#45 - Feature: explicit matching of 'starred' items

- new keyword added to support items starred with Obsidian core plugin 'Starred'
  - the keyword is `starred:`
- detection and more user friendly handling of the general error condition when the File Explorer is not available
  - new ribbon status icon shape to indicate the general error plus detailed error logged to the console

README.md

@@ -578,6 +578,12 @@ States of the ribbon icon:
 	- Fix the problem in specification and click the ribbon icon to re-enable custom sorting.
 	- If syntax error is not fixed, the notice baloon with show error details. Syntax error details are also visible in
 	  the developer console
+- ![General Error](./docs/icons/icon-general-error.png) Plugin suspended. General error.
+    - File Explorer not available or other type of general error
+    - File Explorer is a core Obsidian plugin (named __Files__) and thus can be disabled in Obsidian settings
+    - Some community plugins (like __MAKE.md__) also disable the File Explorer by default
+    - See obsidinan developer console for detailed error message
+    - To fix the problem, enable the File Explorer (in Obsidian or in the community plugin responsible for hididing it)
 - ![Sorting not applied](./docs/icons/icon-not-applied.png) Plugin enabled but the custom sorting was not applied.
 	- This can happen when reinstalling the plugin and in similar cases
 	- Click the ribbon icon twice to re-enable the custom sorting.

docs/manual.md

@@ -1,6 +1,6 @@
 > Document is partial, creation in progress
-> Please refer to [README.md](../README.md) for usage examples
+> Please refer to [README.md](../README.md) for more usage examples
-> Check [syntax-reference.md](./syntax-reference.md), maybe that file has already some content?
+> Check also [syntax-reference.md](./syntax-reference.md)
 
 ---
 Some sections added ad-hoc, to be integrated later
@@ -164,3 +164,81 @@ sorting-spec: |
 The artificial separator `---+---` defines a sorting group, which will not match any folders or files
 and is used here to logically separate the series of combined groups into to logical sets
 
+## Matching starred items
+
+The Obsidian core plugin `Starred` allows the user to 'star' files
+The keyword `starred:` allows matching such items. A folder is considered _starred_ if at least one immediate child file is starred
+
+**Example:**
+
+Consider the below sorting spec:
+```yaml
+---
+sorting-spec: |
+  //       Example sorting configuration showing
+    //     how to push the starred items to the top
+    //
+    // the line below applies the sorting specification
+    //  to all folders in the vault
+  target-folder: /*
+    // the sorting order specification for the target folder(s)
+  > advanced created 
+    // the first group of items captures the files and folders which
+    // are 'starred' in Obsidian core 'Starred' plugin.
+    // Items in this group inherit the sorting order of target folder
+  starred:
+    // No further groups specified, which means all other items follow the
+    // starred items, also in the order specified
+---
+```
+
+The above sorting specification pushes the _starred_ items to the top
+To achieve the opposite effect and push the starred items to the bottom, use the below sorting spec:
+
+```yaml
+---
+sorting-spec: |
+  //       Example sorting configuration showing
+    //     how to push the starred items to the bottom
+    //
+    // the line below applies the sorting specification
+    //  to all folders in the vault
+  target-folder: /*
+    // the sorting order specification for the target folder(s)
+  > a-z
+    // the first group of items captures all of the files and folders which don't match any other sorting rule
+    // Items in this group inherit the sorting order of target folder
+  /folders:files
+    // the second group of items captures the files and folders which
+    // are 'starred' in Obsidian core 'Starred' plugin.
+    // Items in this group also inherit the sorting order of target folder
+  starred:
+---
+```
+
+For a broader view, the same effect (as in previous example) can be achieved using the priorities
+of sorting rules:
+
+```yaml
+---
+sorting-spec: |
+  //       Example sorting configuration showing
+    //     how to push the starred items to the bottom
+    //
+    // the line below applies the sorting specification
+    //  to all folders in the vault
+  target-folder: /*
+    // the sorting order specification for the target folder(s)
+  > a-z
+    // the first group of items captures all of the files and folders
+    // Items in this group inherit the sorting order of target folder
+  ...
+    // the second group of items captures the files and folders which
+    // are 'starred' in Obsidian core 'Starred' plugin.
+    // Items in this group also inherit the sorting order of target folder
+    // The priority '/!' indicator tells to evaluate this sorting rule before other rules
+    // If it were not used, the prevoius rule '...' would eat all of the folders and items
+    // and the starred items wouldn't be pushed to the bottom
+  /! starred:
+---
+```

docs/syntax-reference.md

@@ -144,6 +144,7 @@ Some tokens have shorter equivalents, which can be used interchangeably:
 - `/:files` --> `/:` e.g. `/:files Chapter \.d+ ...` is equivalent to `/: Chapter \.d+ ...`
 - `/:files.` --> `/:.` e.g. `/:files. ... \-D+.md` is equivalent to `/:. ... \-D+.md`
 - `/folders` --> `/` e.g. `/folders Archive...` is equivalent to `/ Archive...`
+- `/folders:files` --> `%` e.g. `/folders:files Chapter...` is equivalent to `% Chapter...`
 
