| // Copyright 2023 The LUCI Authors. |
| // |
| // 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 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // Package lex64 is a base64 variant that preserves lexicographic ordering of |
| // bytestrings. |
| // It does this by using the alphanumeric characters, _, . and - as the alphabet. |
| // - is used as padding since it is the smallest character. |
| // |
| // The codec preserves order and has roundtrip equality. |
| // |
| // This package has two versions of the alphabet. V2 is the default and |
| // is URL-safe. V1 is legacy and is not URL-safe. |
| // |
| // Lex64 V2 is a base64 encoding using the following alphabet: |
| // |
| // .0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz |
| // |
| // The padding character is '-', which precedes the characters above. |
| // Lex64, by default, omits the padding character from generated strings, |
| // but can be made to emit them and conform to rfc4648 (with a different alphabet). |
| // |
| // Lex64 also supports the following legacy alphabet: |
| // |
| // 0123456789=ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz |
| // |
| // At time of writing (2023 Q1), the legacy alphabet is used in Karte. |
| package lex64 |