/// <summary>
/// Returns and removes the first element in a sequence that satisfies both,
/// the condition of the given predicate and the one contained in a query.
/// WhereParser is used to evaluate the query.
/// </summary>
/// <returns>The first element in the sequence that passes the test in the specified predicate function.</returns>
/// <param name="source">An IList<T> to return and remove an element from.</param>
/// <param name="predicate">A query describing a function to test each element for a condition (ignored when null).</param>
/// <param name="query">A query describing a function to test each element for a condition (ignored when null).</param>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
public static TSource PopFirst <TSource>(this List <TSource> source, Func <TSource, bool> predicate, string query)
{
if ((source == null) || ((predicate == null) && String.IsNullOrEmpty(query)))
{
throw new ArgumentNullException("Source or predicate and source are null.");
}
WhereParser.ConditionalStatement statement = WhereParser.Parse(query);
if ((predicate == null) && (statement == null))
{
throw new InvalidOperationException("No predicate was provided and query is null or is not in an acceptable format");
}
else if (predicate == null)
{
return(source.PopFirst(o => statement.Evaluate(o)));
}
else if (statement == null)
{
return(source.PopFirst(predicate));
}
else
{
return(source.PopFirst(o => predicate(o) && statement.Evaluate(o)));
}
}
internal static Condition Parse(string s, ref int cc)
{
// A where clause starts with an identifier followed by a binary operator
// and ends with a value. The type pattern is: io[sn]
char type;
Condition condition = new Condition();
condition.PropertyName = WhereParser.ReadNext(s, ref cc, out type);
if (type != 'i')
{
return(null);
}
condition.Operator = WhereParser.ReadNext(s, ref cc, out type);
if (type != 'o')
{
return(null);
}
condition.Value = WhereParser.ReadNext(s, ref cc, out type);
condition.ValueType = type;
if (type.IsAnyOf('0', 'B', 'n', 's'))
{
return(condition);
}
return(null);
}
/// <summary>
/// Returns and removes the first element in a sequence that satisfies the condition contained in a query.
/// WhereParser is used to evaluate the query.
/// </summary>
/// <returns>The first element in the sequence that passes the test in the specified predicate function.</returns>
/// <param name="source">An IList<T> to return and remove an element from.</param>
/// <param name="query">A query describing a function to test each element for a condition.</param>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
public static TSource PopFirst <TSource>(this List <TSource> source, string query)
{
WhereParser.ConditionalStatement statement = WhereParser.Parse(query);
if (statement == null)
{
throw new InvalidOperationException("query is null or is not in an acceptable format");
}
return(source.PopFirst(o => statement.Evaluate(o)));
}
private static string ReadWhereClauses(string s, ref int cc)
{
Scanner.SkipSpaces(s, ref cc);
int bcc = cc;
// First, read the "where" literal string
char[] where = new char[] { 'w', 'h', 'e', 'r', 'e' };
foreach (char c in where)
{
if (Scanner.ReadChar(c, s, ref cc))
{
continue;
}
cc = bcc;
return(null);
}
// After the "where" literal string, the where clauses come
string clauses = WhereParser.Fetch(s, ref cc);
return(clauses);
}
