/// <summary>
/// Parses a filtering function based on the provided expression.
/// </summary>
/// <typeparam name="T">The type of the elements the filter will be used for.</typeparam>
/// <param name="expression">An expression.</param>
/// <param name="predicate">A function that evaluates the expression in the context of an item of the type <typeparamref name="T"/>.</returns>
/// <param name="error">The reported error, if compilation was unsuccessful.</param>
/// <returns>True if the function could be created; otherwise, false.</returns>
public static bool TryParse <T>(
string filterExpression,
[MaybeNullWhen(false)] out Expression <Func <T, bool> > root,
[MaybeNullWhen(true)] out string error)
{
if (filterExpression == null)
{
throw new ArgumentNullException(nameof(filterExpression));
}
var tokens = FilterExpressionTokenizer.Instance.TryTokenize(filterExpression);
if (!tokens.HasValue)
{
error = tokens.ToString();
root = null;
return(false);
}
try
{
var result = FilterExpressionParser.TryParse <T>(tokens.Value);
if (!result.HasValue)
{
error = result.ToString();
root = null;
return(false);
}
error = null;
root = result.Value;
return(true);
}
catch (Exception err)
{
error = err.Message;
root = null;
return(false);
}
}