public static FilterContainer GenerateFilterDescription <T>(this Expression expression) where T : class
{
var expType = expression.NodeType;
if (expType == ExpressionType.AndAlso)
{
var binaryExpression = expression as BinaryExpression;
var leftFilter = GenerateFilterDescription <T>(binaryExpression.Left);
var rightFilter = GenerateFilterDescription <T>(binaryExpression.Right);
var filterDescriptor = new FilterDescriptor <T>();
return(filterDescriptor.And(leftFilter, rightFilter));
}
else if (expType == ExpressionType.Or || expType == ExpressionType.OrElse)
{
var binaryExpression = expression as BinaryExpression;
var leftFilter = GenerateFilterDescription <T>(binaryExpression.Left);
var rightFilter = GenerateFilterDescription <T>(binaryExpression.Right);
var filterDescriptor = new FilterDescriptor <T>();
return(filterDescriptor.Or(leftFilter, rightFilter));
}
else if (expType == ExpressionType.Equal)
{
return(GenerateEqualityFilter <T>(expression));
}
else if (expType == ExpressionType.LessThan || expType == ExpressionType.GreaterThan || expType == ExpressionType.LessThanOrEqual || expType == ExpressionType.GreaterThanOrEqual)
{
return(GenerateComparisonFilter <T>(expression, expType));
}
else if (expType == ExpressionType.MemberAccess)
{
var memberExpression = expression as MemberExpression;
//here we handle binary expressions in the from .field.hasValue
if (memberExpression.Member.Name == "HasValue")
{
var parentFieldExpression = (memberExpression.Expression as MemberExpression);
var parentFieldName = GetFieldNameFromMember(parentFieldExpression);
var filterDescriptor = new FilterDescriptor <T>();
return(filterDescriptor.Exists(parentFieldName));
}
var isProperty = memberExpression.Member.MemberType == MemberTypes.Property;
if (isProperty)
{
var propertyType = ((PropertyInfo)memberExpression.Member).PropertyType;
if (propertyType == typeof(bool))
{
return(GenerateBoolFilter <T>(memberExpression));
}
}
}
else if (expType == ExpressionType.Lambda)
{
var lambda = expression as LambdaExpression;
return(GenerateFilterDescription <T>(lambda.Body));
}
else if (expType == ExpressionType.NotEqual)
{
return(GenerateNotEqualFilter <T>(expression));
}
throw new NotImplementedException();
}