/usr/lib/python2.7/dist-packages/docutils/statemachine.py is in python-docutils 0.12+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 | # $Id: statemachine.py 7464 2012-06-25 13:16:03Z milde $
# Author: David Goodger <goodger@python.org>
# Copyright: This module has been placed in the public domain.
"""
A finite state machine specialized for regular-expression-based text filters,
this module defines the following classes:
- `StateMachine`, a state machine
- `State`, a state superclass
- `StateMachineWS`, a whitespace-sensitive version of `StateMachine`
- `StateWS`, a state superclass for use with `StateMachineWS`
- `SearchStateMachine`, uses `re.search()` instead of `re.match()`
- `SearchStateMachineWS`, uses `re.search()` instead of `re.match()`
- `ViewList`, extends standard Python lists.
- `StringList`, string-specific ViewList.
Exception classes:
- `StateMachineError`
- `UnknownStateError`
- `DuplicateStateError`
- `UnknownTransitionError`
- `DuplicateTransitionError`
- `TransitionPatternNotFound`
- `TransitionMethodNotFound`
- `UnexpectedIndentationError`
- `TransitionCorrection`: Raised to switch to another transition.
- `StateCorrection`: Raised to switch to another state & transition.
Functions:
- `string2lines()`: split a multi-line string into a list of one-line strings
How To Use This Module
======================
(See the individual classes, methods, and attributes for details.)
1. Import it: ``import statemachine`` or ``from statemachine import ...``.
You will also need to ``import re``.
2. Derive a subclass of `State` (or `StateWS`) for each state in your state
machine::
class MyState(statemachine.State):
Within the state's class definition:
a) Include a pattern for each transition, in `State.patterns`::
patterns = {'atransition': r'pattern', ...}
b) Include a list of initial transitions to be set up automatically, in
`State.initial_transitions`::
initial_transitions = ['atransition', ...]
c) Define a method for each transition, with the same name as the
transition pattern::
def atransition(self, match, context, next_state):
# do something
result = [...] # a list
return context, next_state, result
# context, next_state may be altered
Transition methods may raise an `EOFError` to cut processing short.
d) You may wish to override the `State.bof()` and/or `State.eof()` implicit
transition methods, which handle the beginning- and end-of-file.
e) In order to handle nested processing, you may wish to override the
attributes `State.nested_sm` and/or `State.nested_sm_kwargs`.
If you are using `StateWS` as a base class, in order to handle nested
indented blocks, you may wish to:
- override the attributes `StateWS.indent_sm`,
`StateWS.indent_sm_kwargs`, `StateWS.known_indent_sm`, and/or
`StateWS.known_indent_sm_kwargs`;
- override the `StateWS.blank()` method; and/or
- override or extend the `StateWS.indent()`, `StateWS.known_indent()`,
and/or `StateWS.firstknown_indent()` methods.
3. Create a state machine object::
sm = StateMachine(state_classes=[MyState, ...],
initial_state='MyState')
4. Obtain the input text, which needs to be converted into a tab-free list of
one-line strings. For example, to read text from a file called
'inputfile'::
input_string = open('inputfile').read()
input_lines = statemachine.string2lines(input_string)
5. Run the state machine on the input text and collect the results, a list::
results = sm.run(input_lines)
6. Remove any lingering circular references::
sm.unlink()
"""
__docformat__ = 'restructuredtext'
import sys
import re
import types
import unicodedata
from docutils import utils
from docutils.utils.error_reporting import ErrorOutput
class StateMachine:
"""
A finite state machine for text filters using regular expressions.
The input is provided in the form of a list of one-line strings (no
newlines). States are subclasses of the `State` class. Transitions consist
of regular expression patterns and transition methods, and are defined in
each state.
The state machine is started with the `run()` method, which returns the
results of processing in a list.
"""
def __init__(self, state_classes, initial_state, debug=False):
"""
Initialize a `StateMachine` object; add state objects.
Parameters:
- `state_classes`: a list of `State` (sub)classes.
- `initial_state`: a string, the class name of the initial state.
- `debug`: a boolean; produce verbose output if true (nonzero).
"""
self.input_lines = None
"""`StringList` of input lines (without newlines).
Filled by `self.run()`."""
self.input_offset = 0
"""Offset of `self.input_lines` from the beginning of the file."""
self.line = None
"""Current input line."""
self.line_offset = -1
"""Current input line offset from beginning of `self.input_lines`."""
self.debug = debug
"""Debugging mode on/off."""
self.initial_state = initial_state
"""The name of the initial state (key to `self.states`)."""
self.current_state = initial_state
"""The name of the current state (key to `self.states`)."""
self.states = {}
"""Mapping of {state_name: State_object}."""
self.add_states(state_classes)
self.observers = []
"""List of bound methods or functions to call whenever the current
line changes. Observers are called with one argument, ``self``.
Cleared at the end of `run()`."""
self._stderr = ErrorOutput()
"""Wrapper around sys.stderr catching en-/decoding errors"""
def unlink(self):
"""Remove circular references to objects no longer required."""
for state in self.states.values():
state.unlink()
self.states = None
def run(self, input_lines, input_offset=0, context=None,
input_source=None, initial_state=None):
"""
Run the state machine on `input_lines`. Return results (a list).
Reset `self.line_offset` and `self.current_state`. Run the
beginning-of-file transition. Input one line at a time and check for a
matching transition. If a match is found, call the transition method
and possibly change the state. Store the context returned by the
transition method to be passed on to the next transition matched.
