Spell the doc directive's content=none through spellAttributes from one constant

src/markdown/block-directive.ts

@@ -4,7 +4,7 @@ import type { JsonValue } from '../json-value.ts'
 import { blockNodeModel } from '../adf/block-nodes.ts'
 import { isAdfMark } from '../adf/document.ts'
 import { serializeCanonicalJson } from '../canonical-json.ts'
-import { spellDirectiveOpener } from './directive-syntax.ts'
+import { spellAttributes, spellDirectiveOpener } from './directive-syntax.ts'
 
 const argumentByType = new Map(
   Object.entries({
@@ -17,7 +17,9 @@ const argumentByType = new Map(
 export const documentName = 'doc'
 
 // spec/flavour.md, Directives: a document holding no content key, which the empty string cannot spell.
-export const documentSpelling = spellDirectiveOpener(documentName, undefined, '{content=none}')
+export const documentAttribute = { key: 'content', value: 'none' } as const
+
+export const documentSpelling = spellDirectiveOpener(documentName, undefined, spellAttributes([[documentAttribute.key, documentAttribute.value]]))
 
 export const listBreakName = 'listBreak'
 

src/markdown/parse/markdown-to-adf.ts

@@ -7,7 +7,7 @@ import type { LineContainer } from '../line-container.ts'
 import type { LinkDefinitions } from './inline-content.ts'
 import { carryFencePrefix, readCarriedBlock } from '../opaque-carry.ts'
 import { commonMarkSpelling, type SpellingMemo } from '../emit/adf-to-markdown.ts'
-import { documentName, documentSpelling, listBreakName, listBreakSpelling } from '../block-directive.ts'
+import { documentAttribute, documentName, documentSpelling, listBreakName, listBreakSpelling } from '../block-directive.ts'
 import { failure, faulted, positioned, success, type ConvertErrorPath, type ParseError, type Result, type SourcePosition } from '../../result.ts'
 import { inlineLeaves } from '../emit/plain-inline.ts'
 import { languageSlot } from '../code-language.ts'
@@ -83,8 +83,8 @@ function listBreakFault(block: DirectiveBlock, previous: Block | undefined, next
 }
 
 function documentFault(block: DirectiveBlock): ConvertFault | undefined {
-  const content = block.attributes.get('content')
-  if (block.argument === undefined && block.attributes.size === 1 && content?.spelling === 'none') return undefined
+  const spelled = block.attributes.get(documentAttribute.key)
+  if (block.argument === undefined && block.attributes.size === 1 && spelled?.spelling === documentAttribute.value) return undefined
   return unsupportedNodeShape(`${documentName} spells the one form ${documentSpelling}: this one spells another`)
 }