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425702e7ba
* linting * yet more linting * yet more linting * yet more linting * yet more linting * yet more linting
312 lines
6.9 KiB
Go
312 lines
6.9 KiB
Go
// Package csv implements the sq driver for CSV/TSV et al.
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package csv
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import (
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"context"
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"database/sql"
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"encoding/csv"
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"errors"
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"io"
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"strconv"
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"github.com/neilotoole/lg"
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"github.com/neilotoole/sq/cli/output/csvw"
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"github.com/neilotoole/sq/libsq/core/errz"
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"github.com/neilotoole/sq/libsq/driver"
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"github.com/neilotoole/sq/libsq/source"
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)
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const (
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// TypeCSV is the CSV driver type.
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TypeCSV = source.Type("csv")
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// TypeTSV is the TSV driver type.
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TypeTSV = source.Type("tsv")
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)
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// Provider implements driver.Provider.
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type Provider struct {
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Log lg.Log
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Scratcher driver.ScratchDatabaseOpener
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Files *source.Files
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}
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// DriverFor implements driver.Provider.
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func (d *Provider) DriverFor(typ source.Type) (driver.Driver, error) {
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switch typ { //nolint:exhaustive
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case TypeCSV:
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return &driveri{log: d.Log, typ: TypeCSV, scratcher: d.Scratcher, files: d.Files}, nil
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case TypeTSV:
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return &driveri{log: d.Log, typ: TypeTSV, scratcher: d.Scratcher, files: d.Files}, nil
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}
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return nil, errz.Errorf("unsupported driver type %q", typ)
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}
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// Driver implements driver.Driver.
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type driveri struct {
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log lg.Log
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typ source.Type
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scratcher driver.ScratchDatabaseOpener
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files *source.Files
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}
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// DriverMetadata implements driver.Driver.
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func (d *driveri) DriverMetadata() driver.Metadata {
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md := driver.Metadata{Type: d.typ, Monotable: true}
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if d.typ == TypeCSV {
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md.Description = "Comma-Separated Values"
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md.Doc = "https://en.wikipedia.org/wiki/Comma-separated_values"
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} else {
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md.Description = "Tab-Separated Values"
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md.Doc = "https://en.wikipedia.org/wiki/Tab-separated_values"
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}
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return md
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}
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// Open implements driver.Driver.
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func (d *driveri) Open(ctx context.Context, src *source.Source) (driver.Database, error) {
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dbase := &database{
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log: d.log,
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src: src,
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files: d.files,
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}
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var err error
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dbase.impl, err = d.scratcher.OpenScratch(ctx, src.Handle)
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if err != nil {
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return nil, err
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}
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err = importCSV(ctx, d.log, src, d.files.OpenFunc(src), dbase.impl)
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if err != nil {
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return nil, err
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}
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return dbase, nil
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}
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// Truncate implements driver.Driver.
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func (d *driveri) Truncate(ctx context.Context, src *source.Source, tbl string, reset bool) (int64, error) {
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// TODO: CSV could support Truncate for local files
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return 0, errz.Errorf("truncate not supported for %s", d.DriverMetadata().Type)
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}
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// ValidateSource implements driver.Driver.
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func (d *driveri) ValidateSource(src *source.Source) (*source.Source, error) {
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if src.Type != d.typ {
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return nil, errz.Errorf("expected source type %q but got %q", d.typ, src.Type)
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}
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if src.Options != nil || len(src.Options) > 0 {
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d.log.Debugf("opts: %v", src.Options.Encode())
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key := "header"
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v := src.Options.Get(key)
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if v != "" {
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_, err := strconv.ParseBool(v)
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if err != nil {
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return nil, errz.Errorf(`unable to parse option %q: %v`, key, err)
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}
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}
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}
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return src, nil
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}
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// Ping implements driver.Driver.
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func (d *driveri) Ping(ctx context.Context, src *source.Source) error {
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d.log.Debugf("driver %q attempting to ping %q", d.typ, src)
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r, err := d.files.Open(src)
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if err != nil {
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return err
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}
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defer d.log.WarnIfCloseError(r)
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return nil
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}
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// database implements driver.Database.
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type database struct {
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log lg.Log
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src *source.Source
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impl driver.Database
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files *source.Files
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}
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// DB implements driver.Database.
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func (d *database) DB() *sql.DB {
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return d.impl.DB()
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}
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// SQLDriver implements driver.Database.