Accumulate the results returned by the transition methods in a list.
Run the end-of-file transition. Finally, return the accumulated
results.
Parameters:
- `input_lines`: a list of strings without newlines, or `StringList`.
- `input_offset`: the line offset of `input_lines` from the beginning
of the file.
- `context`: application-specific storage.
- `input_source`: name or path of source of `input_lines`.
- `initial_state`: name of initial state.
"""
self.runtime_init()
if isinstance(input_lines, StringList):
self.input_lines = input_lines
else:
self.input_lines = StringList(input_lines, source=input_source)
self.input_offset = input_offset
self.line_offset = -1
self.current_state = initial_state or self.initial_state
if self.debug:
print >>self._stderr, (
u'\nStateMachine.run: input_lines (line_offset=%s):\n| %s'
% (self.line_offset, u'\n| '.join(self.input_lines)))
transitions = None
results = []
state = self.get_state()
try:
if self.debug:
print >>self._stderr, '\nStateMachine.run: bof transition'
context, result = state.bof(context)
results.extend(result)
while True:
try:
try:
self.next_line()
if self.debug:
source, offset = self.input_lines.info(
self.line_offset)
print >>self._stderr, (
u'\nStateMachine.run: line (source=%r, '
u'offset=%r):\n| %s'
% (source, offset, self.line))
context, next_state, result = self.check_line(
context, state, transitions)
except EOFError:
if self.debug:
print >>self._stderr, (
'\nStateMachine.run: %s.eof transition'
% state.__class__.__name__)
result = state.eof(context)
results.extend(result)
break
else:
results.extend(result)
except TransitionCorrection, exception:
self.previous_line() # back up for another try
transitions = (exception.args[0],)
if self.debug:
print >>self._stderr, (
'\nStateMachine.run: TransitionCorrection to '
'state "%s", transition %s.'
% (state.__class__.__name__, transitions[0]))
continue
except StateCorrection, exception:
self.previous_line() # back up for another try
next_state = exception.args[0]
if len(exception.args) == 1:
transitions = None
else:
transitions = (exception.args[1],)
if self.debug:
print >>self._stderr, (
'\nStateMachine.run: StateCorrection to state '
'"%s", transition %s.'
% (next_state, transitions[0]))
else:
transitions = None
state = self.get_state(next_state)
except:
if self.debug:
self.error()
raise
self.observers = []
return results
def get_state(self, next_state=None):
"""
Return current state object; set it first if `next_state` given.
Parameter `next_state`: a string, the name of the next state.
Exception: `UnknownStateError` raised if `next_state` unknown.
"""
if next_state:
if self.debug and next_state != self.current_state:
print >>self._stderr, (
'\nStateMachine.get_state: Changing state from '
'"%s" to "%s" (input line %s).'
% (self.current_state, next_state,
self.abs_line_number()))
self.current_state = next_state
try:
return self.states[self.current_state]
except KeyError:
raise UnknownStateError(self.current_state)
def next_line(self, n=1):
"""Load `self.line` with the `n`'th next line and return it."""
try:
try:
self.line_offset += n
self.line = self.input_lines[self.line_offset]
except IndexError:
self.line = None
raise EOFError
return self.line
finally:
self.notify_observers()
def is_next_line_blank(self):
"""Return 1 if the next line is blank or non-existant."""
try:
return not self.input_lines[self.line_offset + 1].strip()
except IndexError:
return 1
def at_eof(self):
"""Return 1 if the input is at or past end-of-file."""
return self.line_offset >= len(self.input_lines) - 1
def at_bof(self):
"""Return 1 if the input is at or before beginning-of-file."""
return self.line_offset <= 0
def previous_line(self, n=1):
"""Load `self.line` with the `n`'th previous line and return it."""
self.line_offset -= n
if self.line_offset < 0:
self.line = None
else:
self.line = self.input_lines[self.line_offset]
self.notify_observers()
return self.line
def goto_line(self, line_offset):
"""Jump to absolute line offset `line_offset`, load and return it."""
try:
try:
self.line_offset = line_offset - self.input_offset
self.line = self.input_lines[self.line_offset]
except IndexError:
self.line = None
raise EOFError
return self.line
finally:
self.notify_observers()
def get_source(self, line_offset):
"""Return source of line at absolute line offset `line_offset`."""
return self.input_lines.source(line_offset - self.input_offset)
def abs_line_offset(self):
"""Return line offset of current line, from beginning of file."""
return self.line_offset + self.input_offset
def abs_line_number(self):
"""Return line number of current line (counting from 1)."""
return self.line_offset + self.input_offset + 1
def get_source_and_line(self, lineno=None):
"""Return (source, line) tuple for current or given line number.
Looks up the source and line number in the `self.input_lines`
StringList instance to count for included source files.
If the optional argument `lineno` is given, convert it from an
absolute line number to the corresponding (source, line) pair.
