/// <summary>
/// Throws a <see cref="ParseException"/> if the specified <paramref name="parser"/> does not match.
/// </summary>
/// <typeparam name="TSource">The type of the source elements.</typeparam>
/// <typeparam name="TResult">The type of the elements that are generated from parsing the source elements.</typeparam>
/// <param name="parser">The parser that must succeed otherwise a <see cref="ParseException"/> is thrown.</param>
/// <returns>A parser that yields the matches from the specified <paramref name="parser"/> or throws
/// a <see cref="ParseException"/> if there are no matches.</returns>
public static IObservableParser <TSource, TResult> Required <TSource, TResult>(
this IObservableParser <TSource, TResult> parser)
{
Contract.Requires(parser != null);
Contract.Ensures(Contract.Result <IObservableParser <TSource, TResult> >() != null);
return(parser.Required(index => new ParseException(index)));
}
/// <summary>
/// Throws a <see cref="ParseException"/> with a message returned by the specified function if the specified
/// <paramref name="parser"/> does not match.
/// </summary>
/// <typeparam name="TSource">The type of the source elements.</typeparam>
/// <typeparam name="TResult">The type of the elements that are generated from parsing the source elements.</typeparam>
/// <param name="parser">The parser that must succeed otherwise a <see cref="ParseException"/> is thrown.</param>
/// <param name="errorMessageFactory">A function that returns a <see cref="string"/> describing the failed expectation
/// to be used as the message in the <see cref="ParseException"/>.</param>
/// <returns>A parser that yields the matches from the specified <paramref name="parser"/> or throws
/// a <see cref="ParseException"/> with a message returned by the specified functions if there are no matches.</returns>
public static IObservableParser <TSource, TResult> Required <TSource, TResult>(
this IObservableParser <TSource, TResult> parser,
Func <string> errorMessageFactory)
{
Contract.Requires(parser != null);
Contract.Requires(errorMessageFactory != null);
Contract.Ensures(Contract.Result <IObservableParser <TSource, TResult> >() != null);
return(parser.Required(index => new ParseException(index, errorMessageFactory())));
}
/// <summary>
/// Throws a <see cref="ParseException"/> with the specified message if the specified <paramref name="parser"/>
/// does not match.
/// </summary>
/// <typeparam name="TSource">The type of the source elements.</typeparam>
/// <typeparam name="TResult">The type of the elements that are generated from parsing the source elements.</typeparam>
/// <param name="parser">The parser that must succeed otherwise a <see cref="ParseException"/> is thrown.</param>
/// <param name="errorMessage">A <see cref="string"/> that describes the failed expectation to be used as the message
/// in the <see cref="ParseException"/>.</param>
/// <returns>A parser that yields the matches from the specified <paramref name="parser"/> or throws
/// a <see cref="ParseException"/> with the specified message if there are no matches.</returns>
public static IObservableParser <TSource, TResult> Required <TSource, TResult>(
this IObservableParser <TSource, TResult> parser,
string errorMessage)
{
Contract.Requires(parser != null);
Contract.Requires(!string.IsNullOrWhiteSpace(errorMessage));
Contract.Ensures(Contract.Result <IObservableParser <TSource, TResult> >() != null);
return(parser.Required(index => new ParseException(index, errorMessage)));
}