Changes to tty/utf16.go. All files

tty/utf16.go

new file mode 100644@@ -0,0 +1,47 @@+// Copyright 2026 The TCell 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 tty++import (+	"unicode/utf16"+	"unicode/utf8"+)++// decodeUTF16Rune decodes one UTF-16 code unit at a time while preserving+// malformed input as replacement characters instead of silently discarding it.+func decodeUTF16Rune(surrogate *rune, wc rune) []rune {+	switch {+	case wc >= 0xD800 && wc <= 0xDBFF:+		if *surrogate != 0 {+			*surrogate = wc+			return []rune{utf8.RuneError}+		}+		*surrogate = wc+		return nil+	case wc >= 0xDC00 && wc <= 0xDFFF:+		if *surrogate == 0 {+			return []rune{utf8.RuneError}+		}+		decoded := utf16.DecodeRune(*surrogate, wc)+		*surrogate = 0+		return []rune{decoded}+	default:+		if *surrogate != 0 {+			*surrogate = 0+			return []rune{utf8.RuneError, wc}+		}+		return []rune{wc}+	}+}