 Additional shorter equivalents to allow single-liners like `sorting-spec: \< a-z`:
 - `order-asc:` --> `\<` e.g. `order-asc: modified` is equivalent to `\< modified`

src/custom-sort/custom-sort-types.ts

@@ -7,7 +7,8 @@ export enum CustomSortGroupType {
 	ExactPrefix,						  // ... while the Outsiders captures items which didn't match any of other defined groups
 	ExactSuffix,
 	ExactHeadAndTail, // Like W...n or Un...ed, which is shorter variant of typing the entire title
-	HasMetadataField  // Notes (or folder's notes) containing a specific metadata field
+	HasMetadataField,  // Notes (or folder's notes) containing a specific metadata field
+	StarredOnly
 }
 
 export enum CustomSortOrder {

src/custom-sort/custom-sort.spec.ts

@@ -11,6 +11,7 @@ import {
 } from './custom-sort';
 import {CustomSortGroupType, CustomSortOrder, CustomSortSpec, RegExpSpec} from './custom-sort-types';
 import {CompoundDashNumberNormalizerFn, CompoundDotRomanNumberNormalizerFn} from "./sorting-spec-processor";
+import {findStarredFile_pathParam, Starred_PluginInstance} from "../utils/StarredPluginSignature";
 
 const mockTFile = (basename: string, ext: string, size?: number, ctime?: number, mtime?: number): TFile => {
 	return {
@@ -51,7 +52,7 @@ const mockTFolderWithChildren = (name: string): TFolder => {
 	const child4: TFile = mockTFile('Child file 2 created as newest, not modified at all', 'md', 100, TIMESTAMP_NEWEST, TIMESTAMP_NEWEST)
 	const child5: TFile = mockTFile('Child file 3 created inbetween, modified inbetween', 'md', 100, TIMESTAMP_INBETWEEN, TIMESTAMP_INBETWEEN)
 
-	return mockTFolder('Mock parent folder', [child1, child2, child3, child4, child5])
+	return mockTFolder(name, [child1, child2, child3, child4, child5])
 }
 
