tailscale/util/strs/strs.go

// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package strs contains string-related utility funcs.
package strs

import "strings"

// CutPrefix returns s without the provided leading prefix string
// and reports whether it found the prefix.
// If s doesn't start with prefix, CutPrefix returns s, false.
// If prefix is the empty string, CutPrefix returns s, true.
//
// TODO: remove this once Go 1.20 is out with it.
// See https://github.com/tailscale/tailscale/issues/5309
func CutPrefix(s, prefix string) (after string, found bool) {
	if !strings.HasPrefix(s, prefix) {
		return s, false
	}
	return s[len(prefix):], true
}

// CutSuffix returns s without the provided ending suffix string
// and reports whether it found the suffix.
// If s doesn't end with suffix, CutSuffix returns s, false.
// If suffix is the empty string, CutSuffix returns s, true.
//
// See https://github.com/tailscale/tailscale/issues/5309
// TODO: remove this once Go 1.20 is out with it.
func CutSuffix(s, suffix string) (before string, found bool) {
	if !strings.HasSuffix(s, suffix) {
		return s, false
	}
	return s[:len(s)-len(suffix)], true
}