/// <summary>
/// If the result is empty, format the fragment of text describing the error.
/// </summary>
/// <returns>The error fragment.</returns>
public string FormatErrorMessageFragment()
{
if (ErrorMessage != null)
{
return(ErrorMessage);
}
string message;
if (Remainder.IsAtEnd)
{
message = "unexpected end of input";
}
else
{
var next = Remainder.ConsumeToken().Value;
var appearance = Presentation.FormatAppearance(next.Kind, next.ToStringValue());
message = $"unexpected {appearance}";
}
if (Expectations != null)
{
var expected = Friendly.List(Expectations);
message += $", expected {expected}";
}
return(message);
}
/// <inheritdoc />
public override string ToString()
{
if (Remainder == TokenList <TKind> .Empty)
{
return("(Empty result.)");
}
if (HasValue)
{
return($"Successful parsing of {Value}.");
}
var message = FormatErrorMessageFragment();
var location = "";
if (!Remainder.IsAtEnd)
{
var next = Remainder.ConsumeToken().Value;
var sourcePosition = ErrorPosition.HasValue ? ErrorPosition : next.Position;
location = $" (line {sourcePosition.Line}, column {sourcePosition.Column})";
}
return($"Syntax error{location}: {message}.");
}
/// <inheritdoc />
public override string ToString()
{
if (Remainder == TokenList <TKind> .Empty)
{
return("(Empty result.)");
}
if (HasValue)
{
return($"Successful parsing of {Value}.");
}
var message = FormatErrorMessageFragment();
var location = "";
if (!Remainder.IsAtEnd)
{
// Since the message notes `end of input`, don't report line/column here.
var sourcePosition = SubTokenErrorPosition.HasValue ? SubTokenErrorPosition : Remainder.ConsumeToken().Value.Position;
location = $" (line {sourcePosition.Line}, column {sourcePosition.Column})";
}
return($"Syntax error{location}: {message}.");
}