@Override
public String next() throws IOException {
// restore queue
for (int i = 0; i < numTop; i++) {
top[i].current = top[i].fields.next();
if (top[i].current != null) {
queue.add(top[i]);
} else {
// no more fields in this sub-reader
}
}
numTop = 0;
// gather equal top fields
if (queue.size() > 0) {
while (true) {
top[numTop++] = queue.pop();
if (queue.size() == 0 || !(queue.top()).current.equals(top[0].current)) {
break;
}
}
currentField = top[0].current;
} else {
currentField = null;
}
return currentField;
}
/**
* The subs array must be newly initialized FieldsEnum (ie, {@link FieldsEnum#next} has not been
* called.
*/
public MultiFieldsEnum(MultiFields fields, FieldsEnum[] subs, ReaderSlice[] subSlices)
throws IOException {
this.fields = fields;
queue = new FieldMergeQueue(subs.length);
top = new FieldsEnumWithSlice[subs.length];
List<FieldsEnumWithSlice> enumWithSlices = new ArrayList<FieldsEnumWithSlice>();
// Init q
for (int i = 0; i < subs.length; i++) {
assert subs[i] != null;
final String field = subs[i].next();
if (field != null) {
// this FieldsEnum has at least one field
final FieldsEnumWithSlice sub = new FieldsEnumWithSlice(subs[i], subSlices[i], i);
enumWithSlices.add(sub);
sub.current = field;
queue.add(sub);
}
}
}