1 #!/usr/bin/env python 2 3 """ 4 Preparation of run-time attribute lookup tables. 5 6 Copyright (C) 2007, 2008 Paul Boddie <paul@boddie.org.uk> 7 8 This program is free software; you can redistribute it and/or modify it under 9 the terms of the GNU General Public License as published by the Free Software 10 Foundation; either version 3 of the License, or (at your option) any later 11 version. 12 13 This program is distributed in the hope that it will be useful, but WITHOUT 14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 15 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 16 details. 17 18 You should have received a copy of the GNU General Public License along with 19 this program. If not, see <http://www.gnu.org/licenses/>. 20 """ 21 22 from micropython.common import * 23 from micropython.data import * 24 25 class List: 26 27 """ 28 A displaced list containing attribute details and an index mapping names to 29 offsets in the list. This is the optimised form of the table initially 30 constructed to record object attributes. 31 """ 32 33 def __init__(self, names): 34 self.names = names 35 self.displaced = [] 36 self.offsets = {} 37 self.offsets_used = {} 38 39 self.names_index = {} 40 for i, name in enumerate(self.names): 41 self.names_index[name] = i 42 43 def __len__(self): 44 return len(self.displaced) 45 46 def __getitem__(self, i): 47 return self.displaced[i] 48 49 def get_code(self, name): 50 51 "Return the code/offset of the given 'name'." 52 53 return self.offsets.get(name) 54 55 def get_name(self, code): 56 57 "Return the name for the given 'code' or offset." 58 59 return self.offsets_used[code] 60 61 # Simulation methods. 62 63 def access(self, objname, attrname): 64 obj_offset = self.offsets.get(objname) 65 attr_index = self.names_index.get(attrname) 66 if obj_offset is None or attr_index is None: 67 return None 68 69 element = self.displaced[obj_offset + attr_index] 70 if element is not None: 71 index, details = element 72 if index == attr_index: 73 return details 74 75 return None 76 77 def dir(self, objname): 78 attributes = {} 79 for name in self.names: 80 attr = self.access(objname, name) 81 if attr is not None: 82 attributes[name] = attr 83 return attributes 84 85 # Update methods. 86 87 def add(self, objname, attributes): 88 89 "Add an entry for 'objname' with the given 'attributes'." 90 91 len_displaced = len(self.displaced) 92 len_attributes = len(attributes) 93 94 # Try to fit the row into the list, starting from the beginning and 95 # skipping places where an existing row has been fitted. 96 97 for offset in xrange(0, len_displaced): 98 if self.offsets_used.has_key(offset): 99 continue 100 if self._fit_row(offset, attributes, len_displaced): 101 self.offsets_used[offset] = objname 102 self.offsets[objname] = offset 103 self._add_row(offset, attributes, len_displaced) 104 break 105 106 # Where a row could not be fitted within the list, add it to the 107 # end. 108 109 else: 110 self.offsets_used[len_displaced] = objname 111 self.offsets[objname] = len_displaced 112 self._add_row(len_displaced, attributes, len_displaced) 113 114 def _fit_row(self, offset, attributes, len_displaced): 115 116 """ 117 Fit, at the given 'offset', the row of 'attributes' in the displaced 118 list having length 'len_displaced'. 119 Return a true value if this succeeded. 120 """ 121 122 for i, attr in enumerate(attributes): 123 if i + offset >= len_displaced: 124 break 125 element = self.displaced[i + offset] 126 if attr is not None and element is not None: 127 return 0 128 return 1 129 130 def _add_row(self, offset, attributes, len_displaced): 131 132 """ 133 Add, at the given 'offset', the row of 'attributes' in the displaced 134 list having length 'len_displaced'. 135 """ 136 137 # Extend the list if necessary. 138 139 for i in xrange(0, offset + len(attributes) - len_displaced): 140 self.displaced.append(None) 141 142 # Record the attribute details in the list. 143 144 for i, attr in enumerate(attributes): 145 if attr is not None: 146 147 # Each entry is of the form (attribute number, attribute). 148 149 self.displaced[offset+i] = i, attr 150 151 # Image production. 152 153 def as_raw(self): 154 155 "Return the raw contents of the table as a list of values." 156 157 result = [] 158 for entry in self.displaced: 159 if entry is None: 160 result.append(None) 161 else: 162 result.append(self.entry_as_raw(entry)) 163 164 return result 165 166 class ObjectList(List): 167 168 "An object list." 169 170 def entry_as_raw(self, entry): 171 attr_index, attr = entry 172 173 # Support descendants. 