Add conversion between Char and Bytes/BytesView.

builtin/builtin.mbti

@@ -195,6 +195,8 @@ impl BytesView {
   length(Self) -> Int
   op_as_view(Self, start~ : Int = .., end? : Int) -> Self
   op_get(Self, Int) -> Byte
+  to_char_be(Self) -> Char
+  to_char_le(Self) -> Char
   to_double_be(Self) -> Double
   to_double_le(Self) -> Double
   to_float_be(Self) -> Float

builtin/bytesview.mbt

@@ -213,3 +213,13 @@ pub fn BytesView::to_double_be(self : BytesView) -> Double {
 pub fn BytesView::to_double_le(self : BytesView) -> Double {
   self.to_uint64_le().reinterpret_as_double()
 }
+
+///| Converts the 4 bytes long BytesView to a Char in big-endian byte order.
+pub fn BytesView::to_char_be(self : BytesView) -> Char {
+  Char::from_int(self.to_int_be())
+}
+
+///| Converts the 4 bytes long BytesView to a Char in little-endian byte order.
+pub fn BytesView::to_char_le(self : BytesView) -> Char {
+  Char::from_int(self.to_int_le())
+}

builtin/bytesview_test.mbt

@@ -290,3 +290,41 @@ test "panic negative index2" {
   let _ = bs[-1:-2]
 
 }
+
+test "to_char_be" {
+  // test ascii
+  let code_point = 65
+  let bs = code_point.to_be_bytes()
+  let ch = bs[:].to_char_be()
+  assert_eq!('A', ch)
+  // test cjk chars
+  let ch = '清'
+  let i = ch.to_be_bytes()[:].to_int_be()
+  assert_eq!(0x6e05, i)
+  let ch = '浄'
+  let i = ch.to_be_bytes()[:].to_int_be()
+  assert_eq!(0x6d44, i)
+  // test arabic
+  let ch = 'ل'
+  let i = ch.to_be_bytes()[:].to_int_be()
+  assert_eq!(0x0644, i)
+}
+
+test "to_char_le" {
+  // test ascii
+  let code_point = 97
+  let bs = code_point.to_le_bytes()
+  let ch = bs[:].to_char_le()
+  assert_eq!('a', ch)
+  // test cjk
+  let ch = '清'
+  let i = ch.to_le_bytes()[:].to_int_le()
+  assert_eq!(0x6e05, i)
+  let ch = '浄'
+  let i = ch.to_le_bytes()[:].to_int_le()
+  assert_eq!(0x6d44, i)
+  // test arabic
+  let ch = 'ل'
+  let i = ch.to_le_bytes()[:].to_int_le()
+  assert_eq!(0x0644, i)
+}

char/char.mbt

@@ -19,3 +19,13 @@ pub impl Hash for Char with hash(self) { self.to_int() }
 pub impl Hash for Char with hash_combine(self, hasher) -> Unit {
   hasher.combine_char(self)
 }
+
+///|
+pub fn to_be_bytes(self : Char) -> Bytes {
+  self.to_uint().to_be_bytes()
+}
+
+///|
+pub fn to_le_bytes(self : Char) -> Bytes {
+  self.to_uint().to_le_bytes()
+}

char/char.mbti

@@ -3,6 +3,10 @@ package moonbitlang/core/char
 // Values
 
 // Types and methods
+impl Char {
+  to_be_bytes(Char) -> Bytes
+  to_le_bytes(Char) -> Bytes
+}
 impl Hash for Char
 
 // Type aliases

char/moon.pkg.json

@@ -1,3 +1,3 @@
 {
-  "import": ["moonbitlang/core/builtin"]
+  "import": ["moonbitlang/core/builtin", "moonbitlang/core/uint"]
 }