Emitter 2d: the opaque carry in both positions and the reserved info string

src/opaque-carry.ts

@@ -0,0 +1,30 @@
+import type { AdfNode } from './adf-document.ts'
+import type { JsonSpelling } from './canonical-json.ts'
+import { failure, success, type ConvertErrorPath, type Result } from './result.ts'
+import { isJsonValue } from './json-value.ts'
+import { largestNesting } from './nesting.ts'
+import { longestBacktickRun } from './backtick-runs.ts'
+import { serializeCanonicalJson } from './canonical-json.ts'
+import { spellAttributes, spellStringAttribute } from './directive-attributes.ts'
+
+export const carryName = 'adf'
+
+export function carriedBlock(node: AdfNode, path: ConvertErrorPath): Result<string> {
+  const json = carriedJson(node, 'two-space', path)
+  if (!json.ok) return json
+  const fence = '`'.repeat(Math.max(3, longestBacktickRun(json.value) + 1))
+  return success(`${fence}${carryName}\n${json.value}\n${fence}`)
+}
+
+export function carriedInline(node: AdfNode, path: ConvertErrorPath): Result<string> {
+  const json = carriedJson(node, 'compact', path)
+  if (!json.ok) return json
+  return success(`:${carryName}${spellAttributes([['json', spellStringAttribute(json.value)]])}`)
+}
+
+function carriedJson(node: AdfNode, spelling: JsonSpelling, path: ConvertErrorPath): Result<string> {
+  if (!isJsonValue(node)) {
+    return failure('unsupported-node-shape', `a carried node nests deeper than the ${largestNesting} levels the emitter carries`, path)
+  }
+  return success(serializeCanonicalJson(node, spelling))
+}