private void CharString()
{
while (Peek() != '\'' && !IsAtEnd())
{
if (Peek() == '\\')
{
Advance();
}
if (Peek() == '\n')
{
Line++;
}
Advance();
}
// Unterminated string.
if (IsAtEnd())
{
Cox.Error(Line, "Unterminated string.");
return;
}
// The closing ".
Advance();
// Trim the surrounding quotes.
String value = Source.Substring(Start + 1, Current - Start - 1);
AddToken(TokenType.STRING, value);
}
public String String()
{
while (Peek() != '"' && !IsAtEnd())
{
if (Peek() == '\\')
{
Advance();
}
if (Peek() == '\n')
{
Line++;
}
Advance();
}
// Unterminated string.
if (IsAtEnd())
{
Cox.Error(Line, "Unterminated string.");
return(null);
}
// The closing ".
Advance();
// Trim the surrounding quotes.
return(Source.Substring(Start + 1
, Current - Start - 2));
}
public object VisitThisExpr(This expr)
{
if (currentClass == ClassType.NONE)
{
Cox.Error(expr.Keyword, "Cannot use 'this' outside of a class.");
}
else
{
ResolveLocal(expr, expr.Keyword);
}
return(null);
}
public object VisitVariableExpr(Variable expr)
{
if (scopes.Count > 0)
{
if (scopes.Peek().ContainsKey(expr.Name.Lexeme) && scopes.Peek()[expr.Name.Lexeme] == false)
{
Cox.Error(expr.Name, "Cannot read local variable in its own initializer.");
}
}
ResolveLocal(expr, expr.Name);
return(null);
}
public object VisitSuperExpr(Super expr)
{
if (currentClass == ClassType.NONE)
{
Cox.Error(expr.Keyword, "Cannot use 'super' outside of a class.");
}
else if (currentClass != ClassType.SUBCLASS)
{
Cox.Error(expr.Keyword, "Cannot use 'super' in a class with no superclass.");
}
else
{
ResolveLocal(expr, expr.Keyword);
}
return(null);
}
public void Interpret(List <Stmt> statements, Dictionary <Expr, Int32> locals)
{
Locals = locals;
try
{
foreach (Stmt statement in statements)
{
Execute(statement);
}
}
catch (RuntimeError error)
{
Cox.RuntimeError(error);
}
}
private void Declare(Token name)
{
// Don't need to track top level variables.
if (scopes.Count == 0)
{
return;
}
Dictionary <String, Boolean> scope = scopes.Peek();
if (scope.ContainsKey(name.Lexeme))
{
Cox.Error(name, "Variable with this name already Declared in this scope.");
}
scope.Add(name.Lexeme, false);
}
public object VisitReturnStmt(Return stmt)
{
if (currentFunction == FunctionType.NONE)
{
Cox.Error(stmt.Keyword, "Cannot return from top-level code.");
}
if (stmt.Value != null)
{
if (currentFunction == FunctionType.INITIALIZER)
{
Cox.Error(stmt.Keyword, "Cannot return a value from an initializer.");
}
Resolve(stmt.Value);
}
return(null);
}
protected override void ScanToken()
{
Char c = Advance();
switch (c)
{
case '[':
AddToken(TokenType.LSQRBRACE); // TODO
break;
case ']':
AddToken(TokenType.RSQRBRACE); // TODO
break;
case '$':
AddToken(TokenType.DOLLAR);
if (Match('"'))
{
var value = String().Substring(1); // Strip of the leading quote
var scanner = new StringInterpolationScanner(value);
var t = scanner.Scan();
Tokens.AddRange(t);
}
else
{
Cox.Error(Line, $"Expected '\"'");
}
break;
case '(':
AddToken(TokenType.LPAREN);
break;
case ')':
AddToken(TokenType.RPAREN);
break;
case '{':
AddToken(TokenType.LBRACE);
break;
case '}':
AddToken(TokenType.RBRACE);
break;
case ',':
AddToken(TokenType.COMMA);
break;
case '.':
AddToken(TokenType.DOT);
break;
case '-':
if (Match('-'))
{
AddToken(TokenType.MINUS_MINUS);
}
else
{
if (Match('='))
{
AddToken(TokenType.MINUS_EQUALS);
}
else
{
AddToken(TokenType.MINUS);
}
}
break;
case '+':
if (Match('+'))
{
AddToken(TokenType.PLUS_PLUS);
}
else
{
if (Match('='))
{
AddToken(TokenType.PLUS_EQUALS);
}
else
{
AddToken(TokenType.PLUS);
}
}
break;
case '*':
if (Match('='))
{
AddToken(TokenType.MUL_EQUALS);
}
else
{
AddToken(TokenType.MUL);
}
break;
case '/':
if (Match('='))
{
AddToken(TokenType.DIV_EQUALS);
}
else
{
if (Match('/'))
{
// A comment goes until the end of the line.
while (Peek() != '\n' && !IsAtEnd())
{
Advance();
}
}
else
{
if (Match('*'))
{
// Multi line comment, we need to look for a */
while (!(Peek() == '*' && PeekNext() == '/') && !IsAtEnd())
{
if (Peek() == '\n')
{
Line++;
}
Advance();
}
if (IsAtEnd())
{
Cox.Error(Line, $"End-of-File found, '*/' expected");
}
else
{
Advance();
Advance();
}
}
else
{
AddToken(TokenType.DIV);
}
}
}
break;
case ';':
AddToken(TokenType.SEMICOLON);
break;
case ':':
AddToken(TokenType.COLON);
break;
case '?':
AddToken(TokenType.QUESTIONMARK);
break;
case '&':
if (Match('&'))
{
AddToken(TokenType.AND);
}
else
{
AddToken(TokenType.BINARY_AND);
}
break;
case '|':
if (Match('|'))
{
AddToken(TokenType.OR);
}
else
{
AddToken(TokenType.BINARY_OR);
}
break;
case '^':
AddToken(TokenType.BINARY_XOR);
break;
case '~':
AddToken(TokenType.BINARY_NOT);
break;
case '!':
AddToken(Match('=') ? TokenType.BANG_EQUAL : TokenType.BANG);
break;
case '=':
AddToken(Match('=') ? TokenType.EQUAL_EQUAL : TokenType.EQUAL);
break;
case '<':
if (Match('<'))
{
AddToken(TokenType.BINARY_LEFTSHIFT);
}
else
if (Match('='))
{
AddToken(TokenType.LESS_EQUAL);
}
else
{
AddToken(TokenType.LESS);
}
break;
case '>':
if (Match('>'))
{
AddToken(TokenType.BINARY_RIGHTSHIFT);
}
else
if (Match('='))
{
AddToken(TokenType.GREATER_EQUAL);
}
else
{
AddToken(TokenType.GREATER);
}
break;
case '"':
{
String value = String();
if (value != null)
{
AddToken(TokenType.STRING, value);
}
}
break;
case ' ':
case '\t':
case '\r':
break;
case '\n':
Line++;
break;
default:
if (Char.IsDigit(c))
{
Number();
}
else
if (Char.IsLetter(c) || c == '_')
{
Identifier();
}
else
{
Cox.Error(Line, $"Unexpected Character {c}");
}
break;
}
}
private ParseError Error(Token token, String message)
{
Cox.Error(token, message);
return(new ParseError());
}