private Expression PrimaryExpression()
{
if (Current.Kind == TokenKind.StringStart)
return ReadString();
if (Current.Kind == TokenKind.ID) {
Token id = Consume();
Expression exp;
// if ( follows ID, we have a function call
if (Current.Kind == TokenKind.LParen) {
Consume(); // consume LParen
Expression[] args = ReadArguments();
Consume(TokenKind.RParen);
exp = new FunctionCallExpression(id.Line, id.Column, id.Text, args);
} else // else, we just have id
exp = new IdExpression(id.Line, id.Column, id.Text);
// while we have ".", keep chaining up field access or method call
while (Current.Kind == TokenKind.Dot ||
Current.Kind == TokenKind.LBracket) {
if (Current.Kind == TokenKind.Dot) {
Consume(); // consume DOT
Token field = Consume(TokenKind.ID); // consume ID after dot
// if "(" after ID, then it's a method call
if (Current.Kind == TokenKind.LParen) {
Consume(); // consume "("
Expression[] args = ReadArguments();
Consume(TokenKind.RParen); // read ")"
exp = new MethodCallExpression(field.Line, field.Column, exp, field.Text, args);
} else
exp = new FieldAccessExpression(field.Line, field.Column, exp, field.Text);
} else { // must be LBracket
// array access
Token bracket = Current;
Consume(); // consume [
Expression indexExp = TopExpression();
Consume(TokenKind.RBracket);
exp = new ArrayAccessExpression(bracket.Line, bracket.Column, exp, indexExp);
}
}
return exp;
}
if (Current.Kind == TokenKind.Integer) {
int value = Int32.Parse(Current.Text);
IntegerLiteralExpression intLiteral = new IntegerLiteralExpression(Current.Line, Current.Column, value);
Consume(); // consume int
return intLiteral;
}
if (Current.Kind == TokenKind.Double) {
double value = Double.Parse(Current.Text);
DoubleLiteralExpression dLiteral = new DoubleLiteralExpression(Current.Line, Current.Column, value);
Consume(); // consume int
return dLiteral;
}
if (Current.Kind == TokenKind.BooleanTrue) {
BooleanLiteralExpression bLiteral = new BooleanLiteralExpression(Current.Line, Current.Column, true);
Consume();
return bLiteral;
}
if (Current.Kind == TokenKind.BooleanFalse) {
BooleanLiteralExpression bLiteral = new BooleanLiteralExpression(Current.Line, Current.Column, false);
Consume();
return bLiteral;
}
if (Current.Kind == TokenKind.LParen) {
Consume(); // eat (
Expression exp = TopExpression();
Consume(TokenKind.RParen); // eat )
return exp;
}
throw new ParseException("Invalid token in expression: " + Current.Kind + ". Was expecting ID or string.",
Current.Line, Current.Column);
}
private object EvaluateArrayAccess(ArrayAccessExpression arrayAccess)
{
object obj = EvaluateExpression(arrayAccess.Expression);
object index = EvaluateExpression(arrayAccess.Index);
if (obj is Array) {
Array array = (Array)obj;
if (index is int)
return array.GetValue((int)index);
throw new TemplateException("Index of array has to be integer", arrayAccess.Line, arrayAccess.Column);
}
return EvaluateMethodCall(obj, "get_Item", new object[] { index });
}