public static bool GetValueFromExpressionWithoutConversion(Expression expression, out object value)
{
switch (expression.NodeType)
{
case ExpressionType.Constant:
value = ((ConstantExpression)expression).Value;
return(true);
case ExpressionType.MemberAccess:
value = GetMemberValue(((MemberExpression)expression));
return(true);
case ExpressionType.MemberInit:
var memberInitExpression = ((MemberInitExpression)expression);
value = Expression.Lambda(memberInitExpression).Compile().DynamicInvoke();
return(true);
case ExpressionType.New:
value = GetNewExpressionValue(expression);
return(true);
case ExpressionType.Lambda:
value = ((LambdaExpression)expression).Compile().DynamicInvoke();
return(true);
case ExpressionType.Call:
value = Expression.Lambda(expression).Compile().DynamicInvoke();
return(true);
case ExpressionType.Convert:
var unaryExpression = ((UnaryExpression)expression);
if (TypeSystem.IsNullableType(unaryExpression.Type))
{
return(GetValueFromExpressionWithoutConversion(unaryExpression.Operand, out value));
}
value = Expression.Lambda(expression).Compile().DynamicInvoke();
return(true);
case ExpressionType.NewArrayInit:
var expressions = ((NewArrayExpression)expression).Expressions;
var values = new object[expressions.Count];
value = null;
if (expressions.Where((t, i) => !GetValueFromExpressionWithoutConversion(t, out values[i])).Any())
{
return(false);
}
value = values;
return(true);
case ExpressionType.NewArrayBounds:
value = null;
expressions = ((NewArrayExpression)expression).Expressions;
var constantExpression = (ConstantExpression)expressions.FirstOrDefault();
if (constantExpression == null)
{
return(false);
}
if (constantExpression.Value.GetType() != typeof(int))
{
return(false);
}
var length = (int)constantExpression.Value;
value = new object[length];
return(true);
default:
value = null;
return(false);
}
}
