ladybird/Meta/Utils/css_dimensions.py
Callum Law c96e8f15e5 Meta: Make CSS dimension loading reusable
Aside from the existing users this will also be used within the
CSSGrammar parser
2026-05-13 11:00:07 +01:00

116 lines
4.4 KiB
Python

import json
import sys
from typing import Any
_css_dimensions: dict[str, Any] | None = None
def json_is_valid(dimensions_data: dict[str, Any], json_path: str) -> bool:
is_valid = True
most_recent_dimension_name = ""
for dimension_name, units in dimensions_data.items():
if dimension_name.lower() < most_recent_dimension_name.lower():
print(
f"{json_path}: Dimension `{dimension_name}` is in the wrong position. "
"Please keep this list alphabetical!",
file=sys.stderr,
)
is_valid = False
most_recent_dimension_name = dimension_name
if not isinstance(units, dict):
print(f"{json_path}: Dimension `{dimension_name}` is not an object", file=sys.stderr)
is_valid = False
continue
most_recent_unit_name = ""
canonical_unit = None
for unit_name, unit in units.items():
# Units should be in alphabetical order
if unit_name.lower() < most_recent_unit_name.lower():
print(
f"{json_path}: {dimension_name} unit `{unit_name}` is in the wrong position. "
"Please keep this list alphabetical!",
file=sys.stderr,
)
is_valid = False
most_recent_unit_name = unit_name
if not isinstance(unit, dict):
print(f"{json_path}: {dimension_name} unit `{unit_name}` is not an object", file=sys.stderr)
is_valid = False
continue
is_canonical_unit = unit.get("is-canonical-unit") is True
number_of_canonical_unit = unit.get("number-of-canonical-unit")
relative_to = unit.get("relative-to")
provided_count = (
(1 if is_canonical_unit else 0)
+ (1 if number_of_canonical_unit is not None else 0)
+ (1 if relative_to is not None else 0)
)
if provided_count != 1:
print(
f"{json_path}: {dimension_name} unit `{unit_name}` must have exactly 1 of "
"`is-canonical-unit: true`, `number-of-canonical-unit`, or `relative-to` provided.",
file=sys.stderr,
)
is_valid = False
if is_canonical_unit:
if canonical_unit is not None:
print(
f"{json_path}: {dimension_name} unit `{unit_name}` marked canonical, "
f"but `{canonical_unit}` was already. Must have exactly 1.",
file=sys.stderr,
)
is_valid = False
else:
canonical_unit = unit_name
if relative_to is not None:
if dimension_name == "length":
if relative_to not in ("font", "viewport"):
print(
f"{json_path}: {dimension_name} unit `{unit_name}` is marked as relative to "
f"`{relative_to}`, which is unsupported.",
file=sys.stderr,
)
is_valid = False
else:
print(
f"{json_path}: {dimension_name} unit `{unit_name}` is marked as relative, "
"but only relative length units are currently supported.",
file=sys.stderr,
)
is_valid = False
if canonical_unit is None:
print(
f"{json_path}: {dimension_name} has no unit marked as canonical. Must have exactly 1.",
file=sys.stderr,
)
is_valid = False
return is_valid
def load_css_dimensions(json_path: str) -> None:
global _css_dimensions
with open(json_path, "r", encoding="utf-8") as json_file:
dimensions_data = json.load(json_file)
if not isinstance(dimensions_data, dict):
raise RuntimeError(f"{json_path}: expected a JSON object")
if not json_is_valid(dimensions_data, json_path):
raise RuntimeError(f"{json_path}: invalid CSS dimensions data")
_css_dimensions = dimensions_data
def get_css_dimensions() -> dict[str, Any]:
if _css_dimensions is None:
raise RuntimeError("CSS dimensions have not been initialized")
return _css_dimensions