public static Parser <TToken, IEnumerable <T> > Many <TToken, T>(this Parser <TToken, T> parser)
{
if (parser == null)
{
throw new ArgumentNullException(nameof(parser));
}
return((i, n) =>
{
var rest = i;
var result = new List <T>();
var r = parser(i, n);
while (r.IsSuccess)
{
if (rest.Equals(r.Rest))
{
break;
}
result.Add(r.Value);
rest = r.Rest;
r = parser(rest, n);
}
return ParserResult <TToken, IEnumerable <T> > .Success(rest, result);
});
}
internal static Parser <char, T> TryConvert <T>(string str, Func <string, T> converter)
{
return((i, n) =>
{
try
{
return ParserResult <char, T> .Success(i, converter(str));
}
catch (FormatException)
{
return ParserResult <char, T> .Failure(i, $"Failed to parse {str}");
}
});
}
public static Parser <ScriptToken, ScriptToken> ScriptToken(Func <int, bool> predicate, string expected)
{
return(i =>
{
if (i.AtEnd)
{
return ParserResult <ScriptToken, ScriptToken> .Failure(i, new[] { expected }, "Unexpected end of input");
}
if (predicate(i.GetCurrent().Tag))
{
return ParserResult <ScriptToken, ScriptToken> .Success(i.Advance(), i.GetCurrent());
}
return ParserResult <ScriptToken, ScriptToken> .Failure(i, $"Unexpected {i.GetCurrent()}");
});
}
public static Parser <TToken, IEnumerable <T> > Repeat <TToken, T>(
this Parser <TToken, T> parser,
int minimumCount,
int maximumCount
)
{
if (parser == null)
{
throw new ArgumentNullException(nameof(parser));
}
return((i, net) =>
{
var remainder = i;
var result = new List <T>();
for (var n = 0; n < maximumCount; ++n)
{
var r = parser(remainder, net);
if (!r.IsSuccess && n < minimumCount)
{
var what = r.Rest.AtEnd
? "end of input"
: r.Rest.GetCurrent().ToString();
var msg = $"Unexpected '{what}'";
var exp = minimumCount == maximumCount
? $"'{string.Join(", ", r.Expected)}' {minimumCount} times, but found {n}"
: $"'{string.Join(", ", r.Expected)}' between {minimumCount} and {maximumCount} times, but found {n}";
return ParserResult <TToken, IEnumerable <T> > .Failure(i, new[] { exp }, msg);
}
if (!ReferenceEquals(remainder, r.Rest))
{
result.Add(r.Value);
}
remainder = r.Rest;
}
return ParserResult <TToken, IEnumerable <T> > .Success(remainder, result);
});
}
public static Parser <char, char> Char(Func <char, bool> predicate, string expected)
{
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
return((i, n) =>
{
if (i.AtEnd)
{
return ParserResult <char, char> .Failure(i, new[] { expected }, "Unexpected end of input");
}
if (predicate(i.GetCurrent()))
{
return ParserResult <char, char> .Success(i.Advance(), i.GetCurrent());
}
return ParserResult <char, char> .Failure(i, new[] { expected }, $"Unexpected '{i.GetCurrent()}'");
});
}
/// <summary> /// Lift to a parser monad world /// </summary> /// <param name="v"></param> /// <typeparam name="TToken"></typeparam> /// <typeparam name="T"></typeparam> /// <returns></returns> public static Parser <TToken, T> Return <TToken, T>(T v) => (i, n) => ParserResult <TToken, T> .Success(i, v);