 const MockedLoc: Pos = {
@@ -879,6 +880,193 @@ describe('determineSortingGroup', () => {
 			} as FolderItemForSorting);
 		})
 	})
+	describe('CustomSortGroupType.StarredOnly', () => {
+		it('should not match not starred file', () => {
+			// given
+			const file: TFile = mockTFile('References', 'md', 111, MOCK_TIMESTAMP + 222, MOCK_TIMESTAMP + 333);
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['/'],
+				groups: [{
+					type: CustomSortGroupType.StarredOnly
+				}]
+			}
+			const starredPluginInstance: Partial<Starred_PluginInstance> = {
+				findStarredFile: jest.fn( function(filePath: findStarredFile_pathParam): TFile | null {
+					return null
+				})
+			}
+
+			// when
+			const result = determineSortingGroup(file, sortSpec, {
+				starredPluginInstance: starredPluginInstance as Starred_PluginInstance
+			})
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 1,  // The lastIdx+1, group not determined
+				isFolder: false,
+				sortString: "References.md",
+				ctimeNewest: MOCK_TIMESTAMP + 222,
+				ctimeOldest: MOCK_TIMESTAMP + 222,
+				mtime: MOCK_TIMESTAMP + 333,
+				path: 'Some parent folder/References.md'
+			});
+			expect(starredPluginInstance.findStarredFile).toHaveBeenCalledTimes(1)
+		})
+		it('should match starred file', () => {
+			// given
+			const file: TFile = mockTFile('References', 'md', 111, MOCK_TIMESTAMP + 222, MOCK_TIMESTAMP + 333);
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['/'],
+				groups: [{
+					type: CustomSortGroupType.StarredOnly
+				}]
+			}
+			const starredPluginInstance: Partial<Starred_PluginInstance> = {
+				findStarredFile: jest.fn( function(filePath: findStarredFile_pathParam): TFile | null {
+					return filePath.path === 'Some parent folder/References.md' ? file : null
+				})
+			}
+
+			// when
+			const result = determineSortingGroup(file, sortSpec, {
+				starredPluginInstance: starredPluginInstance as Starred_PluginInstance
+			})
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 0,
+				isFolder: false,
+				sortString: "References.md",
+				ctimeNewest: MOCK_TIMESTAMP + 222,
+				ctimeOldest: MOCK_TIMESTAMP + 222,
+				mtime: MOCK_TIMESTAMP + 333,
+				path: 'Some parent folder/References.md'
+			});
+			expect(starredPluginInstance.findStarredFile).toHaveBeenCalledTimes(1)
+		})
+		it('should not match empty folder', () => {
+			// given
+			const folder: TFolder = mockTFolder('TestEmptyFolder');
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['/'],
+				groups: [{
+					type: CustomSortGroupType.StarredOnly
+				}]
+			}
+			const starredPluginInstance: Partial<Starred_PluginInstance> = {
+				findStarredFile: jest.fn( function(filePath: findStarredFile_pathParam): TFile | null {
+					return filePath.path === 'Some parent folder/References.md' ? {} as TFile : null
+				})
+			}
+
+			// when
+			const result = determineSortingGroup(folder, sortSpec, {
+				starredPluginInstance: starredPluginInstance as Starred_PluginInstance
+			})
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 1,  // The lastIdx+1, group not determined
+				isFolder: true,
+				sortString: "TestEmptyFolder",
+				ctimeNewest: 0,
+				ctimeOldest: 0,
+				mtime: 0,
+				path: 'TestEmptyFolder',
+				folder: {
+					children: [],
+					isRoot: expect.any(Function),
+					name: "TestEmptyFolder",
+					parent: {},
+					path: "TestEmptyFolder",
+					vault: {}
+				}
+			});
+			expect(starredPluginInstance.findStarredFile).not.toHaveBeenCalled()
+		})
+		it('should not match folder w/o starred items', () => {
+			// given
+			const folder: TFolder = mockTFolderWithChildren('TestEmptyFolder');
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['/'],
+				groups: [{
+					type: CustomSortGroupType.StarredOnly
+				}]
+			}
+			const starredPluginInstance: Partial<Starred_PluginInstance> = {
+				findStarredFile: jest.fn( function(filePath: findStarredFile_pathParam): TFile | null {
+					return filePath.path === 'Some parent folder/References.md' ? {} as TFile : null
+				})
+			}
+
+			// when
+			const result = determineSortingGroup(folder, sortSpec, {
+				starredPluginInstance: starredPluginInstance as Starred_PluginInstance
+			})
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 1,  // The lastIdx+1, group not determined
+				isFolder: true,
+				sortString: "TestEmptyFolder",
+				ctimeNewest: 0,
+				ctimeOldest: 0,
+				mtime: 0,
+				path: 'TestEmptyFolder',
+				folder: {
+					children: expect.any(Array),
+					isRoot: expect.any(Function),
+					name: "TestEmptyFolder",
+					parent: {},
+					path: "TestEmptyFolder",
+					vault: {}
+				}
+			});
+			expect(starredPluginInstance.findStarredFile).toHaveBeenCalledTimes(folder.children.filter(f => (f as any).isRoot === undefined).length)
+		})
+		it('should match folder with one starred item', () => {
+			// given
+			const folder: TFolder = mockTFolderWithChildren('TestEmptyFolder');
+			const sortSpec: CustomSortSpec = {
+				targetFoldersPaths: ['/'],
+				groups: [{
+					type: CustomSortGroupType.StarredOnly
+				}]
+			}
+			const starredPluginInstance: Partial<Starred_PluginInstance> = {
+				findStarredFile: jest.fn(function (filePath: findStarredFile_pathParam): TFile | null {
+					return filePath.path === 'Some parent folder/Child file 2 created as newest, not modified at all.md' ? {} as TFile : null
+				})
+			}
+
+			// when
+			const result = determineSortingGroup(folder, sortSpec, {
+				starredPluginInstance: starredPluginInstance as Starred_PluginInstance
+			})
+
+			// then
+			expect(result).toEqual({
+				groupIdx: 0,
+				isFolder: true,
+				sortString: "TestEmptyFolder",
+				ctimeNewest: 0,
+				ctimeOldest: 0,
+				mtime: 0,
+				path: 'TestEmptyFolder',
+				folder: {
+					children: expect.any(Array),
+					isRoot: expect.any(Function),
+					name: "TestEmptyFolder",
+					parent: {},
+					path: "TestEmptyFolder",
+					vault: {}
+				}
+			});
+				// assume optimized checking of starred items -> first match ends the check
+			expect(starredPluginInstance.findStarredFile).toHaveBeenCalledTimes(2)
+		})
+	})
 	describe('when sort by metadata is involved', () => {
 		it('should correctly read direct metadata from File item (order by metadata set on group) alph', () => {
 			// given
@@ -1367,34 +1555,10 @@ describe('determineFolderDatesIfNeeded', () => {
 			}],
 			outsidersGroupIdx: OUTSIDERS_GROUP_IDX
 		}
-		const cardinality = {[OUTSIDERS_GROUP_IDX]: 10}  // Group 0 contains 10 items
 
 		// when
 		const result: FolderItemForSorting = determineSortingGroup(folder, sortSpec)
-		determineFolderDatesIfNeeded([result], sortSpec, cardinality)
+		determineFolderDatesIfNeeded([result], sortSpec)
-
-		// then
-		expect(result.ctimeOldest).toEqual(DEFAULT_FOLDER_CTIME)
-		expect(result.ctimeNewest).toEqual(DEFAULT_FOLDER_CTIME)
-		expect(result.mtime).toEqual(DEFAULT_FOLDER_CTIME)
-	})
-	it('should not be triggered if not needed - the folder is an only item', () => {
-		// given
-		const folder: TFolder = mockTFolderWithChildren('Test folder 1')
-		const OUTSIDERS_GROUP_IDX = 0
-		const sortSpec: CustomSortSpec = {
-			targetFoldersPaths: ['/'],
-			groups: [{
-				type: CustomSortGroupType.Outsiders,
-				order: CustomSortOrder.byModifiedTimeAdvanced
-			}],
-			outsidersGroupIdx: OUTSIDERS_GROUP_IDX
-		}
-		const cardinality = {[OUTSIDERS_GROUP_IDX]: 1}  // Group 0 contains the folder alone
-
-		// when
-		const result: FolderItemForSorting = determineSortingGroup(folder, sortSpec)
-		determineFolderDatesIfNeeded([result], sortSpec, cardinality)
 
