Search stems in the dictionary using a trie

trie.go

package main

import (
	"bufio"
	"flag"
	"io/ioutil"
	"log"
	"net"
	"os"
	"strconv"
	"strings"
	"unicode"
)

type Node struct {
	children map[byte]*Node
}

func NewNode() *Node {
	return &Node{children: make(map[byte]*Node)}
}

func (n *Node) Add(word string) {
	for _, letter := range word {
		val := byte(letter)

		if _, ok := n.children[val]; !ok {
			n.children[val] = NewNode()
		}

		n = n.children[val]
	}
}

func (n *Node) Contains(word string) bool {
	for _, letter := range word {
		val := byte(letter)

		if _, ok := n.children[val]; !ok {
			return false
		}

		n = n.children[val]
	}
	return true
}

var trie = NewNode()

func init() {
	if file, err := os.Open("/usr/share/dict/words"); err != nil {
		log.Fatalln(err)
	} else {
		defer file.Close()
		scanner := bufio.NewScanner(file)
	SCAN:
		for scanner.Scan() {
			word := scanner.Text()
			if unicode.IsUpper(rune(word[0])) {
				continue
			}
			for _, letter := range word {
				if !unicode.IsLetter(letter) {
					continue SCAN
				}
			}
			trie.Add(word)
		}
	}
	flag.Parse()
}

func main() {
	if ln, err := net.Listen("tcp", flag.Arg(0)); err != nil {
		log.Fatalln(err)
	} else {
		defer ln.Close()
		for {
			if conn, err := ln.Accept(); err != nil {
				log.Println(err)
			} else {
				go func() {
					defer conn.Close()
					if message, err := ioutil.ReadAll(bufio.NewReader(conn)); err != nil {
						log.Println(err)
					} else {
						conn.Write([]byte(strconv.FormatBool(trie.Contains(strings.TrimSpace(string(message))))))
					}
				}()
			}
		}
	}
}