"""
if lineno is None:
offset = self.line_offset
else:
offset = lineno - self.input_offset - 1
try:
src, srcoffset = self.input_lines.info(offset)
srcline = srcoffset + 1
except (TypeError):
# line is None if index is "Just past the end"
src, srcline = self.get_source_and_line(offset + self.input_offset)
return src, srcline + 1
except (IndexError): # `offset` is off the list
src, srcline = None, None
# raise AssertionError('cannot find line %d in %s lines' %
# (offset, len(self.input_lines)))
# # list(self.input_lines.lines())))
# assert offset == srcoffset, str(self.input_lines)
# print "get_source_and_line(%s):" % lineno,
# print offset + 1, '->', src, srcline
# print self.input_lines
return (src, srcline)
def insert_input(self, input_lines, source):
self.input_lines.insert(self.line_offset + 1, '',
source='internal padding after '+source,
offset=len(input_lines))
self.input_lines.insert(self.line_offset + 1, '',
source='internal padding before '+source,
offset=-1)
self.input_lines.insert(self.line_offset + 2,
StringList(input_lines, source))
def get_text_block(self, flush_left=False):
"""
Return a contiguous block of text.
If `flush_left` is true, raise `UnexpectedIndentationError` if an
indented line is encountered before the text block ends (with a blank
line).
"""
try:
block = self.input_lines.get_text_block(self.line_offset,
flush_left)
self.next_line(len(block) - 1)
return block
except UnexpectedIndentationError, err:
block = err.args[0]
self.next_line(len(block) - 1) # advance to last line of block
raise
def check_line(self, context, state, transitions=None):
"""
Examine one line of input for a transition match & execute its method.
Parameters:
- `context`: application-dependent storage.
- `state`: a `State` object, the current state.
- `transitions`: an optional ordered list of transition names to try,
instead of ``state.transition_order``.
Return the values returned by the transition method:
- context: possibly modified from the parameter `context`;
- next state name (`State` subclass name);
- the result output of the transition, a list.
When there is no match, ``state.no_match()`` is called and its return
value is returned.
"""
if transitions is None:
transitions = state.transition_order
state_correction = None
if self.debug:
print >>self._stderr, (
'\nStateMachine.check_line: state="%s", transitions=%r.'
% (state.__class__.__name__, transitions))
for name in transitions:
pattern, method, next_state = state.transitions[name]
match = pattern.match(self.line)
if match:
if self.debug:
print >>self._stderr, (
'\nStateMachine.check_line: Matched transition '
'"%s" in state "%s".'
% (name, state.__class__.__name__))
return method(match, context, next_state)
else:
if self.debug:
print >>self._stderr, (
'\nStateMachine.check_line: No match in state "%s".'
% state.__class__.__name__)
return state.no_match(context, transitions)
def add_state(self, state_class):
"""
Initialize & add a `state_class` (`State` subclass) object.
Exception: `DuplicateStateError` raised if `state_class` was already
added.
"""
statename = state_class.__name__
if statename in self.states:
raise DuplicateStateError(statename)
self.states[statename] = state_class(self, self.debug)
def add_states(self, state_classes):
"""
Add `state_classes` (a list of `State` subclasses).
"""
for state_class in state_classes:
self.add_state(state_class)
def runtime_init(self):
"""
Initialize `self.states`.
"""
for state in self.states.values():
state.runtime_init()
def error(self):
"""Report error details."""
type, value, module, line, function = _exception_data()
print >>self._stderr, u'%s: %s' % (type, value)
print >>self._stderr, 'input line %s' % (self.abs_line_number())
print >>self._stderr, (u'module %s, line %s, function %s' %
(module, line, function))
def attach_observer(self, observer):
"""
The `observer` parameter is a function or bound method which takes two
arguments, the source and offset of the current line.
"""
self.observers.append(observer)
def detach_observer(self, observer):
self.observers.remove(observer)
def notify_observers(self):
for observer in self.observers:
try:
info = self.input_lines.info(self.line_offset)
except IndexError:
info = (None, None)
observer(*info)
class State:
"""
State superclass. Contains a list of transitions, and transition methods.
Transition methods all have the same signature. They take 3 parameters:
- An `re` match object. ``match.string`` contains the matched input line,
``match.start()`` gives the start index of the match, and
``match.end()`` gives the end index.
- A context object, whose meaning is application-defined (initial value
``None``). It can be used to store any information required by the state
machine, and the retured context is passed on to the next transition
method unchanged.
- The name of the next state, a string, taken from the transitions list;
normally it is returned unchanged, but it may be altered by the
transition method if necessary.
Transition methods all return a 3-tuple:
- A context object, as (potentially) modified by the transition method.
- The next state name (a return value of ``None`` means no state change).
- The processing result, a list, which is accumulated by the state
machine.
Transition methods may raise an `EOFError` to cut processing short.
There are two implicit transitions, and corresponding transition methods
are defined: `bof()` handles the beginning-of-file, and `eof()` handles
the end-of-file. These methods have non-standard signatures and return
values. `bof()` returns the initial context and results, and may be used
to return a header string, or do any other processing needed. `eof()`
should handle any remaining context and wrap things up; it returns the
final processing result.
Typical applications need only subclass `State` (or a subclass), set the
`patterns` and `initial_transitions` class attributes, and provide
corresponding transition methods. The default object initialization will
take care of constructing the list of transitions.
"""
patterns = None
"""
{Name: pattern} mapping, used by `make_transition()`. Each pattern may
be a string or a compiled `re` pattern. Override in subclasses.
"""
initial_transitions = None
"""
A list of transitions to initialize when a `State` is instantiated.
Each entry is either a transition name string, or a (transition name, next
state name) pair. See `make_transitions()`. Override in subclasses.
"""
nested_sm = None
"""
The `StateMachine` class for handling nested processing.
If left as ``None``, `nested_sm` defaults to the class of the state's
controlling state machine. Override it in subclasses to avoid the default.
