63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
package progress
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import (
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"bytes"
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"fmt"
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"io"
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)
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// Writer buffers writes until flush, at which time the last screen is cleared
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// and the current buffer contents are written. This is useful for
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// implementing progress displays, such as those implemented in docker and
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// git.
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type Writer struct {
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buf bytes.Buffer
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w io.Writer
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lines int
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}
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// NewWriter returns a writer
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func NewWriter(w io.Writer) *Writer {
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return &Writer{
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w: w,
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}
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}
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// Write the provided bytes
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func (w *Writer) Write(p []byte) (n int, err error) {
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return w.buf.Write(p)
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}
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// Flush should be called when refreshing the current display.
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func (w *Writer) Flush() error {
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if w.buf.Len() == 0 {
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return nil
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}
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if err := w.clear(); err != nil {
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return err
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}
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w.lines = bytes.Count(w.buf.Bytes(), []byte("\n"))
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if _, err := w.w.Write(w.buf.Bytes()); err != nil {
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return err
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}
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w.buf.Reset()
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return nil
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}
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// TODO(stevvooe): The following are system specific. Break these out if we
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// decide to build this package further.
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func (w *Writer) clear() error {
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for i := 0; i < w.lines; i++ {
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if _, err := fmt.Fprintf(w.w, "\x1b[0A\x1b[2K\r"); err != nil {
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return err
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}
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}
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return nil
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}
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