 		// then
 		expect(result.ctimeOldest).toEqual(DEFAULT_FOLDER_CTIME)
@@ -1413,11 +1577,10 @@ describe('determineFolderDatesIfNeeded', () => {
 			}],
 			outsidersGroupIdx: OUTSIDERS_GROUP_IDX
 		}
-		const cardinality = {[OUTSIDERS_GROUP_IDX]: 10}  // Group 0 contains 10 items
 
 		// when
 		const result: FolderItemForSorting = determineSortingGroup(folder, sortSpec)
-		determineFolderDatesIfNeeded([result], sortSpec, cardinality)
+		determineFolderDatesIfNeeded([result], sortSpec)
 
 		// then
 		expect(result.ctimeOldest).toEqual(TIMESTAMP_OLDEST)

src/custom-sort/custom-sort.ts

@@ -1,4 +1,16 @@
-import {FrontMatterCache, requireApiVersion, TAbstractFile, TFile, TFolder} from 'obsidian';
+import {
+	App,
+	FrontMatterCache,
+	InstalledPlugin,
+	requireApiVersion,
+	TAbstractFile,
+	TFile,
+	TFolder
+} from 'obsidian';
+import {
+	Starred_PluginInstance,
+	StarredPlugin_findStarredFile_methodName
+} from '../utils/StarredPluginSignature'
 import {
 	CustomSortGroup,
 	CustomSortGroupType,
@@ -140,7 +152,11 @@ export const matchGroupRegex = (theRegex: RegExpSpec, nameForMatching: string):
 	return [false, undefined, undefined]
 }
 
-export const determineSortingGroup = function (entry: TFile | TFolder, spec: CustomSortSpec): FolderItemForSorting {
+export interface Context {
+	starredPluginInstance?: Starred_PluginInstance
+}
+
+export const determineSortingGroup = function (entry: TFile | TFolder, spec: CustomSortSpec, ctx?: Context): FolderItemForSorting {
 	let groupIdx: number
 	let determined: boolean = false
 	let matchedGroup: string | null | undefined
@@ -235,6 +251,19 @@ export const determineSortingGroup = function (entry: TFile | TFolder, spec: Cus
 					}
 				}
 				break
+			case CustomSortGroupType.StarredOnly:
+				if (ctx?.starredPluginInstance) {
+					let starred: boolean
+					if (aFile) {
+						starred = !!ctx.starredPluginInstance[StarredPlugin_findStarredFile_methodName]({path: entry.path})
+					} else { // aFolder
+						starred = determineStarredStatusOfFolder(entry as TFolder, ctx.starredPluginInstance)
+					}
+					if (starred) {
+						determined = true
+					}
+				}
+				break
 			case CustomSortGroupType.MatchAll:
 				determined = true;
 				break
@@ -360,11 +389,30 @@ export const determineDatesForFolder = (folder: TFolder, now: number): [Modified
 	return [mtimeOfFolder, ctimeNewestOfFolder, ctimeOldestOfFolder]
 }
 
-export const determineFolderDatesIfNeeded = (folderItems: Array<FolderItemForSorting>, sortingSpec: CustomSortSpec, sortingGroupsCardinality: {[key: number]: number} = {}) => {
+export const StarredCorePluginId: string = 'starred'
+
+export const getStarredPlugin = (app?: App): Starred_PluginInstance | undefined => {
+	const starredPlugin: InstalledPlugin | undefined = app?.internalPlugins?.getPluginById(StarredCorePluginId)
+	if (starredPlugin && starredPlugin.enabled && starredPlugin.instance) {
+		const starredPluginInstance: Starred_PluginInstance = starredPlugin.instance as Starred_PluginInstance
+		// defensive programming, in case Obsidian changes its internal APIs
+		if (typeof starredPluginInstance?.[StarredPlugin_findStarredFile_methodName] === 'function') {
+			return starredPluginInstance
+		}
+	}
+}
+
+export const determineStarredStatusOfFolder = (folder: TFolder, starredPluginInstance: Starred_PluginInstance): boolean => {
+	return folder.children.some((folderItem) => {
+		return !isFolder(folderItem) && starredPluginInstance[StarredPlugin_findStarredFile_methodName]({path: folderItem.path})
+	})
+}
+
+export const determineFolderDatesIfNeeded = (folderItems: Array<FolderItemForSorting>, sortingSpec: CustomSortSpec) => {
 	const Now: number = Date.now()
 	folderItems.forEach((item) => {
 		const groupIdx: number | undefined = item.groupIdx
-		if (groupIdx !== undefined && sortingGroupsCardinality[groupIdx] > 1) {
+		if (groupIdx !== undefined) {
 			const groupOrder: CustomSortOrder | undefined = sortingSpec.groups[groupIdx].order
 			if (sortOrderNeedsFolderDates(groupOrder)) {
 				if (item.folder) {
@@ -377,8 +425,8 @@ export const determineFolderDatesIfNeeded = (folderItems: Array<FolderItemForSor
 