"""
nested_sm_kwargs = None
"""
Keyword arguments dictionary, passed to the `nested_sm` constructor.
Two keys must have entries in the dictionary:
- Key 'state_classes' must be set to a list of `State` classes.
- Key 'initial_state' must be set to the name of the initial state class.
If `nested_sm_kwargs` is left as ``None``, 'state_classes' defaults to the
class of the current state, and 'initial_state' defaults to the name of
the class of the current state. Override in subclasses to avoid the
defaults.
"""
def __init__(self, state_machine, debug=False):
"""
Initialize a `State` object; make & add initial transitions.
Parameters:
- `statemachine`: the controlling `StateMachine` object.
- `debug`: a boolean; produce verbose output if true.
"""
self.transition_order = []
"""A list of transition names in search order."""
self.transitions = {}
"""
A mapping of transition names to 3-tuples containing
(compiled_pattern, transition_method, next_state_name). Initialized as
an instance attribute dynamically (instead of as a class attribute)
because it may make forward references to patterns and methods in this
or other classes.
"""
self.add_initial_transitions()
self.state_machine = state_machine
"""A reference to the controlling `StateMachine` object."""
self.debug = debug
"""Debugging mode on/off."""
if self.nested_sm is None:
self.nested_sm = self.state_machine.__class__
if self.nested_sm_kwargs is None:
self.nested_sm_kwargs = {'state_classes': [self.__class__],
'initial_state': self.__class__.__name__}
def runtime_init(self):
"""
Initialize this `State` before running the state machine; called from
`self.state_machine.run()`.
"""
pass
def unlink(self):
"""Remove circular references to objects no longer required."""
self.state_machine = None
def add_initial_transitions(self):
"""Make and add transitions listed in `self.initial_transitions`."""
if self.initial_transitions:
names, transitions = self.make_transitions(
self.initial_transitions)
self.add_transitions(names, transitions)
def add_transitions(self, names, transitions):
"""
Add a list of transitions to the start of the transition list.
Parameters:
- `names`: a list of transition names.
- `transitions`: a mapping of names to transition tuples.
Exceptions: `DuplicateTransitionError`, `UnknownTransitionError`.
"""
for name in names:
if name in self.transitions:
raise DuplicateTransitionError(name)
if name not in transitions:
raise UnknownTransitionError(name)
self.transition_order[:0] = names
self.transitions.update(transitions)
def add_transition(self, name, transition):
"""
Add a transition to the start of the transition list.
Parameter `transition`: a ready-made transition 3-tuple.
Exception: `DuplicateTransitionError`.
"""
if name in self.transitions:
raise DuplicateTransitionError(name)
self.transition_order[:0] = [name]
self.transitions[name] = transition
def remove_transition(self, name):
"""
Remove a transition by `name`.
Exception: `UnknownTransitionError`.
"""
try:
del self.transitions[name]
self.transition_order.remove(name)
except:
raise UnknownTransitionError(name)
def make_transition(self, name, next_state=None):
"""
Make & return a transition tuple based on `name`.
This is a convenience function to simplify transition creation.
Parameters:
- `name`: a string, the name of the transition pattern & method. This
`State` object must have a method called '`name`', and a dictionary
`self.patterns` containing a key '`name`'.
- `next_state`: a string, the name of the next `State` object for this
transition. A value of ``None`` (or absent) implies no state change
(i.e., continue with the same state).
Exceptions: `TransitionPatternNotFound`, `TransitionMethodNotFound`.
"""
if next_state is None:
next_state = self.__class__.__name__
try:
pattern = self.patterns[name]
if not hasattr(pattern, 'match'):
pattern = re.compile(pattern)
except KeyError:
raise TransitionPatternNotFound(
'%s.patterns[%r]' % (self.__class__.__name__, name))
try:
method = getattr(self, name)
except AttributeError:
raise TransitionMethodNotFound(
'%s.%s' % (self.__class__.__name__, name))
return (pattern, method, next_state)
def make_transitions(self, name_list):
"""
Return a list of transition names and a transition mapping.
Parameter `name_list`: a list, where each entry is either a transition
name string, or a 1- or 2-tuple (transition name, optional next state
name).
"""
stringtype = type('')
names = []
transitions = {}
for namestate in name_list:
if type(namestate) is stringtype:
transitions[namestate] = self.make_transition(namestate)
names.append(namestate)
else:
transitions[namestate[0]] = self.make_transition(*namestate)
names.append(namestate[0])
return names, transitions
def no_match(self, context, transitions):
"""
Called when there is no match from `StateMachine.check_line()`.
Return the same values returned by transition methods:
- context: unchanged;
- next state name: ``None``;
- empty result list.
Override in subclasses to catch this event.
"""
return context, None, []
def bof(self, context):
"""
Handle beginning-of-file. Return unchanged `context`, empty result.
Override in subclasses.
Parameter `context`: application-defined storage.
"""
return context, []
def eof(self, context):
"""
Handle end-of-file. Return empty result.
Override in subclasses.
Parameter `context`: application-defined storage.
"""
return []
def nop(self, match, context, next_state):
"""
A "do nothing" transition method.
Return unchanged `context` & `next_state`, empty result. Useful for
simple state changes (actionless transitions).
"""
return context, next_state, []
class StateMachineWS(StateMachine):
"""
`StateMachine` subclass specialized for whitespace recognition.
There are three methods provided for extracting indented text blocks:
- `get_indented()`: use when the indent is unknown.
