Ensure modifier dependency sanity post-deletion

This changeset ensures that if a dependant modifier's dependency is
deleted that the aforementioned modifier is deleted as well. Since this is
something of a large change, we ask for the user to confirm the operation
before actually doing so.

korman/operators/op_modifier.py

@@ -17,6 +17,7 @@ import bpy
 from bpy.props import *
 import time
 
+from ..ordered_set import OrderedSet
 from ..properties import modifiers
 
 def _fetch_modifiers():
@@ -71,17 +72,64 @@ class ModifierRemoveOperator(ModifierOperator, bpy.types.Operator):
                                   default=-1,
                                   options={"HIDDEN"})
 
+    mods2delete = CollectionProperty(type=modifiers.PlasmaModifierSpec, options=set())
+
+    def draw(self, context):
+        layout = self.layout
+        mods = context.object.plasma_modifiers
+
+        layout.label("This action will remove the following modifiers:")
+        layout = layout.column_flow(align=True)
+        for i in self.mods2delete:
+            mod = getattr(mods, i.name)
+            layout.label("    {}".format(mod.bl_label), icon=getattr(mod, "bl_icon", "NONE"))
+
     def execute(self, context):
-        assert self.active_modifier >= 0
+        want2delete = set((i.name for i in self.mods2delete))
+        mods = sorted(context.object.plasma_modifiers.modifiers, key=lambda x: x.display_order)
+        subtract = 0
 
-        for mod in context.object.plasma_modifiers.modifiers:
+        for mod in mods:
-            if mod.display_order == self.active_modifier:
+            if mod.pl_id in want2delete:
                 mod.display_order = -1
                 mod.destroyed()
-            elif mod.display_order > self.active_modifier:
+                subtract += 1
-                mod.display_order -= 1
+            else:
+                mod.display_order -= subtract
         return {"FINISHED"}
 
+    def invoke(self, context, event):
+        assert self.active_modifier >= -1
+        mods = context.object.plasma_modifiers
+        self.mods2delete.clear()
+
+        want2delete = OrderedSet()
+        for i in mods.modifiers:
+            if i.display_order == self.active_modifier:
+                want2delete.add(i.pl_id)
+                break
+        else:
+            raise IndexError()
+
+        # Here's the rub
+        # When we start, we should have just one modifier in want2delete
+        # HOWEVER, the mod may have dependencies, which in turn may have more deps
+        # So we collect them into the list... you dig?
+        for i in want2delete:
+            for mod in modifiers.PlasmaModifierProperties.__subclasses__():
+                if not getattr(mods, mod.pl_id).enabled:
+                    continue
+                if i in getattr(mod, "pl_depends", set()):
+                    want2delete.add(mod.pl_id)
+        for i in want2delete:
+            mod = self.mods2delete.add()
+            mod.name = i
+
+        if len(want2delete) == 1:
+            return self.execute(context)
+        else:
+            return context.window_manager.invoke_props_dialog(self)
+
 
 class ModifierMoveOperator(ModifierOperator):
     def swap_modifier_ids(self, mods, s1, s2):