 export const folderSort = function (sortingSpec: CustomSortSpec, order: string[]) {
 	let fileExplorer = this.fileExplorer
-	const sortingGroupsCardinality: {[key: number]: number} = {}
 	sortingSpec._mCache = sortingSpec.plugin?.app.metadataCache
+	const starredPluginInstance: Starred_PluginInstance | undefined = getStarredPlugin(sortingSpec?.plugin?.app)
 
 	const folderItems: Array<FolderItemForSorting> = (sortingSpec.itemsToHide ?
 		this.file.children.filter((entry: TFile | TFolder) => {
@@ -387,16 +435,14 @@ export const folderSort = function (sortingSpec: CustomSortSpec, order: string[]
 		:
 		this.file.children)
 		.map((entry: TFile | TFolder) => {
-			const itemForSorting: FolderItemForSorting = determineSortingGroup(entry, sortingSpec)
+			const itemForSorting: FolderItemForSorting = determineSortingGroup(entry, sortingSpec, {
-			const groupIdx: number | undefined = itemForSorting.groupIdx
+				starredPluginInstance: starredPluginInstance
-			if (groupIdx !== undefined) {
+			})
-				sortingGroupsCardinality[groupIdx] = 1 + (sortingGroupsCardinality[groupIdx] ?? 0)
-			}
 			return itemForSorting
 		})
 
 	// Finally, for advanced sorting by modified date, for some folders the modified date has to be determined
-	determineFolderDatesIfNeeded(folderItems, sortingSpec, sortingGroupsCardinality)
+	determineFolderDatesIfNeeded(folderItems, sortingSpec)
 
 	folderItems.sort(function (itA: FolderItemForSorting, itB: FolderItemForSorting) {
 		return compareTwoItems(itA, itB, sortingSpec);

src/custom-sort/icons.ts

@@ -4,6 +4,7 @@ export const ICON_SORT_ENABLED_ACTIVE: string = 'custom-sort-icon-active'
 export const ICON_SORT_SUSPENDED: string = 'custom-sort-icon-suspended'
 export const ICON_SORT_ENABLED_NOT_APPLIED: string = 'custom-sort-icon-enabled-not-applied'
 export const ICON_SORT_SUSPENDED_SYNTAX_ERROR: string = 'custom-sort-icon-syntax-error'
+export const ICON_SORT_SUSPENDED_GENERAL_ERROR: string = 'custom-sort-icon-general-error'
 
