check errors

src/textual/css/parse.py

@@ -44,7 +44,7 @@ def _add_specificity(
         specificity2: Specificity triple.
 
     Returns:
-        Combined specificity
+        Combined specificity.
     """
     a1, b1, c1 = specificity1
     a2, b2, c2 = specificity2

src/textual/css/stylesheet.py

@@ -248,7 +248,7 @@ def _parse_rules(
         except TokenError:
             raise
         except Exception as error:
-            raise StylesheetError(f"failed to parse css; {error}")
+            raise StylesheetError(f"failed to parse css; {error}") from None
 
         self._parse_cache[cache_key] = rules
         return rules

src/textual/css/tokenize.py

@@ -57,9 +57,22 @@
     selector_start=IDENTIFIER,
     variable_name=rf"{VARIABLE_REF}:",
     declaration_set_end=r"\}",
-    nested=r"\&",
 ).expect_eof(True)
 
+expect_root_nested = Expect(
+    "selector or end of file",
+    whitespace=r"\s+",
+    comment_start=COMMENT_START,
+    comment_line=COMMENT_LINE,
+    selector_start_id=r"\#" + IDENTIFIER,
+    selector_start_class=r"\." + IDENTIFIER,
+    selector_start_universal=r"\*",
+    selector_start=IDENTIFIER,
+    variable_name=rf"{VARIABLE_REF}:",
+    declaration_set_end=r"\}",
+    nested=r"\&",
+)
+
 # After a variable declaration e.g. "$warning-text: TOKENS;"
 #              for tokenizing variable value ------^~~~~~~^
 expect_variable_name_continue = Expect(
@@ -173,7 +186,7 @@ class TokenizerState:
         "declaration_set_start": expect_declaration,
         "declaration_name": expect_declaration_content,
         "declaration_end": expect_declaration,
-        "declaration_set_end": expect_root_scope,
+        "declaration_set_end": expect_root_nested,
         "nested": expect_selector_continue,
     }
 
@@ -182,6 +195,7 @@ def __call__(self, code: str, read_from: CSSLocation) -> Iterable[Token]:
         expect = self.EXPECT
         get_token = tokenizer.get_token
         get_state = self.STATE_MAP.get
+        nest_level = 0
         while True:
             token = get_token(expect)
             name = token.name
@@ -192,6 +206,13 @@ def __call__(self, code: str, read_from: CSSLocation) -> Iterable[Token]:
                 continue
             elif name == "eof":
                 break
+            elif name == "declaration_set_start":
+                nest_level += 1
+            elif name == "declaration_set_end":
+                nest_level -= 1
+                expect = expect_root_nested if nest_level else expect_root_scope
+                yield token
+                continue
             expect = get_state(name, expect)
             yield token
 

src/textual/css/tokenizer.py

@@ -215,13 +215,12 @@ def get_token(self, expect: Expect) -> Token:
                     self.read_from,
                     self.code,
                     (line_no + 1, col_no + 1),
-                    "Unexpected end of file",
+                    "Unexpected end of file; did you forget a '}' ?",
                 )
         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)
-            message = f"Expected one of {expected}.; Did you forget a semicolon at the end of a line?"
             raise TokenError(
                 self.read_from,
                 self.code,
@@ -288,7 +287,7 @@ def skip_to(self, expect: Expect) -> Token:
                     self.read_from,
                     self.code,
                     (line_no, col_no),
-                    "Unexpected end of file",
+                    "Unexpected end of file; did you forget a '}' ?",
                 )
             line = self.lines[line_no]
             match = expect.search(line, col_no)

tests/css/test_nested_css.py

@@ -1,13 +1,17 @@
+import pytest
+
 from textual.app import App, ComposeResult
 from textual.color import Color
 from textual.containers import Vertical
+from textual.css.parse import parse
+from textual.css.tokenizer import EOFError, TokenError
 from textual.widgets import Label
 
 
 class NestedApp(App):
     CSS = """
     Screen {
-        #foo {
+        & > #foo {
             background: red;
             #egg {
                 background: green;
@@ -36,3 +40,21 @@ async def test_nest_app():
         assert app.query_one("#foo").styles.color == Color.parse("magenta")
         assert app.query_one("#egg").styles.background == Color.parse("green")
         assert app.query_one("#foo .paul").styles.background == Color.parse("blue")
+
+
+@pytest.mark.parametrize(
+    ("css", "exception"),
+    [
+        ("Selector {", EOFError),
+        ("Selector{ Foo {", EOFError),
+        ("Selector{ Foo {}", EOFError),
+        ("> {}", TokenError),
+        ("&", TokenError),
+        ("&.foo", TokenError),
+        ("{", TokenError),
+    ],
+)
+def test_parse_errors(css: str, exception: type[Exception]) -> None:
+    """Check some CSS which should fail."""
+    with pytest.raises(exception):
+        list(parse("", css, ("foo", "")))