fix for specificity (#3963)

* fix for specificity

* changelog

* docstrings

Author: willmcgugan

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.47.1] - 2023-01-05
+
+### Fixed
+
+- Fixed nested specificity https://github.com/Textualize/textual/pull/3963
+
 ## [0.47.0] - 2024-01-04
 
 ### Fixed
@@ -1568,6 +1574,7 @@ https://textual.textualize.io/blog/2022/11/08/version-040/#version-040
 - New handler system for messages that doesn't require inheritance
 - Improved traceback handling
 
+[0.47.1]: https://github.com/Textualize/textual/compare/v0.47.0...v0.47.1
 [0.47.0]: https://github.com/Textualize/textual/compare/v0.46.0...v0.47.0
 [0.46.0]: https://github.com/Textualize/textual/compare/v0.45.1...v0.46.0
 [0.45.1]: https://github.com/Textualize/textual/compare/v0.45.0...v0.45.1

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "textual"
-version = "0.47.0"
+version = "0.47.1"
 homepage = "https://github.com/Textualize/textual"
 repository = "https://github.com/Textualize/textual"
 documentation = "https://textual.textualize.io/"

src/textual/css/model.py

@@ -12,21 +12,35 @@
 from .types import Specificity3
 
 if TYPE_CHECKING:
+    from typing_extensions import Self
+
     from ..dom import DOMNode
 
 
 class SelectorType(Enum):
+    """Type of selector."""
+
     UNIVERSAL = 1
+    """i.e. * operator"""
     TYPE = 2
+    """A CSS type, e.g  Label"""
     CLASS = 3
+    """CSS class, e.g. .loaded"""
     ID = 4
+    """CSS ID, e.g. #main"""
     NESTED = 5
+    """Placeholder for nesting operator, i.e &"""
 
 
 class CombinatorType(Enum):
+    """Type of combinator."""
+
     SAME = 1
+    """Selector is combined with previous selector"""
     DESCENDENT = 2
+    """Selector is a descendant of the previous selector"""
     CHILD = 3
+    """Selector is an immediate child of the previous selector"""
 
 
 @dataclass
@@ -116,6 +130,8 @@ def _check_id(self, node: DOMNode) -> bool:
 
 @dataclass
 class Declaration:
+    """A single CSS declaration (not yet processed)."""
+
     token: Token
     name: str
     tokens: list[Token] = field(default_factory=list)
@@ -124,6 +140,8 @@ class Declaration:
 @rich.repr.auto(angular=True)
 @dataclass
 class SelectorSet:
+    """A set of selectors associated with a rule set."""
+
     selectors: list[Selector] = field(default_factory=list)
     specificity: Specificity3 = (0, 0, 0)
 
@@ -141,6 +159,21 @@ def __rich_repr__(self) -> rich.repr.Result:
         yield selectors
         yield None, self.specificity
 
+    def _total_specificity(self) -> Self:
+        """Calculate total specificity of selectors.
+
+        Returns:
+            Self.
+        """
+        id_total = class_total = type_total = 0
+        for selector in self.selectors:
+            _id, _class, _type = selector.specificity
+            id_total += _id
+            class_total += _class
+            type_total += _type
+        self.specificity = (id_total, class_total, type_total)
+        return self
+
     @classmethod
     def from_selectors(cls, selectors: list[list[Selector]]) -> Iterable[SelectorSet]:
         for selector_list in selectors:

src/textual/css/parse.py

@@ -46,6 +46,7 @@ def _add_specificity(
     Returns:
         Combined specificity.
     """
+
     a1, b1, c1 = specificity1
     a2, b2, c2 = specificity2
     return (a1 + a2, b1 + b2, c1 + c2)
@@ -228,9 +229,8 @@ def combine_selectors(
                             SelectorSet(
                                 combine_selectors(
                                     rule_selector, recursive_selectors.selectors
-                                ),
-                                (recursive_selectors.specificity),
-                            )
+                                )
+                            )._total_specificity()
                             for recursive_selectors in rule_set.selector_set
                         ],
                         rule_set.styles,

src/textual/css/tokenizer.py

@@ -103,12 +103,19 @@ def __rich__(self) -> RenderableType:
 
 
 class EOFError(TokenError):
-    pass
+    """Indicates that the CSS ended prematurely."""
 
