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) 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, location/position. 188 189 return (attr_index, attr.is_static_attribute(), position) 190 191 class ParameterList(List): 192 193 "A parameter list." 194 195 def entry_as_raw(self, entry): 196 # param_index, position = entry 197 return entry 198 199 class Table: 200 201 "A lookup table." 202 203 TableError = TableError 204 list_class = None # overridden 205 206 def __init__(self): 207 self.attributes = set() 208 self.table = {} 209 self.objnames = [] 210 self.names = [] 211 self.displaced_list = None 212 self.raw = None 213 214 def add(self, objname, attributes): 215 216 "For the given 'objname' add the given 'attributes' to the table." 217 218 self.table[objname] = attributes 219 for name, origin in attributes.items(): 220 self.attributes.add(name) 221 222 if self.displaced_list is not None: 223 self.displaced_list.add(objname, self.matrix_row(attributes)) 224 225 def object_names(self): 226 227 "Return the object names used in the table." 228 229 self.objnames = self.objnames or list(self.table.keys()) 230 return self.objnames 231 232 def attribute_names(self): 233 234 "Return the attribute names used in the table." 235 236 self.names = self.names or list(self.attributes) 237 return self.names 238 239 def get_index(self, name): 240 241 "Return the index of the given 'name'." 242 243 try: 244 return self.attribute_names().index(name) 245 except ValueError: 246 raise TableError, "Name %r is not registered as an attribute in the table." % name 247 248 def as_matrix(self): 249 250 """ 251 Return the table as a matrix mapping object names to lists of attributes 252 arranged in the order of the recorded attribute names. 253 """ 254 255 matrix = {} 256 for objname, attributes in self.table.items(): 257 matrix[objname] = self.matrix_row(attributes) 258 return matrix 259 260 def matrix_row(self, attributes): 261 262 "Return a matrix row for the given 'attributes'." 263 264 row = [] 265 for name in self.attribute_names(): 266 row.append(attributes.get(name)) 267 return row 268 269 def all_attribute_positions(self, name): 270 271 """ 272 Return a list of positions for the attribute with the given 'name' from 273 all known objects. 274 """ 275 276 all = set() 277 for attributes in self.table.values(): 278 if attributes.has_key(name): 279 all.add(attributes[name]) 280 return all 281 282 def all_possible_objects(self, names): 283 284 """ 285 Return a list of object names supporting the given attribute 'names'. 286 """ 287 288 possible = [] 289 for objname, attributes in self.table.items(): 290 found = 1 291 for name in names: 292 if not attributes.has_key(name): 293 found = 0 294 break 295 if found: 296 possible.append(objname) 297 return possible 298 299 def as_list(self): 300 301 """ 302 Return a displaced list object encoding the table in a more compact form 303 than that provided by the matrix representation. This list will be 304 updated with new entries if added to this object using the 'add' method. 305 """ 306 307 if self.displaced_list is None: 308 self.displaced_list = self.list_class(self.attribute_names()) 309 310 # Visit each row of the matrix. 311 312 matrix_by_usage = [] 313 size = len(self.attributes) 314 315 # Add rows in descending order of utilisation. 316 317 for objname, attributes in self.as_matrix().items(): 318 matrix_by_usage.append((size - attributes.count(None), objname, attributes)) 319 320 matrix_by_usage.sort() 321 matrix_by_usage.reverse() 322 323 for usage, objname, attributes in matrix_by_usage: 324 self.displaced_list.add(objname, attributes) 325 326 return self.displaced_list 327 328 def as_raw(self): 329 330 "Return the raw contents of the table as a list of values." 331 332 if self.raw is None: 333 self.raw = self.as_list().as_raw() 334 return self.raw 335 336 class ObjectTable(Table): 337 338 "An object table." 339 340 list_class = ObjectList 341 342 class ParameterTable(Table): 343 344 "A parameter table." 345 346 list_class = ParameterList 347 348 # vim: tabstop=4 expandtab shiftwidth=4