 export function addIcons() {
 	addIcon(ICON_SORT_ENABLED_ACTIVE,
@@ -24,6 +25,14 @@ export function addIcons() {
 <path d="M 11.096126 55.71973 L 20.217128 41.991214 C 21.134003 40.611175 22.99602 40.235707 24.376058 41.15258 C 24.708624 41.373533 24.99374 41.65865 25.21469 41.991214 L 34.33569 55.71973 C 35.252567 57.09977 34.8771 58.96179 33.49706 59.87866 C 33.005085 60.20552 32.42757 60.37988 31.83691 60.37988 L 13.594907 60.37988 C 11.938053 60.37988 10.594907 59.036736 10.594907 57.37988 C 10.594907 56.78922 10.769266 56.21171 11.096126 55.71973 Z" stroke="red" stroke-width="2" fill="none"/>  
 <path d="M 2.5382185 90.37054 L 20.217128 63.76105 C 21.134003 62.38101 22.99602 62.005545 24.376058 62.92242 C 24.708624 63.14337 24.99374 63.428486 25.21469 63.76105 L 42.8936 90.37054 C 43.810475 91.75058 43.435006 93.6126 42.05497 94.52947 C 41.562993 94.85633 40.985477 95.03069 40.39482 95.03069 L 5.0369993 95.03069 C 3.380145 95.03069 2.0369993 93.68755 2.0369993 92.03069 C 2.0369993 91.44004 2.2113584 90.86252 2.5382185 90.37054 Z" stroke="red" stroke-width="2" fill="none"/>  
 <path d="M 88.33569 46.24901 L 79.21469 59.97753 C 78.297815 61.35757 76.4358 61.73304 75.05576 60.81616 C 74.72319 60.59521 74.43808 60.310096 74.21713 59.97753 L 65.09613 46.24901 C 64.17925 44.868973 64.55472 43.006957 65.93476 42.09008 C 66.42673 41.76322 67.00425 41.588863 67.59491 41.588863 L 85.83691 41.588863 C 87.49377 41.588863 88.83691 42.93201 88.83691 44.58886 C 88.83691 45.17952 88.66255 45.757036 88.33569 46.24901 Z" fill="red"/>  
+<path d="M 88.33569 77.48964 L 79.21469 91.21816 C 78.297815 92.5982 76.4358 92.97366 75.05576 92.05679 C 74.72319 91.83584 74.43808 91.55072 74.21713 91.21816 L 65.09613 77.48964 C 64.17925 76.1096 64.55472 74.247585 65.93476 73.33071 C 66.42673 73.00385 67.00425 72.82949 67.59491 72.82949 L 85.83691 72.82949 C 87.49377 72.82949 88.83691 74.17264 88.83691 75.82949 C 88.83691 76.42015 88.66255 76.99766 88.33569 77.48964 Z" fill="red"/>`
+	)
+	addIcon(ICON_SORT_SUSPENDED_GENERAL_ERROR,
+		`<path d="M 93.54751 9.983795 L 79.21469 31.556912 C 78.297815 32.93695 76.4358 33.31242 75.05576 32.395544 C 74.72319 32.174593 74.43808 31.88948 74.21713 31.556912 L 59.8843 9.983795 C 58.96743 8.603756 59.3429 6.74174 60.722935 5.824865 C 61.21491 5.4980047 61.792426 5.3236456 62.383084 5.3236456 L 91.04873 5.3236456 C 92.70559 5.3236456 94.04873 6.666791 94.04873 8.323646 C 94.04873 8.914304 93.87437 9.49182 93.54751 9.983795 Z" fill="red"/>  
+<path d="M 11.096126 32.678017 L 20.217128 18.949499 C 21.134003 17.56946 22.99602 17.193992 24.376058 18.110867 C 24.708624 18.331818 24.99374 18.616933 25.21469 18.949499 L 34.33569 32.678017 C 35.252567 34.058055 34.8771 35.92007 33.49706 36.836947 C 33.005085 37.163807 32.42757 37.338166 31.83691 37.338166 L 13.594907 37.338166 C 11.938053 37.338166 10.594907 35.99502 10.594907 34.338166 C 10.594907 33.747508 10.769266 33.16999 11.096126 32.678017 Z" fill="red"/>  
+<path d="M 11.096126 55.71973 L 20.217128 41.991214 C 21.134003 40.611175 22.99602 40.235707 24.376058 41.15258 C 24.708624 41.373533 24.99374 41.65865 25.21469 41.991214 L 34.33569 55.71973 C 35.252567 57.09977 34.8771 58.96179 33.49706 59.87866 C 33.005085 60.20552 32.42757 60.37988 31.83691 60.37988 L 13.594907 60.37988 C 11.938053 60.37988 10.594907 59.036736 10.594907 57.37988 C 10.594907 56.78922 10.769266 56.21171 11.096126 55.71973 Z" fill="red"/>  
+<path d="M 2.5382185 90.37054 L 20.217128 63.76105 C 21.134003 62.38101 22.99602 62.005545 24.376058 62.92242 C 24.708624 63.14337 24.99374 63.428486 25.21469 63.76105 L 42.8936 90.37054 C 43.810475 91.75058 43.435006 93.6126 42.05497 94.52947 C 41.562993 94.85633 40.985477 95.03069 40.39482 95.03069 L 5.0369993 95.03069 C 3.380145 95.03069 2.0369993 93.68755 2.0369993 92.03069 C 2.0369993 91.44004 2.2113584 90.86252 2.5382185 90.37054 Z" fill="red"/>  
+<path d="M 88.33569 46.24901 L 79.21469 59.97753 C 78.297815 61.35757 76.4358 61.73304 75.05576 60.81616 C 74.72319 60.59521 74.43808 60.310096 74.21713 59.97753 L 65.09613 46.24901 C 64.17925 44.868973 64.55472 43.006957 65.93476 42.09008 C 66.42673 41.76322 67.00425 41.588863 67.59491 41.588863 L 85.83691 41.588863 C 87.49377 41.588863 88.83691 42.93201 88.83691 44.58886 C 88.83691 45.17952 88.66255 45.757036 88.33569 46.24901 Z" fill="red"/>  
 <path d="M 88.33569 77.48964 L 79.21469 91.21816 C 78.297815 92.5982 76.4358 92.97366 75.05576 92.05679 C 74.72319 91.83584 74.43808 91.55072 74.21713 91.21816 L 65.09613 77.48964 C 64.17925 76.1096 64.55472 74.247585 65.93476 73.33071 C 66.42673 73.00385 67.00425 72.82949 67.59491 72.82949 L 85.83691 72.82949 C 87.49377 72.82949 88.83691 74.17264 88.83691 75.82949 C 88.83691 76.42015 88.66255 76.99766 88.33569 77.48964 Z" fill="red"/>`
 	)
 	addIcon(ICON_SORT_ENABLED_NOT_APPLIED,

src/custom-sort/sorting-spec-processor.spec.ts

@@ -29,6 +29,9 @@ target-folder: tricky folder
  < a-z by-metadata: Some-dedicated-field
 with-metadata: Pages 
  > a-z by-metadata: 
+starred:
+/:files starred:
+/folders starred:
 
 :::: Conceptual model
 /: Entities
@@ -82,6 +85,9 @@ target-folder: tricky folder 2
  < a-z by-metadata: Some-dedicated-field
 % with-metadata: Pages 
  > a-z by-metadata:
+/folders:files starred:
+/:files starred:
+/folders starred:
 
