Read the inline nodes and the marks back, and keep the whitespace CommonMark does not strip

src/markdown/text-directive.ts

@@ -0,0 +1,25 @@
+import type { ConvertFault } from '../result.ts'
+import type { DirectiveSpan, Read } from './directive-syntax.ts'
+import { spellAttributes, spellStringAttribute } from './directive-syntax.ts'
+
+const name = 'text'
+const whitespaceRun = /^(?:[ \t]+|\n+)$/
+
+export function spellTextDirective(text: string): string {
+  return `:${name}${spellAttributes([[name, spellStringAttribute(text)]])}`
+}
+
+export function readTextDirective(span: DirectiveSpan): Read<string> | undefined {
+  if (span.name !== name) return undefined
+  if (span.content !== undefined) return { fault: unsupported(`${name} takes no content`) }
+  const spelled = span.attributes.get(name)
+  if (spelled === undefined || span.attributes.size !== 1) return { fault: unsupported(`${name} holds one ${name} attribute alone`) }
+  const spelling = spellStringAttribute(spelled.decoded)
+  if (spelling !== spelled.spelling) return { fault: unsupported(`${name} spells its ${name} attribute as ${name}=${spelling}`) }
+  if (!whitespaceRun.test(spelled.decoded)) return { fault: unsupported(`${name} spells one run of spaces and tabs, or one run of newlines`) }
+  return { value: spelled.decoded }
+}
+
+function unsupported(message: string): ConvertFault {
+  return { code: 'unsupported-node-shape', message }
+}