getPostings method
Filters the PostingsMap by terms.
Returns a subset of the PostingsMap instance that only contains
entires with a key in the terms
collection.
Implementation
PostingsMap getPostings(Iterable<String> terms) {
final PostingsMap retVal = {};
for (final term in terms) {
final posting = this[term];
if (posting != null) {
retVal[term] = posting;
}
}
return retVal;
}