public Result <TextSpan, TextSpan> Parse(ParseText text, TextSpan span)
{
if (span.IsEmpty)
{
return(new Unmatched <TextSpan, TextSpan>(span));
}
if (span.Length == 2 && text[span.Start] == '"' && text[span.Start + 1] == '"')
{
return(new Success <TextSpan, TextSpan>(new TextSpan(span.Start, 2), TextSpan.FromBounds(span.Start + 2, span.End)));
}
var index = text.IndexOf(_settings.EscapeCharacter, span);
if (index < 0)
{
return(new Success <TextSpan, TextSpan>(span, new TextSpan(span.End, 0)));
}
var builder = new StringBuilder(span.Length);
int offset = span.Start;
while ((index >= 0) && offset < span.End)
{
text.AppendTo(builder, TextSpan.FromBounds(offset, index - offset));
offset = ParseEscapeSequence(builder, text, TextSpan.FromBounds(index, span.End));
index = text.IndexOf(_settings.EscapeCharacter, TextSpan.FromBounds(offset, span.End));
}
if (offset < span.End)
{
text.AppendTo(builder, TextSpan.FromBounds(offset, span.End));
offset = span.End;
}
return(new Success <TextSpan, TextSpan>(TextSpan.FromBounds(span.Start, offset), TextSpan.FromBounds(offset, span.End)));
}
int ParseEscapeSequence(StringBuilder builder, ParseText body, TextSpan span)
{
if (span.Length < 3)
{
body.AppendTo(builder, span);
return(span.End);
}
char key = body[span.Start + 1];
char closing = body[span.Start + 2];
if (closing == _settings.EscapeCharacter)
{
switch (key)
{
case 'F':
builder.Append(_settings.FieldSeparator);
break;
case 'S':
builder.Append(_settings.ComponentSeparator);
break;
case 'T':
builder.Append(_settings.SubComponentSeparator);
break;
case 'R':
builder.Append(_settings.RepetitionSeparator);
break;
case 'E':
builder.Append(_settings.EscapeCharacter);
break;
case 'X': // if we get empty hex data, skip it as well
case 'Z': // locally defined we pass through
break;
case 'H': // we don't translate highlighting, so just skip it
case 'N':
default:
body.AppendTo(builder, new TextSpan(span.Start, 3));
break;
}
return(span.Start + 3);
}
// while we could strip this out, it seems like there would be no other way to get
// access to this data, so I think it makes sense to leave it in the text and let
// the application deal with it since it may want to use it.
if (key == 'X' || key == 'Z' || key == '.') // hexadecimal data or locally defined data
{
int end = body.IndexOf(_settings.EscapeCharacter, new TextSpan(span.Start + 2, span.Length - 2));
if (end > 0)
{
body.AppendTo(builder, TextSpan.FromBounds(span.Start, end + 1));
return(end + 1);
}
}
body.AppendTo(builder, new TextSpan(span.Start, 1));
return(span.Start + 1);
}
