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package dataset
import (
"bufio"
"bytes"
"fmt"
"iter"
"os"
"path/filepath"
"slices"
)
type FileReader struct {
shards []string
delimiters []string // TODO single delimiter
err error
}
func NewFileReader(name, pattern string) (*FileReader, error) {
var shards []string
if matches, err := filepath.Glob(filepath.Join(name, pattern)); err != nil {
return nil, err
} else {
shards = matches
}
if len(shards) == 0 {
return nil, fmt.Errorf("no matching files in %q", name)
}
slices.Sort(shards)
return &FileReader{
shards: shards,
delimiters: []string{"\r\n", "\n"},
}, nil
}
func (f *FileReader) SetDelimiters(delimiters ...string) *FileReader {
f.delimiters = delimiters
return f
}
func (f *FileReader) Num() (int, error) {
return len(f.shards), nil
}
func (f *FileReader) Err() error {
return f.err
}
func (f *FileReader) Texts() iter.Seq2[int, string] {
return func(yield func(int, string) bool) {
for n, name := range f.shards {
for text := range f.read(name) {
if f.err != nil {
return
}
if !yield(n, text) {
return
}
}
}
}
}
func (f *FileReader) read(name string) iter.Seq[string] {
return func(yield func(string) bool) {
var file *os.File
if r, err := os.Open(name); err != nil {
f.err = err
return
} else {
file = r
}
defer file.Close()
delimiters := make([][]byte, len(f.delimiters))
for i, d := range f.delimiters {
delimiters[i] = []byte(d)
}
slices.SortFunc(delimiters, func(a, b []byte) int {
return len(b) - len(a)
})
scanner := bufio.NewScanner(file)
buf := make([]byte, 0, 1024*1024)
scanner.Buffer(buf, 1024*1024)
scanner.Split(func(data []byte, atEOF bool) (advance int, token []byte, err error) {
if atEOF && len(data) == 0 {
return 0, nil, nil
}
i, l := -1, -1
for _, d := range delimiters {
if j := bytes.Index(data, d); j >= 0 && (i < 0 || j < i) {
i, l = j, len(d)
}
}
if i >= 0 {
return i + l, data[:i+l], nil // TODO option to consume delimiter
}
if atEOF {
return len(data), data, nil
}
return 0, nil, nil
})
for scanner.Scan() {
if !yield(scanner.Text()) {
return
}
}
if err := scanner.Err(); err != nil {
f.err = err
}
}
}
|
