public IToken Produce()
{
var context = this.Context;
var text = context.Text;
var length = context.Length;
var c = text[context.Index];
if (c == ':')
{
var nameCharsCount = 0;
var initialIndex = context.Index;
var index = initialIndex + 1;
var column = context.Column + 1;
while (true)
{
if (index == length)
{
break;
}
c = text[index];
if (c == ':')
{
ThrowBadKeywordException(context.Line, context.Column);
}
if (!TinyLispHelper.IsAcceptableSymbolNameChar(c))
{
break;
}
nameCharsCount++;
index++;
column++;
}
if (nameCharsCount == 0)
{
ThrowBadKeywordException(context.Line, context.Column);
}
var delta = index - initialIndex;
var keywordName = text.Substring(initialIndex, delta);
var token = new KeywordToken(
keywordName,
new Position(context.Line, context.Column),
delta);
context.Advance(delta, 0, column);
return(token);
}
else
{
return(null);
}
}
public IToken Produce()
{
var context = this.Context;
var text = context.Text;
var length = context.Length;
var c = text[context.Index];
if (TinyLispHelper.IsAcceptableSymbolNameChar(c))
{
var gotSign = c == '+' || c == '-';
var pureDigits = 0;
if (!gotSign)
{
pureDigits = LexingHelper.IsDigit(c) ? 1 : 0;
}
var gotNonDigits = false;
var initialIndex = context.Index;
var initialColumn = context.Column;
var index = initialIndex + 1;
var column = context.Column + 1;
while (true)
{
if (index == length)
{
break;
}
c = text[index];
if (c == ':')
{
throw new LexingException("Bad symbol name.", new Position(context.Line, context.Column));
}
if (!TinyLispHelper.IsAcceptableSymbolNameChar(c))
{
break;
}
if (LexingHelper.IsDigit(c))
{
if (!gotNonDigits)
{
pureDigits++;
}
}
else
{
gotNonDigits = true;
pureDigits = 0;
}
index++;
column++;
}
var couldBeInt = pureDigits > 0;
if (couldBeInt)
{
throw new LexingException("Symbol producer delivered an integer.", new Position(context.Line, context.Column));
}
var delta = index - initialIndex;
var str = text.Substring(initialIndex, delta); // todo: use ReadOnlySpan<char> instead of Substring everywhere.
var symbolToken = new LispSymbolToken(str, new Position(context.Line, initialColumn), delta);
context.Advance(delta, 0, column);
return(symbolToken);
}
else
{
return(null);
}
}