Mercurial > lcfOS
comparison python/pyyacc.py @ 395:3b0c495e3008
Speed improvements
| author | Windel Bouwman |
|---|---|
| date | Fri, 23 May 2014 14:28:03 +0200 |
| parents | 173e20a47fda |
| children |
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| 394:988f3fb861e4 | 395:3b0c495e3008 |
|---|---|
| 300 self.production = production | 300 self.production = production |
| 301 self.dotpos = dotpos | 301 self.dotpos = dotpos |
| 302 assert self.dotpos <= len(self.production.symbols) | 302 assert self.dotpos <= len(self.production.symbols) |
| 303 self.look_ahead = look_ahead | 303 self.look_ahead = look_ahead |
| 304 self._is_shift = self.dotpos < len(self.production.symbols) | 304 self._is_shift = self.dotpos < len(self.production.symbols) |
| 305 | 305 self.IsShift = self._is_shift |
| 306 def getdata(self): | 306 if self.IsShift: |
| 307 """ Gets the members as a tuple """ | 307 self.Next = self.production.symbols[self.dotpos] |
| 308 return (self.production, self.dotpos, self.look_ahead) | 308 self._data = (self.production, self.dotpos, self.look_ahead) |
| 309 self._hash = self._data.__hash__() | |
| 309 | 310 |
| 310 def __eq__(self, other): | 311 def __eq__(self, other): |
| 311 if type(other) is type(self): | 312 if type(other) is type(self): |
| 312 return self.getdata() == other.getdata() | 313 return self._data == other._data |
| 313 return False | 314 return False |
| 314 | 315 |
| 315 def __hash__(self): | 316 def __hash__(self): |
| 316 return self.getdata().__hash__() | 317 return self._hash |
| 317 | 318 |
| 318 @property | 319 @property |
| 319 def IsReduce(self): | 320 def IsReduce(self): |
| 320 """ Check if this item has the dot at the end """ | 321 """ Check if this item has the dot at the end """ |
| 321 return not self._is_shift | 322 return not self._is_shift |
| 322 | 323 |
| 323 @property | |
| 324 def IsShift(self): | |
| 325 """ Check if this item is a shift item, i.e. the dot can proceed """ | |
| 326 return self._is_shift | |
| 327 | |
| 328 @property | |
| 329 def Next(self): | |
| 330 """ Returns the symbol after the dot """ | |
| 331 return self.production.symbols[self.dotpos] | |
| 332 | |
| 333 def can_shift_over(self, symbol): | 324 def can_shift_over(self, symbol): |
| 334 """ Determines if this item can shift over the given symbol """ | 325 """ Determines if this item can shift over the given symbol """ |
| 335 return self.IsShift and self.Next == symbol | 326 return self._is_shift and self.Next == symbol |
| 336 | 327 |
| 337 def shifted(self): | 328 def shifted(self): |
| 338 """ Creates a new item that is shifted one position """ | 329 """ Creates a new item that is shifted one position """ |
| 339 return Item(self.production, self.dotpos + 1, self.look_ahead) | 330 return Item(self.production, self.dotpos + 1, self.look_ahead) |
| 340 | 331 |
| 354 args = (name, predot, postdot, self.look_ahead) | 345 args = (name, predot, postdot, self.look_ahead) |
| 355 return '[{0} -> {1} . {2} -> {3}]'.format(*args) | 346 return '[{0} -> {1} . {2} -> {3}]'.format(*args) |
| 356 | 347 |
| 357 | 348 |
| 358 class LRParser: | 349 class LRParser: |
| 359 """ LR parser automata """ | 350 """ LR parser automata. This class takes goto and action table |
| 351 and can then process a sequence of tokens. | |
| 352 """ | |
| 360 def __init__(self, action_table, goto_table, start_symbol): | 353 def __init__(self, action_table, goto_table, start_symbol): |
| 361 self.action_table = action_table | 354 self.action_table = action_table |
| 362 self.goto_table = goto_table | 355 self.goto_table = goto_table |
| 363 self.start_symbol = start_symbol | 356 self.start_symbol = start_symbol |
| 364 | 357 |