pulumi/pkg/util/cmdutil/spinner.go

73 lines
1.9 KiB
Go

// Copyright 2016-2017, Pulumi Corporation. All rights reserved.
package cmdutil
import (
"fmt"
"os"
"time"
"golang.org/x/crypto/ssh/terminal"
)
// NewSpinnerAndTicker returns a new Spinner and a ticker that will fire an event when the next call to Spinner.Tick()
// should be called. NewSpinnerAndTicket takes into account if stdout is connected to a tty or not and returns either a
// nice animated spinner that updates quickly or a simple spinner that just prints a dot on each tick and updates
// slowly.
func NewSpinnerAndTicker() (Spinner, *time.Ticker) {
if terminal.IsTerminal(int(os.Stdout.Fd())) {
return &ttySpinner{}, time.NewTicker(time.Second / 8)
}
return &dotSpinner{}, time.NewTicker(time.Second * 20)
}
// Spinner represents a very simple progress reporter.
type Spinner interface {
// Print the next frame of the spinner. After Tick() has been called, there should be no writes to Stdout before
// calling Reset().
Tick()
// Called to release ownership of stdout, so others may write to it.
Reset()
}
var spinFrames = []string{"|", "/", "-", "\\"}
// ttySpinner is the spinner that can be used when standard out is a tty. When we are connected to a TTY we can erase
// characters we've written and provide a nice quick progress spinner.
type ttySpinner struct {
index int
}
func (spin *ttySpinner) Tick() {
fmt.Printf("\r \r")
fmt.Printf(spinFrames[spin.index])
spin.index = (spin.index + 1) % len(spinFrames)
}
func (spin *ttySpinner) Reset() {
fmt.Printf("\r \r")
spin.index = 0
}
// dotSpinner is the spinner that can be used when standard out is not a tty. In this case, we just write a single
// dot on each tick.
type dotSpinner struct {
hasWritten bool
}
func (spin *dotSpinner) Tick() {
if !spin.hasWritten {
fmt.Printf("still working")
}
fmt.Printf(".")
spin.hasWritten = true
}
func (spin *dotSpinner) Reset() {
if spin.hasWritten {
fmt.Println()
}
spin.hasWritten = false
}