registry.py 文件源码

def parse_unit_name(self, unit_name, case_sensitive=True):
        """Parse a unit to identify prefix, unit name and suffix
        by walking the list of prefix and suffix.

        :rtype: (str, str, str)
        """
        stw = unit_name.startswith
        edw = unit_name.endswith
        for suffix, prefix in itertools.product(self._suffixes, self._prefixes):
            if stw(prefix) and edw(suffix):
                name = unit_name[len(prefix):]
                if suffix:
                    name = name[:-len(suffix)]
                    if len(name) == 1:
                        continue
                if case_sensitive:
                    if name in self._units:
                        yield (self._prefixes[prefix].name,
                               self._units[name].name,
                               self._suffixes[suffix])
                else:
                    for real_name in self._units_casei.get(name.lower(), ()):
                        yield (self._prefixes[prefix].name,
                               self._units[real_name].name,
                               self._suffixes[suffix])