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1538 lines
56 KiB
1538 lines
56 KiB
# $Id: statemachine.py 7464 2012-06-25 13:16:03Z milde $ |
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# Author: David Goodger <goodger@python.org> |
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# Copyright: This module has been placed in the public domain. |
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""" |
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A finite state machine specialized for regular-expression-based text filters, |
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this module defines the following classes: |
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|
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- `StateMachine`, a state machine |
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- `State`, a state superclass |
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- `StateMachineWS`, a whitespace-sensitive version of `StateMachine` |
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- `StateWS`, a state superclass for use with `StateMachineWS` |
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- `SearchStateMachine`, uses `re.search()` instead of `re.match()` |
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- `SearchStateMachineWS`, uses `re.search()` instead of `re.match()` |
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- `ViewList`, extends standard Python lists. |
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- `StringList`, string-specific ViewList. |
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Exception classes: |
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- `StateMachineError` |
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- `UnknownStateError` |
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- `DuplicateStateError` |
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- `UnknownTransitionError` |
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- `DuplicateTransitionError` |
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- `TransitionPatternNotFound` |
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- `TransitionMethodNotFound` |
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- `UnexpectedIndentationError` |
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- `TransitionCorrection`: Raised to switch to another transition. |
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- `StateCorrection`: Raised to switch to another state & transition. |
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Functions: |
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- `string2lines()`: split a multi-line string into a list of one-line strings |
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How To Use This Module |
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====================== |
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(See the individual classes, methods, and attributes for details.) |
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1. Import it: ``import statemachine`` or ``from statemachine import ...``. |
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You will also need to ``import re``. |
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2. Derive a subclass of `State` (or `StateWS`) for each state in your state |
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machine:: |
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class MyState(statemachine.State): |
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Within the state's class definition: |
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|
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a) Include a pattern for each transition, in `State.patterns`:: |
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patterns = {'atransition': r'pattern', ...} |
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b) Include a list of initial transitions to be set up automatically, in |
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`State.initial_transitions`:: |
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initial_transitions = ['atransition', ...] |
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c) Define a method for each transition, with the same name as the |
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transition pattern:: |
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def atransition(self, match, context, next_state): |
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# do something |
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result = [...] # a list |
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return context, next_state, result |
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# context, next_state may be altered |
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Transition methods may raise an `EOFError` to cut processing short. |
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d) You may wish to override the `State.bof()` and/or `State.eof()` implicit |
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transition methods, which handle the beginning- and end-of-file. |
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e) In order to handle nested processing, you may wish to override the |
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attributes `State.nested_sm` and/or `State.nested_sm_kwargs`. |
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If you are using `StateWS` as a base class, in order to handle nested |
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indented blocks, you may wish to: |
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- override the attributes `StateWS.indent_sm`, |
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`StateWS.indent_sm_kwargs`, `StateWS.known_indent_sm`, and/or |
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`StateWS.known_indent_sm_kwargs`; |
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- override the `StateWS.blank()` method; and/or |
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- override or extend the `StateWS.indent()`, `StateWS.known_indent()`, |
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and/or `StateWS.firstknown_indent()` methods. |
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3. Create a state machine object:: |
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sm = StateMachine(state_classes=[MyState, ...], |
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initial_state='MyState') |
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4. Obtain the input text, which needs to be converted into a tab-free list of |
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one-line strings. For example, to read text from a file called |
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'inputfile':: |
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input_string = open('inputfile').read() |
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input_lines = statemachine.string2lines(input_string) |
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5. Run the state machine on the input text and collect the results, a list:: |
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results = sm.run(input_lines) |
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6. Remove any lingering circular references:: |
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sm.unlink() |
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""" |
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__docformat__ = 'restructuredtext' |
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import sys |
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import re |
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import types |
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import unicodedata |
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from docutils import utils |
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from docutils.utils.error_reporting import ErrorOutput |
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class StateMachine: |
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""" |
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A finite state machine for text filters using regular expressions. |
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The input is provided in the form of a list of one-line strings (no |
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newlines). States are subclasses of the `State` class. Transitions consist |
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of regular expression patterns and transition methods, and are defined in |
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each state. |
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The state machine is started with the `run()` method, which returns the |
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results of processing in a list. |
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""" |
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def __init__(self, state_classes, initial_state, debug=False): |
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""" |
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Initialize a `StateMachine` object; add state objects. |
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Parameters: |
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- `state_classes`: a list of `State` (sub)classes. |
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- `initial_state`: a string, the class name of the initial state. |
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- `debug`: a boolean; produce verbose output if true (nonzero). |
