|
| 1 | +# encoding: utf-8 |
| 2 | + |
| 3 | +""" |
| 4 | +Base classes and other objects used by enumerations |
| 5 | +""" |
| 6 | + |
| 7 | +from __future__ import absolute_import, print_function |
| 8 | + |
| 9 | +import sys |
| 10 | +import textwrap |
| 11 | + |
| 12 | + |
| 13 | +def alias(*aliases): |
| 14 | + """ |
| 15 | + Decorating a class with @alias('FOO', 'BAR', ..) allows the class to |
| 16 | + be referenced by each of the names provided as arguments. |
| 17 | + """ |
| 18 | + def decorator(cls): |
| 19 | + # alias must be set in globals from caller's frame |
| 20 | + caller = sys._getframe(1) |
| 21 | + globals_dict = caller.f_globals |
| 22 | + for alias in aliases: |
| 23 | + globals_dict[alias] = cls |
| 24 | + return cls |
| 25 | + return decorator |
| 26 | + |
| 27 | + |
| 28 | +class _DocsPageFormatter(object): |
| 29 | + """ |
| 30 | + Formats a RestructuredText documention page (string) for the enumeration |
| 31 | + class parts passed to the constructor. An immutable one-shot service |
| 32 | + object. |
| 33 | + """ |
| 34 | + def __init__(self, clsname, clsdict): |
| 35 | + self._clsname = clsname |
| 36 | + self._clsdict = clsdict |
| 37 | + |
| 38 | + @property |
| 39 | + def page_str(self): |
| 40 | + """ |
| 41 | + The RestructuredText documentation page for the enumeration. This is |
| 42 | + the only API member for the class. |
| 43 | + """ |
| 44 | + tmpl = '.. _%s:\n\n%s\n\n%s\n\n----\n\n%s' |
| 45 | + components = ( |
| 46 | + self._ms_name, self._page_title, self._intro_text, |
| 47 | + self._member_defs |
| 48 | + ) |
| 49 | + return tmpl % components |
| 50 | + |
| 51 | + @property |
| 52 | + def _intro_text(self): |
| 53 | + """ |
| 54 | + The docstring of the enumeration, formatted for use at the top of the |
| 55 | + documentation page |
| 56 | + """ |
| 57 | + try: |
| 58 | + cls_docstring = self._clsdict['__doc__'] |
| 59 | + except KeyError: |
| 60 | + cls_docstring = '' |
| 61 | + return textwrap.dedent(cls_docstring).strip() |
| 62 | + |
| 63 | + def _member_def(self, member): |
| 64 | + """ |
| 65 | + Return an individual member definition formatted as an RST glossary |
| 66 | + entry, wrapped to fit within 78 columns. |
| 67 | + """ |
| 68 | + member_docstring = textwrap.dedent(member.docstring).strip() |
| 69 | + member_docstring = textwrap.fill( |
| 70 | + member_docstring, width=78, initial_indent=' '*4, |
| 71 | + subsequent_indent=' '*4 |
| 72 | + ) |
| 73 | + return '%s\n%s\n' % (member.name, member_docstring) |
| 74 | + |
| 75 | + @property |
| 76 | + def _member_defs(self): |
| 77 | + """ |
| 78 | + A single string containing the aggregated member definitions section |
| 79 | + of the documentation page |
| 80 | + """ |
| 81 | + members = self._clsdict['__members__'] |
| 82 | + member_defs = [ |
| 83 | + self._member_def(member) for member in members |
| 84 | + if member.name is not None |
| 85 | + ] |
| 86 | + return '\n'.join(member_defs) |
| 87 | + |
| 88 | + @property |
| 89 | + def _ms_name(self): |
| 90 | + """ |
| 91 | + The Microsoft API name for this enumeration |
| 92 | + """ |
| 93 | + return self._clsdict['__ms_name__'] |
| 94 | + |
| 95 | + @property |
| 96 | + def _page_title(self): |
| 97 | + """ |
| 98 | + The title for the documentation page, formatted as code (surrounded |
| 99 | + in double-backtics) and underlined with '=' characters |
| 100 | + """ |
| 101 | + title_underscore = '=' * (len(self._clsname)+4) |
| 102 | + return '``%s``\n%s' % (self._clsname, title_underscore) |
| 103 | + |
| 104 | + |
| 105 | +class MetaEnumeration(type): |
| 106 | + """ |
| 107 | + The metaclass for Enumeration and its subclasses. Adds a name for each |
| 108 | + named member and compiles state needed by the enumeration class to |
| 109 | + respond to other attribute gets |
| 110 | + """ |
| 111 | + def __new__(meta, clsname, bases, clsdict): |
| 112 | + meta._add_enum_members(clsdict) |
| 113 | + meta._collect_valid_settings(clsdict) |
| 114 | + meta._generate_docs_page(clsname, clsdict) |
| 115 | + return type.__new__(meta, clsname, bases, clsdict) |
| 116 | + |
| 117 | + @classmethod |
| 118 | + def _add_enum_members(meta, clsdict): |
| 119 | + """ |
