422 lines
12 KiB
Python
422 lines
12 KiB
Python
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"""
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Utilities for interpreting CSS from Stylers for formatting non-HTML outputs.
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"""
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from __future__ import annotations
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import re
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from typing import (
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TYPE_CHECKING,
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Callable,
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)
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import warnings
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from pandas.errors import CSSWarning
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from pandas.util._exceptions import find_stack_level
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if TYPE_CHECKING:
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from collections.abc import (
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Generator,
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Iterable,
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Iterator,
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)
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def _side_expander(prop_fmt: str) -> Callable:
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"""
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Wrapper to expand shorthand property into top, right, bottom, left properties
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Parameters
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----------
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side : str
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The border side to expand into properties
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Returns
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-------
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function: Return to call when a 'border(-{side}): {value}' string is encountered
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"""
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def expand(self, prop, value: str) -> Generator[tuple[str, str], None, None]:
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"""
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Expand shorthand property into side-specific property (top, right, bottom, left)
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Parameters
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----------
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prop (str): CSS property name
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value (str): String token for property
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Yields
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------
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Tuple (str, str): Expanded property, value
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"""
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tokens = value.split()
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try:
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mapping = self.SIDE_SHORTHANDS[len(tokens)]
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except KeyError:
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warnings.warn(
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f'Could not expand "{prop}: {value}"',
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CSSWarning,
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stacklevel=find_stack_level(),
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)
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return
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for key, idx in zip(self.SIDES, mapping):
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yield prop_fmt.format(key), tokens[idx]
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return expand
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def _border_expander(side: str = "") -> Callable:
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"""
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Wrapper to expand 'border' property into border color, style, and width properties
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Parameters
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----------
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side : str
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The border side to expand into properties
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Returns
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-------
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function: Return to call when a 'border(-{side}): {value}' string is encountered
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"""
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if side != "":
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side = f"-{side}"
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def expand(self, prop, value: str) -> Generator[tuple[str, str], None, None]:
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"""
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Expand border into color, style, and width tuples
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Parameters
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----------
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prop : str
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CSS property name passed to styler
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value : str
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Value passed to styler for property
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Yields
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------
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Tuple (str, str): Expanded property, value
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"""
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tokens = value.split()
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if len(tokens) == 0 or len(tokens) > 3:
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warnings.warn(
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f'Too many tokens provided to "{prop}" (expected 1-3)',
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CSSWarning,
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stacklevel=find_stack_level(),
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)
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# TODO: Can we use current color as initial value to comply with CSS standards?
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border_declarations = {
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f"border{side}-color": "black",
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f"border{side}-style": "none",
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f"border{side}-width": "medium",
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}
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for token in tokens:
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if token.lower() in self.BORDER_STYLES:
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border_declarations[f"border{side}-style"] = token
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elif any(ratio in token.lower() for ratio in self.BORDER_WIDTH_RATIOS):
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border_declarations[f"border{side}-width"] = token
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else:
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border_declarations[f"border{side}-color"] = token
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# TODO: Warn user if item entered more than once (e.g. "border: red green")
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# Per CSS, "border" will reset previous "border-*" definitions
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yield from self.atomize(border_declarations.items())
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return expand
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class CSSResolver:
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"""
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A callable for parsing and resolving CSS to atomic properties.
