/**
* Currently the allowable shard keys are either
* i) a hashed single field, e.g. { a : "hashed" }, or
* ii) a compound list of ascending, potentially-nested field paths, e.g. { a : 1 , b.c : 1 }
*/
static vector<FieldRef*> parseShardKeyPattern(const BSONObj& keyPattern) {
OwnedPointerVector<FieldRef> parsedPaths;
static const vector<FieldRef*> empty;
BSONObjIterator patternIt(keyPattern);
while (patternIt.more()) {
BSONElement patternEl = patternIt.next();
parsedPaths.push_back(new FieldRef(patternEl.fieldNameStringData()));
const FieldRef& patternPath = *parsedPaths.back();
// Empty path
if (patternPath.numParts() == 0)
return empty;
// Extra "." in path?
if (patternPath.dottedField() != patternEl.fieldNameStringData())
return empty;
// Empty parts of the path, ".."?
for (size_t i = 0; i < patternPath.numParts(); ++i) {
if (patternPath.getPart(i).size() == 0)
return empty;
}
// Numeric and ascending (1.0), or "hashed" and single field
if (!patternEl.isNumber()) {
if (keyPattern.nFields() != 1 || !isHashedPatternEl(patternEl))
return empty;
}
else if (patternEl.numberInt() != 1) {
return empty;
}
}
return parsedPaths.release();
}