- `get_known_indented()`: use when the indent is known for all lines.
- `get_first_known_indented()`: use when only the first line's indent is
known.
"""
def get_indented(self, until_blank=False, strip_indent=True):
"""
Return a block of indented lines of text, and info.
Extract an indented block where the indent is unknown for all lines.
:Parameters:
- `until_blank`: Stop collecting at the first blank line if true.
- `strip_indent`: Strip common leading indent if true (default).
:Return:
- the indented block (a list of lines of text),
- its indent,
- its first line offset from BOF, and
- whether or not it finished with a blank line.
"""
offset = self.abs_line_offset()
indented, indent, blank_finish = self.input_lines.get_indented(
self.line_offset, until_blank, strip_indent)
if indented:
self.next_line(len(indented) - 1) # advance to last indented line
while indented and not indented[0].strip():
indented.trim_start()
offset += 1
return indented, indent, offset, blank_finish
def get_known_indented(self, indent, until_blank=False, strip_indent=True):
"""
Return an indented block and info.
Extract an indented block where the indent is known for all lines.
Starting with the current line, extract the entire text block with at
least `indent` indentation (which must be whitespace, except for the
first line).
:Parameters:
- `indent`: The number of indent columns/characters.
- `until_blank`: Stop collecting at the first blank line if true.
- `strip_indent`: Strip `indent` characters of indentation if true
(default).
:Return:
- the indented block,
- its first line offset from BOF, and
- whether or not it finished with a blank line.
"""
offset = self.abs_line_offset()
indented, indent, blank_finish = self.input_lines.get_indented(
self.line_offset, until_blank, strip_indent,
block_indent=indent)
self.next_line(len(indented) - 1) # advance to last indented line
while indented and not indented[0].strip():
indented.trim_start()
offset += 1
return indented, offset, blank_finish
def get_first_known_indented(self, indent, until_blank=False,
strip_indent=True, strip_top=True):
"""
Return an indented block and info.
Extract an indented block where the indent is known for the first line
and unknown for all other lines.
:Parameters:
- `indent`: The first line's indent (# of columns/characters).
- `until_blank`: Stop collecting at the first blank line if true
(1).
- `strip_indent`: Strip `indent` characters of indentation if true
(1, default).
- `strip_top`: Strip blank lines from the beginning of the block.
:Return:
- the indented block,
- its indent,
- its first line offset from BOF, and
- whether or not it finished with a blank line.
"""
offset = self.abs_line_offset()
indented, indent, blank_finish = self.input_lines.get_indented(
self.line_offset, until_blank, strip_indent,
first_indent=indent)
self.next_line(len(indented) - 1) # advance to last indented line
if strip_top:
while indented and not indented[0].strip():
indented.trim_start()
offset += 1
return indented, indent, offset, blank_finish
class StateWS(State):
"""
State superclass specialized for whitespace (blank lines & indents).
Use this class with `StateMachineWS`. The transitions 'blank' (for blank
lines) and 'indent' (for indented text blocks) are added automatically,
before any other transitions. The transition method `blank()` handles
blank lines and `indent()` handles nested indented blocks. Indented
blocks trigger a new state machine to be created by `indent()` and run.
The class of the state machine to be created is in `indent_sm`, and the
constructor keyword arguments are in the dictionary `indent_sm_kwargs`.
The methods `known_indent()` and `firstknown_indent()` are provided for
indented blocks where the indent (all lines' and first line's only,
respectively) is known to the transition method, along with the attributes
`known_indent_sm` and `known_indent_sm_kwargs`. Neither transition method
is triggered automatically.
"""
indent_sm = None
"""
The `StateMachine` class handling indented text blocks.
If left as ``None``, `indent_sm` defaults to the value of
`State.nested_sm`. Override it in subclasses to avoid the default.
"""
indent_sm_kwargs = None
"""
Keyword arguments dictionary, passed to the `indent_sm` constructor.
If left as ``None``, `indent_sm_kwargs` defaults to the value of
`State.nested_sm_kwargs`. Override it in subclasses to avoid the default.
"""
known_indent_sm = None
"""
The `StateMachine` class handling known-indented text blocks.
If left as ``None``, `known_indent_sm` defaults to the value of
`indent_sm`. Override it in subclasses to avoid the default.
"""
known_indent_sm_kwargs = None
"""
Keyword arguments dictionary, passed to the `known_indent_sm` constructor.
If left as ``None``, `known_indent_sm_kwargs` defaults to the value of
`indent_sm_kwargs`. Override it in subclasses to avoid the default.
"""
ws_patterns = {'blank': ' *$',
'indent': ' +'}
"""Patterns for default whitespace transitions. May be overridden in
subclasses."""
ws_initial_transitions = ('blank', 'indent')
"""Default initial whitespace transitions, added before those listed in
`State.initial_transitions`. May be overridden in subclasses."""
def __init__(self, state_machine, debug=False):
"""
Initialize a `StateSM` object; extends `State.__init__()`.
Check for indent state machine attributes, set defaults if not set.
"""
State.__init__(self, state_machine, debug)
if self.indent_sm is None:
self.indent_sm = self.nested_sm
if self.indent_sm_kwargs is None:
self.indent_sm_kwargs = self.nested_sm_kwargs
if self.known_indent_sm is None:
self.known_indent_sm = self.indent_sm
if self.known_indent_sm_kwargs is None:
self.known_indent_sm_kwargs = self.indent_sm_kwargs
def add_initial_transitions(self):
"""
Add whitespace-specific transitions before those defined in subclass.
