public static void appendEscapedCodePoint(StringBuilder sb, int codePoint, String language) {
		switch (language) {
			case "CSharp":
			case "Python3":
			case "Cpp":
			case "Go":
			case "PHP":
				String format = Character.isSupplementaryCodePoint(codePoint) ? "\\U%08X" : "\\u%04X";
				sb.append(String.format(format, codePoint));
				break;
			case "Swift":
				sb.append(String.format("\\u{%04X}", codePoint));
				break;
			case "Java":
			case "JavaScript":
			case "TypeScript":
			case "Dart":
			default:
				if (Character.isSupplementaryCodePoint(codePoint)) {
					// char is not an 'integral' type, so we have to explicitly convert
					// to int before passing to the %X formatter or else it throws.
					sb.append(String.format("\\u%04X", (int)Character.highSurrogate(codePoint)));
					sb.append(String.format("\\u%04X", (int)Character.lowSurrogate(codePoint)));
				}
				else {
					sb.append(String.format("\\u%04X", codePoint));
				}
				break;
		}
	}
Utility class to escape Unicode code points using various
languages' syntax.
tool/src/org/antlr/v4/codegen/UnicodeEscapes.java