private void checkFirstAndSecond(final Form form) throws ParseException {
SExpression initVal = form.getChild(1);
// als init-Wert ist Symbol (oder Subtyp) oder eine Form erlaubt.
// Nur s-expression reicht nicht aus
if (!initVal.isNil() && !(initVal instanceof Symbol) && initVal.getTyp() != TSExpression.FORM) {
error("form or symbol expected", form.getChild(1));
}
}
private ParameterDefinition suppliedTestInit(final Form form) throws ParseException {
// invariante: laenge childs == 3
checkFirstAndSecond(form);
if (form.getChild(2).getTyp() != TSExpression.SYMBOL) {
error("symbol expected", form.getChild(2));
}
return new ParameterDefinition(
form.getFunctionSymbol(), form.getChild(1), (Symbol) form.getChild(2));
}
private ParameterDefinition initForm(final Form form) throws ParseException {
if (form.isNil()) {
error("NIL not allowed here", form);
}
List<SExpression> childs = form.getChildren();
if (childs.size() == 2) {
return simpleInit(form);
} else if (childs.size() == 3) {
return suppliedTestInit(form);
} else {
error("Parameter list must be of length 2 or 3", form);
return null; // wird nie erreicht
}
}
private ParameterDefinition simpleInit(final Form form) throws ParseException {
// invariante: laenge childs == 2
checkFirstAndSecond(form);
return new ParameterDefinition(form.getFunctionSymbol(), form.getChild(1), null);
}