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41 lines
575 B
Go
41 lines
575 B
Go
package iox
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import (
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"bytes"
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"io"
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"os"
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)
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const bufSize = 32 * 1024
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// CountLines returns the number of lines in file.
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func CountLines(file string) (int, error) {
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f, err := os.Open(file)
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if err != nil {
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return 0, err
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}
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defer f.Close()
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var noEol bool
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buf := make([]byte, bufSize)
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count := 0
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lineSep := []byte{'\n'}
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for {
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c, err := f.Read(buf)
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count += bytes.Count(buf[:c], lineSep)
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switch {
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case err == io.EOF:
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if noEol {
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count++
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}
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return count, nil
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case err != nil:
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return count, err
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}
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noEol = c > 0 && buf[c-1] != '\n'
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}
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}
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