public SEXP evaluate(SEXP expression, Environment rho) {
if (expression instanceof Symbol) {
return evaluateSymbol((Symbol) expression, rho);
} else if (expression instanceof ExpressionVector) {
return evaluateExpressionVector((ExpressionVector) expression, rho);
} else if (expression instanceof FunctionCall) {
return evaluateCall((FunctionCall) expression, rho);
} else if (expression instanceof Promise) {
return expression.force(this);
} else if (expression != Null.INSTANCE && expression instanceof PromisePairList) {
throw new EvalException("'...' used in an incorrect context");
} else {
clearInvisibleFlag();
return expression;
}
}
