[common] PySignal file

Add PySignal file from https://github.com/dgovil/PySignal

meshroom/common/PySignal.py

@@ -0,0 +1,313 @@
+# https://github.com/dgovil/PySignal
+
+__author__ = "Dhruv Govil"
+__copyright__ = "Copyright 2016, Dhruv Govil"
+__credits__ = ["Dhruv Govil", "John Hood", "Jason Viloria", "Adric Worley", "Alex Widener"]
+__license__ = "MIT"
+__version__ = "1.1.3"
+__maintainer__ = "Dhruv Govil"
+__email__ = "dhruvagovil@gmail.com"
+__status__ = "Beta"
+
+import inspect
+import sys
+import weakref
+from functools import partial
+
+
+# weakref.WeakMethod backport
+try:
+    from weakref import WeakMethod
+
+except ImportError:
+    import types
+
+    class WeakMethod(object):
+        """Light WeakMethod backport compiled from various sources. Tested in 2.7"""
+
+        def __init__(self, func):
+            if inspect.ismethod(func):
+                self._obj = weakref.ref(func.__self__)
+                self._func = weakref.ref(func.__func__)
+
+            else:
+                self._obj = None
+
+                try:
+                    self._func = weakref.ref(func.__func__)
+
+                # Rather than attempting to handle this, raise the same exception
+                # you get from WeakMethod.
+                except AttributeError:
+                    raise TypeError("argument should be a bound method, not %s" % type(func))
+
+        def __call__(self):
+            if self._obj is not None:
+                obj = self._obj()
+                func = self._func()
+                if func is None or obj is None:
+                    return None
+
+                else:
+                    return types.MethodType(func, obj, obj.__class__)
+
+            elif self._func is not None:
+                return self._func()
+
+            else:
+                return None
+
+        def __eq__(self, other):
+            try:
+                return type(self) is type(other) and self() == other()
+
+            except Exception:
+                return False
+
+        def __ne__(self, other):
+            return not self.__eq__(other)
+
+
+class Signal(object):
+    """
+    The Signal is the core object that handles connection and emission .
+    """
+
+    def __init__(self):
+        super(Signal, self).__init__()
+        self._block = False
+        self._sender = None
+        self._slots = []
+
+    def __call__(self, *args, **kwargs):
+        self.emit(*args, **kwargs)
+
+    def emit(self, *args, **kwargs):
+        """
+        Calls all the connected slots with the provided args and kwargs unless block is activated
+        """
+        if self._block:
+            return
+
+        def _get_sender():
+            """Try to get the bound, class or module method calling the emit."""
+            prev_frame = sys._getframe(2)
+            func_name = prev_frame.f_code.co_name
+
+            # Faster to try/catch than checking for 'self'
+            try:
+                return getattr(prev_frame.f_locals['self'], func_name)
+
+            except KeyError:
+                return getattr(inspect.getmodule(prev_frame), func_name)
+
+        # Get the sender
+        try:
+            self._sender = WeakMethod(_get_sender())
+
+        # Account for when func_name is at '<module>'
+        except AttributeError:
+            self._sender = None
+
+        # Handle unsupported module level methods for WeakMethod.
+        # TODO: Support module level methods.
+        except TypeError:
+            self._sender = None
+
+        for slot in self._slots:
+            if not slot:
+                continue
+            elif isinstance(slot, partial):
+                slot()
+            elif isinstance(slot, weakref.WeakKeyDictionary):
+                # For class methods, get the class object and call the method accordingly.
+                for obj, method in slot.items():
+                    method(obj, *args, **kwargs)
+            elif isinstance(slot, weakref.ref):
+                # If it's a weakref, call the ref to get the instance and then call the func
+                # Don't wrap in try/except so we don't risk masking exceptions from the actual func call
+                tested_slot = slot()
+                if tested_slot is not None:
+                    tested_slot(*args, **kwargs)
+            else:
+                # Else call it in a standard way. Should be just lambdas at this point
+                slot(*args, **kwargs)
+
+    def connect(self, slot):
+        """
+        Connects the signal to any callable object
+        """
+        if not callable(slot):
+            raise ValueError("Connection to non-callable '%s' object failed" % slot.__class__.__name__)
+
+        if isinstance(slot, (partial, Signal)) or '<' in slot.__name__:
+            # If it's a partial, a Signal or a lambda. The '<' check is the only py2 and py3 compatible way I could find
+            if slot not in self._slots:
+                self._slots.append(slot)
+        elif inspect.ismethod(slot):
+            # Check if it's an instance method and store it with the instance as the key
+            slotSelf = slot.__self__
+            slotDict = weakref.WeakKeyDictionary()
+            slotDict[slotSelf] = slot.__func__
+            if slotDict not in self._slots:
