github.com/axw/juju@v0.0.0-20161005053422-4bd6544d08d4/cmd/helpers.go (about)

     1  // Copyright 2014 Canonical Ltd.
     2  // Licensed under the AGPLv3, see LICENCE file for details.
     3  
     4  package cmd
     5  
     6  import (
     7  	"bufio"
     8  	"io"
     9  	"strings"
    10  
    11  	"github.com/juju/cmd"
    12  	"github.com/juju/errors"
    13  )
    14  
    15  // This file contains helper functions for generic operations commonly needed
    16  // when implementing a command.
    17  
    18  type userAbortedError string
    19  
    20  func (e userAbortedError) Error() string {
    21  	return string(e)
    22  }
    23  
    24  // IsUserAbortedError returns true if err is of type userAbortedError.
    25  func IsUserAbortedError(err error) bool {
    26  	_, ok := errors.Cause(err).(userAbortedError)
    27  	return ok
    28  }
    29  
    30  // UserConfirmYes returns an error if we do not read a "y" or "yes" from user
    31  // input.
    32  func UserConfirmYes(ctx *cmd.Context) error {
    33  	scanner := bufio.NewScanner(ctx.Stdin)
    34  	scanner.Scan()
    35  	err := scanner.Err()
    36  	if err != nil && err != io.EOF {
    37  		return errors.Trace(err)
    38  	}
    39  	answer := strings.ToLower(scanner.Text())
    40  	if answer != "y" && answer != "yes" {
    41  		return errors.Trace(userAbortedError("aborted"))
    42  	}
    43  	return nil
    44  }