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/*
* flag.go - Definitions for flags and associated formatting functions.
*
* Copyright 2017 Google Inc.
* Author: Joe Richey (joerichey@google.com)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package cmd
import (
"flag"
"fmt"
"strconv"
"time"
)
// Flag represents a command line flag that can be passed to a command. Note
// that Flag also conforms to the cli.Flag interface. The Name, ArgName, and
// Usage of the Flag can be used to format it in a short form with ShortFormat,
// or in it's full format with the String method.
type Flag interface {
fmt.Stringer
Apply(*flag.FlagSet)
GetName() string
GetArgName() string
GetUsage() string
}
// How the first usage line for a Flag should appear. We have two formats:
// --name
// --name=<argName>
// The <argName> appears if the prettyFlag's GetArgName() method returns a
// non-empty string. The returned string from shortFormat() does not include
// any leading or trailing whitespace.
func ShortFormat(f Flag) string {
if argName := f.GetArgName(); argName != "" {
return fmt.Sprintf("--%s=%s", f.GetName(), argName)
}
return fmt.Sprintf("--%s", f.GetName())
}
// How our flags should appear when displaying their usage. An example would be:
// --help
// Prints help screen for commands and subcommands.
//
// If defaultString is specified, this if appended to the usage. Example:
//
// --legacy
// Allow for support of older kernels with ext4 (before v4.8) and
// F2FS (before v4.6) filesystems. (default: true)
func longFormat(f Flag, defaultString ...string) string {
usage := f.GetUsage()
if len(defaultString) > 0 {
usage += fmt.Sprintf(" (default: %v)", defaultString[0])
}
usage = wrapText(usage, 2)
return fmt.Sprintf("\t%s\n%s", ShortFormat(f), usage)
}
// BoolFlag is a Flag of type bool.
type BoolFlag struct {
Name string
Usage string
Default bool
Value bool
}
func (f *BoolFlag) String() string {
if !f.Default {
return longFormat(f)
}
return longFormat(f, strconv.FormatBool(f.Default))
}
// Apply uses BoolFlag's value to set a flag.BoolVar on the FlagSet.
func (f *BoolFlag) Apply(s *flag.FlagSet) { s.BoolVar(&f.Value, f.Name, f.Default, f.Usage) }
// GetName just returns BoolFlag's name.
func (f *BoolFlag) GetName() string { return f.Name }
// GetArgName returns nothing as BoolFlags don't have an argument name.
func (f *BoolFlag) GetArgName() string { return "" }
// GetUsage returns BoolFlag's usage.
func (f *BoolFlag) GetUsage() string { return f.Usage }
// StringFlag is a Flag of type string.
type StringFlag struct {
Name string
ArgName string
Usage string
Default string
Value string
}
func (f *StringFlag) String() string {
if f.Default == "" {
return longFormat(f)
}
return longFormat(f, strconv.Quote(f.Default))
}
// Apply uses StringFlag's value to set a flag.StringVar on the FlagSet.
func (f *StringFlag) Apply(s *flag.FlagSet) { s.StringVar(&f.Value, f.Name, f.Default, f.Usage) }
// GetName just returns StringFlag's name.
func (f *StringFlag) GetName() string { return f.Name }
// GetArgName returns StringFlag's argument name.
func (f *StringFlag) GetArgName() string { return f.ArgName }
// GetUsage returns StringFlag's usage.
func (f *StringFlag) GetUsage() string { return f.Usage }
// DurationFlag is a Flag of type time.Duration.
type DurationFlag struct {
Name string
ArgName string
Usage string
Default time.Duration
Value time.Duration
}
func (f *DurationFlag) String() string {
if f.Default == 0 {
return longFormat(f)
}
return longFormat(f, f.Default.String())
}
// Apply uses DurationFlag's value to set a flag.DurationVar on the FlagSet.
func (f *DurationFlag) Apply(s *flag.FlagSet) { s.DurationVar(&f.Value, f.Name, f.Default, f.Usage) }
// GetName just returns DurationFlag's name.
func (f *DurationFlag) GetName() string { return f.Name }
// GetArgName returns DurationFlag's argument name.
func (f *DurationFlag) GetArgName() string { return f.ArgName }
// GetUsage returns DurationFlag's usage.
func (f *DurationFlag) GetUsage() string { return f.Usage }
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