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// Copyright 2017 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package getopt
import (
"fmt"
"runtime"
"strings"
)
// Value is the interface to the dynamic value stored in a flag. Flags of type
// Value are declared using the Flag and FlagLong functions.
type Value interface {
// Set converts value into the appropriate type and assigns it to the
// receiver value. Option details are provided via opt (such as the
// flags name).
//
// Set is used to reset the value of an option to its default value
// (which is stored in string form internally).
Set(value string, opt Option) error
// String returns the value of the flag as a string.
String() string
}
var thisPackage string
// init initializes thisPackage to our full package with the trailing .
// included.
func init() {
pc, _, _, ok := runtime.Caller(0)
if !ok {
return
}
f := runtime.FuncForPC(pc)
if f == nil {
return
}
thisPackage = f.Name()
x := strings.LastIndex(thisPackage, "/")
if x < 0 {
return
}
y := strings.Index(thisPackage[x:], ".")
if y < 0 {
return
}
// thisPackage includes the trailing . after the package name.
thisPackage = thisPackage[:x+y+1]
}
// calledFrom returns a string containing the file and linenumber of the first
// stack frame above us that is not part of this package and is not a test.
// This is used to determine where a flag was initialized.
func calledFrom() string {
for i := 2; ; i++ {
pc, file, line, ok := runtime.Caller(i)
if !ok {
return ""
}
if !strings.HasSuffix(file, "_test.go") {
f := runtime.FuncForPC(pc)
if f != nil && strings.HasPrefix(f.Name(), thisPackage) {
continue
}
}
return fmt.Sprintf("%s:%d", file, line)
}
}
func (s *Set) addFlag(p Value, name string, short rune, helpvalue ...string) Option {
opt := &option{
short: short,
long: name,
value: p,
defval: p.String(),
}
switch len(helpvalue) {
case 2:
opt.name = helpvalue[1]
fallthrough
case 1:
opt.help = helpvalue[0]
case 0:
default:
panic("Too many strings for String helpvalue")
}
if where := calledFrom(); where != "" {
opt.where = where
}
if opt.short == 0 && opt.long == "" {
fmt.Fprintf(stderr, opt.where+": no short or long option given")
exit(1)
}
s.AddOption(opt)
return opt
}
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