pve

pve/node.py

@@ -0,0 +1,100 @@
+# People's Video Editor: high quality, GPU accelerated mp4 editor
+# Copyright (C) 2025 Roz K <roz@rozk.net>
+#
+# This file is part of People's Video Editor.
+#
+# People's Video Editor is free software: you can redistribute it and/or modify it under the terms of the
+# GNU General Public License as published by the Free Software Foundation, either version 3 of the License,
+# or (at your option) any later version.
+#
+# People's Video Editor is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along with People's Video Editor.
+# If not, see <https://www.gnu.org/licenses/>.
+
+from weakref import ref
+
+class Node:
+    __slots__ = 'parent', 'children', 'state', '__weakref__'
+
+    STATE_NEW      = 0
+    STATE_MODIFIED = 1
+    STATE_BUILT    = 2
+
+    def __init__(self, parent = None, children = None):
+        self.parent = None
+        self.children = None
+        self.state = Node.STATE_NEW
+        if children is not None:
+            self.add_children(children)
+        if parent is not None:
+            parent.add_child(self)
+
+    def __del__(self):
+        if self.parent is not None:
+            self.parent().remove_child(self)
+
+    def add_child(self, child: Node):
+        assert child.parent is None
+        child.parent = ref(self)
+        if self.children is None:
+            self.children = [child]
+        else:
+            self.children.append(child)
+        child.state = Node.STATE_NEW
+        self.set_modified()
+
+    def add_children(self, children):
+        for child in children:
+            self.add_child(child)
+
+    def remove_child(self, child: Node):
+        assert child.parent is self
+        child.parent = None
+        self.children.remove(child)
+        self.set_modified()
+
+    def remove_children(self, children):
+        for child in children:
+            self.remove_child(child)
+
+    def is_new(self):
+        return self.state == Node.STATE_NEW
+
+    def needs_rebuilding(self):
+        return self.state != Node.STATE_BUILT
+
+    def set_modified(self):
+        if self.needs_rebuilding():
+            return
+        self.state = Node.STATE_MODIFIED
+        if self.parent is not None:
+            self.set_parent_modified(self.parent())
+
+    def set_parent_modified(self, parent):
+        parent.set_modified()
+
+    def rebuild(self):
+        if not self.needs_rebuilding():
+            return True
+        if self.children is not None:
+            if not self.rebuild_children(self.children):
+                return False
+        if not self.build():
+            return False
+        self.state = Node.STATE_BUILT
+        return True
+
+    def rebuild_children(self, children):
+        for child in children:
+            if not self.rebuild_child(child):
+                return False
+        return True
+
+    def rebuild_child(self, child):
+        return child.rebuild()
+
+    def build(self):
+        return True