10b - the lift, with alert words, task markers and == shared with the reduction

src/markdown/plain-conventions.ts

@@ -0,0 +1,54 @@
+type AlertMarker = { folded: boolean; length: number; panelType: string }
+
+export const foldedAlertMarker = '[!NOTE]-'
+export const highlightDelimiter = '=='
+
+const alertWords: Readonly<Record<string, string>> = {
+  error: 'CAUTION',
+  info: 'NOTE',
+  note: 'IMPORTANT',
+  success: 'TIP',
+  tip: 'TIP',
+  warning: 'WARNING',
+}
+
+const panelTypesByWord: Readonly<Record<string, string>> = {
+  attention: 'warning',
+  bug: 'error',
+  caution: 'error',
+  check: 'success',
+  danger: 'error',
+  done: 'success',
+  error: 'error',
+  fail: 'error',
+  failure: 'error',
+  hint: 'tip',
+  important: 'note',
+  missing: 'error',
+  success: 'success',
+  tip: 'tip',
+  warning: 'warning',
+}
+
+export function alertMarker(panelType: unknown): string {
+  const word = typeof panelType === 'string' && Object.hasOwn(alertWords, panelType) ? alertWords[panelType] : undefined
+  return `[!${word ?? 'NOTE'}]`
+}
+
+export function readAlertMarker(text: string): AlertMarker | undefined {
+  const marker = /^\[!([\w-]+)\]([+-]?)/.exec(text)
+  if (marker === null) return undefined
+  const word = (marker[1] ?? '').toLowerCase()
+  const panelType = Object.hasOwn(panelTypesByWord, word) ? panelTypesByWord[word] : undefined
+  return { folded: marker[2] !== '', length: marker[0].length, panelType: panelType ?? 'info' }
+}
+
+export function taskMarker(state: unknown): string {
+  return state === 'DONE' ? '[x]' : '[ ]'
+}
+
+export function readTaskMarker(text: string): { length: number; state: 'DONE' | 'TODO' } | undefined {
+  const marker = /^\[([ xX])\]/.exec(text)
+  if (marker === null) return undefined
+  return { length: marker[0].length, state: marker[1] === ' ' ? 'TODO' : 'DONE' }
+}