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# -*- coding: utf-8 -*- |
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# ----------------------------------------------------------------------------- |
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# Copyright (c) 2015 Yann Lanthony |
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# Copyright (c) 2017-2018 Spyder Project Contributors |
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# |
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# Licensed under the terms of the MIT License |
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# (See LICENSE.txt for details) |
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# ----------------------------------------------------------------------------- |
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"""The filesystem watcher api.""" |
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# yapf: disable |
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from __future__ import absolute_import |
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# Standard library imports |
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import functools |
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import logging |
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import time |
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_log = logging.getLogger(__name__) |
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def retry(n, interval=0.1): |
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"""Retry a function or method n times before raising an exception. |
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:param n: Number of times to retry |
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:param interval: Time to sleep before attempts |
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""" |
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def decorate(fn): |
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@functools.wraps(fn) |
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def attempt(*args, **kwargs): |
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attempts = 0 |
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while True: |
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try: |
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return fn(*args, **kwargs) |
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except Exception: |
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attempts += 1 |
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if n <= attempts: |
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raise |
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time.sleep(interval) |
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return attempt |
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return decorate |
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# yapf: enable |
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class Watcher(object): |
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"""Watcher base class. |
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Watchers monitor a file or directory and call the on_change method when a |
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change occurs. The on_change method should trigger the compiler function |
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passed in during construction and dispatch the result to all connected |
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callbacks. |
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Watcher implementations must inherit from this base class. Subclasses |
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should perform any setup required in the setup method, rather than |
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overriding __init__. |
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""" |
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def __init__(self, watch_dir, compiler, args=None, kwargs=None): |
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"""Store initialization values and call Watcher.setup.""" |
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self._watch_dir = watch_dir |
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self._compiler = compiler |
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self._args = args or () |
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self._kwargs = kwargs or {} |
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self._callbacks = set() |
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self._log = _log |
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self.setup() |
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def setup(self): |
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"""Perform any setup required here. |
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Rather than implement __init__, subclasses can perform any setup in |
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this method. |
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""" |
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return NotImplemented |
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def start(self): |
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"""Start this Watcher.""" |
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return NotImplemented |
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def stop(self): |
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"""Stop this Watcher.""" |
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return NotImplemented |
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def join(self): |
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"""Wait for this Watcher to finish.""" |
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return NotImplemented |
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@retry(5) |
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def compile(self): |
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"""Call the Watcher's compiler.""" |
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self._log.debug( |
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'Compiling sass...%s(*%s, **%s)', |
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self._compiler, |
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self._args, |
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self._kwargs, |
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) |
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return self._compiler(*self._args, **self._kwargs) |
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def compile_and_dispatch(self): |
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"""Compile and dispatch the resulting css to connected callbacks.""" |
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self._log.debug('Compiling and dispatching....') |
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try: |
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css = self.compile() |
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except Exception: |
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self._log.exception('Failed to compile...') |
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return |
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self.dispatch(css) |
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def dispatch(self, css): |
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"""Dispatch css to connected callbacks.""" |
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self._log.debug('Dispatching callbacks...') |
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for callback in self._callbacks: |
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callback(css) |
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def on_change(self): |
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"""Call when a change is detected. |
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Subclasses must call this method when they detect a change. Subclasses |
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may also override this method in order to manually compile and dispatch |
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callbacks. For example, a Qt implementation may use signals and slots |
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to ensure that compiling and executing callbacks happens in the main |
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GUI thread. |
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""" |
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self._log.debug('Change detected...') |
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self.compile_and_dispatch() |
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def connect(self, fn): |
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"""Connect a callback to this Watcher. |
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All callbacks are called when a change is detected. Callbacks are |
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passed the compiled css. |
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""" |
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self._log.debug('Connecting callback: %s', fn) |
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self._callbacks.add(fn) |
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def disconnect(self, fn): |
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"""Disconnect a callback from this Watcher.""" |
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self._log.debug('Disconnecting callback: %s', fn) |
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self._callbacks.discard(fn) |
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spyder-ide /
qtsass