Extends `State.add_initial_transitions()`.
"""
State.add_initial_transitions(self)
if self.patterns is None:
self.patterns = {}
self.patterns.update(self.ws_patterns)
names, transitions = self.make_transitions(
self.ws_initial_transitions)
self.add_transitions(names, transitions)
def blank(self, match, context, next_state):
"""Handle blank lines. Does nothing. Override in subclasses."""
return self.nop(match, context, next_state)
def indent(self, match, context, next_state):
"""
Handle an indented text block. Extend or override in subclasses.
Recursively run the registered state machine for indented blocks
(`self.indent_sm`).
"""
indented, indent, line_offset, blank_finish = \
self.state_machine.get_indented()
sm = self.indent_sm(debug=self.debug, **self.indent_sm_kwargs)
results = sm.run(indented, input_offset=line_offset)
return context, next_state, results
def known_indent(self, match, context, next_state):
"""
Handle a known-indent text block. Extend or override in subclasses.
Recursively run the registered state machine for known-indent indented
blocks (`self.known_indent_sm`). The indent is the length of the
match, ``match.end()``.
"""
indented, line_offset, blank_finish = \
self.state_machine.get_known_indented(match.end())
sm = self.known_indent_sm(debug=self.debug,
**self.known_indent_sm_kwargs)
results = sm.run(indented, input_offset=line_offset)
return context, next_state, results
def first_known_indent(self, match, context, next_state):
"""
Handle an indented text block (first line's indent known).
Extend or override in subclasses.
Recursively run the registered state machine for known-indent indented
blocks (`self.known_indent_sm`). The indent is the length of the
match, ``match.end()``.
"""
indented, line_offset, blank_finish = \
self.state_machine.get_first_known_indented(match.end())
sm = self.known_indent_sm(debug=self.debug,
**self.known_indent_sm_kwargs)
results = sm.run(indented, input_offset=line_offset)
return context, next_state, results
class _SearchOverride:
"""
Mix-in class to override `StateMachine` regular expression behavior.
Changes regular expression matching, from the default `re.match()`
(succeeds only if the pattern matches at the start of `self.line`) to
`re.search()` (succeeds if the pattern matches anywhere in `self.line`).
When subclassing a `StateMachine`, list this class **first** in the
inheritance list of the class definition.
"""
def match(self, pattern):
"""
Return the result of a regular expression search.
Overrides `StateMachine.match()`.
Parameter `pattern`: `re` compiled regular expression.
"""
return pattern.search(self.line)
class SearchStateMachine(_SearchOverride, StateMachine):
"""`StateMachine` which uses `re.search()` instead of `re.match()`."""
pass
class SearchStateMachineWS(_SearchOverride, StateMachineWS):
"""`StateMachineWS` which uses `re.search()` instead of `re.match()`."""
pass
class ViewList:
"""
List with extended functionality: slices of ViewList objects are child
lists, linked to their parents. Changes made to a child list also affect
the parent list. A child list is effectively a "view" (in the SQL sense)
of the parent list. Changes to parent lists, however, do *not* affect
active child lists. If a parent list is changed, any active child lists
should be recreated.
The start and end of the slice can be trimmed using the `trim_start()` and
`trim_end()` methods, without affecting the parent list. The link between
child and parent lists can be broken by calling `disconnect()` on the
child list.
Also, ViewList objects keep track of the source & offset of each item.
This information is accessible via the `source()`, `offset()`, and
`info()` methods.
"""
def __init__(self, initlist=None, source=None, items=None,
parent=None, parent_offset=None):
self.data = []
"""The actual list of data, flattened from various sources."""
self.items = []
"""A list of (source, offset) pairs, same length as `self.data`: the
source of each line and the offset of each line from the beginning of
its source."""
self.parent = parent
"""The parent list."""
self.parent_offset = parent_offset
"""Offset of this list from the beginning of the parent list."""
if isinstance(initlist, ViewList):
self.data = initlist.data[:]
self.items = initlist.items[:]
elif initlist is not None:
self.data = list(initlist)
if items:
self.items = items
else:
self.items = [(source, i) for i in range(len(initlist))]
assert len(self.data) == len(self.items), 'data mismatch'
def __str__(self):
return str(self.data)
def __repr__(self):
return '%s(%s, items=%s)' % (self.__class__.__name__,
self.data, self.items)
def __lt__(self, other): return self.data < self.__cast(other)
def __le__(self, other): return self.data <= self.__cast(other)
def __eq__(self, other): return self.data == self.__cast(other)
def __ne__(self, other): return self.data != self.__cast(other)
def __gt__(self, other): return self.data > self.__cast(other)
def __ge__(self, other): return self.data >= self.__cast(other)
def __cmp__(self, other): return cmp(self.data, self.__cast(other))
def __cast(self, other):
if isinstance(other, ViewList):
return other.data
else:
return other
def __contains__(self, item): return item in self.data
def __len__(self): return len(self.data)
