/
query_impl.go
139 lines (119 loc) · 2.41 KB
/
query_impl.go
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package query
import (
"sort"
)
func DerivedResults(qr Results, ch <-chan Result) Results {
return &results{
query: qr.Query(),
proc: qr.Process(),
res: ch,
}
}
// NaiveFilter applies a filter to the results.
func NaiveFilter(qr Results, filter Filter) Results {
ch := make(chan Result)
go func() {
defer close(ch)
defer qr.Close()
for e := range qr.Next() {
if e.Error != nil || filter.Filter(e.Entry) {
ch <- e
}
}
}()
return DerivedResults(qr, ch)
}
// NaiveLimit truncates the results to a given int limit
func NaiveLimit(qr Results, limit int) Results {
ch := make(chan Result)
go func() {
defer close(ch)
defer qr.Close()
l := 0
for e := range qr.Next() {
if e.Error != nil {
ch <- e
continue
}
ch <- e
l++
if limit > 0 && l >= limit {
break
}
}
}()
return ResultsWithChan(qr.Query(), ch)
}
// NaiveOffset skips a given number of results
func NaiveOffset(qr Results, offset int) Results {
ch := make(chan Result)
go func() {
defer close(ch)
defer qr.Close()
sent := 0
for e := range qr.Next() {
if e.Error != nil {
ch <- e
}
if sent < offset {
sent++
continue
}
ch <- e
}
}()
return ResultsWithChan(qr.Query(), ch)
}
// NaiveOrder reorders results according to given orders.
// WARNING: this is the only non-stream friendly operation!
func NaiveOrder(qr Results, orders ...Order) Results {
// Short circuit.
if len(orders) == 0 {
return qr
}
ch := make(chan Result)
var entries []Entry
go func() {
defer close(ch)
defer qr.Close()
for e := range qr.Next() {
if e.Error != nil {
ch <- e
}
entries = append(entries, e.Entry)
}
sort.Slice(entries, func(i int, j int) bool {
return Less(orders, entries[i], entries[j])
})
for _, e := range entries {
ch <- Result{Entry: e}
}
}()
return DerivedResults(qr, ch)
}
func NaiveQueryApply(q Query, qr Results) Results {
if q.Prefix != "" {
qr = NaiveFilter(qr, FilterKeyPrefix{q.Prefix})
}
for _, f := range q.Filters {
qr = NaiveFilter(qr, f)
}
if len(q.Orders) > 0 {
qr = NaiveOrder(qr, q.Orders...)
}
if q.Offset != 0 {
qr = NaiveOffset(qr, q.Offset)
}
if q.Limit != 0 {
// TODO: Offset?
qr = NaiveLimit(qr, q.Limit)
}
return qr
}
func ResultEntriesFrom(keys []string, vals [][]byte) []Entry {
re := make([]Entry, len(keys))
for i, k := range keys {
re[i] = Entry{Key: k, Value: vals[i]}
}
return re
}