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"""
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UNIT_RATIOS = {
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"pt": ("pt", 1),
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"em": ("em", 1),
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"rem": ("pt", 12),
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"ex": ("em", 0.5),
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# 'ch':
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"px": ("pt", 0.75),
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"pc": ("pt", 12),
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"in": ("pt", 72),
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"cm": ("in", 1 / 2.54),
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"mm": ("in", 1 / 25.4),
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"q": ("mm", 0.25),
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"!!default": ("em", 0),
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}
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FONT_SIZE_RATIOS = UNIT_RATIOS.copy()
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FONT_SIZE_RATIOS.update(
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{
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"%": ("em", 0.01),
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"xx-small": ("rem", 0.5),
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"x-small": ("rem", 0.625),
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"small": ("rem", 0.8),
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"medium": ("rem", 1),
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"large": ("rem", 1.125),
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"x-large": ("rem", 1.5),
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"xx-large": ("rem", 2),
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"smaller": ("em", 1 / 1.2),
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"larger": ("em", 1.2),
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"!!default": ("em", 1),
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}
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)
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MARGIN_RATIOS = UNIT_RATIOS.copy()
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MARGIN_RATIOS.update({"none": ("pt", 0)})
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BORDER_WIDTH_RATIOS = UNIT_RATIOS.copy()
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BORDER_WIDTH_RATIOS.update(
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{
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"none": ("pt", 0),
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"thick": ("px", 4),
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"medium": ("px", 2),
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"thin": ("px", 1),
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# Default: medium only if solid
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}
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)
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BORDER_STYLES = [
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"none",
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"hidden",
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"dotted",
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"dashed",
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"solid",
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"double",
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"groove",
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"ridge",
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"inset",
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"outset",
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"mediumdashdot",
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"dashdotdot",
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"hair",
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"mediumdashdotdot",
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"dashdot",
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"slantdashdot",
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"mediumdashed",
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]
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SIDE_SHORTHANDS = {
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1: [0, 0, 0, 0],
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2: [0, 1, 0, 1],
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3: [0, 1, 2, 1],
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4: [0, 1, 2, 3],
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}
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SIDES = ("top", "right", "bottom", "left")
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CSS_EXPANSIONS = {
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**{
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(f"border-{prop}" if prop else "border"): _border_expander(prop)
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for prop in ["", "top", "right", "bottom", "left"]
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},
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**{
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f"border-{prop}": _side_expander(f"border-{{:s}}-{prop}")
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for prop in ["color", "style", "width"]
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},
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"margin": _side_expander("margin-{:s}"),
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"padding": _side_expander("padding-{:s}"),
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}
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def __call__(
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self,
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declarations: str | Iterable[tuple[str, str]],
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inherited: dict[str, str] | None = None,
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) -> dict[str, str]:
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"""
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The given declarations to atomic properties.
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Parameters
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----------
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declarations_str : str | Iterable[tuple[str, str]]
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A CSS string or set of CSS declaration tuples
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e.g. "font-weight: bold; background: blue" or
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{("font-weight", "bold"), ("background", "blue")}
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inherited : dict, optional
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Atomic properties indicating the inherited style context in which
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declarations_str is to be resolved. ``inherited`` should already
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be resolved, i.e. valid output of this method.
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Returns
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-------
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dict
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Atomic CSS 2.2 properties.
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Examples
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--------
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>>> resolve = CSSResolver()
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>>> inherited = {'font-family': 'serif', 'font-weight': 'bold'}
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>>> out = resolve('''
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... border-color: BLUE RED;
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... font-size: 1em;
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... font-size: 2em;
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... font-weight: normal;
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... font-weight: inherit;
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... ''', inherited)
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>>> sorted(out.items()) # doctest: +NORMALIZE_WHITESPACE
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[('border-bottom-color', 'blue'),
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('border-left-color', 'red'),
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('border-right-color', 'red'),
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('border-top-color', 'blue'),
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('font-family', 'serif'),
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('font-size', '24pt'),
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('font-weight', 'bold')]
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"""
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if isinstance(declarations, str):
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declarations = self.parse(declarations)
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props = dict(self.atomize(declarations))
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if inherited is None:
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inherited = {}