174 175 if isinstance(attr, Class): 176 return (attr_index, None, None, None) 177 178 if attr.parent is not None: 179 location = attr.parent.location or 0 180 else: 181 location = 0 182 if attr.position is not None: 183 position = attr.position + location + 1 # skip structure header 184 else: 185 position = None # NOTE: Should fix unpositioned attributes. 186 187 # Attribute index/code, attribute type, context instance override flag, location/position. 188 189 return (attr_index, attr.is_class_attribute(), attr.defined_within_hierarchy(), position) 190 191 class ParameterList(List): 192 193 "A parameter list." 194 195 def entry_as_raw(self, entry): 196 return entry 197 198 class Table: 199 200 "A lookup table." 201 202 TableError = TableError 203 list_class = None # overridden 204 205 def __init__(self): 206 self.attributes = set() 207 self.table = {} 208 self.objnames = [] 209 self.names = [] 210 self.displaced_list = None 211 self.raw = None 212 213 def add(self, objname, attributes): 214 215 "For the given 'objname' add the given 'attributes' to the table." 216 217 self.table[objname] = attributes 218 for name, origin in attributes.items(): 219 self.attributes.add(name) 220 221 if self.displaced_list is not None: 222 self.displaced_list.add(objname, self.matrix_row(attributes)) 223 224 def object_names(self): 225 226 "Return the object names used in the table." 227 228 self.objnames = self.objnames or list(self.table.keys()) 229 return self.objnames 230 231 def attribute_names(self): 232 233 "Return the attribute names used in the table." 234 235 self.names = self.names or list(self.attributes) 236 return self.names 237 238 def get_index(self, name): 239 240 "Return the index of the given 'name'." 241 242 try: 243 return self.attribute_names().index(name) 244 except ValueError: 245 raise TableError, "Name %r is not registered as an attribute in the table." % name 246 247 def as_matrix(self): 248 249 """ 250 Return the table as a matrix mapping object names to lists of attributes 251 arranged in the order of the recorded attribute names. 252 """ 253 254 matrix = {} 255 for objname, attributes in self.table.items(): 256 matrix[objname] = self.matrix_row(attributes) 257 return matrix 258 259 def matrix_row(self, attributes): 260 261 "Return a matrix row for the given 'attributes'." 262 263 row = [] 264 for name in self.attribute_names(): 265 row.append(attributes.get(name)) 266 return row 267 268 def all_attribute_positions(self, name): 269 270 """ 271 Return a list of positions for the attribute with the given 'name' from 272 all known objects. 273 """ 274 275 all = set() 276 for attributes in self.table.values(): 277 if attributes.has_key(name): 278 all.add(attributes[name]) 279 return all 280 281 def all_possible_objects(self, names): 282 283 """ 284 Return a list of object names supporting the given attribute 'names'. 285 """ 286 287 possible = [] 288 for objname, attributes in self.table.items(): 289 found = 1 290 for name in names: 291 if not attributes.has_key(name): 292 found = 0 293 break 294 if found: 295 possible.append(objname) 296 return possible 297 298 def as_list(self): 299 300 """ 301 Return a displaced list object encoding the table in a more compact form 302 than that provided by the matrix representation. This list will be 303 updated with new entries if added to this object using the 'add' method. 304 """ 305 306 if self.displaced_list is None: 307 self.displaced_list = self.list_class(self.attribute_names()) 308 309 # Visit each row of the matrix. 310 311 matrix_by_usage = [] 312 size = len(self.attributes) 313 314 # Add rows in descending order of utilisation. 315 316 for objname, attributes in self.as_matrix().items(): 317 matrix_by_usage.append((size - attributes.count(None), objname, attributes)) 318 319 matrix_by_usage.sort() 320 matrix_by_usage.reverse() 321 322 for usage, objname, attributes in matrix_by_usage: 323 self.displaced_list.add(objname, attributes) 324 325 return self.displaced_list 326 327 def as_raw(self): 328 329 "Return the raw contents of the table as a list of values." 330 331 if self.raw is None: 332 self.raw = self.as_list().as_raw() 333 return self.raw 334 335 class ObjectTable(Table): 336 337 "An object table." 338 339 list_class = ObjectList 340 341 class ParameterTable(Table): 342 343 "A parameter table." 344 345 list_class = ParameterList 346 347 # vim: tabstop=4 expandtab shiftwidth=4