Create a selected and not-selected filter.

It's treated like a normal filterMemberships, but unlike all of the other ones (which are derivable entirely from the card itself) this FilterMap is stored in a different part of state.

Part of #688. Part of #174.

src/filters.ts

@@ -144,6 +144,9 @@ const MISSING_CONCEPT_FILTER_NAME = 'missing-concept';
 const SAME_TYPE_FILTER_NAME = 'same-type';
 const DIFFERENT_TYPE_FILTER_NAME = 'different-type';
 
+export const SELECTED_FILTER_NAME = 'selected';
+const NOT_SELECTED_FILTER_NAME = 'not-selected';
+
 /*
 * filterEquivalent - the name of the filter that, when applied to the everything
   set, will filter down to contain just the items in that set (although
@@ -1991,6 +1994,7 @@ export const INVERSE_FILTER_NAMES = Object.assign(
 	{
 		'unstarred': 'starred',
 		'unread': 'read',
+		[NOT_SELECTED_FILTER_NAME]: SELECTED_FILTER_NAME,
 		[ALL_FILTER_NAME]: NONE_FILTER_NAME,
 		[TODO_COMBINED_INVERSE_FILTER_NAME]: TODO_COMBINED_FILTER_NAME,
 	},

src/selectors.ts

@@ -25,7 +25,8 @@ import {
 	limitFilter,
 	excludeFilter,
 	cardsFilter,
-	cardTypeFilter
+	cardTypeFilter,
+	SELECTED_FILTER_NAME
 } from './filters.js';
 
 import {
@@ -155,7 +156,8 @@ import {
 	ViewMode,
 	ReferenceType,
 	SortExtra,
-	CardDiff
+	CardDiff,
+	Filters
 } from './types.js';
 
 import {
@@ -231,7 +233,7 @@ export const selectEditorMinimized = (state : State) => state.editor ? state.edi
 export const selectEditingUpdatedFromContentEditable = (state : State) => state.editor ? state.editor.updatedFromContentEditable : {};
 export const selectEditingPendingReferenceType = (state : State) : ReferenceType => state.editor ? state.editor.pendingReferenceType : 'ack';
 export const selectPendingSlug = (state : State) => state.editor ? state.editor.pendingSlug : '';
-export const selectFilters = (state : State) => state.collection ? state.collection.filters : {};
+const selectBaseFilters = (state : State) => state.collection ? state.collection.filters : {};
 const selectFiltersSnapshot = (state : State) => state.collection ? state.collection.filtersSnapshot : {};
 export const selectSections = (state : State) => state.data ? state.data.sections : {};
 export const selectTags = (state : State) => state.data ? state.data.tags : {};
@@ -431,6 +433,15 @@ export const selectKeyboardNavigates = createSelector(
 	(editing, find, compose) => !editing && !find && !compose
 );
 
+export const selectFilters = createSelector(
+	selectBaseFilters,
+	selectExplicitlySelectedCardIDs,
+	(baseFilters, selectedCards) : Filters => ({
+		...baseFilters,
+		[SELECTED_FILTER_NAME]: selectedCards
+	})
+);
+
 //This is just the userPermissions fetched; for the actual permissions object in
 //use, see selectCOmposedPermissions.
 const selectUserPermissions = (state : State) => state.user ? state.user.userPermissions : {};