 
 @rich.repr.auto
 class Expect:
+    """Object that describes the format of tokens."""
+
     def __init__(self, description: str, **tokens: str) -> None:
+        """Create Expect object.
+
+        Args:
+            description: Description of this class of tokens, used in errors.
+        """
         self.description = f"Expected {description}"
         self.names = list(tokens.keys())
         self.regexes = list(tokens.values())
@@ -190,14 +197,35 @@ def __rich_repr__(self) -> rich.repr.Result:
 
 
 class Tokenizer:
+    """Tokenizes Textual CSS."""
+
     def __init__(self, text: str, read_from: CSSLocation = ("", "")) -> None:
+        """Initialize the tokenizer.
+
+        Args:
+            text: String containing CSS.
+            read_from: Information regarding where the CSS was read from.
+        """
         self.read_from = read_from
         self.code = text
         self.lines = text.splitlines(keepends=True)
         self.line_no = 0
         self.col_no = 0
 
     def get_token(self, expect: Expect) -> Token:
+        """Get the next token.
+
+        Args:
+            expect: Expect object which describes which tokens may be read.
+
+        Raises:
+            EOFError: If there is an unexpected end of file.
+            TokenError: If there is an error with the token.
+
+        Returns:
+            A new Token.
+        """
+
         line_no = self.line_no
         col_no = self.col_no
         if line_no >= len(self.lines):
@@ -220,7 +248,6 @@ def get_token(self, expect: Expect) -> Token:
         line = self.lines[line_no]
         match = expect.match(line, col_no)
         if match is None:
-            expected = friendly_list(" ".join(name.split("_")) for name in expect.names)
             raise TokenError(
                 self.read_from,
                 self.code,
@@ -278,6 +305,17 @@ def get_token(self, expect: Expect) -> Token:
         return token
 
     def skip_to(self, expect: Expect) -> Token:
+        """Skip tokens.
+
+        Args:
+            expect: Expect object describing the expected token.
+
+        Raises:
+            EOFError: If end of file is reached.
+
+        Returns:
+            A new token.
+        """
         line_no = self.line_no
         col_no = self.col_no
 

tests/snapshot_tests/__snapshots__/test_snapshots.ambr

@@ -0,0 +1,61 @@
+from textual.app import App, ComposeResult
+from textual.widgets import Static
+
+
+class BaseTester(Static, can_focus=True):
+    DEFAULT_CSS = """
+    BaseTester:focus {
+        background: yellow;
+        border: thick magenta;
+    }
+    """
+
+
+class NonNestedCSS(BaseTester):
+    DEFAULT_CSS = """
+    NonNestedCSS {
+        width: 1fr;
+        height: 1fr;
+        background: red 10%;
+        border: blank;
+    }
+
+    NonNestedCSS:focus {
+        background: red 20%;
+        border: round red;
+    }
+    """
+
+
+class NestedCSS(BaseTester):
+    DEFAULT_CSS = """
+    NestedCSS {
+        width: 1fr;
+        height: 1fr;
+        background: green 10%;
+        border: blank;
+
+        &:focus {
+            background: green 20%;
+            border: round green;
+        }
+    }
+    """
+
+
+class NestedPseudoClassesApp(App[None]):
+    AUTO_FOCUS = "NestedCSS"
+
+    CSS = """
+    Screen {
+        layout: horizontal;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        yield NonNestedCSS("This isn't using nested CSS")
+        yield NestedCSS("This is using nested CSS")
+
+
+if __name__ == "__main__":
+    NestedPseudoClassesApp().run()

tests/snapshot_tests/snapshot_apps/nested_specificity.py

@@ -974,3 +974,8 @@ def test_tree_clearing_and_expansion(snap_compare):
     # https://github.com/Textualize/textual/issues/3557
     assert snap_compare(SNAPSHOT_APPS_DIR / "tree_clearing.py")
 
+
+def test_nested_specificity(snap_compare):
+    """Test specificity of nested rules is working."""
+    # https://github.com/Textualize/textual/issues/3961
+    assert snap_compare(SNAPSHOT_APPS_DIR / "nested_specificity.py")