Add utf_codepoint to stdlib

1 files changed, 20 insertions, 0 deletions

diff --git a/src/gleam/utf_codepoint.gleam b/src/gleam/utf_codepoint.gleam
new file mode 100644
index 0000000..2c3cb04
--- /dev/null
+++ b/src/gleam/utf_codepoint.gleam
@@ -0,0 +1,20 @@
+import gleam/result
+
+pub type UtfCodepoint = UtfCodepoint
+
+pub type Error {
+  Invalid
+}
+
+external fn int_to_utf8_codepoint(Int) -> UtfCodepoint =
+  "gleam_stdlib" "identity"
+
+pub fn from_int(value: Int) -> Result(UtfCodepoint, Error) {
+  case value {
+    i if i > 1114111 -> Error(Invalid)
+    i if i == 65534 -> Error(Invalid)
+    i if i == 65535 -> Error(Invalid)
+    i if i >= 55296 && i <= 57343 -> Error(Invalid)
+    i -> Ok(int_to_utf8_codepoint(i))
+  }
+}