/// <summary>
/// Retrieves the filter definition from the expression
/// </summary>
/// <param name="expression">Filter expression</param>
/// <returns>A filter definition based on an expression</returns>
internal static FilterDefinition FromExpression(String expression)
{
List<string> filterTokens = expression.TrimmedSplit("|");
// Invalid number of segments
if (filterTokens.Count != 1 && filterTokens.Count != 2)
throw new InvalidFilterDefinitionException(
InvalidFilterDefinitionException.ErrorCause.InvalidNumberOfDefinitionElements);
// Missing function name or arguments
if (filterTokens.Count == 1 && expression.Contains("|"))
throw new InvalidFilterDefinitionException(
InvalidFilterDefinitionException.ErrorCause.FunctionNameOrArgumentMissing);
string functionName = filterTokens.First();
if (functionName.ContainsWhitespace())
throw new InvalidFilterDefinitionException(
InvalidFilterDefinitionException.ErrorCause.FunctionNameContainsWhitespace,
functionName);
FilterDefinition definition = new FilterDefinition(functionName);
if (filterTokens.Count == 2)
{
List<string> arguments = filterTokens[1].TrimmedSplit(",");
List<FilterArgumentDefinition> argumentDefinitions =
arguments
.Select(a => FilterArgumentDefinition.FromArgumentExpression(a))
.ToList();
definition.Arguments.AddRange(argumentDefinitions);
}
return definition;
}
/// <summary>
/// Checks whether the item should be included in the output
/// </summary>
/// <param name="filterDefinition">A filter definition object with name and arguments</param>
/// <param name="behavior">Specifies what happens when a filter is missing</param>
/// <returns>True if current item should be included</returns>
internal bool IsIncludedWithFilter(FilterDefinition filterDefinition, MissingFilterBehavior behavior)
{
if (!filterMap.ContainsKey(filterDefinition.Function))
{
switch (behavior)
{
case MissingFilterBehavior.IncludeItem:
return true;
case MissingFilterBehavior.OmitItem:
return false;
case MissingFilterBehavior.ThrowException:
default:
throw new FilterNotFoundException(filterDefinition.Function);
}
}
// Find a filter
FilterFunction predicate = filterMap[filterDefinition.Function];
// Create filter arguments
IEnumerable<CollapseFilterArgument> arguments =
filterDefinition.Arguments
.Select(arg => new CollapseFilterArgument(GetObject(arg.Path), arg.Name));
// Run the predicate to see if the item should be included
return predicate(
new CollapseFilterArgumentCollection(arguments));
}
