/
kvSaveLoad.go
161 lines (143 loc) · 2.66 KB
/
kvSaveLoad.go
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package main
import (
"bufio"
"encoding/gob"
"fmt"
"os"
"strings"
)
type myElement struct {
Name string
Surname string
Id string
}
var DATA = make(map[string]myElement)
var DATAFILE = "/tmp/dataFile.gob"
func save() error {
fmt.Println("Saving", DATAFILE)
err := os.Remove(DATAFILE)
if err != nil {
fmt.Println(err)
}
saveTo, err := os.Create(DATAFILE)
if err != nil {
fmt.Println("Cannot create", DATAFILE)
return err
}
defer saveTo.Close()
encoder := gob.NewEncoder(saveTo)
err = encoder.Encode(DATA)
if err != nil {
fmt.Println("Cannot save to", DATAFILE)
return err
}
return nil
}
func load() error {
fmt.Println("Loading", DATAFILE)
loadFrom, err := os.Open(DATAFILE)
defer loadFrom.Close()
if err != nil {
fmt.Println("Empty key/value store!")
return err
}
decoder := gob.NewDecoder(loadFrom)
decoder.Decode(&DATA)
return nil
}
func ADD(k string, n myElement) bool {
if k == "" {
return false
}
if LOOKUP(k) == nil {
DATA[k] = n
return true
}
return false
}
func DELETE(k string) bool {
if LOOKUP(k) != nil {
delete(DATA, k)
return true
}
return false
}
func LOOKUP(k string) *myElement {
_, ok := DATA[k]
if ok {
n := DATA[k]
return &n
} else {
return nil
}
}
func CHANGE(k string, n myElement) bool {
DATA[k] = n
return true
}
func PRINT() {
for k, d := range DATA {
fmt.Printf("key: %s value: %v\n", k, d)
}
}
func main() {
err := load()
if err != nil {
fmt.Println(err)
}
scanner := bufio.NewScanner(os.Stdin)
for scanner.Scan() {
text := scanner.Text()
text = strings.TrimSpace(text)
tokens := strings.Fields(text)
switch len(tokens) {
case 0:
continue
case 1:
tokens = append(tokens, "")
tokens = append(tokens, "")
tokens = append(tokens, "")
tokens = append(tokens, "")
case 2:
tokens = append(tokens, "")
tokens = append(tokens, "")
tokens = append(tokens, "")
case 3:
tokens = append(tokens, "")
tokens = append(tokens, "")
case 4:
tokens = append(tokens, "")
}
switch tokens[0] {
case "PRINT":
PRINT()
case "STOP":
err = save()
if err != nil {
fmt.Println(err)
}
return
case "DELETE":
if !DELETE(tokens[1]) {
fmt.Println("Delete operation failed!")
}
case "ADD":
n := myElement{tokens[2], tokens[3], tokens[4]}
if !ADD(tokens[1], n) {
fmt.Println("Add operation failed!")
}
case "LOOKUP":
n := LOOKUP(tokens[1])
if n != nil {
fmt.Printf("%v\n", *n)
}
case "CHANGE":
n := myElement{tokens[2], tokens[3], tokens[4]}
if !CHANGE(tokens[1], n) {
fmt.Println("Update operation failed!")
}
default:
fmt.Println("Unknown command – please try again!")
}
}
}