# The __getitem__()/__setitem__() methods check whether the index
# is a slice first, since indexing a native list with a slice object
# just works.
def __getitem__(self, i):
if isinstance(i, types.SliceType):
assert i.step in (None, 1), 'cannot handle slice with stride'
return self.__class__(self.data[i.start:i.stop],
items=self.items[i.start:i.stop],
parent=self, parent_offset=i.start or 0)
else:
return self.data[i]
def __setitem__(self, i, item):
if isinstance(i, types.SliceType):
assert i.step in (None, 1), 'cannot handle slice with stride'
if not isinstance(item, ViewList):
raise TypeError('assigning non-ViewList to ViewList slice')
self.data[i.start:i.stop] = item.data
self.items[i.start:i.stop] = item.items
assert len(self.data) == len(self.items), 'data mismatch'
if self.parent:
self.parent[(i.start or 0) + self.parent_offset
: (i.stop or len(self)) + self.parent_offset] = item
else:
self.data[i] = item
if self.parent:
self.parent[i + self.parent_offset] = item
def __delitem__(self, i):
try:
del self.data[i]
del self.items[i]
if self.parent:
del self.parent[i + self.parent_offset]
except TypeError:
assert i.step is None, 'cannot handle slice with stride'
del self.data[i.start:i.stop]
del self.items[i.start:i.stop]
if self.parent:
del self.parent[(i.start or 0) + self.parent_offset
: (i.stop or len(self)) + self.parent_offset]
def __add__(self, other):
if isinstance(other, ViewList):
return self.__class__(self.data + other.data,
items=(self.items + other.items))
else:
raise TypeError('adding non-ViewList to a ViewList')
def __radd__(self, other):
if isinstance(other, ViewList):
return self.__class__(other.data + self.data,
items=(other.items + self.items))
else:
raise TypeError('adding ViewList to a non-ViewList')
def __iadd__(self, other):
if isinstance(other, ViewList):
self.data += other.data
else:
raise TypeError('argument to += must be a ViewList')
return self
def __mul__(self, n):
return self.__class__(self.data * n, items=(self.items * n))
__rmul__ = __mul__
def __imul__(self, n):
self.data *= n
self.items *= n
return self
def extend(self, other):
if not isinstance(other, ViewList):
raise TypeError('extending a ViewList with a non-ViewList')
if self.parent:
self.parent.insert(len(self.data) + self.parent_offset, other)
self.data.extend(other.data)
self.items.extend(other.items)
def append(self, item, source=None, offset=0):
if source is None:
self.extend(item)
else:
if self.parent:
self.parent.insert(len(self.data) + self.parent_offset, item,
source, offset)
self.data.append(item)
self.items.append((source, offset))
def insert(self, i, item, source=None, offset=0):
if source is None:
if not isinstance(item, ViewList):
raise TypeError('inserting non-ViewList with no source given')
self.data[i:i] = item.data
self.items[i:i] = item.items
if self.parent:
index = (len(self.data) + i) % len(self.data)
self.parent.insert(index + self.parent_offset, item)
else:
self.data.insert(i, item)
self.items.insert(i, (source, offset))
if self.parent:
index = (len(self.data) + i) % len(self.data)
self.parent.insert(index + self.parent_offset, item,
source, offset)
def pop(self, i=-1):
if self.parent:
index = (len(self.data) + i) % len(self.data)
self.parent.pop(index + self.parent_offset)
self.items.pop(i)
return self.data.pop(i)
def trim_start(self, n=1):
"""
Remove items from the start of the list, without touching the parent.
"""
if n > len(self.data):
raise IndexError("Size of trim too large; can't trim %s items "
"from a list of size %s." % (n, len(self.data)))
elif n < 0:
raise IndexError('Trim size must be >= 0.')
del self.data[:n]
del self.items[:n]
if self.parent:
self.parent_offset += n
def trim_end(self, n=1):
"""
Remove items from the end of the list, without touching the parent.
"""
if n > len(self.data):
raise IndexError("Size of trim too large; can't trim %s items "
"from a list of size %s." % (n, len(self.data)))
elif n < 0:
raise IndexError('Trim size must be >= 0.')
del self.data[-n:]
del self.items[-n:]
def remove(self, item):
index = self.index(item)
del self[index]
def count(self, item): return self.data.count(item)
def index(self, item): return self.data.index(item)
def reverse(self):
self.data.reverse()
self.items.reverse()
self.parent = None
def sort(self, *args):
tmp = zip(self.data, self.items)
tmp.sort(*args)
self.data = [entry[0] for entry in tmp]
self.items = [entry[1] for entry in tmp]
self.parent = None
def info(self, i):
"""Return source & offset for index `i`."""
try:
return self.items[i]
except IndexError:
if i == len(self.data): # Just past the end
return self.items[i - 1][0], None
else:
raise
def source(self, i):
"""Return source for index `i`."""
return self.info(i)[0]
def offset(self, i):
"""Return offset for index `i`."""
return self.info(i)[1]
def disconnect(self):
"""Break link between this list and parent list."""
self.parent = None
def xitems(self):
"""Return iterator yielding (source, offset, value) tuples."""
for (value, (source, offset)) in zip(self.data, self.items):
yield (source, offset, value)
def pprint(self):
"""Print the list in `grep` format (`source:offset:value` lines)"""
for line in self.xitems():
print "%s:%d:%s" % line
class StringList(ViewList):
"""A `ViewList` with string-specific methods."""
def trim_left(self, length, start=0, end=sys.maxint):
"""
Trim `length` characters off the beginning of each item, in-place,
from index `start` to `end`. No whitespace-checking is done on the
trimmed text. Does not affect slice parent.
"""
self.data[start:end] = [line[length:]
for line in self.data[start:end]]
def get_text_block(self, start, flush_left=False):
"""
Return a contiguous block of text.