korman/ordered_set.py

@@ -0,0 +1,200 @@
+"""
+An OrderedSet is a custom MutableSet that remembers its order, so that every
+entry has an index that can be looked up.
+
+Based on a recipe originally posted to ActiveState Recipes by Raymond Hettiger,
+and released under the MIT license.
+
+Rob Speer's changes are as follows:
+
+    - changed the content from a doubly-linked list to a regular Python list.
+      Seriously, who wants O(1) deletes but O(N) lookups by index?
+    - add() returns the index of the added item
+    - index() just returns the index of an item
+    - added a __getstate__ and __setstate__ so it can be pickled
+    - added __getitem__
+
+Updated for Python 3.5 by Adam Johnson
+"""
+import collections.abc
+
+SLICE_ALL = slice(None)
+__version__ = '2.0.1'
+
+
+def is_iterable(obj):
+    """
+    Are we being asked to look up a list of things, instead of a single thing?
+    We check for the `__iter__` attribute so that this can cover types that
+    don't have to be known by this module, such as NumPy arrays.
+
+    Strings, however, should be considered as atomic values to look up, not
+    iterables. The same goes for tuples, since they are immutable and therefore
+    valid entries.
+
+    We don't need to check for the Python 2 `unicode` type, because it doesn't
+    have an `__iter__` attribute anyway.
+    """
+    return hasattr(obj, '__iter__') and not isinstance(obj, str) and not isinstance(obj, tuple)
+
+
+class OrderedSet(collections.abc.MutableSet):
+    """
+    An OrderedSet is a custom MutableSet that remembers its order, so that
+    every entry has an index that can be looked up.
+    """
+    def __init__(self, iterable=None):
+        self.items = []
+        self.map = {}
+        if iterable is not None:
+            self |= iterable
+
+    def __len__(self):
+        return len(self.items)
+
+    def __getitem__(self, index):
+        """
+        Get the item at a given index.
+
+        If `index` is a slice, you will get back that slice of items. If it's
+        the slice [:], exactly the same object is returned. (If you want an
+        independent copy of an OrderedSet, use `OrderedSet.copy()`.)
+
+        If `index` is an iterable, you'll get the OrderedSet of items
+        corresponding to those indices. This is similar to NumPy's
+        "fancy indexing".
+        """
+        if index == SLICE_ALL:
+            return self
+        elif hasattr(index, '__index__') or isinstance(index, slice):
+            result = self.items[index]
+            if isinstance(result, list):
+                return OrderedSet(result)
+            else:
+                return result
+        elif is_iterable(index):
+            return OrderedSet([self.items[i] for i in index])
+        else:
+            raise TypeError("Don't know how to index an OrderedSet by %r" %
+                    index)
+
+    def copy(self):
+        return OrderedSet(self)
+
+    def __getstate__(self):
+        if len(self) == 0:
+            # The state can't be an empty list.
+            # We need to return a truthy value, or else __setstate__ won't be run.
+            #
+            # This could have been done more gracefully by always putting the state
+            # in a tuple, but this way is backwards- and forwards- compatible with
+            # previous versions of OrderedSet.
+            return (None,)
+        else:
+            return list(self)
+
+    def __setstate__(self, state):
+        if state == (None,):
+            self.__init__([])
+        else:
+            self.__init__(state)
+
+    def __contains__(self, key):
+        return key in self.map
+
+    def add(self, key):
+        """
+        Add `key` as an item to this OrderedSet, then return its index.
+
+        If `key` is already in the OrderedSet, return the index it already
+        had.
+        """
+        if key not in self.map:
+            self.map[key] = len(self.items)
+            self.items.append(key)
+        return self.map[key]
+    append = add
+
+    def update(self, sequence):
+        """
+        Update the set with the given iterable sequence, then return the index
+        of the last element inserted.
+        """
+        item_index = None
+        try:
+            for item in sequence:
+                item_index = self.add(item)
+        except TypeError:
+            raise ValueError('Argument needs to be an iterable, got %s' % type(sequence))
+        return item_index
+
+    def index(self, key):
+        """
+        Get the index of a given entry, raising an IndexError if it's not
+        present.
+
+        `key` can be an iterable of entries that is not a string, in which case
+        this returns a list of indices.
+        """
+        if is_iterable(key):
+            return [self.index(subkey) for subkey in key]
+        return self.map[key]
+
+    def pop(self):
+        """
+        Remove and return the last element from the set.
+
+        Raises KeyError if the set is empty.
+        """
+        if not self.items:
+            raise KeyError('Set is empty')
+
+        elem = self.items[-1]
+        del self.items[-1]
+        del self.map[elem]
+        return elem
+
+    def discard(self, key):
+        """
+        Remove an element.  Do not raise an exception if absent.
+
+        The MutableSet mixin uses this to implement the .remove() method, which
+        *does* raise an error when asked to remove a non-existent item.
+        """
+        if key in self:
+            i = self.items.index(key)
+            del self.items[i]
+            del self.map[key]
+            for k, v in self.map.items():
+                if v >= i:
+                    self.map[k] = v - 1
+
+    def clear(self):
+        """
+        Remove all items from this OrderedSet.
+        """
+        del self.items[:]
+        self.map.clear()
+
+    def __iter__(self):
+        return iter(self.items)
+
+    def __reversed__(self):
+        return reversed(self.items)
+
+    def __repr__(self):
+        if not self:
+            return '%s()' % (self.__class__.__name__,)
+        return '%s(%r)' % (self.__class__.__name__, list(self))
+
+    def __eq__(self, other):
+        if isinstance(other, OrderedSet):
+            return len(self) == len(other) and self.items == other.items
+        try:
+            other_as_set = set(other)
+        except TypeError:
+            # If `other` can't be converted into a set, it's not equal.
+            return False
+        else:
+            return set(self) == other_as_set
+

korman/properties/modifiers/__init__.py

@@ -66,6 +66,10 @@ class PlasmaModifiers(bpy.types.PropertyGroup):
         bpy.types.Object.plasma_modifiers = bpy.props.PointerProperty(type=cls)
 
 
+class PlasmaModifierSpec(bpy.types.PropertyGroup):
+    pass
+
+
 def modifier_mapping():
     """This returns a dict mapping Plasma Modifier categories to names"""