 :::: Conceptual model
 /:files Entities
@@ -165,11 +171,22 @@ const expectedSortSpecsExampleA: { [key: string]: CustomSortSpec } = {
 			type: CustomSortGroupType.HasMetadataField,
 			withMetadataFieldName: 'Pages',
 			order: CustomSortOrder.byMetadataFieldAlphabeticalReverse
+		}, {
+			type: CustomSortGroupType.StarredOnly,
+			order: CustomSortOrder.alphabetical
+		}, {
+			type: CustomSortGroupType.StarredOnly,
+			filesOnly: true,
+			order: CustomSortOrder.alphabetical
+		}, {
+			type: CustomSortGroupType.StarredOnly,
+			foldersOnly: true,
+			order: CustomSortOrder.alphabetical
 		}, {
 			order: CustomSortOrder.alphabetical,
 			type: CustomSortGroupType.Outsiders
 		}],
-		outsidersGroupIdx: 2,
+		outsidersGroupIdx: 5,
 		targetFoldersPaths: [
 			'tricky folder 2'
 		]

src/custom-sort/sorting-spec-processor.ts

@@ -188,12 +188,15 @@ const FilesWithExtGroupShortLexeme: string = '/:.'
 const FoldersGroupVerboseLexeme: string = '/folders'
 const FoldersGroupShortLexeme: string = '/'
 const AnyTypeGroupLexemeShort: string = '%'  // See % as a combination of / and :
-const AnyTypeGroupLexeme: string = '/%'  // See % as a combination of / and :
+const AnyTypeGroupLexeme1: string = '/folders:files'
+const AnyTypeGroupLexeme2: string = '/%'  // See % as a combination of / and :
 const HideItemShortLexeme: string = '--%'  // See % as a combination of / and :
 const HideItemVerboseLexeme: string = '/--hide:'
 
 const MetadataFieldIndicatorLexeme: string = 'with-metadata:'
 
+const StarredItemsIndicatorLexeme: string = 'starred:'
+
 const CommentPrefix: string = '//'
 
 const PriorityModifierPrio1Lexeme: string = '/!'
@@ -232,7 +235,8 @@ const SortingGroupPrefixes: { [key: string]: SortingGroupType } = {
 	[FoldersGroupShortLexeme]: {foldersOnly: true},
 	[FoldersGroupVerboseLexeme]: {foldersOnly: true},
 	[AnyTypeGroupLexemeShort]: {},
-	[AnyTypeGroupLexeme]: {},
+	[AnyTypeGroupLexeme1]: {},
+	[AnyTypeGroupLexeme2]: {},
 	[HideItemShortLexeme]: {itemToHide: true},
 	[HideItemVerboseLexeme]: {itemToHide: true}
 }
@@ -1337,6 +1341,13 @@ export class SortingSpecProcessor {
 						foldersOnly: spec.foldersOnly,
 						matchFilenameWithExt: spec.matchFilenameWithExt
 					}
+				} else if (theOnly.startsWith(StarredItemsIndicatorLexeme)) {
+					return {
+						type: CustomSortGroupType.StarredOnly,
+						filesOnly: spec.filesOnly,
+						foldersOnly: spec.foldersOnly,
+						matchFilenameWithExt: spec.matchFilenameWithExt
+					}
 				} else {
 					// For non-three dots single text line assume exact match group
 					return {

src/main.ts

@@ -23,6 +23,7 @@ import {
 	ICON_SORT_ENABLED_ACTIVE,
 	ICON_SORT_ENABLED_NOT_APPLIED,
 	ICON_SORT_SUSPENDED,
+	ICON_SORT_SUSPENDED_GENERAL_ERROR,
 	ICON_SORT_SUSPENDED_SYNTAX_ERROR
 } from "./custom-sort/icons";
 
@@ -124,8 +125,39 @@ export default class CustomSortPlugin extends Plugin {
 		}
 	}
 
