Returns the leading surrogate (a high surrogate code unit) of the surrogate pair representing the specified supplementary character (Unicode code point) in the UTF-16 encoding. If the specified character is not a supplementary character, an unspecified char is returned.

If isSupplementaryCodePoint(x) is true, then isHighSurrogate (highSurrogate(x)) and toCodePoint (highSurrogate(x), lowSurrogate (x)) == x are also always true.

Parameters:

codePoint

a supplementary character (Unicode code point)

Returns:  the leading surrogate code unit used to represent the character in the UTF-16 encoding

Since:  1.7