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|
package main
import (
"bufio"
"bytes"
"encoding/json"
"fmt"
"io"
"os"
"strings"
)
type Manager struct {
Input Input
Filter Filter
Output Output
}
type Input interface {
Start() chan *Work
}
type StdinInput struct {
retchan chan *Work
}
type Filter interface {
Filter(chan *Work) chan *Work
}
type StringFilter struct {
retchan chan *Work
FilterFuncMap map[string]func(string) string
}
type Output interface {
Output(chan *Work)
}
type StdoutOutput struct {
}
type Work struct {
data []byte
err error
}
func (i *StdinInput) Start() chan *Work {
i.retchan = make(chan *Work, 100)
r := bufio.NewReader(os.Stdin)
go func() {
for {
bs, err := r.ReadBytes(byte('\n'))
if err == io.EOF {
break
}
if err != nil {
fmt.Printf("Error when reading input from Stdin: %q", err)
os.Exit(1)
}
i.retchan <- &Work{data: bs}
}
close(i.retchan)
}()
return i.retchan
}
func (f *StringFilter) Filter(ic chan *Work) chan *Work {
f.retchan = make(chan *Work, 100)
if f.FilterFuncMap == nil {
f.FilterFuncMap = make(map[string]func(string) string, 10)
f.FilterFuncMap["F"] = func(s string) string { return strings.ToUpper(s) }
}
go func() {
for w := range ic {
dec := json.NewDecoder(bytes.NewReader(w.data))
jm := make(map[string]string, 10)
err := dec.Decode(&jm)
if err == io.EOF {
fmt.Printf("EOF jm: %v\n", jm)
f.retchan <- w
continue
}
if err != nil {
fmt.Printf("Error when decoding JSON: %q\n", err)
w.err = err
}
changed := false
for k, v := range jm {
ff, ok := f.FilterFuncMap[k]
if !ok {
continue
}
jm[k] = ff(v)
changed = true
}
if changed {
bs, err := json.Marshal(jm)
if err != nil {
fmt.Printf("Error when marshalling JSON: %q\n", err)
w.err = err
} else {
w.data = bs
}
}
f.retchan <- w
}
close(f.retchan)
}()
return f.retchan
}
func (o *StdoutOutput) Output(wc chan *Work) {
for w := range wc {
fmt.Printf("%s\n", w.data)
}
}
func (m *Manager) Go() {
ic := m.Input.Start()
fc := m.Filter.Filter(ic)
m.Output.Output(fc)
}
func main() {
m := Manager{
Input: &StdinInput{},
Filter: &StringFilter{},
Output: &StdoutOutput{},
}
m.Go()
}
|
