sq/drivers/csv/detect_header.go
Neil O'Toole c5cf6c0cc0
#217: Configurable timestamp format (#218)
* Moved time functions from pkg stringz to pkg timez

* Refactor options.Opt

* wip: initial work on configurable time layout

* wip: most printers now respect format.datetime and friends

* Folded pkg timefmt into timez

* Refactor options.Opt; refine options

* Add 'sq config set OPTION --help' mechanism

* Finished completion of OptDateFormatAsNumber and OptTimeFormatAsNumber
2023-05-06 20:36:34 -06:00

111 lines
2.6 KiB
Go

package csv
import (
"context"
"strings"
"github.com/neilotoole/sq/libsq/core/lg"
"github.com/neilotoole/sq/libsq/core/lg/lga"
"github.com/neilotoole/sq/drivers"
"github.com/neilotoole/sq/libsq/core/options"
"github.com/neilotoole/sq/libsq/core/errz"
"github.com/neilotoole/sq/libsq/core/kind"
)
// hasHeaderRow returns true if a header row is explicitly
// set in opts, or if detectHeaderRow detects that the first
// row of recs seems to be a header.
func hasHeaderRow(ctx context.Context, recs [][]string, opts options.Options) (bool, error) {
if drivers.OptIngestHeader.IsSet(opts) {
b := drivers.OptIngestHeader.Get(opts)
lg.FromContext(ctx).Debug("CSV ingest header explicitly specified: skipping header detection",
lga.Key, drivers.OptIngestHeader.Key(),
lga.Val, b)
return b, nil
}
return detectHeaderRow(recs)
}
// detectHeaderRow returns true if recs has a header row.
// The recs arg should be regularly shaped: each rec should
// have the same number of fields.
func detectHeaderRow(recs [][]string) (hasHeader bool, err error) {
if len(recs) < 2 {
// If zero records, obviously no header row.
// If one record... well, is there any way of determining if
// it's a header row or not? Probably best to treat it as a data row.
return false, nil
}
firstRowHash, err := calcKindHash(recs[0:1])
if err != nil {
return false, err
}
remainderHash, err := calcKindHash(recs[1:])
if err != nil {
return false, err
}
if firstRowHash != remainderHash {
return true, nil
}
return false, nil
}
// Hash generates a hash from the kinds returned by
// the detectors. The detectors should already have
// sampled data.
//
// TODO: move Hash to pkg libsq/core/kind?
func Hash(detectors []*kind.Detector) (h string, err error) {
if len(detectors) == 0 {
return "", errz.New("no kind detectors")
}
kinds := make([]kind.Kind, len(detectors))
for i := range detectors {
kinds[i], _, err = detectors[i].Detect()
if err != nil {
return "", err
}
}
// TODO: use an actual hash function
hash := strings.Builder{}
for i := range kinds {
if i > 0 {
hash.WriteRune('|')
}
hash.WriteString(kinds[i].String())
}
h = hash.String()
return h, nil
}
func calcKindHash(recs [][]string) (string, error) {
if len(recs) == 0 || len(recs[0]) == 0 {
return "", errz.New("no records")
}
fieldCount := len(recs[0])
detectors := make([]*kind.Detector, len(recs[0]))
for i := 0; i < fieldCount; i++ {
detectors[i] = kind.NewDetector()
}
for i := range recs {
for j := range recs[i] {
detectors[j].Sample(recs[i][j])
}
}
return Hash(detectors)
}