98 lines
1.9 KiB
Go
98 lines
1.9 KiB
Go
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package main
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import (
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"fmt"
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"bufio"
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"strings"
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"os"
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"errors"
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"encoding/hex"
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)
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type DbInterface struct {
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db *MemDatabase
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trie *Trie
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}
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func NewDBInterface() *DbInterface {
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db, _ := NewMemDatabase()
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trie := NewTrie(db, "")
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return &DbInterface{db: db, trie: trie}
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}
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func (i *DbInterface) ValidateInput(action string, argumentLength int) error {
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err := false
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var expArgCount int
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switch {
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case action == "update" && argumentLength != 2:
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err = true
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expArgCount = 2
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case action == "get" && argumentLength != 1:
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err = true
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expArgCount = 1
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case (action == "quit" || action == "exit") && argumentLength != 0:
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err = true
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expArgCount = 0
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}
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if err {
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return errors.New(fmt.Sprintf("'%s' requires %d args, got %d", action, expArgCount, argumentLength))
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} else {
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return nil
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}
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}
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func (i *DbInterface) ParseInput(input string) bool {
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scanner := bufio.NewScanner(strings.NewReader(input))
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scanner.Split(bufio.ScanWords)
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count := 0
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var tokens []string
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for scanner.Scan() {
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count++
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tokens = append(tokens, scanner.Text())
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}
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if err := scanner.Err(); err != nil {
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fmt.Fprintln(os.Stderr, "reading input:", err)
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}
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if len(tokens) == 0 { return true }
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err := i.ValidateInput(tokens[0], count-1)
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if err != nil {
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fmt.Println(err)
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} else {
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switch tokens[0] {
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case "update":
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i.trie.Update(tokens[1], tokens[2])
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fmt.Println(hex.EncodeToString([]byte(i.trie.root)))
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case "get":
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fmt.Println(i.trie.Get(tokens[1]))
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case "exit", "quit", "q":
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return false
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default:
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fmt.Println("Unknown command:", tokens[0])
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}
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}
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return true
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}
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func (i *DbInterface) Start() {
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reader := bufio.NewReader(os.Stdin)
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for {
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fmt.Printf("db >>> ")
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str, _, err := reader.ReadLine()
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if err != nil {
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fmt.Println("Error reading input", err)
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} else {
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if !i.ParseInput(string(str)) {
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return
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}
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}
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}
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}
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