If `flush_left` is true, raise `UnexpectedIndentationError` if an
indented line is encountered before the text block ends (with a blank
line).
"""
end = start
last = len(self.data)
while end < last:
line = self.data[end]
if not line.strip():
break
if flush_left and (line[0] == ' '):
source, offset = self.info(end)
raise UnexpectedIndentationError(self[start:end], source,
offset + 1)
end += 1
return self[start:end]
def get_indented(self, start=0, until_blank=False, strip_indent=True,
block_indent=None, first_indent=None):
"""
Extract and return a StringList of indented lines of text.
Collect all lines with indentation, determine the minimum indentation,
remove the minimum indentation from all indented lines (unless
`strip_indent` is false), and return them. All lines up to but not
including the first unindented line will be returned.
:Parameters:
- `start`: The index of the first line to examine.
- `until_blank`: Stop collecting at the first blank line if true.
- `strip_indent`: Strip common leading indent if true (default).
- `block_indent`: The indent of the entire block, if known.
- `first_indent`: The indent of the first line, if known.
:Return:
- a StringList of indented lines with mininum indent removed;
- the amount of the indent;
- a boolean: did the indented block finish with a blank line or EOF?
"""
indent = block_indent # start with None if unknown
end = start
if block_indent is not None and first_indent is None:
first_indent = block_indent
if first_indent is not None:
end += 1
last = len(self.data)
while end < last:
line = self.data[end]
if line and (line[0] != ' '
or (block_indent is not None
and line[:block_indent].strip())):
# Line not indented or insufficiently indented.
# Block finished properly iff the last indented line blank:
blank_finish = ((end > start)
and not self.data[end - 1].strip())
break
stripped = line.lstrip()
if not stripped: # blank line
if until_blank:
blank_finish = 1
break
elif block_indent is None:
line_indent = len(line) - len(stripped)
if indent is None:
indent = line_indent
else:
indent = min(indent, line_indent)
end += 1
else:
blank_finish = 1 # block ends at end of lines
block = self[start:end]
if first_indent is not None and block:
block.data[0] = block.data[0][first_indent:]
if indent and strip_indent:
block.trim_left(indent, start=(first_indent is not None))
return block, indent or 0, blank_finish
def get_2D_block(self, top, left, bottom, right, strip_indent=True):
block = self[top:bottom]
indent = right
for i in range(len(block.data)):
# get slice from line, care for combining characters
ci = utils.column_indices(block.data[i])
try:
left = ci[left]
except IndexError:
left += len(block.data[i]) - len(ci)
try:
right = ci[right]
except IndexError:
right += len(block.data[i]) - len(ci)
block.data[i] = line = block.data[i][left:right].rstrip()
if line:
indent = min(indent, len(line) - len(line.lstrip()))
if strip_indent and 0 < indent < right:
block.data = [line[indent:] for line in block.data]
return block
def pad_double_width(self, pad_char):
"""
Pad all double-width characters in self by appending `pad_char` to each.
For East Asian language support.
"""
if hasattr(unicodedata, 'east_asian_width'):
east_asian_width = unicodedata.east_asian_width
else:
return # new in Python 2.4
for i in range(len(self.data)):
line = self.data[i]
if isinstance(line, unicode):
new = []
for char in line:
new.append(char)
if east_asian_width(char) in 'WF': # 'W'ide & 'F'ull-width
new.append(pad_char)
self.data[i] = ''.join(new)
def replace(self, old, new):
"""Replace all occurrences of substring `old` with `new`."""
for i in range(len(self.data)):
self.data[i] = self.data[i].replace(old, new)
class StateMachineError(Exception): pass
class UnknownStateError(StateMachineError): pass
class DuplicateStateError(StateMachineError): pass
class UnknownTransitionError(StateMachineError): pass
class DuplicateTransitionError(StateMachineError): pass
class TransitionPatternNotFound(StateMachineError): pass
class TransitionMethodNotFound(StateMachineError): pass
class UnexpectedIndentationError(StateMachineError): pass
class TransitionCorrection(Exception):
"""
Raise from within a transition method to switch to another transition.
Raise with one argument, the new transition name.
"""
class StateCorrection(Exception):
"""
Raise from within a transition method to switch to another state.
Raise with one or two arguments: new state name, and an optional new
transition name.
"""
def string2lines(astring, tab_width=8, convert_whitespace=False,
whitespace=re.compile('[\v\f]')):
"""
Return a list of one-line strings with tabs expanded, no newlines, and
trailing whitespace stripped.
Each tab is expanded with between 1 and `tab_width` spaces, so that the
next character's index becomes a multiple of `tab_width` (8 by default).
Parameters:
- `astring`: a multi-line string.
- `tab_width`: the number of columns between tab stops.
- `convert_whitespace`: convert form feeds and vertical tabs to spaces?
"""
if convert_whitespace:
astring = whitespace.sub(' ', astring)
return [s.expandtabs(tab_width).rstrip() for s in astring.splitlines()]
def _exception_data():
"""
Return exception information:
- the exception's class name;
- the exception object;
- the name of the file containing the offending code;
- the line number of the offending code;
- the function name of the offending code.
"""
type, value, traceback = sys.exc_info()
while traceback.tb_next:
traceback = traceback.tb_next
code = traceback.tb_frame.f_code
return (type.__name__, value, code.co_filename, traceback.tb_lineno,
code.co_name)
|