exec/writer.go

package exec

import "io"

// Write to many streamings and if closed remove from list
type Writers struct {
	Std    []io.Writer
	Closed bool
}

func (p *Writers) AddNewWriter(w io.Writer) {
	if !p.Closed {
		p.Std = append(p.Std, w)
	}
}

func (p *Writers) Close() error {
	p.Closed = true
	return nil
}

func (p *Writers) Write(w []byte) (int, error) {
	if p.Closed {
		return 0, io.EOF
	}

	for indexWriter := range p.Std {
		if p.Std[indexWriter] == nil {
			continue
		}
		switch _, err := p.Std[indexWriter].Write(w); err {
		case nil:
			continue
		case io.EOF, io.ErrUnexpectedEOF:
			p.Std[indexWriter] = nil
		default:
			return 0, err
		}
	}

	for writeIndex := 0; writeIndex < len(p.Std); writeIndex++ {
		if p.Std[writeIndex] != nil {
			continue
		} else if writeIndex == len(p.Std) {
			p.Std = p.Std[writeIndex-1:]
		} else if writeIndex == 0 {
			p.Std = p.Std[1:]
		} else {
			p.Std = append(p.Std[writeIndex:], p.Std[writeIndex+1:]...)
		}
		writeIndex -= 2
	}

	return len(w), nil
}