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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package opt defines optional types.
package opt
import (
"fmt"
"strconv"
)
// Bool represents an optional boolean to be JSON-encoded. The string
// is either "true", "false", or the empty string to mean unset.
//
// As a special case, the underlying string may also be the string
// "unset" as as a synonym for the empty string. This lets the
// explicit unset value be exchanged over an encoding/json "omitempty"
// field without it being dropped.
type Bool string
// NewBool constructs a new Bool value equal to b. The returned Bool is set,
// unless Set("") or Clear() methods are called.
func NewBool(b bool) Bool {
return Bool(strconv.FormatBool(b))
}
func (b *Bool) Set(v bool) {
*b = Bool(strconv.FormatBool(v))
}
func (b *Bool) Clear() { *b = "" }
func (b Bool) Get() (v bool, ok bool) {
switch b {
case "true":
return true, true
case "false":
return false, true
default:
return false, false
}
}
// Scan implements database/sql.Scanner.
func (b *Bool) Scan(src any) error {
if src == nil {
*b = ""
return nil
}
switch src := src.(type) {
case bool:
if src {
*b = "true"
} else {
*b = "false"
}
return nil
case int64:
if src == 0 {
*b = "false"
} else {
*b = "true"
}
return nil
default:
return fmt.Errorf("opt.Bool.Scan: invalid type %T: %v", src, src)
}
}
// EqualBool reports whether b is equal to v.
// If b is empty or not a valid bool, it reports false.
func (b Bool) EqualBool(v bool) bool {
p, ok := b.Get()
return ok && p == v
}
var (
trueBytes = []byte("true")
falseBytes = []byte("false")
nullBytes = []byte("null")
)
func (b Bool) MarshalJSON() ([]byte, error) {
switch b {
case "true":
return trueBytes, nil
case "false":
return falseBytes, nil
case "", "unset":
return nullBytes, nil
}
return nil, fmt.Errorf("invalid opt.Bool value %q", string(b))
}
func (b *Bool) UnmarshalJSON(j []byte) error {
switch string(j) {
case "true":
*b = "true"
case "false":
*b = "false"
case "null":
*b = "unset"
default:
return fmt.Errorf("invalid opt.Bool value %q", j)
}
return nil
}
// BoolFlag is a wrapper for Bool that implements [flag.Value].
type BoolFlag struct {
*Bool
}
// Set the value of b, using any value supported by [strconv.ParseBool].
func (b *BoolFlag) Set(s string) error {
v, err := strconv.ParseBool(s)
if err != nil {
return err
}
b.Bool.Set(v)
return nil
}
// String returns "true" or "false" if the value is set, or an empty string otherwise.
func (b *BoolFlag) String() string {
if b == nil || b.Bool == nil {
return ""
}
if v, ok := b.Bool.Get(); ok {
return strconv.FormatBool(v)
}
return ""
}
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