#89 - Support for multi-level sorting

- added run-time execution logic for multi-level sorting
- modified the sorter-by-metadata (required change for multi-level sorting)
- adjusted unit tests
- NO NEW UNIT TESTS
- no syntax added to support specification of multi-level (remains to be done)

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

@@ -4,6 +4,7 @@ import {
 	DEFAULT_FOLDER_MTIME,
 	determineFolderDatesIfNeeded,
 	determineSortingGroup,
+	EQUAL_OR_UNCOMPARABLE,
 	FolderItemForSorting,
 	matchGroupRegex,
 	sorterByMetadataField,
@@ -2315,7 +2316,7 @@ describe('CustomSortOrder.byMetadataFieldAlphabetical', () => {
 		expect(result1).toBe(SORT_FIRST_GOES_EARLIER)
 		expect(result2).toBe(SORT_FIRST_GOES_LATER)
 	})
-	it('should correctly fallback to alphabetical if no metadata on both items', () => {
+	it('should refuse comparison if no metadata on both items', () => {
 		// given
 		const itemA: Partial<FolderItemForSorting> = {
 			sortString: 'ccc'
@@ -2331,9 +2332,9 @@ describe('CustomSortOrder.byMetadataFieldAlphabetical', () => {
 		const result3: number = sorter(itemB as FolderItemForSorting, itemB as FolderItemForSorting)
 
 		// then
-		expect(result1).toBe(SORT_FIRST_GOES_EARLIER)
+		expect(result1).toBe(EQUAL_OR_UNCOMPARABLE)
-		expect(result2).toBe(SORT_FIRST_GOES_LATER)
+		expect(result2).toBe(EQUAL_OR_UNCOMPARABLE)
-		expect(result3).toBe(SORT_ITEMS_ARE_EQUAL)
+		expect(result3).toBe(EQUAL_OR_UNCOMPARABLE)
 	})
 })
 
@@ -2397,7 +2398,7 @@ describe('CustomSortOrder.byMetadataFieldAlphabeticalReverse', () => {
 		expect(result1).toBe(SORT_FIRST_GOES_LATER)
 		expect(result2).toBe(SORT_FIRST_GOES_EARLIER)
 	})
-	it('should correctly fallback to alphabetical reverse if no metadata on both items', () => {
+	it('should refrain from comparing if no metadata on both items', () => {
 		// given
 		const itemA: Partial<FolderItemForSorting> = {
 			sortString: 'ccc'
@@ -2413,9 +2414,9 @@ describe('CustomSortOrder.byMetadataFieldAlphabeticalReverse', () => {
 		const result3: number = sorter(itemB as FolderItemForSorting, itemB as FolderItemForSorting)
 
 		// then
-		expect(result1).toBe(SORT_FIRST_GOES_LATER)
+		expect(result1).toBe(EQUAL_OR_UNCOMPARABLE)
-		expect(result2).toBe(SORT_FIRST_GOES_EARLIER)
+		expect(result2).toBe(EQUAL_OR_UNCOMPARABLE)
-		expect(result3).toBe(SORT_ITEMS_ARE_EQUAL)
+		expect(result3).toBe(EQUAL_OR_UNCOMPARABLE)
 	})
 })
 
@@ -2428,9 +2429,9 @@ describe('sorterByMetadataField', () => {
 		[true,'mmm','mmm',1, 'e', 'd'],
 		[true,'abc',undefined,-1, 'a','a'],
 		[true,undefined,'klm',1, 'b','b'],
-		[true,undefined,undefined,0, 'a','a'],
+		[true,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'a','a'],
-		[true,undefined,undefined,-1, 'a','b'],
+		[true,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'a','b'],
-		[true,undefined,undefined,1, 'd','c'],
+		[true,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'd','c'],
 		[false,'abc','def',1, 'a', 'a'],
 		[false,'xyz','klm',-1, 'b', 'b'],
 		[false,'mmm','mmm',0, 'c', 'c'],
@@ -2438,9 +2439,9 @@ describe('sorterByMetadataField', () => {
 		[false,'mmm','mmm',-1, 'e', 'd'],
 		[false,'abc',undefined,1, 'a','a'],
 		[false,undefined,'klm',-1, 'b','b'],
-		[false,undefined,undefined,0, 'a','a'],
+		[false,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'a','a'],
-		[false,undefined,undefined,1, 'a','b'],
+		[false,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'a','b'],
-		[false,undefined,undefined,-1, 'd','c'],
+		[false,undefined,undefined,EQUAL_OR_UNCOMPARABLE, 'd','c'],
 
