80 lines
1.2 KiB
Go
80 lines
1.2 KiB
Go
package main
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import (
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"bufio"
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"fmt"
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"os"
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"strings"
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"sync"
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)
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/*
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@Ref: https://livebook.manning.com/book/go-in-practice/chapter-3/65
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1. --reac flag is able to do the race detection
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2. How to use scanner to split the word in a file
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3. sync.Mutex usage
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*/
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func main() {
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wg := sync.WaitGroup{}
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w := newWords()
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for _, file := range os.Args[1:] {
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wg.Add(1)
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go func(filename string) {
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tallyWords(filename, w)
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wg.Done()
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}(file)
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}
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wg.Wait()
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fmt.Println("Words that appear more than once:")
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for word, count := range w.found {
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if count > 1 {
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fmt.Printf("%s: %d\n", word, count)
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}
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}
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}
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type words struct {
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sync.Mutex
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found map[string]int
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}
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func newWords() *words {
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return &words{found: make(map[string]int)}
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}
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func (w *words) add(word string, n int) {
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w.Lock()
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defer w.Unlock()
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count, ok := w.found[word]
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if !ok {
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w.found[word] = n
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return
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}
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w.found[word] = count + n
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}
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func tallyWords(filename string, dist *words) error {
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file, err := os.Open(filename)
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if err != nil {
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return err
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}
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defer file.Close()
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scanner := bufio.NewScanner(file)
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scanner.Split(bufio.ScanWords)
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for scanner.Scan() {
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word := strings.ToLower(scanner.Text())
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dist.add(word, 1)
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}
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return scanner.Err()
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}
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