Support copy() built-in for type params.

nevkontakte · nevkontakte · commit 72ba5b11bf9a · 2023-11-12T19:59:08.000Z
diff --git a/compiler/expressions.go b/compiler/expressions.go
@@ -1112,10 +1112,8 @@ func (fc *funcContext) translateBuiltin(name string, sig *types.Signature, args
 		)
 	case "copy":
 		args = fc.expandTupleArgs(args)
-		if basic, isBasic := fc.pkgCtx.TypeOf(args[1]).Underlying().(*types.Basic); isBasic && isString(basic) {
-			return fc.formatExpr("$copyString(%e, %e)", args[0], args[1])
-		}
-		return fc.formatExpr("$copySlice(%e, %e)", args[0], args[1])
+		dst, src := args[0], args[1]
+		return fc.formatExpr("%s.$copy(%e, %e)", fc.typeName(fc.pkgCtx.TypeOf(src)), dst, src)
 	case "print":
 		args = fc.expandTupleArgs(args)
 		return fc.formatExpr("$print(%s)", strings.Join(fc.translateExprSlice(args, nil), ", "))
diff --git a/compiler/prelude/types.js b/compiler/prelude/types.js
@@ -94,6 +94,7 @@ var $newType = (size, kind, string, named, pkg, exported, constructor) => {
             typ.wrap = (v) => new typ(v);
             typ.keyFor = x => { return "$" + x; };
             typ.$len = (v) => v.length;
+            typ.$copy = (dst, src) => $copyString(dst, src);
             break;
 
         case $kindFloat32:
@@ -267,6 +268,7 @@ var $newType = (size, kind, string, named, pkg, exported, constructor) => {
             typ.$make = (size, capacity) => $makeSlice(typ, size, capacity);
             typ.$len = (v) => v.$length;
             typ.$cap = (v) => v.$capacity;
+            typ.$copy = (dst, src) => $copySlice(dst, src);
             break;
 
         case $kindStruct:
diff --git a/compiler/utils.go b/compiler/utils.go
@@ -704,6 +704,8 @@ func toJavaScriptType(t *types.Basic) string {
 		return "Int32"
 	case types.UnsafePointer:
 		return "UnsafePointer"
+	case types.UntypedString:
+		return "String"
 	default:
 		name := t.String()
 		return strings.ToUpper(name[:1]) + name[1:]
diff --git a/tests/typeparams/builtins_test.go b/tests/typeparams/builtins_test.go
@@ -225,3 +225,34 @@ func TestDelete(t *testing.T) {
 		t.Errorf("Got: delete(...) = %#v. Want: %#v", got, want)
 	}
 }
+
+func _copy[D []byte, S []byte | string](dst D, src S) int {
+	return copy(dst, src)
+}
+
+func TestCopy(t *testing.T) {
+	t.Run("string", func(t *testing.T) {
+		src := "abc"
+		got := make([]byte, 3)
+		n := _copy(got, src)
+		want := []byte{'a', 'b', 'c'}
+		if !reflect.DeepEqual(want, got) {
+			t.Errorf("Got: copy result: %v. Want: %v", got, want)
+		}
+		if n != 3 {
+			t.Errorf("Got: copied %d elements. Want: 3", n)
+		}
+	})
+	t.Run("slice", func(t *testing.T) {
+		src := []byte{'a', 'b', 'c', 'd'}
+		got := make([]byte, 3)
+		n := _copy(got, src)
+		want := []byte{'a', 'b', 'c'}
+		if !reflect.DeepEqual(want, got) {
+			t.Errorf("Got: copy result: %v. Want: %v", got, want)
+		}
+		if n != 3 {
+			t.Errorf("Got: copied %d elements. Want: 3", n)
+		}
+	})
+}
