T2));
UnaryExpression constant3 = Expression.Convert(Expression.Constant(default(T3)), typeof(T3));
ReplacerVisitor toReplacer1 = new ReplacerVisitor(expression.Parameters[0], constant1);
ReplacerVisitor toReplacer2 = new ReplacerVisitor(expression.Parameters[1], constant2);
ReplacerVisitor toReplacer3 = new ReplacerVisitor(expression.Parameters[2], constant3);
ReplacerVisitor backReplacer1 = new ReplacerVisitor(constant1, expression.Parameters[0]);
ReplacerVisitor backReplacer2 = new ReplacerVisitor(constant2, expression.Parameters[1]);
ReplacerVisitor backReplacer3 = new ReplacerVisitor(constant3, expression.Parameters[2]);
Expression body1 = toReplacer3.Visit(toReplacer2.Visit(toReplacer1.Visit(expression.Body)));
Expression <Func <TestExpression <T> > > lambda1 = Expression.Lambda <Func <TestExpression <T> > >(body1);
TestExpression <T> testExpression = lambda1.Compile().Invoke();
Expression body2 = backReplacer3.Visit(backReplacer2.Visit(backReplacer1.Visit(testExpression.Expression)));
Expression <Func <T1, T2, T3, T> > lambda2 = Expression.Lambda <Func <T1, T2, T3, T> >(body2, expression.Parameters[0], expression.Parameters[1], expression.Parameters[2]);
return(new TestExpression <Func <T1, T2, T3, T> >(lambda2));
}
private void TestExpression(Random rnd, Expression expression, ParameterExpression originalParameter)
{
var parameter = Expression.Parameter(typeof(TestViewModel[]), "par");
var count = 0;
var expr = new ReplacerVisitor(originalParameter, () => Expression.ArrayIndex(parameter, Expression.Constant(count++))).Visit(expression);
Func <TestViewModel[], object> compile(Expression e) =>
Expression.Lambda <Func <TestViewModel[], object> >(Expression.Convert(e, typeof(object)), parameter).Compile();
var withNullCheks = compile(ExpressionNullPropagationVisitor.PropagateNulls(expr, _ => true));
var withoutNullChecks = compile(expr);
var args = Enumerable.Repeat(new TestViewModel {
StringProp = "ll", StringProp2 = "pp", TestViewModel2 = new TestViewModel2()
}, count).ToArray();
var settings = DefaultSerializerSettingsProvider.Instance.Settings;
Assert.AreEqual(JsonConvert.SerializeObject(withNullCheks(args), settings), JsonConvert.SerializeObject(withoutNullChecks(args), settings));
foreach (var i in Enumerable.Range(0, args.Length).Shuffle(rnd))
{
args[i] = null;
withNullCheks(args);
}
}
public static TestExpression Expr <T1>(TestExpression <T1> var, Expression <Action <T1> > expression)
{
ParameterExpression parameter = expression.Parameters[0];
ReplacerVisitor replacer = new ReplacerVisitor(parameter, var.Expression);
Expression rewrittenExpression = replacer.Visit(expression.Body);
return(new TestExpression(rewrittenExpression));
}
public static TestExpression Expr <T1, T2>(TestExpression <T1> var1, TestExpression <T2> var2, Expression <Action <T1, T2> > expression)
{
ParameterExpression parameter1 = expression.Parameters[0];
ParameterExpression parameter2 = expression.Parameters[1];
ReplacerVisitor replacer1 = new ReplacerVisitor(parameter1, var1.Expression);
ReplacerVisitor replacer2 = new ReplacerVisitor(parameter2, var2.Expression);
Expression rewrittenExpression = replacer2.Visit(replacer1.Visit(expression.Body));
return(new TestExpression(rewrittenExpression));
}
public static TestExpression <T> Expr <T1, T2, T3, T>(TestExpression <T1> var1, TestExpression <T2> var2, TestExpression <T3> var3, Expression <Func <T1, T2, T3, T> > expression)
{
ParameterExpression parameter1 = expression.Parameters[0];
ParameterExpression parameter2 = expression.Parameters[1];
ParameterExpression parameter3 = expression.Parameters[2];
ReplacerVisitor replacer1 = new ReplacerVisitor(parameter1, var1.Expression);
ReplacerVisitor replacer2 = new ReplacerVisitor(parameter2, var2.Expression);
ReplacerVisitor replacer3 = new ReplacerVisitor(parameter3, var3.Expression);
Expression rewrittenExpression = replacer3.Visit(replacer2.Visit(replacer1.Visit(expression.Body)));
return(new TestExpression <T>(rewrittenExpression));
}
public static TestExpression Expr <T1, T2, T3, T4, T5>(TestExpression <T1> var1, TestExpression <T2> var2, TestExpression <T3> var3, TestExpression <T4> var4, TestExpression <T5> var5, Expression <Action <T1, T2, T3, T4, T5> > expression)
{
ParameterExpression parameter1 = expression.Parameters[0];
ParameterExpression parameter2 = expression.Parameters[1];
ParameterExpression parameter3 = expression.Parameters[2];
ParameterExpression parameter4 = expression.Parameters[3];
ParameterExpression parameter5 = expression.Parameters[4];
ReplacerVisitor replacer1 = new ReplacerVisitor(parameter1, var1.Expression);
ReplacerVisitor replacer2 = new ReplacerVisitor(parameter2, var2.Expression);
ReplacerVisitor replacer3 = new ReplacerVisitor(parameter3, var3.Expression);
ReplacerVisitor replacer4 = new ReplacerVisitor(parameter4, var4.Expression);
ReplacerVisitor replacer5 = new ReplacerVisitor(parameter5, var5.Expression);
Expression rewrittenExpression = replacer5.Visit(replacer4.Visit(replacer4.Visit(replacer3.Visit(replacer2.Visit(replacer1.Visit(expression.Body))))));
return(new TestExpression(rewrittenExpression));
}
