fix(dart): count named / optional-positional parameter groups in args (#2309)

gitgalaxy/core/detector.py

@@ -4835,6 +4835,51 @@ def _count_top_level_args(self, args_str: str, treat_as_body: bool = False) -> i
         if not body.strip():
             return 0
 
+        # #2309: Dart's named (`{...}`) and optional-positional (`[...]`) parameter
+        # groups are always the TERMINAL element of a parameter list -- `({a, b})`,
+        # `([a, b])`, `(pos, {a, b})` -- and the commas inside them are real argument
+        # separators. `{`/`[` otherwise read as nesting in the loop below, hiding
+        # every one of those commas (`EditableText({super.key, required this.x, ...})`
+        # measured 1 arg instead of ~40). Neutralise just that one terminal group's
+        # own delimiters so its members land at the top level. A `{...}`/`[...]` that
+        # is a default-value literal (`{int x = const [1, 2]}`) is never flush against
+        # the body's end, so it stays nested and its commas stay (correctly) ignored.
+        if self.primary_lang_id == "dart":
+            stripped_end = len(body.rstrip())
+            if stripped_end and body[stripped_end - 1] in "}]":
+                gdepth = 0
+                g_instr = False
+                g_quote = ""
+                last_group_open = -1
+                gi = 0
+                while gi < stripped_end:
+                    gch = body[gi]
+                    if g_instr:
+                        if gch == "\\":
+                            gi += 2
+                            continue
+                        if gch == g_quote:
+                            g_instr = False
+                    elif gch in ("'", '"', "`"):
+                        g_instr = True
+                        g_quote = gch
+                    elif gch in "([{":
+                        if gch in "[{" and gdepth == 0:
+                            last_group_open = gi
+                        gdepth += 1
+                    elif gch in ")]}":
+                        gdepth = max(0, gdepth - 1)
+                    gi += 1
+                if last_group_open != -1 and gdepth == 0:
+                    # the terminal group closes at stripped_end-1; blank both delimiters
+                    body = (
+                        body[:last_group_open]
+                        + " "
+                        + body[last_group_open + 1 : stripped_end - 1]
+                        + " "
+                        + body[stripped_end:]
+                    )
+
         depth = 0
         in_string = False
         quote_char = ""

gitgalaxy/standards/language_standards.py

@@ -39,7 +39,7 @@
 | Cpp | 87.0% | 95.0% | 100.0% | 100.0% |
 | Csharp | 100.0% | 100.0% | 100.0% | 100.0% |
 | Css | 100.0% | 100.0% | N/A | N/A |
-| Dart | 99.4% | 99.3% | 100.0% | 100.0% |
+| Dart | 99.5% | 99.3% | 100.0% | 100.0% |
 | Fortran | 98.6% | 100.0% | 100.0% | 100.0% |
 | Go | 100.0% | 100.0% | 100.0% | 100.0% |
 | Groovy | N/A | N/A | N/A | N/A |

tests/core_engine/test_detector.py

@@ -2494,6 +2494,29 @@ def test_count_top_level_args_angle_brackets_still_track_generics_for_generic_la
     assert cpp_detector._count_top_level_args("(std::vector<int> a, int b)") == 2, "cpp template arg regressed"
 
 
+def test_count_top_level_args_dart_named_and_optional_parameter_groups_2309():
+    """
+    #2309: Dart's named (`{...}`) and optional-positional (`[...]`) parameter
+    groups are the terminal element of a parameter list, and the commas inside
+    them are real argument separators. Before the fix, the group's own `{`/`[`
+    read as nesting and hid every one -- a Flutter widget constructor like
+    `EditableText({super.key, required this.controller, ...})` counted 1 arg
+    instead of ~40. A `{...}`/`[...]` that is a default-VALUE literal instead
+    (never flush against the parameter list's end) must still stay nested.
+    """
+    d = StructuralExtractor("dart", {"dart": {"rules": {}}})
+    assert d._count_top_level_args("({super.key, required this.controller, this.readOnly})") == 3
+    assert d._count_top_level_args("({super.parent})") == 1
+    assert d._count_top_level_args("(this.a, this.b, this.c)") == 3
+    assert d._count_top_level_args("(int a, int b, {required Key k, bool flag = false})") == 4
+    assert d._count_top_level_args("([int a = 1, int b = 2])") == 2
+    assert d._count_top_level_args("({this.a, this.b,})") == 2  # trailing comma
+    assert d._count_top_level_args("()") == 0
+    # default-value literals must NOT leak their internal commas:
+    assert d._count_top_level_args("({List<int> x = const [1, 2, 3]})") == 1
+    assert d._count_top_level_args("({Map<String, int> m = const {'a': 1, 'b': 2}})") == 1
+
+
 def test_count_top_level_args_function_pointer_return_type_1854():
     """
     #1854: a C/C++ function returning a function pointer wraps its own name