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""" |
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self.input_lines = None |
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"""`StringList` of input lines (without newlines). |
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Filled by `self.run()`.""" |
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self.input_offset = 0 |
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"""Offset of `self.input_lines` from the beginning of the file.""" |
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self.line = None |
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"""Current input line.""" |
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self.line_offset = -1 |
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"""Current input line offset from beginning of `self.input_lines`.""" |
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self.debug = debug |
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"""Debugging mode on/off.""" |
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self.initial_state = initial_state |
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"""The name of the initial state (key to `self.states`).""" |
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self.current_state = initial_state |
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"""The name of the current state (key to `self.states`).""" |
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self.states = {} |
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"""Mapping of {state_name: State_object}.""" |
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self.add_states(state_classes) |
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self.observers = [] |
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"""List of bound methods or functions to call whenever the current |
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line changes. Observers are called with one argument, ``self``. |
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Cleared at the end of `run()`.""" |
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self._stderr = ErrorOutput() |
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"""Wrapper around sys.stderr catching en-/decoding errors""" |
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def unlink(self): |
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"""Remove circular references to objects no longer required.""" |
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for state in self.states.values(): |
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state.unlink() |
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self.states = None |
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def run(self, input_lines, input_offset=0, context=None, |
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input_source=None, initial_state=None): |
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""" |
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Run the state machine on `input_lines`. Return results (a list). |
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Reset `self.line_offset` and `self.current_state`. Run the |
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beginning-of-file transition. Input one line at a time and check for a |
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matching transition. If a match is found, call the transition method |
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and possibly change the state. Store the context returned by the |
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transition method to be passed on to the next transition matched. |
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Accumulate the results returned by the transition methods in a list. |
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Run the end-of-file transition. Finally, return the accumulated |
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results. |
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Parameters: |
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- `input_lines`: a list of strings without newlines, or `StringList`. |
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- `input_offset`: the line offset of `input_lines` from the beginning |
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of the file. |
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- `context`: application-specific storage. |
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- `input_source`: name or path of source of `input_lines`. |
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- `initial_state`: name of initial state. |
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""" |
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self.runtime_init() |
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if isinstance(input_lines, StringList): |
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self.input_lines = input_lines |
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else: |
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self.input_lines = StringList(input_lines, source=input_source) |
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self.input_offset = input_offset |
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self.line_offset = -1 |
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self.current_state = initial_state or self.initial_state |
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if self.debug: |
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print >>self._stderr, ( |
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u'\nStateMachine.run: input_lines (line_offset=%s):\n| %s' |
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% (self.line_offset, u'\n| '.join(self.input_lines))) |
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transitions = None |
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results = [] |
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state = self.get_state() |
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try: |
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if self.debug: |
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print >>self._stderr, '\nStateMachine.run: bof transition' |
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context, result = state.bof(context) |
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results.extend(result) |
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while True: |
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try: |
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try: |
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self.next_line() |
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if self.debug: |
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source, offset = self.input_lines.info( |
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self.line_offset) |
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print >>self._stderr, ( |
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u'\nStateMachine.run: line (source=%r, ' |
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u'offset=%r):\n| %s' |
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% (source, offset, self.line)) |
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context, next_state, result = self.check_line( |
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context, state, transitions) |
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except EOFError: |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.run: %s.eof transition' |
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% state.__class__.__name__) |
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result = state.eof(context) |
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results.extend(result) |
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break |
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else: |
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results.extend(result) |
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except TransitionCorrection, exception: |
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self.previous_line() # back up for another try |
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transitions = (exception.args[0],) |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.run: TransitionCorrection to ' |
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'state "%s", transition %s.' |
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% (state.__class__.__name__, transitions[0])) |
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continue |
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except StateCorrection, exception: |
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self.previous_line() # back up for another try |
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next_state = exception.args[0] |
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if len(exception.args) == 1: |
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transitions = None |
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else: |
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transitions = (exception.args[1],) |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.run: StateCorrection to state ' |
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'"%s", transition %s.' |
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% (next_state, transitions[0])) |
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else: |
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transitions = None |
