private static void matchSymbol(Scanner s)
{
if (!s.isInitial())
return;
s.readChar();
while (s.isSubsequent())
s.readChar();
}
// Remove the '"' delimiters surrounding the token that came
// back from the lexer. Also 'unescape' any backslashes.
private static string unescape(string s)
{
// Remove surrounding quotes
s = s.Substring(1, s.Length - 2);
// Regex.Unescape solves the problem of converting \n, \t etc
// for us.
return System.Text.RegularExpressions.Regex.Unescape(s);
}
private static bool matchSymbol(Scanner s)
{
if (!s.isInitial())
return false;
s.readChar();
while (s.isSubsequent())
s.readChar();
return true;
}
public static IEnumerable<Datum> ReadDatums(Assembly assembly, string resourceFile)
{
var stream = assembly.GetManifestResourceStream(resourceFile);
if (stream == null)
throw new Exception(string.Format("Unable to find '{0}' embedded resource", resourceFile));
var s = new Scanner(new StreamReader(stream)) { Filename = resourceFile };
var p = new Parser(s);
Datum d;
while ((d = p.parse()) != null)
{
yield return d;
}
}
public Parser(Scanner s)
{
this.s = s;
initTokens(s.Scan());
}
// .Net method support.
// Check if we received a "." or a ".symbol".
// Given them different tokens so that the parser
// can expand appropriately.
private static TokenType? matchDot(Scanner s)
{
if (s.peek() != '.')
return null;
s.readChar();
matchSymbol(s);
return s.sb.Length > 1 ? TokenType.Symbol : TokenType.Dot;
}
// TODO:
// WE should implement actual reader macros for this part of things.
private static TokenType? matchHash(Scanner s)
{
if (s.peek() != '#')
return null;
s.readChar();
if(s.peek() == '(')
{
s.readChar();
return TokenType.VectorOpen;
}
if(s.isOneOf("tfTF"))
{
s.readChar();
return TokenType.Boolean;
}
throw s.fail("Unrecognized token");
}
// This code is pretty hairy - the problem is
// distinguishing between:
// 1. a floating point number, which may be
// in scientific notification, and might simply begin
// with "."
// 2. A symbol with a dot in it
// 3. Just a lone "." used for separating lists
// It's doubtful that it's entirely correct - but if you find a bug,
// add it as a test to ScannerTest and amend this logic.
private static TokenType? matchNumber(Scanner s)
{
if(s.peek() == '.')
return leadingFloat(s);
if(s.isOneOf("+-"))
{
s.readChar();
if(s.peek() == '.')
return leadingFloat(s);
var num = unsignedNumber(s);
if (num != null)
return num;
matchSymbol(s);
return TokenType.Symbol;
}
return unsignedNumber(s);
}
private static TokenType? leadingFloat(Scanner s)
{
var floatToken = remainingFloat(s);
if (s.sb.Length == 1)
{
matchSymbol(s);
return s.sb.Length == 1 ? TokenType.Dot : TokenType.Symbol;
}
return floatToken;
}
private static TokenType? unsignedNumber(Scanner s)
{
if (!s.isDigit())
return null;
while (s.isDigit())
s.readChar();
if (s.isExponent())
return readExponent(s);
if (s.peek() != '.')
return TokenType.Integer;
return remainingFloat(s);
}
private static TokenType? remainingFloat(Scanner s)
{
s.readChar(); // Skip the '.'
while (s.isDigit() || s.isExponent())
{
if (s.isExponent())
return readExponent(s);
s.readChar();
}
return TokenType.Double;
}
private static TokenType? readExponent(Scanner s)
{
s.readChar(); // Skip exponent market
var read = false;
if (s.isOneOf("+-"))
{
s.readChar();
read = true;
}
while (s.isDigit())
{
read = true;
s.readChar();
}
if(read)
return TokenType.Double;
// It's not a floating point number in exponent format.
// Read it as a symbol instead.
matchSymbol(s);
return TokenType.Symbol;
}
public Parser(Scanner s)
{
this.s = s;
// Skip whitespace and comments
tokens = s.Scan().Where(token => token.Type != TokenType.Space && token.Type != TokenType.Comment).GetEnumerator();
}
