Emitter 2c: the inline node directives, the directive marks and the carried whitespace

src/directive-attributes.ts

@@ -1,13 +1,36 @@
-import type { AttributeKind } from './adf-document.ts'
+import type { AdfAttributes, AttributeKind } from './adf-document.ts'
 import type { JsonValue } from './json-value.ts'
+import { failure, type ConvertErrorPath, type Result } from './result.ts'
 import { serializeCanonicalJson } from './canonical-json.ts'
 
+export type AttributeFault = { key: string; kind: AttributeKind | undefined }
+
+export type AttributeVocabulary = Readonly<Record<string, AttributeKind>>
+
 const bareToken = /^[A-Za-z0-9_-]+$/
 
 export function isBareToken(text: string): boolean {
   return bareToken.test(text)
 }
 
+export function attributeFailure<T>(type: string, fault: AttributeFault, path: ConvertErrorPath): Result<T> {
+  if (fault.kind === undefined) return failure('unspelled-node-attribute', `the ${type} attribute ${fault.key} has no canonical markdown spelling`, path)
+  return failure('unsupported-node-shape', `the ${type} attribute ${fault.key} holds no ${fault.kind}`, path)
+}
+
+export function vocabularyPairs(attrs: AdfAttributes, vocabulary: AttributeVocabulary, slot: string | undefined): AttributeFault | [string, string][] {
+  const pairs: [string, string][] = []
+  for (const [key, value] of Object.entries(attrs)) {
+    if (key === slot) continue
+    const kind = Object.hasOwn(vocabulary, key) ? vocabulary[key] : undefined
+    if (kind === undefined) return { key, kind: undefined }
+    const spelled = spellAttributeValue(value, kind)
+    if (spelled === undefined) return { key, kind }
+    pairs.push([key, spelled])
+  }
+  return pairs
+}
+
 export function spellAttributes(pairs: readonly (readonly [string, string])[]): string {
   if (pairs.length === 0) return ''
   const spelled = [...pairs].sort(([left], [right]) => (left < right ? -1 : 1)).map(([key, value]) => `${key}=${value}`)
@@ -17,15 +40,15 @@ export function spellAttributes(pairs: readonly (readonly [string, string])[]):
 export function spellAttributeValue(value: JsonValue, kind: AttributeKind): string | undefined {
   if (kind === 'json') return spellJsonAttribute(value)
   if (kind === 'boolean') return typeof value === 'boolean' ? `${value}` : undefined
-  if (kind === 'number') return typeof value === 'number' ? spell(JSON.stringify(value)) : undefined
-  return typeof value === 'string' ? spell(value) : undefined
+  if (kind === 'number') return typeof value === 'number' ? spellStringAttribute(JSON.stringify(value)) : undefined
+  return typeof value === 'string' ? spellStringAttribute(value) : undefined
 }
 
 export function spellJsonAttribute(value: JsonValue): string {
   return quote(serializeCanonicalJson(value, 'compact'))
 }
 
-function spell(text: string): string {
+export function spellStringAttribute(text: string): string {
   return isBareToken(text) ? text : quote(text)
 }