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state = self.get_state(next_state) |
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except: |
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if self.debug: |
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self.error() |
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raise |
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self.observers = [] |
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return results |
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|
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def get_state(self, next_state=None): |
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""" |
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Return current state object; set it first if `next_state` given. |
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Parameter `next_state`: a string, the name of the next state. |
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Exception: `UnknownStateError` raised if `next_state` unknown. |
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""" |
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if next_state: |
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if self.debug and next_state != self.current_state: |
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print >>self._stderr, ( |
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'\nStateMachine.get_state: Changing state from ' |
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'"%s" to "%s" (input line %s).' |
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% (self.current_state, next_state, |
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self.abs_line_number())) |
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self.current_state = next_state |
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try: |
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return self.states[self.current_state] |
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except KeyError: |
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raise UnknownStateError(self.current_state) |
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def next_line(self, n=1): |
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"""Load `self.line` with the `n`'th next line and return it.""" |
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try: |
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try: |
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self.line_offset += n |
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self.line = self.input_lines[self.line_offset] |
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except IndexError: |
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self.line = None |
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raise EOFError |
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return self.line |
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finally: |
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self.notify_observers() |
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def is_next_line_blank(self): |
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"""Return 1 if the next line is blank or non-existant.""" |
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try: |
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return not self.input_lines[self.line_offset + 1].strip() |
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except IndexError: |
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return 1 |
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|
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def at_eof(self): |
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"""Return 1 if the input is at or past end-of-file.""" |
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return self.line_offset >= len(self.input_lines) - 1 |
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def at_bof(self): |
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"""Return 1 if the input is at or before beginning-of-file.""" |
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return self.line_offset <= 0 |
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def previous_line(self, n=1): |
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"""Load `self.line` with the `n`'th previous line and return it.""" |
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self.line_offset -= n |
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if self.line_offset < 0: |
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self.line = None |
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else: |
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self.line = self.input_lines[self.line_offset] |
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self.notify_observers() |
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return self.line |
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|
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def goto_line(self, line_offset): |
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"""Jump to absolute line offset `line_offset`, load and return it.""" |
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try: |
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try: |
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self.line_offset = line_offset - self.input_offset |
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self.line = self.input_lines[self.line_offset] |
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except IndexError: |
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self.line = None |
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raise EOFError |
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return self.line |
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finally: |
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self.notify_observers() |
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|
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def get_source(self, line_offset): |
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"""Return source of line at absolute line offset `line_offset`.""" |
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return self.input_lines.source(line_offset - self.input_offset) |
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def abs_line_offset(self): |
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"""Return line offset of current line, from beginning of file.""" |
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return self.line_offset + self.input_offset |
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|
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def abs_line_number(self): |
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"""Return line number of current line (counting from 1).""" |
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return self.line_offset + self.input_offset + 1 |
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|
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def get_source_and_line(self, lineno=None): |
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"""Return (source, line) tuple for current or given line number. |
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Looks up the source and line number in the `self.input_lines` |
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StringList instance to count for included source files. |
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|
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If the optional argument `lineno` is given, convert it from an |
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absolute line number to the corresponding (source, line) pair. |
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""" |
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if lineno is None: |
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offset = self.line_offset |
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else: |
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offset = lineno - self.input_offset - 1 |
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try: |
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src, srcoffset = self.input_lines.info(offset) |
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srcline = srcoffset + 1 |
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except (TypeError): |
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# line is None if index is "Just past the end" |
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src, srcline = self.get_source_and_line(offset + self.input_offset) |
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return src, srcline + 1 |
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except (IndexError): # `offset` is off the list |
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src, srcline = None, None |
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# raise AssertionError('cannot find line %d in %s lines' % |
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# (offset, len(self.input_lines))) |
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# # list(self.input_lines.lines()))) |
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# assert offset == srcoffset, str(self.input_lines) |
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# print "get_source_and_line(%s):" % lineno, |
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# print offset + 1, '->', src, srcline |
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# print self.input_lines |
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return (src, srcline) |
