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74 lines
1.8 KiB
74 lines
1.8 KiB
3 years ago
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// Copyright 2018 by David A. Golden. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package stringprep
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var errHasLCat = "BiDi string can't have runes from category L"
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var errFirstRune = "BiDi string first rune must have category R or AL"
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var errLastRune = "BiDi string last rune must have category R or AL"
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// Check for prohibited characters from table C.8
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func checkBiDiProhibitedRune(s string) error {
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for _, r := range s {
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if TableC8.Contains(r) {
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return Error{Msg: errProhibited, Rune: r}
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}
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}
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return nil
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}
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// Check for LCat characters from table D.2
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func checkBiDiLCat(s string) error {
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for _, r := range s {
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if TableD2.Contains(r) {
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return Error{Msg: errHasLCat, Rune: r}
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}
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}
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return nil
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}
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// Check first and last characters are in table D.1; requires non-empty string
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func checkBadFirstAndLastRandALCat(s string) error {
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rs := []rune(s)
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if !TableD1.Contains(rs[0]) {
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return Error{Msg: errFirstRune, Rune: rs[0]}
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}
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n := len(rs) - 1
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if !TableD1.Contains(rs[n]) {
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return Error{Msg: errLastRune, Rune: rs[n]}
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}
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return nil
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}
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// Look for RandALCat characters from table D.1
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func hasBiDiRandALCat(s string) bool {
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for _, r := range s {
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if TableD1.Contains(r) {
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return true
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}
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}
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return false
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}
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// Check that BiDi rules are satisfied ; let empty string pass this rule
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func passesBiDiRules(s string) error {
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if len(s) == 0 {
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return nil
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}
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if err := checkBiDiProhibitedRune(s); err != nil {
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return err
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}
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if hasBiDiRandALCat(s) {
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if err := checkBiDiLCat(s); err != nil {
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return err
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}
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if err := checkBadFirstAndLastRandALCat(s); err != nil {
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return err
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}
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}
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return nil
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}
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