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props = self._update_initial(props, inherited)
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props = self._update_font_size(props, inherited)
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return self._update_other_units(props)
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def _update_initial(
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self,
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props: dict[str, str],
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inherited: dict[str, str],
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) -> dict[str, str]:
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# 1. resolve inherited, initial
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for prop, val in inherited.items():
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if prop not in props:
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props[prop] = val
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new_props = props.copy()
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for prop, val in props.items():
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if val == "inherit":
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val = inherited.get(prop, "initial")
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if val in ("initial", None):
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# we do not define a complete initial stylesheet
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del new_props[prop]
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else:
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new_props[prop] = val
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return new_props
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def _update_font_size(
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self,
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props: dict[str, str],
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inherited: dict[str, str],
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) -> dict[str, str]:
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# 2. resolve relative font size
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if props.get("font-size"):
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props["font-size"] = self.size_to_pt(
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props["font-size"],
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self._get_font_size(inherited),
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conversions=self.FONT_SIZE_RATIOS,
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)
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return props
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def _get_font_size(self, props: dict[str, str]) -> float | None:
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if props.get("font-size"):
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font_size_string = props["font-size"]
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return self._get_float_font_size_from_pt(font_size_string)
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return None
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def _get_float_font_size_from_pt(self, font_size_string: str) -> float:
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assert font_size_string.endswith("pt")
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return float(font_size_string.rstrip("pt"))
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def _update_other_units(self, props: dict[str, str]) -> dict[str, str]:
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font_size = self._get_font_size(props)
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# 3. TODO: resolve other font-relative units
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for side in self.SIDES:
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prop = f"border-{side}-width"
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if prop in props:
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props[prop] = self.size_to_pt(
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props[prop],
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em_pt=font_size,
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conversions=self.BORDER_WIDTH_RATIOS,
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)
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for prop in [f"margin-{side}", f"padding-{side}"]:
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if prop in props:
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# TODO: support %
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props[prop] = self.size_to_pt(
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props[prop],
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em_pt=font_size,
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conversions=self.MARGIN_RATIOS,
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)
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return props
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def size_to_pt(self, in_val, em_pt=None, conversions=UNIT_RATIOS) -> str:
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def _error():
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warnings.warn(
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f"Unhandled size: {repr(in_val)}",
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CSSWarning,
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stacklevel=find_stack_level(),
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)
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return self.size_to_pt("1!!default", conversions=conversions)
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match = re.match(r"^(\S*?)([a-zA-Z%!].*)", in_val)
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if match is None:
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return _error()
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val, unit = match.groups()
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if val == "":
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# hack for 'large' etc.
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val = 1
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else:
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try:
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val = float(val)
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except ValueError:
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return _error()
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while unit != "pt":
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if unit == "em":
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if em_pt is None:
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unit = "rem"
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else:
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val *= em_pt
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unit = "pt"
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continue
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try:
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unit, mul = conversions[unit]
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except KeyError:
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return _error()
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val *= mul
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val = round(val, 5)
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if int(val) == val:
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size_fmt = f"{int(val):d}pt"
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else:
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size_fmt = f"{val:f}pt"
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return size_fmt
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def atomize(self, declarations: Iterable) -> Generator[tuple[str, str], None, None]:
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for prop, value in declarations:
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prop = prop.lower()
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value = value.lower()
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if prop in self.CSS_EXPANSIONS:
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expand = self.CSS_EXPANSIONS[prop]
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yield from expand(self, prop, value)
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else:
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yield prop, value
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def parse(self, declarations_str: str) -> Iterator[tuple[str, str]]:
|
||
|
|
"""
|
||
|
|
Generates (prop, value) pairs from declarations.
|
||
|
|
|
||
|
|
In a future version may generate parsed tokens from tinycss/tinycss2
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
declarations_str : str
|
||
|
|
"""
|
||
|
|
for decl in declarations_str.split(";"):
|
||
|
|
if not decl.strip():
|
||
|
|
continue
|
||
|
|
prop, sep, val = decl.partition(":")
|
||
|
|
prop = prop.strip().lower()
|
||
|
|
# TODO: don't lowercase case sensitive parts of values (strings)
|
||
|
|
val = val.strip().lower()
|
||
|
|
if sep:
|
||
|
|
yield prop, val
|
||
|
|
else:
|
||
|
|
warnings.warn(
|
||
|
|
f"Ill-formatted attribute: expected a colon in {repr(decl)}",
|
||
|
|
CSSWarning,
|
||
|
|
stacklevel=find_stack_level(),
|
||
|
|
)
|