+	checkFileExplorerIsAvailableAndPatchable(logWarning: boolean = true): FileExplorerView | undefined {
+		let fileExplorerView: FileExplorerView | undefined = this.getFileExplorer()
+		if (fileExplorerView
+			&& typeof fileExplorerView.createFolderDom === 'function'
+			&& typeof fileExplorerView.requestSort === 'function') {
+			return fileExplorerView
+		} else {
+			// Various scenarios when File Explorer was turned off (e.g. by some other plugin)
+			if (logWarning) {
+				this.logWarningFileExplorerNotAvailable()
+			}
+			return undefined
+		}
+	}
+
+	logWarningFileExplorerNotAvailable() {
+		const msg = `custom-sort v${this.manifest.version}: failed to locate File Explorer. The 'Files' core plugin can be disabled.\n`
+			+ `Some community plugins can also disable it.\n`
+			+ `See the example of MAKE.md plugin: https://github.com/Make-md/makemd/issues/25\n`
+			+ `You can find there instructions on how to re-enable the File Explorer in MAKE.md plugin`
+		console.warn(msg)
+	}
+
 	// Safe to suspend when suspended and re-enable when enabled
 	switchPluginStateTo(enabled: boolean, updateRibbonBtnIcon: boolean = true) {
+		let fileExplorerView: FileExplorerView | undefined = this.checkFileExplorerIsAvailableAndPatchable()
+		if (fileExplorerView && !this.fileExplorerFolderPatched) {
+			this.fileExplorerFolderPatched = this.patchFileExplorerFolder(fileExplorerView);
+
+			if (!this.fileExplorerFolderPatched) {
+				fileExplorerView = undefined
+			}
+		}
 		this.settings.suspended = !enabled;
 		this.saveSettings()
 		let iconToSet: string
@@ -136,20 +168,24 @@ export default class CustomSortPlugin extends Plugin {
 		} else {
 			this.readAndParseSortingSpec();
 			if (this.sortSpecCache) {
-				this.showNotice('Custom sort ON');
+				if (fileExplorerView) {
-				this.initialAutoOrManualSortingTriggered = true
+					this.showNotice('Custom sort ON');
-				iconToSet = ICON_SORT_ENABLED_ACTIVE
+					this.initialAutoOrManualSortingTriggered = true
+					iconToSet = ICON_SORT_ENABLED_ACTIVE
+				} else {
+					this.showNotice('Custom sort GENERAL PROBLEM. See console for detailed message.');
+					iconToSet = ICON_SORT_SUSPENDED_GENERAL_ERROR
+					this.settings.suspended = true
+					this.saveSettings()
+				}
 			} else {
 				iconToSet = ICON_SORT_SUSPENDED_SYNTAX_ERROR
 				this.settings.suspended = true
 				this.saveSettings()
 			}
 		}
-		const fileExplorerView: FileExplorerView | undefined = this.getFileExplorer()
+
 		if (fileExplorerView) {
-			if (!this.fileExplorerFolderPatched) {
-				this.fileExplorerFolderPatched = this.patchFileExplorerFolder(fileExplorerView);
-			}
 			if (this.fileExplorerFolderPatched) {
 				fileExplorerView.requestSort();
 			}
@@ -215,7 +251,7 @@ export default class CustomSortPlugin extends Plugin {
 						this.initialAutoOrManualSortingTriggered = true
 						if (this.sortSpecCache) { // successful read of sorting specifications?
 							this.showNotice('Custom sort ON')
-							const fileExplorerView: FileExplorerView | undefined = this.getFileExplorer()
+							const fileExplorerView: FileExplorerView | undefined = this.checkFileExplorerIsAvailableAndPatchable(false)
 							if (fileExplorerView) {
 								setIcon(this.ribbonIconEl, ICON_SORT_ENABLED_ACTIVE)
 								fileExplorerView.requestSort()
@@ -260,13 +296,15 @@ export default class CustomSortPlugin extends Plugin {
 	}
 
 	// For the idea of monkey-patching credits go to https://github.com/nothingislost/obsidian-bartender
-	patchFileExplorerFolder(fileExplorer?: FileExplorerView): boolean {
+	patchFileExplorerFolder(patchableFileExplorer?: FileExplorerView): boolean {
 		let plugin = this;
-		fileExplorer = fileExplorer ?? this.getFileExplorer()
+		// patching file explorer might fail here because of various non-error reasons.
-		if (fileExplorer) {
+		// That's why not showing and not logging error message here
+		patchableFileExplorer = patchableFileExplorer ?? this.checkFileExplorerIsAvailableAndPatchable(false)
+		if (patchableFileExplorer) {
 			// @ts-ignore
 			let tmpFolder = new TFolder(Vault, "");
-			let Folder = fileExplorer.createFolderDom(tmpFolder).constructor;
+			let Folder = patchableFileExplorer.createFolderDom(tmpFolder).constructor;
 			const uninstallerOfFolderSortFunctionWrapper: MonkeyAroundUninstaller = around(Folder.prototype, {
 				sort(old: any) {
 					return function (...args: any[]) {

src/types/types.d.ts

@@ -1,4 +1,4 @@
-import {TFolder, WorkspaceLeaf} from "obsidian";
+import {PluginInstance, TFolder, WorkspaceLeaf} from "obsidian";
 
 // Needed to support monkey-patching of the folder sort() function
 
@@ -7,10 +7,28 @@ declare module 'obsidian' {
 		viewByType: Record<string, (leaf: WorkspaceLeaf) => unknown>;
 	}
 
+	// undocumented internal interface - for experimental features
+	export interface PluginInstance {
+		id: string;
+	}
+
 	export interface App {
+		internalPlugins: InternalPlugins; // undocumented internal API - for experimental features
 		viewRegistry: ViewRegistry;
 	}
 
+	// undocumented internal interface - for experimental features
+	export interface InstalledPlugin {
+		enabled: boolean;
+		instance: PluginInstance;
+	}
+
+	// undocumented internal interface - for experimental features
+	export interface InternalPlugins {
+		plugins: Record<string, InstalledPlugin>;
+		getPluginById(id: string): InstalledPlugin;
+	}
+
 	interface FileExplorerFolder {
 	}
 

src/utils/StarredPluginSignature.ts

@@ -0,0 +1,11 @@
+import {PluginInstance, TFile} from "obsidian";
+
+export const StarredPlugin_findStarredFile_methodName = 'findStarredFile'
+
+export interface findStarredFile_pathParam {
+    path: string
+}
+
+export interface Starred_PluginInstance extends PluginInstance {
+    [StarredPlugin_findStarredFile_methodName]: (filePath: findStarredFile_pathParam) => TFile | null
+}