| 120 | + Dispatch ``.add_to_enum()`` call to each member so it can do its |
| 121 | + thing to properly add itself to the enumeration class. This |
| 122 | + delegation allows member sub-classes to add specialized behaviors. |
| 123 | + """ |
| 124 | + enum_members = clsdict['__members__'] |
| 125 | + for member in enum_members: |
| 126 | + member.add_to_enum(clsdict) |
| 127 | + |
| 128 | + @classmethod |
| 129 | + def _collect_valid_settings(meta, clsdict): |
| 130 | + """ |
| 131 | + Return a sequence containing the enumeration values that are valid |
| 132 | + assignment values. Return-only values are excluded. |
| 133 | + """ |
| 134 | + enum_members = clsdict['__members__'] |
| 135 | + valid_settings = [] |
| 136 | + for member in enum_members: |
| 137 | + valid_settings.extend(member.valid_settings) |
| 138 | + clsdict['_valid_settings'] = valid_settings |
| 139 | + |
| 140 | + @classmethod |
| 141 | + def _generate_docs_page(meta, clsname, clsdict): |
| 142 | + """ |
| 143 | + Return the RST documentation page for the enumeration. |
| 144 | + """ |
| 145 | + clsdict['__docs_rst__'] = ( |
| 146 | + _DocsPageFormatter(clsname, clsdict).page_str |
| 147 | + ) |
| 148 | + |
| 149 | + |
| 150 | +class EnumerationBase(object): |
| 151 | + """ |
| 152 | + Base class for all enumerations, used directly for enumerations requiring |
| 153 | + only basic behavior. It's __dict__ is used below in the Python 2+3 |
| 154 | + compatible metaclass definition. |
| 155 | + """ |
| 156 | + __members__ = () |
| 157 | + __ms_name__ = '' |
| 158 | + |
| 159 | + @classmethod |
| 160 | + def is_valid_setting(cls, value): |
| 161 | + """ |
| 162 | + Return |True| if *value* is an assignable value, |False| if it is |
| 163 | + a return value-only member or not a member value. |
| 164 | + """ |
| 165 | + return value in cls._valid_settings |
| 166 | + |
| 167 | + |
| 168 | +Enumeration = MetaEnumeration( |
| 169 | + 'Enumeration', (object,), dict(EnumerationBase.__dict__) |
| 170 | +) |
| 171 | + |
| 172 | + |
| 173 | +class XmlEnumeration(Enumeration): |
| 174 | + """ |
| 175 | + Provides ``to_xml()`` and ``from_xml()`` methods in addition to base |
| 176 | + enumeration features |
| 177 | + """ |
| 178 | + __members__ = () |
| 179 | + __ms_name__ = '' |
| 180 | + |
| 181 | + @classmethod |
| 182 | + def from_xml(cls, xml_val): |
| 183 | + """ |
| 184 | + Return the enumeration member corresponding to the XML value |
| 185 | + *xml_val*. |
| 186 | + """ |
| 187 | + return cls._xml_to_member[xml_val] |
| 188 | + |
| 189 | + @classmethod |
| 190 | + def to_xml(cls, enum_val): |
| 191 | + """ |
| 192 | + Return the XML value of the enumeration value *enum_val*. |
| 193 | + """ |
| 194 | + return cls._member_to_xml[enum_val] |
| 195 | + |
| 196 | + |
| 197 | +class EnumMember(object): |
| 198 | + """ |
| 199 | + Used in the enumeration class definition to define a member value and its |
| 200 | + mappings |
| 201 | + """ |
| 202 | + def __init__(self, name, value, docstring): |
| 203 | + self._name = name |
| 204 | + if isinstance(value, int): |
| 205 | + value = EnumValue(name, value, docstring) |
| 206 | + self._value = value |
| 207 | + self._docstring = docstring |
| 208 | + |
| 209 | + def add_to_enum(self, clsdict): |
| 210 | + """ |
| 211 | + Add a name to *clsdict* for this member. |
| 212 | + """ |
| 213 | + self.register_name(clsdict) |
| 214 | + |
| 215 | + @property |
| 216 | + def docstring(self): |
| 217 | + """ |
| 218 | + The description of this member |
| 219 | + """ |
| 220 | + return self._docstring |
| 221 | + |
| 222 | + @property |
| 223 | + def name(self): |
| 224 | + """ |
| 225 | + The distinguishing name of this member within the enumeration class, |
| 226 | + e.g. 'MIDDLE' for MSO_VERTICAL_ANCHOR.MIDDLE, if this is a named |
| 227 | + member. Otherwise the primitive value such as |None|, |True| or |
| 228 | + |False|. |
| 229 | + """ |
| 230 | + return self._name |
| 231 | + |
| 232 | + def register_name(self, clsdict): |
| 233 | + """ |
| 234 | + Add a member name to the class dict *clsdict* containing the value of |
| 235 | + this member object. Where the name of this object is None, do |
| 236 | + nothing; this allows out-of-band values to be defined without adding |
