bool Accept(params Category[] categories)
{
foreach (var category in categories) {
if(category == token.Category) {
accepted = token;
GetNextToken ();
return true;
}
}
accepted = Token.ErrorToken();
return false;
}
void AddError(Token found, params Category[] expected)
{
string errorMsg = "Expecting " + expected [0];
for (int i=1; i <expected.Length; i++) {
errorMsg = errorMsg + " or " + expected[i];
}
errorMsg = errorMsg + ", but found " + found.Category;
errors.AddError(token, ErrorType.SyntaxError, errorMsg);
throw new SyntaxErrorException();
}
void GetNextToken()
{
if (scanner.HasNext ()) {
token = scanner.Next ();
}
}
public bool IsLocked(Token identifier)
{
return symbolLock.Contains(identifier.Lexeme);
}
public void Lock(Token identifier)
{
symbolLock.Push(identifier.Lexeme);
}
public string GetVariableType(Token identifier)
{
SymbolTableEntry entry;
symbols.TryGetValue(identifier.Lexeme, out entry);
return entry.VariableType;
}
public bool IsDeclared(Token identifier)
{
return symbols.ContainsKey(identifier.Lexeme);
}
public void Declare(Token identifier, Token type)
{
Declare (identifier, type, null);
}
public object GetValue(Token identifier)
{
SymbolTableEntry entry;
symbols.TryGetValue(identifier.Lexeme, out entry);
return entry.Value;
}
public void Assign(Token token, object value)
{
SymbolTableEntry entry;
symbols.TryGetValue(token.Lexeme, out entry);
entry.Value = value;
}
public void Declare(Token identifier, Token type, object value)
{
symbols.Add(identifier.Lexeme, new SymbolTableEntry( type.Lexeme, value));
}
public void AddError(Token token, ErrorType type, string message)
{
var err = new ErrorEntry(token, type, message);
AddError (err);
}
public ErrorEntry(Token token, ErrorType type, string message)
{
this.NearToken = token;
this.Type = type;
this.Message = message;
}
void ValidateAssignmentAndDoAction(Token identifier, Action action)
{
if (symbolTable.IsDeclared (identifier)) {
if (symbolTable.IsLocked (identifier)) {
errors.AddError (identifier, ErrorType.SemanticError, "Variable is being used by a for loop and cannot be assigned to");
} else {
//do action if assignment to identifier is valid
action();
}
} else {
errors.AddError (identifier, ErrorType.SemanticError, "Cannot assign to a variable that is undeclared");
}
}
/*
* Private methods
*/
Token ScanNextToken()
{
lexeme = "";
category = Category.NONE;
lexemeBeginLine = -1;
lexemeBeginColumn = -1;
if (charStream.EndOfStream) {
throw new EndOfStreamException();
}
ReadLexeme ();
SkipBlank();
DecideCategory();
Token token = new Token ();
token.Lexeme = lexeme;
token.Category = category;
token.Line = lexemeBeginLine;
token.Column = lexemeBeginColumn;
return token;
}
//give tokens to the builder
public void Offer(Token next)
{
inputStack.Push (next);
}
