proposal: bufio: Scanner.IterText/Scanner.IterBytes

pkierski commented 15 hours ago

Proposal Details

Once iterators are introduced in 1.23 there is growing number of libraries based on this feature. Reading data by lines or words are quite common task and could be accomplished with for ... range loop. It requires just two simple methods for bufio.Scanner:

func (s *Scanner) IterText() iter.Seq[string] {
    return func(yield func(string) bool) {
        for s.Scan() {
            if !yield(s.Text()) {
                break
            }
        }
    }
}

func (s *Scanner) IterBytes() iter.Seq[[]byte] {
    return func(yield func([]byte) bool) {
        for s.Scan() {
            if !yield(s.Bytes()) {
                break
            }
        }
    }
}

Reading whole file as collection of lines could be like:

    f, err := os.Open("file.txt")
    if err != nil {
        panic(err)
    }
    defer f.Close()
    scanner := bufio.NewScanner(f)

    // read all lines as slice of strings
    lines := slices.Collect(scanner.IterText())

    // instead of:
    // lines := make([]string, 0)
    // for scanner.Scan() {
    //  lines = append(lines, scanner.Text())
    // }