// retrieve a quoted sugar token (' ` , ,@) and advance our position
private Token QuoteSugar()
{
TokenType type;
builder.Clear();
switch (Character)
{
case '\'':
type = TokenType.Quote;
break;
case '`':
type = TokenType.QuasiQuote;
break;
case ',':
type = TokenType.Unquote;
break;
default:
throw TokenizerError.SyntaxError("tokenizer", "unexpected character", lastToken);
}
builder.Append((char)Character);
NextChar();
if (Character == '@')
{
type = TokenType.UnquoteSplicing;
NextChar();
builder.Append((char)Character);
}
return(DefineToken(type, builder.ToString( )));
}
public char GetCharacter( )
{
Debug.Assert(type == TokenType.Character);
if (value.Length == 3)
{
return(System.Convert.ToChar(value[2]));
}
else
{
var c = (char)0;
if (NamedCharacter.NameToCharacter(value, out c))
{
return(c);
}
throw TokenizerError.SyntaxError("get-character", "improperly formed char value", this);
}
}
// -- Parse value --------------------------------------------------------------------------------
public bool GetBool()
{
Debug.Assert(type == TokenType.Boolean);
if (value == "#t")
{
return(true);
}
else if (value == "#f")
{
return(false);
}
else
{
throw TokenizerError.SyntaxError("get-bool", "improperly formed bool value", this);
}
}
public int GetInteger()
{
try
{
switch (type)
{
case TokenType.Integer:
return(StringParser.GetInteger(value));
case TokenType.Heximal:
return(StringParser.GetHexadecimal(value));
default:
throw TokenizerError.SyntaxError("get-integer", "wrong token type", this);
}
}
catch (System.Exception)
{
throw TokenizerError.SyntaxError("get-integer", "improperly formed int value", this);
}
}
// retrieve a string literal token and advance our position
private Token StringLiteral()
{
builder.Clear();
NextChar();
var type = TokenType.String;
var matchingQuotes = false;
while (Character >= 0)
{
// if we get an escape, increment the position some more and map the escaped character to what it should be
if (Character == '\\')
{
NextChar();
builder.Append(MapEscaped(Character));
NextChar();
continue;
}
// unescaped quote? We're done with this string.
if (Character == '"')
{
NextChar();
matchingQuotes = true;
break;
}
builder.Append((char)Character);
NextChar();
}
// we didn't get opening and closing quotes :(
if (!matchingQuotes)
{
throw TokenizerError.SyntaxError("tokenizer", "unmatched quotes in string literal", lastToken);
}
return(DefineToken(type, builder.ToString()));
}
// retrieve a number literal token (int or decimal) and advance our position
private Token NumberLiteral()
{
var type = TokenType.Integer;
builder.Clear();
while (Character >= 0 && IsNumericalPart(Character))
{
// if we get a decimal we're no longer working with an integer
if (Character == '.')
{
if (type == TokenType.Floating)
{
throw TokenizerError.SyntaxError("tokenizer", "error in numerical literal", lastToken);
}
type = TokenType.Floating;
}
builder.Append((char)Character);
NextChar();
}
return(DefineToken(type, builder.ToString( )));
}
// retrieve a vector literal marker, boolean token, or character literal token and advance our position
private Token VectorOrBooleanOrChar()
{
builder.Clear();
var boolLiterals = new List <char> {
'F', 'f', 't', 'T'
};
var nextc = reader.Peek();
if (boolLiterals.Contains((char)nextc))
{
// boolean literal!
builder.Append((char)Character);
NextChar(); // skip #
if (Character >= 0)
{
builder.Append((char)Character);
NextChar(); // skip F,f,t,T
}
return(DefineToken(TokenType.Boolean, builder.ToString( )));
}
else if (nextc == '(')
{
// vector literal!
NextChar(); // skip #
NextChar(); // skip (
return(DefineToken(TokenType.OpenVector, "("));
}
else if (nextc == '\\')
{
// char literal!
while (Character >= 0 && !IsWhitespace(Character))
{
if (builder.Size < 3)
{
builder.Append((char)Character);
NextChar();
}
else
{
if (!IsEOF(Character) && IsSymbolPart(Character))
{
builder.Append((char)Character);
NextChar();
}
else
{
break;
}
}
}
return(DefineToken(TokenType.Character, builder.ToString( )));
}
else if (nextc == 'x')
{
builder.Append((char)Character);
NextChar(); // skip #
builder.Append((char)Character);
NextChar(); // skip x
// char literal!
while (Character >= 0 && IsHeximalPart(Character))
{
builder.Append((char)Character);
NextChar();
}
return(DefineToken(TokenType.Heximal, builder.ToString( )));
}
//else if (nextc == '!')
//{
// builder.Append((char)Character);
// NextChar(); // skip #
// builder.Append((char)Character);
// NextChar(); // skip !
// // char literal!
// while (Character >= 0 && IsSymbolPart(Character))
// {
// builder.Append((char)Character);
// NextChar();
// }
// return DefineToken(TokenType.Symbol, builder.ToString());
//}
else
{
throw TokenizerError.SyntaxError("tokenizer", "inside '#' but no matching characters to construct a token", lastToken);
}
}