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November 15, 2016 09:41
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import ( | |
"bufio" | |
"context" | |
"io" | |
) | |
type CancelableScanner struct { | |
*bufio.Scanner | |
data chan string | |
err chan error | |
ctx context.Context | |
} | |
func NewCancelableScanner(ctx context.Context, r io.Reader) *CancelableScanner { | |
return &CancelableScanner{ | |
bufio.NewScanner(r), | |
make(chan string), | |
make(chan error), | |
ctx, | |
} | |
} | |
func (s *CancelableScanner) Start() *CancelableScanner { | |
go func() { | |
for s.Scan() { | |
s.data <- s.Text() | |
} | |
if err := s.Err(); err != nil { | |
s.err <- err | |
} | |
close(s.data) | |
close(s.err) | |
}() | |
return s | |
} | |
func (s *CancelableScanner) ReadOne() (string, error) { | |
select { | |
case <-s.ctx.Done(): | |
return "", context.Canceled | |
case str, ok := <-s.data: | |
if !ok { | |
return "", io.EOF | |
} | |
return str, nil | |
case err, ok := <-s.err: | |
if !ok { | |
return "", io.EOF | |
} | |
return "", err | |
} | |
} |
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