@Override
public SEXP apply(Context context, Environment rho, FunctionCall call, PairList args) {
PairList matchedArguments = ClosureDispatcher.matchArguments(formals, args);
SEXP exprArgument = matchedArguments.findByTag(EXPR_ARGUMENT);
SEXP envArgument = matchedArguments.findByTag(ENV_ARGUMENT);
// Substitute handles ... in an idiosyncratic way:
// Only the first argument is used, and there is no attempt to
// match subsequent arguments against the 'env' argument.
SEXP expr;
if (exprArgument == Symbols.ELLIPSES) {
SEXP ellipses = rho.getVariable(Symbols.ELLIPSES);
if (ellipses == Null.INSTANCE) {
expr = Null.INSTANCE;
} else {
PromisePairList.Node promisePairList = (PromisePairList.Node) ellipses;
Promise promisedArg = (Promise) promisePairList.getValue();
expr = promisedArg.getExpression();
}
} else {
expr = exprArgument;
}
return substitute(expr, buildContext(context, rho, envArgument));
}
