feat: Stubs and RowGroups now inherit from Sequence

gt/_gt_data.py

@@ -1,5 +1,40 @@
 from __future__ import annotations
 
+from typing import overload, TypeVar
+from collections import abc
+from dataclasses import dataclass
+
+
+T = TypeVar("T")
+
+
+class _Sequence(abc.Sequence[T]):
+    _d: list[T]
+
+    def __init__(self, data: Any):
+        self._d = data
+
+    @overload
+    def __getitem__(self, ii: int) -> T:
+        ...
+
+    @overload
+    def __getitem__(self, ii: slice) -> _Sequence[T]:
+        ...
+
+    def __getitem__(self, ii: int | slice) -> T | _Sequence[T]:
+        if isinstance(ii, slice):
+            return self.__class__(self._d[ii])
+
+        return self._d[ii]
+
+    def __len__(self):
+        return len(self._d)
+
+    def __repr__(self):
+        return f"{type(self).__name__}({self._d.__repr__()})"
+
+
 # Body ----
 __Body = None
 
@@ -144,12 +179,13 @@ def _get_effective_number_of_columns(self) -> int:
 from ._tbl_data import TblData, n_rows
 
 
+@dataclass
 class RowInfo:
     # TODO: Make `rownum_i` readonly
     rownum_i: int
-    group_id: Optional[str]
-    rowname: Optional[str]
-    group_label: Optional[str]
+    group_id: Optional[str] = None
+    rowname: Optional[str] = None
+    group_label: Optional[str] = None
     built: bool = False
 
     # The components of the stub are:
@@ -159,30 +195,23 @@ class RowInfo:
     # `group_label` = None
     # `built` = False
 
-    def __init__(
-        self,
-        rownum_i: int,
-        group_id: Optional[str] = None,
-        rowname: Optional[str] = None,
-        group_label: Optional[str] = None,
-        built: bool = False,
-    ):
-        self.rownum_i = rownum_i
-        self.group_id = group_id
-        self.rowname = rowname
-        self.group_label = group_label
-        self.built = built
 
+class Stub(_Sequence[RowInfo]):
+    _d: list[RowInfo]
 
-class Stub:
-    def __init__(self, data: TblData):
-        # Obtain a list of row indices from the data and initialize
-        # the `_stub` from that
-        row_indices = list(range(n_rows(data)))
+    def __init__(self, data: TblData | list[RowInfo]):
+        if isinstance(data, list):
+            self._d = list(data)
+
+        else:
+            # Obtain a list of row indices from the data and initialize
+            # the `_stub` from that
+            row_indices = list(range(n_rows(data)))
+
+            # Obtain the column names from the data and initialize the
+            # `_boxhead` from that
+            self._d = [RowInfo(col) for col in row_indices]
 
-        # Obtain the column names from the data and initialize the
-        # `_boxhead` from that
-        self._stub: list[RowInfo] = [RowInfo(col) for col in row_indices]
 
 
 # Row groups ----
@@ -191,11 +220,14 @@ def __init__(self, data: TblData):
 from typing import Optional
 
 
-class RowGroups:
-    row_groups: Optional[str]
+class RowGroups(_Sequence[str]):
+    _d: list[str]
 
-    def __init__(self):
-        pass
+    def __init__(self, group_ids: Optional[list[str]] = None):
+        if group_ids is None:
+            self._d = []
+        else:
+            self._d = group_ids
 
 
 # Spanners ----
@@ -723,12 +755,17 @@ class GTData:
 
     @classmethod
     def from_data(cls, data: TblData, locale: str | None = None):
+        stub = Stub(data)
+
+        group_ids = set(row.group_id for row in stub if row.group_id is not None)
+        row_groups = list(group_ids)
+
         return cls(
             _tbl_data=data,
             _body=Body(data, data),
             _boxhead=Boxhead(data),     # uses get_tbl_data()
-            _stub=Stub(data),           # uses get_tbl_data
-            _row_groups=RowGroups(),
+            _stub=stub,           # uses get_tbl_data
+            _row_groups=RowGroups(row_groups),
             _spanners=Spanners(),
             _heading=Heading(),
             _stubhead=Stubhead(),