hotime/vendor/github.com/xdg-go/stringprep/bidi.go
2022-10-19 21:32:34 +08:00

74 lines
1.8 KiB
Go

// Copyright 2018 by David A. Golden. All rights reserved.
//
// 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
package stringprep
var errHasLCat = "BiDi string can't have runes from category L"
var errFirstRune = "BiDi string first rune must have category R or AL"
var errLastRune = "BiDi string last rune must have category R or AL"
// Check for prohibited characters from table C.8
func checkBiDiProhibitedRune(s string) error {
for _, r := range s {
if TableC8.Contains(r) {
return Error{Msg: errProhibited, Rune: r}
}
}
return nil
}
// Check for LCat characters from table D.2
func checkBiDiLCat(s string) error {
for _, r := range s {
if TableD2.Contains(r) {
return Error{Msg: errHasLCat, Rune: r}
}
}
return nil
}
// Check first and last characters are in table D.1; requires non-empty string
func checkBadFirstAndLastRandALCat(s string) error {
rs := []rune(s)
if !TableD1.Contains(rs[0]) {
return Error{Msg: errFirstRune, Rune: rs[0]}
}
n := len(rs) - 1
if !TableD1.Contains(rs[n]) {
return Error{Msg: errLastRune, Rune: rs[n]}
}
return nil
}
// Look for RandALCat characters from table D.1
func hasBiDiRandALCat(s string) bool {
for _, r := range s {
if TableD1.Contains(r) {
return true
}
}
return false
}
// Check that BiDi rules are satisfied ; let empty string pass this rule
func passesBiDiRules(s string) error {
if len(s) == 0 {
return nil
}
if err := checkBiDiProhibitedRune(s); err != nil {
return err
}
if hasBiDiRandALCat(s) {
if err := checkBiDiLCat(s); err != nil {
return err
}
if err := checkBadFirstAndLastRandALCat(s); err != nil {
return err
}
}
return nil
}