#27 - support for true alphabetical order

- added new token 'true a-z'
- unit tests coverage of the extended logic
- added example in README.md

README.md

@@ -308,7 +308,7 @@ sorting-spec: |
 
 the line `... part \d+` says: group all notes and folders with name ending with 'part' followed by a number. Then order
 them by the number. And for clarity the subsequent (indented) line is added ` < a-z` which sets the order to
-alphanumerical ascending.
+alphabetical ascending.
 
 The effect is:
 
@@ -411,6 +411,35 @@ sorting-spec: |
 ---
 ```
 
+## Alphabetical, Natural and True Alphabetical sorting orders
+
+The 'A-Z' sorting (visible in Obsidian UI of file explorer) at some point before the 1.0.0 release of Obsidian actually became the so-called 'natural' sort order.
+For explanation of the term go to [Natural sort order](https://en.wikipedia.org/wiki/Natural_sort_order) on Wikipedia.
+The plugin follows the convention and the sorting specified by `< a-z` or `> a-z` triggers the _'natural sort order'_.
+
+To allow the true alphabetical sort order, as suggested by the ticket [27: Not alphanumeric, but natural sort order?](https://github.com/SebastianMC/obsidian-custom-sort/issues/27)
+a distinct syntax was introduced: `< true a-z` and `> true a-z`
+
+What is the difference?
+Using the example from the mentioned ticket: the items '0x01FF', '0x02FF' and '0x0200' sorted in _natural order_ go as:
+- 0x01FF -> the number 01 in the text is recognized
+- 0x02FF -> the number 02 in the text is recognized
+- 0x0200 -> the number 0200 in the text is recognized and it causes the third position of the item, because 0200 > 02
+
+The same items when sorted in _true alphabetical_ order go as:
+- 0x01FF
+- 0x0200
+- 0x02FF -> the character 'F' following '2' goes after the character '0', that's why 0x02FF follows the 0x0200
+
+You can use the order `< true a-z` or `> true a-z` to trigger the true alphabetical sorting, like in the ticket:
+```yaml
+sorting-spec: |
+ target-folder: MaDo/...
+ > true a-z
+ target-folder: MaDo/Sandbox/SortingBug
+ < true a-z
+```
+
 ## Location of sorting specification YAML entry
 
 You can keep the custom sorting specifications in any of the following locations (or in all of them):

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

@@ -9,7 +9,9 @@ export enum CustomSortGroupType {
 
 export enum CustomSortOrder {
 	alphabetical = 1,  // = 1 to allow: if (customSortOrder) { ...
+	trueAlphabetical,
 	alphabeticalReverse,
+	trueAlphabeticalReverse,
 	byModifiedTime,   // New to old
 	byModifiedTimeAdvanced,
 	byModifiedTimeReverse,  // Old to new

src/custom-sort/custom-sort.ts

@@ -8,6 +8,12 @@ let Collator = new Intl.Collator(undefined, {
 	numeric: true,
 }).compare;
 
+let CollatorTrueAlphabetical = new Intl.Collator(undefined, {
+	usage: "sort",
+	sensitivity: "base",
+	numeric: false,
+}).compare;
+
 export interface FolderItemForSorting {
 	path: string
 	groupIdx?: number  // the index itself represents order for groups
@@ -24,7 +30,9 @@ type SorterFn = (a: FolderItemForSorting, b: FolderItemForSorting) => number
 
 let Sorters: { [key in CustomSortOrder]: SorterFn } = {
 	[CustomSortOrder.alphabetical]: (a: FolderItemForSorting, b: FolderItemForSorting) => Collator(a.sortString, b.sortString),
+	[CustomSortOrder.trueAlphabetical]: (a: FolderItemForSorting, b: FolderItemForSorting) => CollatorTrueAlphabetical(a.sortString, b.sortString),
 	[CustomSortOrder.alphabeticalReverse]: (a: FolderItemForSorting, b: FolderItemForSorting) => Collator(b.sortString, a.sortString),
+	[CustomSortOrder.trueAlphabeticalReverse]: (a: FolderItemForSorting, b: FolderItemForSorting) => CollatorTrueAlphabetical(b.sortString, a.sortString),
 	[CustomSortOrder.byModifiedTime]: (a: FolderItemForSorting, b: FolderItemForSorting) => (a.isFolder && b.isFolder) ? Collator(a.sortString, b.sortString) : (a.mtime - b.mtime),
 	[CustomSortOrder.byModifiedTimeAdvanced]: (a: FolderItemForSorting, b: FolderItemForSorting) => a.mtime - b.mtime,
 	[CustomSortOrder.byModifiedTimeReverse]: (a: FolderItemForSorting, b: FolderItemForSorting) => (a.isFolder && b.isFolder) ? Collator(a.sortString, b.sortString) : (b.mtime - a.mtime),

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

@@ -436,6 +436,46 @@ describe('SortingSpecProcessor', () => {
 	})
 })
 
+const txtInputTrueAlphabeticalSortAttr: string = `
+target-folder: AAA
+< true a-z
+target-folder: BBB
+> true a-z
+`
+
+const expectedSortSpecForTrueAlphabeticalSorting: { [key: string]: CustomSortSpec } = {
+	"AAA": {
+		defaultOrder: CustomSortOrder.trueAlphabetical,
+		groups: [{
+			order: CustomSortOrder.trueAlphabetical,
+			type: CustomSortGroupType.Outsiders
+		}],
+		outsidersGroupIdx: 0,
+		targetFoldersPaths: ['AAA']
+	},
+	"BBB": {
+		defaultOrder: CustomSortOrder.trueAlphabeticalReverse,
+		groups: [{
+			order: CustomSortOrder.trueAlphabeticalReverse,
+			type: CustomSortGroupType.Outsiders
+		}],
+		outsidersGroupIdx: 0,
+		targetFoldersPaths: ['BBB']
+	}
+}
+
+describe('SortingSpecProcessor', () => {
+	let processor: SortingSpecProcessor;
+	beforeEach(() => {
+		processor = new SortingSpecProcessor();
+	});
+	it('should recognize the true alphabetical (and reverse) sorting attribute for a folder', () => {
+		const inputTxtArr: Array<string> = txtInputTrueAlphabeticalSortAttr.split('\n')
+		const result = processor.parseSortSpecFromText(inputTxtArr, 'mock-folder', 'custom-name-note.md')
+		expect(result?.sortSpecByPath).toEqual(expectedSortSpecForTrueAlphabeticalSorting)
+	})
+})
+
 const txtInputSimplistic1: string = `
 target-folder: /*
 /:files

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

@@ -84,6 +84,7 @@ interface CustomSortOrderAscDescPair {
 // remember about .toLowerCase() before comparison!
 const OrderLiterals: { [key: string]: CustomSortOrderAscDescPair } = {
 	'a-z': {asc: CustomSortOrder.alphabetical, desc: CustomSortOrder.alphabeticalReverse},
+	'true a-z': {asc: CustomSortOrder.trueAlphabetical, desc: CustomSortOrder.trueAlphabeticalReverse},
 	'created': {asc: CustomSortOrder.byCreatedTime, desc: CustomSortOrder.byCreatedTimeReverse},
 	'modified': {asc: CustomSortOrder.byModifiedTime, desc: CustomSortOrder.byModifiedTimeReverse},
 	'advanced modified': {asc: CustomSortOrder.byModifiedTimeAdvanced, desc: CustomSortOrder.byModifiedTimeReverseAdvanced},