private void addNonTerminal(String EBNF) {
String p = "<([\\w-]+)>[\\s]*::=(" + "([\\s]*(<[\\w-]+>|(\"[^\"]*\")|[|\\[\\]{}])" + ")+)";
Matcher m = Pattern.compile(p).matcher(EBNF);
m.find();
NonTerminal nt = new NonTerminal(m.group(1));
List<? extends EBNFBranch> branches = EBNFBranch.getBranches(m.group(2));
assert (branches.size() > 0);
if (nonTerminals.size() == 0) {
startSymbol = nt;
}
nonTerminals.put(nt, branches);
}
/**
* SIGH...
*
* @return
*/
public BNF toBNF() {
// first thing first, make a deep copy of current EBNF
// then play / return with the copy
EBNF ebnf = clone();
// auto generate new non terminal names
StringIterator quanNames = new StringIterator("quan_{000}");
int oldHash = ebnf.hashCode();
int newHash = ebnf.hashCode();
boolean exceptionTriggered;
do {
oldHash = newHash;
exceptionTriggered = false;
Iterator<NonTerminal> i = ebnf.nonTerminals.keySet().iterator();
try {
// travel through all non terminals
while (i.hasNext()) {
NonTerminal iii = i.next();
Iterator<? extends EBNFBranch> j = ebnf.nonTerminals.get(iii).iterator();
// travel through all branches for each non terminal
while (j.hasNext()) {
EBNFBranch jjj = j.next();
List l = jjj.getElementList();
// travel through all elements for each branch
for (int n = 0; n < l.size(); n++) {
if (l.get(n) instanceof Quantification) {
// found a quantification
Quantification q = ((Quantification) l.get(n));
// substitude it with a new non terminal
NonTerminal newnt = new NonTerminal(quanNames.next());
l.set(n, newnt);
// modify the element list for the new nt a little bit
List<EBNFBranch> li = (List<EBNFBranch>) q.getBranchList();
if ((q.getMaxOccurrance() == 1) && (q.getMinOccurrance() == 0)) {
// [..]
boolean containsEpsilon = false;
for (int k = 0; k < li.size(); k++) {
if (Terminal.epsilon.equals(li.get(k).getElementList().get(0))) {
// this branch contains epsilon
// (branches that contain epsilon contains only 1 element)
containsEpsilon = true;
}
}
// add new epsilon branch if currently don't have one
if (!containsEpsilon) {
li.add(new EBNFBranch());
}
} else if ((q.getMaxOccurrance() == -1) && (q.getMinOccurrance() == 0)) {
boolean containsEpsilon = false;
// {...}
for (int k = 0; k < li.size(); k++) {
if (Terminal.epsilon.equals(li.get(k).getElementList().get(0))) {
containsEpsilon = true;
// keep the only one epsilon branch untouched
} else {
// add the new non terminal to the end of
// each non epsilon branch
li.get(k).getElementList().add(newnt);
}
}
if (!containsEpsilon) {
li.add(new EBNFBranch());
}
}
// add the new non terminal to new EBNF
ebnf.nonTerminals.put(newnt, li);
}
}
}
}
} catch (ConcurrentModificationException e) {
exceptionTriggered = true;
}
newHash = ebnf.hashCode();
} while ((newHash != oldHash) || exceptionTriggered);
return new BNF(ebnf.startSymbol, ebnf.nonTerminals);
}
