80 lines
1.6 KiB
Go
80 lines
1.6 KiB
Go
// Copyright © 2018 Inanc Gumus
|
|
// Learn Go Programming Course
|
|
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
|
//
|
|
// For more tutorials : https://learngoprogramming.com
|
|
// In-person training : https://www.linkedin.com/in/inancgumus/
|
|
// Follow me on twitter: https://twitter.com/inancgumus
|
|
|
|
package main
|
|
|
|
import "os"
|
|
|
|
type (
|
|
processFn func(r result)
|
|
inputFn func(processFn) error
|
|
outputFn func([]result) error
|
|
filterFn func(result) (include bool)
|
|
groupFn func(result) (key string)
|
|
)
|
|
|
|
type pipeline struct {
|
|
read inputFn
|
|
write outputFn
|
|
filter filterFn
|
|
group groupFn
|
|
}
|
|
|
|
func (p *pipeline) filterBy(f filterFn) *pipeline { p.filter = f; return p }
|
|
func (p *pipeline) groupBy(f groupFn) *pipeline { p.group = f; return p }
|
|
func (p *pipeline) from(f inputFn) *pipeline { p.read = f; return p }
|
|
func (p *pipeline) to(f outputFn) *pipeline { p.write = f; return p }
|
|
|
|
func (p *pipeline) defaults() {
|
|
if p.filter == nil {
|
|
p.filter = noopFilter
|
|
}
|
|
|
|
if p.group == nil {
|
|
p.group = domainGrouper
|
|
}
|
|
|
|
if p.read == nil {
|
|
p.read = textReader(os.Stdin)
|
|
}
|
|
|
|
if p.write == nil {
|
|
p.write = textWriter(os.Stdout)
|
|
}
|
|
}
|
|
|
|
func (p *pipeline) start() error {
|
|
p.defaults()
|
|
|
|
// retrieve and process the lines
|
|
sum := make(map[string]result)
|
|
|
|
process := func(r result) {
|
|
if !p.filter(r) {
|
|
return
|
|
}
|
|
|
|
k := p.group(r)
|
|
sum[k] = r.add(sum[k])
|
|
}
|
|
|
|
// return err from input reader
|
|
if err := p.read(process); err != nil {
|
|
return err
|
|
}
|
|
|
|
// prepare the results for outputting
|
|
var out []result
|
|
for _, res := range sum {
|
|
out = append(out, res)
|
|
}
|
|
|
|
// return err from output reader
|
|
return p.write(out)
|
|
}
|