refactor: change return type of frontmatter extractor to use undefined

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

commons/src/title-extraction/frontmatter-extractor/extractor.spec.ts

@@ -4,7 +4,6 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { extractFrontmatter } from './extractor.js'
-import type { PresentFrontmatterExtractionResult } from './types.js'
 import { describe, expect, it } from '@jest/globals'
 
 describe('frontmatter extraction', () => {
@@ -12,22 +11,22 @@ describe('frontmatter extraction', () => {
     it('is false when note does not contain three dashes at all', () => {
       const testNote = ['abcdef', 'more text']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is false when note does not start with three dashes', () => {
       const testNote = ['', '---', 'this is not frontmatter']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is false when note start with less than three dashes', () => {
       const testNote = ['--', 'this is not frontmatter']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is false when note starts with three dashes but contains other characters in the same line', () => {
       const testNote = ['--- a', 'this is not frontmatter']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is false when note has no ending marker for frontmatter', () => {
       const testNote = [
@@ -38,75 +37,63 @@ describe('frontmatter extraction', () => {
         'end marker'
       ]
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is false when note end marker is present but with not the same amount of dashes as start marker', () => {
       const testNote = ['---', 'this is not frontmatter', '----', 'content']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(false)
+      expect(extraction).toBeUndefined()
     })
     it('is true when note end marker is present with the same amount of dashes as start marker', () => {
       const testNote = ['---', 'this is frontmatter', '---', 'content']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(true)
+      expect(extraction).toBeDefined()
     })
     it('is true when note end marker is present with the same amount of dashes as start marker but without content', () => {
       const testNote = ['---', 'this is frontmatter', '---']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(true)
+      expect(extraction).toBeDefined()
     })
     it('is true when note end marker is present with the same amount of dots as start marker', () => {
       const testNote = ['---', 'this is frontmatter', '...', 'content']
       const extraction = extractFrontmatter(testNote)
-      expect(extraction.isPresent).toBe(true)
+      expect(extraction).toBeDefined()
     })
   })
 
   describe('lineOffset property', () => {
     it('is correct for single line frontmatter without content', () => {
       const testNote = ['---', 'single line frontmatter', '...']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.lineOffset).toEqual(3)
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.lineOffset).toEqual(3)
     })
     it('is correct for single line frontmatter with content', () => {
       const testNote = ['---', 'single line frontmatter', '...', 'content']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.lineOffset).toEqual(3)
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.lineOffset).toEqual(3)
     })
     it('is correct for multi-line frontmatter without content', () => {
       const testNote = ['---', 'abc', '123', 'def', '...']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.lineOffset).toEqual(5)
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.lineOffset).toEqual(5)
     })
     it('is correct for multi-line frontmatter with content', () => {
       const testNote = ['---', 'abc', '123', 'def', '...', 'content']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.lineOffset).toEqual(5)
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.lineOffset).toEqual(5)
     })
   })
 
   describe('rawText property', () => {
     it('contains single-line frontmatter text', () => {
       const testNote = ['---', 'single-line', '...', 'content']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.rawText).toEqual('single-line')
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.rawText).toEqual('single-line')
     })
     it('contains multi-line frontmatter text', () => {
       const testNote = ['---', 'multi', 'line', '...', 'content']
-      const extraction = extractFrontmatter(
-        testNote
-      ) as PresentFrontmatterExtractionResult
-      expect(extraction.rawText).toEqual('multi\nline')
+      const extraction = extractFrontmatter(testNote)
+      expect(extraction?.rawText).toEqual('multi\nline')
     })
   })
 })

commons/src/title-extraction/frontmatter-extractor/extractor.ts

@@ -20,11 +20,9 @@ const FRONTMATTER_END_REGEX = /^(?:-{3,}|\.{3,})$/
  */
 export const extractFrontmatter = (
   lines: string[]
-): FrontmatterExtractionResult => {
+): FrontmatterExtractionResult | undefined => {
   if (lines.length < 2 || !FRONTMATTER_BEGIN_REGEX.test(lines[0])) {
-    return {
-      isPresent: false
-    }
+    return undefined
   }
   for (let i = 1; i < lines.length; i++) {
     if (
@@ -32,13 +30,10 @@ export const extractFrontmatter = (
       FRONTMATTER_END_REGEX.test(lines[i])
     ) {
       return {
-        isPresent: true,
         rawText: lines.slice(1, i).join('\n'),
         lineOffset: i + 1
       }
     }
   }
-  return {
-    isPresent: false
-  }
+  return undefined
 }

commons/src/title-extraction/frontmatter-extractor/types.ts

@@ -4,16 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-export type FrontmatterExtractionResult =
-  | PresentFrontmatterExtractionResult
-  | NonPresentFrontmatterExtractionResult
-
-export interface PresentFrontmatterExtractionResult {
-  isPresent: true
+export interface FrontmatterExtractionResult {
   rawText: string
   lineOffset: number
 }
-
-interface NonPresentFrontmatterExtractionResult {
-  isPresent: false
-}

frontend/src/components/editor-page/editor-pane/linter/frontmatter-linter.ts

@@ -20,7 +20,7 @@ export class FrontmatterLinter implements Linter {
   lint(view: EditorView): Diagnostic[] {
     const lines = view.state.doc.toString().split('\n')
     const frontmatterExtraction = extractFrontmatter(lines)
-    if (!frontmatterExtraction.isPresent) {
+    if (frontmatterExtraction === undefined) {
       return []
     }
     const startOfYaml = lines[0].length + 1

frontend/src/redux/note-details/build-state-from-updated-markdown-content.ts

@@ -8,7 +8,7 @@ import { initialState } from './initial-state'
 import { createNoteFrontmatterFromYaml } from './raw-note-frontmatter-parser/parser'
 import type { NoteDetails } from './types/note-details'
 import { extractFrontmatter, generateNoteTitle } from '@hedgedoc/commons'
-import type { PresentFrontmatterExtractionResult } from '@hedgedoc/commons'
+import type { FrontmatterExtractionResult } from '@hedgedoc/commons'
 
 /**
  * Copies a {@link NoteDetails} but with another markdown content.
@@ -40,7 +40,7 @@ const buildStateFromMarkdownContentAndLines = (
 ): NoteDetails => {
   const frontmatterExtraction = extractFrontmatter(markdownContentLines)
   const lineStartIndexes = calculateLineStartIndexes(markdownContentLines)
-  if (frontmatterExtraction.isPresent) {
+  if (frontmatterExtraction !== undefined) {
     return buildStateFromFrontmatterUpdate(
       {
         ...state,
@@ -76,7 +76,7 @@ const buildStateFromMarkdownContentAndLines = (
  */
 const buildStateFromFrontmatterUpdate = (
   state: NoteDetails,
-  frontmatterExtraction: PresentFrontmatterExtractionResult
+  frontmatterExtraction: FrontmatterExtractionResult
 ): NoteDetails => {
   if (frontmatterExtraction.rawText === state.rawFrontmatter) {
     return state