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|
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def insert_input(self, input_lines, source): |
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self.input_lines.insert(self.line_offset + 1, '', |
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source='internal padding after '+source, |
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offset=len(input_lines)) |
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self.input_lines.insert(self.line_offset + 1, '', |
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source='internal padding before '+source, |
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offset=-1) |
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self.input_lines.insert(self.line_offset + 2, |
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StringList(input_lines, source)) |
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|
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def get_text_block(self, flush_left=False): |
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""" |
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Return a contiguous block of text. |
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|
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If `flush_left` is true, raise `UnexpectedIndentationError` if an |
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indented line is encountered before the text block ends (with a blank |
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line). |
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""" |
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try: |
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block = self.input_lines.get_text_block(self.line_offset, |
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flush_left) |
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self.next_line(len(block) - 1) |
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return block |
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except UnexpectedIndentationError, err: |
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block = err.args[0] |
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self.next_line(len(block) - 1) # advance to last line of block |
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raise |
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|
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def check_line(self, context, state, transitions=None): |
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""" |
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Examine one line of input for a transition match & execute its method. |
|
|
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Parameters: |
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|
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- `context`: application-dependent storage. |
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- `state`: a `State` object, the current state. |
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- `transitions`: an optional ordered list of transition names to try, |
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instead of ``state.transition_order``. |
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|
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Return the values returned by the transition method: |
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- context: possibly modified from the parameter `context`; |
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- next state name (`State` subclass name); |
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- the result output of the transition, a list. |
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|
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When there is no match, ``state.no_match()`` is called and its return |
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value is returned. |
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""" |
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if transitions is None: |
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transitions = state.transition_order |
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state_correction = None |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.check_line: state="%s", transitions=%r.' |
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% (state.__class__.__name__, transitions)) |
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for name in transitions: |
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pattern, method, next_state = state.transitions[name] |
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match = pattern.match(self.line) |
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if match: |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.check_line: Matched transition ' |
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'"%s" in state "%s".' |
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% (name, state.__class__.__name__)) |
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return method(match, context, next_state) |
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else: |
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if self.debug: |
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print >>self._stderr, ( |
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'\nStateMachine.check_line: No match in state "%s".' |
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% state.__class__.__name__) |
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return state.no_match(context, transitions) |
|
|
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def add_state(self, state_class): |
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""" |
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Initialize & add a `state_class` (`State` subclass) object. |
|
|
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Exception: `DuplicateStateError` raised if `state_class` was already |
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added. |
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""" |
|
statename = state_class.__name__ |
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if statename in self.states: |
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raise DuplicateStateError(statename) |
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self.states[statename] = state_class(self, self.debug) |
|
|
|
def add_states(self, state_classes): |
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""" |
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Add `state_classes` (a list of `State` subclasses). |
|
""" |
|
for state_class in state_classes: |
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self.add_state(state_class) |
|
|
|
def runtime_init(self): |
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""" |
|
Initialize `self.states`. |
|
""" |
|
for state in self.states.values(): |
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state.runtime_init() |
|
|
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def error(self): |
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"""Report error details.""" |
|
type, value, module, line, function = _exception_data() |
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print >>self._stderr, u'%s: %s' % (type, value) |
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print >>self._stderr, 'input line %s' % (self.abs_line_number()) |
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print >>self._stderr, (u'module %s, line %s, function %s' % |
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(module, line, function)) |
|
|
|
def attach_observer(self, observer): |
|
""" |
|
The `observer` parameter is a function or bound method which takes two |
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arguments, the source and offset of the current line. |
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""" |
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self.observers.append(observer) |
|
|
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def detach_observer(self, observer): |
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self.observers.remove(observer) |
|
|
|
def notify_observers(self): |
|
for observer in self.observers: |
|
try: |
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info = self.input_lines.info(self.line_offset) |
|
except IndexError: |
|
info = (None, None) |
|
observer(*info) |
|
|
|
|
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class State: |
|
|
|
""" |
|
State superclass. Contains a list of transitions, and transition methods. |
|
|
|
Transition methods all have the same signature. They take 3 parameters: |
|
|
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- An `re` match object. ``match.string`` contains the matched input line, |
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``match.start()`` gives the start index of the match, and |
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``match.end()`` gives the end index. |
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- A context object, whose meaning is application-defined (initial value |
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``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. |
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- 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: |
|
|
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- 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. |
|
|
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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)
|
|
|