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0868329936
My favorite part of generics. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
102 lines
2.0 KiB
Go
102 lines
2.0 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package opt defines optional types.
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package opt
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import (
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"fmt"
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"strconv"
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)
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// Bool represents an optional boolean to be JSON-encoded.
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// The string can be empty (for unknown or unspecified), or
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// "true" or "false".
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type Bool string
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func (b *Bool) Set(v bool) {
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*b = Bool(strconv.FormatBool(v))
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}
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func (b *Bool) Clear() { *b = "" }
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func (b Bool) Get() (v bool, ok bool) {
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if b == "" {
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return
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}
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v, err := strconv.ParseBool(string(b))
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return v, err == nil
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}
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// Scan implements database/sql.Scanner.
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func (b *Bool) Scan(src any) error {
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if src == nil {
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*b = ""
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return nil
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}
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switch src := src.(type) {
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case bool:
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if src {
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*b = "true"
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} else {
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*b = "false"
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}
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return nil
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case int64:
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if src == 0 {
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*b = "false"
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} else {
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*b = "true"
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}
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return nil
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default:
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return fmt.Errorf("opt.Bool.Scan: invalid type %T: %v", src, src)
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}
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}
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// EqualBool reports whether b is equal to v.
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// If b is empty or not a valid bool, it reports false.
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func (b Bool) EqualBool(v bool) bool {
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p, ok := b.Get()
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return ok && p == v
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}
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var (
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trueBytes = []byte("true")
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falseBytes = []byte("false")
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nullBytes = []byte("null")
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)
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func (b Bool) MarshalJSON() ([]byte, error) {
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switch b {
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case "true":
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return trueBytes, nil
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case "false":
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return falseBytes, nil
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case "":
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return nullBytes, nil
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}
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return nil, fmt.Errorf("invalid opt.Bool value %q", string(b))
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}
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func (b *Bool) UnmarshalJSON(j []byte) error {
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// Note: written with a bunch of ifs instead of a switch
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// because I'm sure the Go compiler optimizes away these
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// []byte->string allocations in an == comparison, but I'm too
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// lazy to check whether that's true in a switch also.
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if string(j) == "true" {
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*b = "true"
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return nil
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}
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if string(j) == "false" {
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*b = "false"
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return nil
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}
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if string(j) == "null" {
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*b = ""
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return nil
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}
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return fmt.Errorf("invalid opt.Bool value %q", j)
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}
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