/// <summary>
/// Determines if current position is at a keyword or
/// at a function name candidate. Function name candidate
/// looks like 'identifier[whitespace](' sequence.
/// </summary>
/// <returns>
/// True if it handled the sequence and it looked
/// like either keyword or a function candidate.
/// </returns>
private void HandleKeywordOrIdentifier()
{
var start = _cs.Position;
var s = this.GetIdentifier();
if (s.Length == 0)
{
AddToken(RTokenType.Unknown, start, 1);
_cs.MoveToNextChar();
return;
}
if (s[0] == '`')
{
AddToken(RTokenType.Identifier, RTokenSubType.None, start, s.Length);
}
else if (Logicals.IsLogical(s))
{
// Tell between F and F()
var logical = true;
if (s.Length == 1)
{
_cs.SkipWhitespace();
if (_cs.CurrentChar == '(')
{
logical = false;
}
}
AddToken(logical ? RTokenType.Logical : RTokenType.Identifier, start, s.Length);
}
else if (s == "NULL")
{
AddToken(RTokenType.Null, RTokenSubType.BuiltinConstant, start, s.Length);
}
else if (s == "NA" || s == "NA_character_" || s == "NA_complex_" || s == "NA_integer_" || s == "NA_real_")
{
AddToken(RTokenType.Missing, RTokenSubType.BuiltinConstant, start, s.Length);
}
else if (s == "Inf")
{
AddToken(RTokenType.Infinity, RTokenSubType.BuiltinConstant, start, s.Length);
}
else if (s == "NaN")
{
AddToken(RTokenType.NaN, RTokenSubType.BuiltinConstant, start, s.Length);
}
else if (Builtins.IsBuiltin(s))
{
AddToken(RTokenType.Identifier, RTokenSubType.BuiltinFunction, start, s.Length);
}
else if (s.StartsWith("as.", StringComparison.Ordinal) || s.StartsWith("is.", StringComparison.Ordinal))
{
AddToken(RTokenType.Identifier, RTokenSubType.TypeFunction, start, s.Length);
}
else if (Keywords.IsKeyword(s))
{
AddToken(RTokenType.Keyword, start, s.Length);
}
else
{
AddToken(RTokenType.Identifier, start, s.Length);
}
}