forked from mirrors/gotosocial
61 lines
2.1 KiB
Go
61 lines
2.1 KiB
Go
|
// GoToSocial
|
||
|
|
// Copyright (C) GoToSocial Authors admin@gotosocial.org
|
||
|
|
// SPDX-License-Identifier: AGPL-3.0-or-later
|
||
|
|
//
|
||
|
|
// This program is free software: you can redistribute it and/or modify
|
||
|
|
// it under the terms of the GNU Affero General Public License as published by
|
||
|
|
// the Free Software Foundation, either version 3 of the License, or
|
||
|
|
// (at your option) any later version.
|
||
|
|
//
|
||
|
|
// This program is distributed in the hope that it will be useful,
|
||
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
// GNU Affero General Public License for more details.
|
||
|
|
//
|
||
|
|
// You should have received a copy of the GNU Affero General Public License
|
||
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||
|
|
|
||
|
|
package text
|
||
|
|
|
||
|
|
import (
|
||
|
|
"strings"
|
||
|
|
|
||
|
|
"github.com/superseriousbusiness/gotosocial/internal/util"
|
||
|
|
"golang.org/x/text/unicode/norm"
|
||
|
|
)
|
||
|
|
|
||
|
|
const (
|
||
|
|
maximumHashtagLength = 100
|
||
|
|
)
|
||
|
|
|
||
|
|
// NormalizeHashtag normalizes the given hashtag text by
|
||
|
|
// removing the initial '#' symbol, and then decomposing
|
||
|
|
// and canonically recomposing chars + combining diacritics
|
||
|
|
// in the text to single unicode characters, following
|
||
|
|
// Normalization Form C (https://unicode.org/reports/tr15/).
|
||
|
|
//
|
||
|
|
// Finally, it will do a check on the normalized string to
|
||
|
|
// ensure that it's below maximumHashtagLength chars, and
|
||
|
|
// contains only unicode letters and numbers. If this passes,
|
||
|
|
// returned bool will be true.
|
||
|
|
func NormalizeHashtag(text string) (string, bool) {
|
||
|
|
// This normalization is specifically to avoid cases
|
||
|
|
// where visually-identical hashtags are stored with
|
||
|
|
// different unicode representations (e.g. with combining
|
||
|
|
// diacritics). It allows a tasteful number of combining
|
||
|
|
// diacritics to be used, as long as they can be combined
|
||
|
|
// with parent characters to form regular letter symbols.
|
||
|
|
normalized := norm.NFC.String(strings.TrimPrefix(text, "#"))
|
||
|
|
|
||
|
|
// Validate normalized.
|
||
|
|
ok := true
|
||
|
|
for i, r := range normalized {
|
||
|
|
if i >= maximumHashtagLength || !util.IsPermittedInHashtag(r) {
|
||
|
|
ok = false
|
||
|
|
break
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return normalized, ok
|
||
|
|
}
|