diff options
Diffstat (limited to 'scss/cssdefs.py')
| -rw-r--r-- | scss/cssdefs.py | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/scss/cssdefs.py b/scss/cssdefs.py index 4a4b122..dd30f7f 100644 --- a/scss/cssdefs.py +++ b/scss/cssdefs.py @@ -184,6 +184,19 @@ BASE_UNIT_CONVERSIONS = { 'dppx': (96, 'dpi'), } + +def get_conversion_factor(unit): + """Look up the "base" unit for this unit and the factor for converting to + it. + + Returns a 2-tuple of `factor, base_unit`. + """ + if unit in BASE_UNIT_CONVERSIONS: + return BASE_UNIT_CONVERSIONS[unit] + else: + return 1, unit + + def convert_units_to_base_units(units): """Convert a set of units into a set of "base" units. @@ -203,6 +216,49 @@ def convert_units_to_base_units(units): return total_factor, tuple(new_units) +def count_base_units(units): + """Returns a dict mapping names of base units to how many times they + appear in the given iterable of units. Effectively this counts how + many length units you have, how many time units, and so forth. + """ + ret = {} + for unit in units: + factor, base_unit = get_conversion_factor(unit) + + ret.setdefault(base_unit, 0) + ret[base_unit] += 1 + + return ret + + +def cancel_base_units(units, to_remove): + """Given a list of units, remove a specified number of each base unit. + + Arguments: + units: an iterable of units + to_remove: a mapping of base_unit => count, such as that returned from + count_base_units + + Returns a 2-tuple of (factor, remaining_units). + """ + + # Copy the dict since we're about to mutate it + to_remove = to_remove.copy() + remaining_units = [] + total_factor = 1 + + for unit in units: + factor, base_unit = get_conversion_factor(unit) + if not to_remove.get(base_unit, 0): + remaining_units.append(unit) + continue + + total_factor *= factor + to_remove[base_unit] -= 1 + + return total_factor, remaining_units + + # A fixed set of units can be omitted when the value is 0 # See: http://www.w3.org/TR/2013/CR-css3-values-20130730/#lengths ZEROABLE_UNITS = frozenset(( |