Dart: Rune type

tool/src/dart/formatter.rs

@@ -210,7 +210,7 @@ impl<'tcx> DartFormatter<'tcx> {
         if cast {
             match prim {
                 PrimitiveType::Bool => "bool",
-                PrimitiveType::Char => "int",
+                PrimitiveType::Char => "Rune",
                 PrimitiveType::Int(_) | PrimitiveType::IntSize(_) => "int",
                 PrimitiveType::Int128(_) => panic!("i128 not supported in Dart"),
                 PrimitiveType::Float(_) => "double",
@@ -240,7 +240,7 @@ impl<'tcx> DartFormatter<'tcx> {
     pub fn fmt_primitive_list_type(&self, prim: hir::PrimitiveType) -> &'static str {
         use diplomat_core::hir::{FloatType, IntType, PrimitiveType};
         match prim {
-            PrimitiveType::Char => "Uint32List",
+            PrimitiveType::Char => "RuneList",
             PrimitiveType::Int(IntType::I8) => "Int8List",
             PrimitiveType::Int(IntType::U8) => "Uint8List",
             PrimitiveType::Int(IntType::I16) => "Int16List",
@@ -260,7 +260,7 @@ impl<'tcx> DartFormatter<'tcx> {
     pub fn fmt_slice_type(&self, prim: hir::PrimitiveType) -> &'static str {
         use diplomat_core::hir::{FloatType, IntType, PrimitiveType};
         match prim {
-            PrimitiveType::Char => "_SliceFfiUint32",
+            PrimitiveType::Char => "_SliceRune",
             PrimitiveType::Int(IntType::I8) => "_SliceFfiInt8",
             PrimitiveType::Int(IntType::U8) => "_SliceFfiUint8",
             PrimitiveType::Int(IntType::I16) => "_SliceFfiInt16",

tool/src/dart/mod.rs

@@ -51,6 +51,7 @@ pub fn run<'cx>(
     }
 
     directives.insert(formatter.fmt_renamed_import("dart:ffi", "ffi"));
+    directives.insert(formatter.fmt_import("dart:typed_data"));
     directives.insert(formatter.fmt_renamed_import("package:ffi/ffi.dart", "ffi2"));
     files.add_file(
         formatter.fmt_file_name("lib"),

tool/templates/dart/init.dart

@@ -1,4 +1,21 @@
 
+/// A [Rune] is a Unicode code point, such as `a`, or `💡`.
+/// 
+/// The recommended way to obtain a [Rune] is to create it from a 
+/// [String], which is conceptually a list of [Runes]. For example,
+/// `'a'.runes.first` is equal to the [Rune] `a`.
+/// 
+/// Dart does not have a character/rune literal, so integer literals
+/// need to be used. For example the Unicode code point U+1F4A1, `💡`,
+/// can be represented by `0x1F4A1`. Note that only values in the ranges
+/// `0x0..0xD7FF` and `0xE000..0x10FFFF` (both inclusive) are Unicode
+/// code points, and hence valid [Rune]s.
+///
+/// A [String] can be constructed from a [Rune] using [String.fromCharCode]. 
+typedef Rune = int;
+/// A list of [Rune]s.
+typedef RuneList = Uint32List;
+
 late final ffi.Pointer<T> Function<T extends ffi.NativeType>(String) _capi;
 void init(String path) => _capi = ffi.DynamicLibrary.open(path).lookup;