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1 package main
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2
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3 import (
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4 "bufio"
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5 "flag"
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6 "fmt"
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7 "os"
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8 )
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9
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10 func main() {
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11 flag.Parse()
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12
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13 files := flag.Args()
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14
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15 var lines []string
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16
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17 // Input
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18 if len( files ) == 0 {
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19 lines = ReverseLines( os.Stdin, nil )
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20 } else {
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21 for _, arg := range files {
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22 f, err := os.Open( arg )
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23 if err != nil {
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24 fmt.Fprintf( os.Stderr, "tac : %v\n", err )
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25 continue
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26 }
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27 l := ReverseLines( f, nil )
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28 f.Close()
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29 lines = append( lines, l... )
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30 }
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31 }
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32
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33 // Output
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34 for _, line := range lines {
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35 fmt.Println( line )
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36 }
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37 }
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38
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39 func ReverseLines( f *os.File, l []string ) []string {
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40 input := bufio.NewScanner( f )
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41 for input.Scan() {
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42 l = append( l, input.Text() )
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43 }
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44 for i, j := 0, len(l) - 1; i < j; i, j = i + 1, j - 1 {
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45 l[i], l[j] = l[j], l[i]
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46 }
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47 return l
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48 }
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49
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