+                self._slots.append(slotDict)
+        else:
+            # If it's just a function then just store it as a weakref.
+            newSlotRef = weakref.ref(slot)
+            if newSlotRef not in self._slots:
+                self._slots.append(newSlotRef)
+
+    def disconnect(self, slot):
+        """
+        Disconnects the slot from the signal
+        """
+        if not callable(slot):
+            return
+
+        if inspect.ismethod(slot):
+            # If it's a method, then find it by its instance
+            slotSelf = slot.__self__
+            for s in self._slots:
+                if (isinstance(s, weakref.WeakKeyDictionary) and
+                        (slotSelf in s) and
+                        (s[slotSelf] is slot.__func__)):
+                    self._slots.remove(s)
+                    break
+        elif isinstance(slot, partial) or '<' in slot.__name__:
+            # If it's a partial or lambda, try to remove directly
+            try:
+                self._slots.remove(slot)
+            except ValueError:
+                pass
+        else:
+            # It's probably a function, so try to remove by weakref
+            try:
+                self._slots.remove(weakref.ref(slot))
+            except ValueError:
+                pass
+
+    def clear(self):
+        """Clears the signal of all connected slots"""
+        self._slots = []
+
+    def block(self, isBlocked):
+        """Sets blocking of the signal"""
+        self._block = bool(isBlocked)
+
+    def sender(self):
+        """Return the callable responsible for emitting the signal, if found."""
+        try:
+            return self._sender()
+
+        except TypeError:
+            return None
+
+
+class ClassSignal(object):
+    """
+    The class signal allows a signal to be set on a class rather than an instance.
+    This emulates the behavior of a PyQt signal
+    """
+    _map = {}
+
+    def __get__(self, instance, owner):
+        if instance is None:
+            # When we access ClassSignal element on the class object without any instance,
+            # we return the ClassSignal itself
+            return self
+        tmp = self._map.setdefault(self, weakref.WeakKeyDictionary())
+        return tmp.setdefault(instance, Signal())
+
+    def __set__(self, instance, value):
+        raise RuntimeError("Cannot assign to a Signal object")
+
+
+class SignalFactory(dict):
+    """
+    The Signal Factory object lets you handle signals by a string based name instead of by objects.
+    """
+
+    def register(self, name, *slots):
+        """
+        Registers a given signal
+        :param name: the signal to register
+        """
+        # setdefault initializes the object even if it exists. This is more efficient
+        if name not in self:
+            self[name] = Signal()
+
+        for slot in slots:
+            self[name].connect(slot)
+
+    def deregister(self, name):
+        """
+        Removes a given signal
+        :param name: the signal to deregister
+        """
+        self.pop(name, None)
+
+    def emit(self, signalName, *args, **kwargs):
+        """
+        Emits a signal by name if it exists. Any additional args or kwargs are passed to the signal
+        :param signalName: the signal name to emit
+        """
+        assert signalName in self, "%s is not a registered signal" % signalName
+        self[signalName].emit(*args, **kwargs)
+
+    def connect(self, signalName, slot):
+        """
+        Connects a given signal to a given slot
+        :param signalName: the signal name to connect to
+        :param slot: the callable slot to register
+        """
+        assert signalName in self, "%s is not a registered signal" % signalName
+        self[signalName].connect(slot)
+
+    def block(self, signals=None, isBlocked=True):
+        """
+        Sets the block on any provided signals, or to all signals
+
+        :param signals: defaults to all signals. Accepts either a single string or a list of strings
+        :param isBlocked: the state to set the signal to
+        """
+        if signals:
+            try:
+                if isinstance(signals, basestring):
+                    signals = [signals]
+            except NameError:
+                if isinstance(signals, str):
+                    signals = [signals]
+
+        signals = signals or self.keys()
+
+        for signal in signals:
+            if signal not in self:
+                raise RuntimeError("Could not find signal matching %s" % signal)
+            self[signal].block(isBlocked)
+
+
+class ClassSignalFactory(object):
+    """
+    The class signal allows a signal factory to be set on a class rather than an instance.
+    """
+    _map = {}
+    _names = set()
+
+    def __get__(self, instance, owner):
+        tmp = self._map.setdefault(self, weakref.WeakKeyDictionary())
+
+        signal = tmp.setdefault(instance, SignalFactory())
+        for name in self._names:
+            signal.register(name)
+
+        return signal
+
+    def __set__(self, instance, value):
+        raise RuntimeError("Cannot assign to a Signal object")
+
+    def register(self, name):
+        """
+        Registers a new signal with the given name
+        :param name: The signal to register
+        """
+        self._names.add(name)