feat: add surrogate utilities to UInt16

uint16/pkg.generated.mbti

@@ -9,8 +9,13 @@ let min_value : UInt16
 // Errors
 
 // Types and methods
+fn UInt16::is_leading_surrogate(UInt16) -> Bool
+fn UInt16::is_surrogate(UInt16) -> Bool
+fn UInt16::is_trailing_surrogate(UInt16) -> Bool
+fn UInt16::to_char(UInt16) -> Char?
 fn UInt16::to_uint(UInt16) -> UInt
 fn UInt16::to_uint64(UInt16) -> UInt64
+fn UInt16::unsafe_to_char(UInt16) -> Char
 impl Add for UInt16
 impl BitAnd for UInt16
 impl BitOr for UInt16

uint16/uint16.mbt

@@ -107,3 +107,62 @@ pub fn UInt16::to_uint(self : UInt16) -> UInt {
 pub fn UInt16::to_uint64(self : UInt16) -> UInt64 {
   self.to_int().to_uint64()
 }
+
+///|
+/// Checks if the integer value represents a UTF-16 leading surrogate.
+/// Leading surrogates are in the range 0xD800 to 0xDBFF.
+///
+/// Example:
+/// ```moonbit
+/// inspect((0xD800 : UInt16).is_leading_surrogate(), content="true")
+/// inspect((0xDBFF : UInt16).is_leading_surrogate(), content="true")
+/// inspect((0xDC00 : UInt16).is_leading_surrogate(), content="false")
+/// inspect((0x41 : UInt16).is_leading_surrogate(), content="false") // 'A'
+/// ```
+pub fn UInt16::is_leading_surrogate(self : Self) -> Bool {
+  self >= 0xD800 && self <= 0xDBFF
+}
+
+///|
+/// Checks if the integer value represents a UTF-16 trailing surrogate.
+/// Trailing surrogates are in the range 0xDC00 to 0xDFFF.
+///
+/// Example:
+/// ```moonbit
+///   inspect((0xDC00 : UInt16).is_trailing_surrogate(), content="true")
+///   inspect((0xDFFF : UInt16).is_trailing_surrogate(), content="true")
+///   inspect((0xD800 : UInt16).is_trailing_surrogate(), content="false")
+///   inspect((0x41 : UInt16).is_trailing_surrogate(), content="false") // 'A'
+/// ```
+pub fn UInt16::is_trailing_surrogate(self : Self) -> Bool {
+  self >= 0xDC00 && self <= 0xDFFF
+}
+
+///|
+/// Checks if the integer value represents any UTF-16 surrogate (leading or trailing).
+/// Surrogates are in the range 0xD800 to 0xDFFF.
+///
+/// Example:
+/// ```moonbit
+///   inspect((0xD800 : UInt16).is_surrogate(), content="true")  // leading surrogate
+///   inspect((0xDC00 : UInt16).is_surrogate(), content="true")  // trailing surrogate
+///   inspect((0xDFFF : UInt16).is_surrogate(), content="true")  // trailing surrogate
+///   inspect((0x41 : UInt16).is_surrogate(), content="false")   // 'A'
+/// ```
+pub fn UInt16::is_surrogate(self : Self) -> Bool {
+  self >= 0xD800 && self <= 0xDFFF
+}
+
+///|
+pub fn UInt16::unsafe_to_char(self : UInt16) -> Char {
+  self.to_int().unsafe_to_char()
+}
+
+///|
+pub fn UInt16::to_char(self : UInt16) -> Char? {
+  if self is (0..=0xD7FF) || self is (0xE000..<_) {
+    Some(self.unsafe_to_char())
+  } else {
+    None
+  }
+}