 	])('straight order %s, comparing %s and %s should return %s for sortStrings %s and %s',
 		(straight: boolean, metadataA: string|undefined, metadataB: string|undefined, order: number, sortStringA: string, sortStringB) => {

src/custom-sort/custom-sort.ts

@@ -4,6 +4,7 @@ import {
 	FrontMatterCache,
 	InstalledPlugin,
 	MetadataCache,
+	Plugin,
 	requireApiVersion,
 	TAbstractFile,
 	TFile,
@@ -38,7 +39,6 @@ import {
 import {
 	expandMacros
 } from "./macros";
-import {Obj} from "tern";
 
 export interface ProcessingContext {
 	// For internal transient use
@@ -82,6 +82,8 @@ const TrueAlphabetical: boolean = true
 const ReverseOrder: boolean = true
 const StraightOrder: boolean = false
 
+export const EQUAL_OR_UNCOMPARABLE: number = 0
+
 export const sorterByMetadataField:(reverseOrder?: boolean, trueAlphabetical?: boolean) => SorterFn = (reverseOrder: boolean, trueAlphabetical?: boolean) => {
 	const collatorCompareFn: CollatorCompareFn = trueAlphabetical ? CollatorTrueAlphabeticalCompare : CollatorCompare
 	return (a: FolderItemForSorting, b: FolderItemForSorting) => {
@@ -100,8 +102,8 @@ export const sorterByMetadataField:(reverseOrder?: boolean, trueAlphabetical?: b
 		// Item with metadata goes before the w/o metadata
 		if (a.metadataFieldValue) return -1
 		if (b.metadataFieldValue) return 1
-		// Fallback -> requested sort by metadata, yet none of two items contain it, use alphabetical by name
+
-		return collatorCompareFn(a.sortString, b.sortString)
+		return EQUAL_OR_UNCOMPARABLE
 	}
 }
 
@@ -190,27 +192,21 @@ export const getSorterFnFor = (sorting: CustomSortOrder, currentUIselectedSortin
 	}
 }
 
-// logic of primary and secondary sorting:
-// 0th - compare groupIdx
-// 1st - apply primary, if 0 then
-// 2nd - apply secondary if present, if 0 or not present then
-// 3rd - apply folder-level order (which also will probably return 0)
-// 4th - apply the UI-selected
-// 5th - if not known, use CustomSortOrder.default
-
-
-
 function getComparator(sortSpec: CustomSortSpec, currentUIselectedSorting?: string): SorterFn {
 	const compareTwoItems = (itA: FolderItemForSorting, itB: FolderItemForSorting) => {
 		if (itA.groupIdx != undefined && itB.groupIdx != undefined) {
 			if (itA.groupIdx === itB.groupIdx) {
 				const group: CustomSortGroup | undefined = sortSpec.groups[itA.groupIdx]
-
+				const primary: number = group?.order ? getSorterFnFor(group.order, currentUIselectedSorting)(itA, itB) : EQUAL_OR_UNCOMPARABLE
-				if (group.secondaryOrder) {
+				if (primary !== EQUAL_OR_UNCOMPARABLE) return primary
-					return getSorterFnFor(group.secondaryOrder ?? CustomSortOrder.default, currentUIselectedSorting)(itA, itB)
+				const secondary: number = group?.secondaryOrder ? getSorterFnFor(group.secondaryOrder, currentUIselectedSorting)(itA, itB) : EQUAL_OR_UNCOMPARABLE
-				} else {
+				if (secondary !== EQUAL_OR_UNCOMPARABLE) return secondary
-					return getSorterFnFor(group?.order ?? CustomSortOrder.default, currentUIselectedSorting)(itA, itB)
+				const folderLevel: number = sortSpec.defaultOrder ? getSorterFnFor(sortSpec.defaultOrder, currentUIselectedSorting)(itA, itB) : EQUAL_OR_UNCOMPARABLE
-				}
+				if (folderLevel !== EQUAL_OR_UNCOMPARABLE) return folderLevel
+				const uiSelected: number = currentUIselectedSorting ? getSorterFnFor(CustomSortOrder.standardObsidian, currentUIselectedSorting)(itA, itB) : EQUAL_OR_UNCOMPARABLE
+				if (uiSelected !== EQUAL_OR_UNCOMPARABLE) return uiSelected
+				const lastResort: number = getSorterFnFor(CustomSortOrder.default)(itA, itB)
+				return lastResort
 			} else {
 				return itA.groupIdx - itB.groupIdx;
 			}