55 lines
1.1 KiB
Go
55 lines
1.1 KiB
Go
|
// For more tutorials: https://blog.learngoprogramming.com
|
||
|
|
//
|
||
|
|
// Copyright © 2018 Inanc Gumus
|
||
|
|
// Learn Go Programming Course
|
||
|
|
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
||
|
|
//
|
||
|
|
|
||
|
|
package pipe
|
||
|
|
|
||
|
|
import (
|
||
|
|
"fmt"
|
||
|
|
"io"
|
||
|
|
"os"
|
||
|
|
)
|
||
|
|
|
||
|
|
// Pipeline takes records from a source, transforms, and sends them to a destionation.
|
||
|
|
type Pipeline struct {
|
||
|
|
src Iterator
|
||
|
|
trans []Transform
|
||
|
|
dst Consumer
|
||
|
|
}
|
||
|
|
|
||
|
|
// New creates a new pipeline.
|
||
|
|
func New(src Iterator, dst Consumer, t ...Transform) *Pipeline {
|
||
|
|
return &Pipeline{
|
||
|
|
src: &logCount{Iterator: src},
|
||
|
|
dst: dst,
|
||
|
|
trans: t,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Default creates a pipeline that reads from a text log and generates a text report.
|
||
|
|
func Default(r io.Reader, w io.Writer, t ...Transform) *Pipeline {
|
||
|
|
return New(NewTextLog(r), NewTextReport(w), t...)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Run the pipeline.
|
||
|
|
func (p *Pipeline) Run() error {
|
||
|
|
defer func() {
|
||
|
|
n := p.src.(*logCount).count()
|
||
|
|
fmt.Fprintf(os.Stderr, "%d records processed.\n", n)
|
||
|
|
}()
|
||
|
|
|
||
|
|
last := p.src
|
||
|
|
|
||
|
|
for _, t := range p.trans {
|
||
|
|
if err := t.Consume(last); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
last = t
|
||
|
|
}
|
||
|
|
|
||
|
|
return p.dst.Consume(last)
|
||
|
|
}
|