Merge pull request #1165 from alfar/develop

Simple history back/forward navigation

manuskript/functions/history/History.py

@@ -0,0 +1,56 @@
+from manuskript.functions.history.NavigatedEvent import NavigatedEvent
+from manuskript.functions.history.Signal import Signal
+
+
+class History():
+    def __init__(self) -> None:
+        self._entries = []
+        self._position = 0
+        self.navigated = Signal()
+        self._navigating = False
+
+    def next(self, entry):
+        if self._navigating:
+            return
+
+        while self._position < len(self._entries) - 1:
+            self._entries.pop()
+
+        self._entries.append(entry)
+        self._position = len(self._entries) - 1
+        self._navigating = True
+        self.navigated.fire(NavigatedEvent(self._position, len(self._entries), entry))
+        self._navigating = False
+
+
+    def replace(self, entry):
+        if self._navigating:
+            return
+
+        while self._position < len(self._entries):
+            self._entries.pop()
+
+        self._entries.append(entry)
+        self._position = len(self._entries) - 1
+        self._navigating = True
+        self.navigated.fire(NavigatedEvent(self._position, len(self._entries), entry))
+        self._navigating = False
+
+    def forward(self):
+        if self._position < len(self._entries) - 1:
+            self._position += 1
+            self._navigating = True
+            self.navigated.fire(NavigatedEvent(self._position, len(self._entries), self._entries[self._position]))
+            self._navigating = False
+
+    def back(self):
+        if self._position > 0:
+            self._position -= 1
+            self._navigating = True
+            self.navigated.fire(NavigatedEvent(self._position, len(self._entries), self._entries[self._position]))
+            self._navigating = False
+
+    def reset(self):
+        self._entries.clear()
+        self._position = 0
+        self.navigated.fire(NavigatedEvent(self._position, len(self._entries), None))

manuskript/functions/history/NavigatedEvent.py

@@ -0,0 +1,5 @@
+class NavigatedEvent():
+    def __init__(self, position, count, entry) -> None:
+        self.position = position
+        self.count = count
+        self.entry = entry

manuskript/functions/history/Signal.py

@@ -0,0 +1,23 @@
+
+class Signal():
+    def __init__(self) -> None:
+        self._methods = []
+
+    def connect(self, func):
+        self._methods.append(func)
+
+    def disconnect(self, func):
+        try:
+            self._methods.remove(func)
+        except ValueError:
+            raise TypeError
+
+    def disconnect(self):
+        if len(self._methods) == 0:
+            raise TypeError
+        self._methods.pop()
+
+    def fire(self, data):
+        for m in self._methods:
+            m(data)
+