| 237 | + a name to the class dict. |
| 238 | + """ |
| 239 | + if self.name is None: |
| 240 | + return |
| 241 | + clsdict[self.name] = self.value |
| 242 | + |
| 243 | + @property |
| 244 | + def valid_settings(self): |
| 245 | + """ |
| 246 | + A sequence containing the values valid for assignment for this |
| 247 | + member. May be zero, one, or more in number. |
| 248 | + """ |
| 249 | + return (self._value,) |
| 250 | + |
| 251 | + @property |
| 252 | + def value(self): |
| 253 | + """ |
| 254 | + The enumeration value for this member, often an instance of |
| 255 | + EnumValue, but may be a primitive value such as |None|. |
| 256 | + """ |
| 257 | + return self._value |
| 258 | + |
| 259 | + |
| 260 | +class EnumValue(int): |
| 261 | + """ |
| 262 | + A named enumeration value, providing __str__ and __doc__ string values |
| 263 | + for its symbolic name and description, respectively. Subclasses int, so |
| 264 | + behaves as a regular int unless the strings are asked for. |
| 265 | + """ |
| 266 | + def __new__(cls, member_name, int_value, docstring): |
| 267 | + return super(EnumValue, cls).__new__(cls, int_value) |
| 268 | + |
| 269 | + def __init__(self, member_name, int_value, docstring): |
| 270 | + super(EnumValue, self).__init__() |
| 271 | + self._member_name = member_name |
| 272 | + self._docstring = docstring |
| 273 | + |
| 274 | + @property |
| 275 | + def __doc__(self): |
| 276 | + """ |
| 277 | + The description of this enumeration member |
| 278 | + """ |
| 279 | + return self._docstring.strip() |
| 280 | + |
| 281 | + def __str__(self): |
| 282 | + """ |
| 283 | + The symbolic name and string value of this member, e.g. 'MIDDLE (3)' |
| 284 | + """ |
| 285 | + return "%s (%d)" % (self._member_name, int(self)) |
| 286 | + |
| 287 | + |
| 288 | +class ReturnValueOnlyEnumMember(EnumMember): |
| 289 | + """ |
| 290 | + Used to define a member of an enumeration that is only valid as a query |
| 291 | + result and is not valid as a setting, e.g. MSO_VERTICAL_ANCHOR.MIXED (-2) |
| 292 | + """ |
| 293 | + @property |
| 294 | + def valid_settings(self): |
| 295 | + """ |
| 296 | + No settings are valid for a return-only value. |
| 297 | + """ |
| 298 | + return () |
| 299 | + |
| 300 | + |
| 301 | +class XmlMappedEnumMember(EnumMember): |
| 302 | + """ |
| 303 | + Used to define a member whose value maps to an XML attribute value. |
| 304 | + """ |
| 305 | + def __init__(self, name, value, xml_value, docstring): |
| 306 | + super(XmlMappedEnumMember, self).__init__(name, value, docstring) |
| 307 | + self._xml_value = xml_value |
| 308 | + |
| 309 | + def add_to_enum(self, clsdict): |
| 310 | + """ |
| 311 | + Compile XML mappings in addition to base add behavior. |
| 312 | + """ |
| 313 | + super(XmlMappedEnumMember, self).add_to_enum(clsdict) |
| 314 | + self.register_xml_mapping(clsdict) |
| 315 | + |
| 316 | + def register_xml_mapping(self, clsdict): |
| 317 | + """ |
| 318 | + Add XML mappings to the enumeration class state for this member. |
| 319 | + """ |
| 320 | + member_to_xml = self._get_or_add_member_to_xml(clsdict) |
| 321 | + member_to_xml[self.value] = self.xml_value |
| 322 | + xml_to_member = self._get_or_add_xml_to_member(clsdict) |
| 323 | + xml_to_member[self.xml_value] = self.value |
| 324 | + |
| 325 | + @property |
| 326 | + def xml_value(self): |
| 327 | + """ |
| 328 | + The XML attribute value that corresponds to this enumeration value |
| 329 | + """ |
| 330 | + return self._xml_value |
| 331 | + |
| 332 | + @staticmethod |
| 333 | + def _get_or_add_member_to_xml(clsdict): |
| 334 | + """ |
| 335 | + Add the enum -> xml value mapping to the enumeration class state |
| 336 | + """ |
| 337 | + if '_member_to_xml' not in clsdict: |
| 338 | + clsdict['_member_to_xml'] = dict() |
| 339 | + return clsdict['_member_to_xml'] |
| 340 | + |
| 341 | + @staticmethod |
| 342 | + def _get_or_add_xml_to_member(clsdict): |
| 343 | + """ |
| 344 | + Add the xml -> enum value mapping to the enumeration class state |
| 345 | + """ |
| 346 | + if '_xml_to_member' not in clsdict: |
| 347 | + clsdict['_xml_to_member'] = dict() |
| 348 | + return clsdict['_xml_to_member'] |
0 commit comments