Unnecessary to read source data in this situdation

data: {d1, d2, d3}
if i search d, all the records will be cached like Cache[d]:{d1, d2, d3}.
Then i search d4, the returned value from Cache[d] is []; if i search c1, the returned value is null.
'[]' is not needed to read the source data again
Merge pull request #38 from sabershi/patch-1

Unnecessary to read source data in this situation