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func (d *database) SQLDriver() driver.SQLDriver {
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return d.impl.SQLDriver()
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}
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// Source implements driver.Database.
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func (d *database) Source() *source.Source {
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return d.src
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}
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// TableMetadata implements driver.Database.
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func (d *database) TableMetadata(ctx context.Context, tblName string) (*source.TableMetadata, error) {
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if tblName != source.MonotableName {
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return nil, errz.Errorf("table name should be %s for CSV/TSV etc., but got: %s",
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source.MonotableName, tblName)
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}
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srcMeta, err := d.SourceMetadata(ctx)
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if err != nil {
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return nil, err
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}
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// There will only ever be one table for CSV.
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return srcMeta.Tables[0], nil
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}
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// SourceMetadata implements driver.Database.
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func (d *database) SourceMetadata(ctx context.Context) (*source.Metadata, error) {
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md, err := d.impl.SourceMetadata(ctx)
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if err != nil {
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return nil, err
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}
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md.Handle = d.src.Handle
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md.Location = d.src.Location
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md.SourceType = d.src.Type
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md.Name, err = source.LocationFileName(d.src)
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if err != nil {
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return nil, err
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}
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md.Size, err = d.files.Size(d.src)
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if err != nil {
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return nil, err
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}
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md.FQName = md.Name
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return md, nil
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}
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// Close implements driver.Database.
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func (d *database) Close() error {
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d.log.Debugf("Close database: %s", d.src)
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return errz.Err(d.impl.Close())
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}
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var (
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_ source.TypeDetectFunc = DetectCSV
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_ source.TypeDetectFunc = DetectTSV
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)
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// DetectCSV implements source.TypeDetectFunc.
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func DetectCSV(ctx context.Context, log lg.Log, openFn source.FileOpenFunc) (detected source.Type, score float32,
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err error) {
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return detectType(ctx, TypeCSV, log, openFn)
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}
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// DetectTSV implements source.TypeDetectFunc.
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func DetectTSV(ctx context.Context, log lg.Log, openFn source.FileOpenFunc) (detected source.Type,
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score float32, err error) {
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return detectType(ctx, TypeTSV, log, openFn)
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}
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func detectType(ctx context.Context, typ source.Type, log lg.Log, openFn source.FileOpenFunc) (detected source.Type,
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score float32, err error) {
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var r io.ReadCloser
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r, err = openFn()
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if err != nil {
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return source.TypeNone, 0, errz.Err(err)
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}
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defer log.WarnIfCloseError(r)
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var delim = csvw.Comma
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if typ == TypeTSV {
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delim = csvw.Tab
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}
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cr := csv.NewReader(&crFilterReader{r: r})
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cr.Comma = delim
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cr.FieldsPerRecord = -1
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score = isCSV(ctx, cr)
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if score > 0 {
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return typ, score, nil
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}
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return source.TypeNone, 0, nil
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}
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const (
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scoreNo float32 = 0
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scoreMaybe float32 = 0.1
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scoreProbably float32 = 0.2
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// scoreYes is less than 1.0 because other detectors
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// (e.g. XLSX) can be more confident.
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scoreYes float32 = 0.9
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)
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// isCSV returns a score indicating the
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// the confidence that cr is reading legitimate CSV, where
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// a score <= 0 is not CSV, a score >= 1 is definitely CSV.
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func isCSV(ctx context.Context, cr *csv.Reader) (score float32) {
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const (
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maxRecords int = 100
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)
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var recordCount, totalFieldCount int
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var avgFields float32
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for i := 0; i < maxRecords; i++ {
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select {
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case <-ctx.Done():
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return 0
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default:
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}
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rec, err := cr.Read()
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if err != nil {
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if errors.Is(err, io.EOF) && rec == nil {
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// This means end of data
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break
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}
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// It's a genuine error
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return scoreNo
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}
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totalFieldCount += len(rec)
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recordCount++
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}
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if recordCount == 0 {
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return scoreNo
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}
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avgFields = float32(totalFieldCount) / float32(recordCount)
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if recordCount == 1 {
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if avgFields <= 2 {
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return scoreMaybe
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}
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return scoreProbably
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}
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// recordCount >= 2
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switch {
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case avgFields <= 1:
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return scoreMaybe
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case avgFields <= 2:
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return scoreProbably
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default:
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// avgFields > 2
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return scoreYes
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}
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}
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