30 lines
850 B
Go
30 lines
850 B
Go
// Copyright (c) 2021 Shivaram Lingamneni
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// Released under the MIT License
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package ircmsg
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import (
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"unicode/utf8"
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)
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// TruncateUTF8Safe truncates a message, respecting UTF8 boundaries. If a message
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// was originally valid UTF8, TruncateUTF8Safe will not make it invalid; instead
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// it will truncate additional bytes as needed, back to the last valid
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// UTF8-encoded codepoint. If a message is not UTF8, TruncateUTF8Safe will truncate
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// at most 3 additional bytes before giving up.
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func TruncateUTF8Safe(message string, byteLimit int) (result string) {
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if len(message) <= byteLimit {
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return message
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}
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message = message[:byteLimit]
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for i := 0; i < (utf8.UTFMax - 1); i++ {
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r, n := utf8.DecodeLastRuneInString(message)
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if r == utf8.RuneError && n <= 1 {
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message = message[:len(message)-1]
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} else {
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break
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}
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}
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return message
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}
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