script/chain.go

package script

import "context"

// Chain chains provided Processors.
// When an error is returned by a Processor in chain, processing
// stops and the error is retuned without running further stages.
func ChainProcessor(processors ...Processor) Processor {
	return func(ctx context.Context, in []string) ([]string, error) {
		var err error
		for _, p := range processors {
			// not checking ctx expiry here,
			// let the processor handle it

			in, err = p(ctx, in)
			if err != nil {
				return nil, err
			}
		}

		return in, nil
	}
}

type chainWriter struct {
	w []Writer
}

func (c *chainWriter) Write(in []string) error {
	for _, w := range c.w {
		if err := w.Write(in); err != nil {
			return err
		}
	}

	return nil
}

func ChainWriter(writers ...Writer) Writer {
	return &chainWriter{
		w: writers,
	}
}