Answer the architecture review: one interrupt rule both directions read

src/markdown/parse/blocks.ts

@@ -1,5 +1,14 @@
 import type { LinkDefinition } from './link-reference-definitions.ts'
-import { atxHeading, claimsDirectiveLine, claimsPipeLine, closingCodeFence, isThematicBreak, openingCodeFence, setextHeadingLevel } from '../commonmark-grammar.ts'
+import {
+  atxHeading,
+  claimsDirectiveLine,
+  claimsPipeLine,
+  closingCodeFence,
+  isThematicBreak,
+  markerInterruptsParagraph,
+  openingCodeFence,
+  setextHeadingLevel,
+} from '../commonmark-grammar.ts'
 import { openingHtmlBlock } from './html-blocks.ts'
 import { readLinkDefinitions } from './link-reference-definitions.ts'
 
@@ -85,10 +94,11 @@ function continuesContainer(walk: Walk, container: OpenContainer, line: string):
 }
 
 function openContainers(walk: Walk, line: string, paragraphOpen: boolean, depth: number): { opened: boolean; rest: string } {
+  const unmatched = walk.stack[depth]
   let opened = false
   let rest = line
   while (leadingColumns(rest) < indentedCodeColumns) {
-    const start = containerStart(rest, opened ? false : paragraphOpen, opened ? undefined : walk.stack[depth])
+    const start = containerStart(rest, opened ? false : paragraphOpen, opened ? undefined : unmatched)
     if (start === undefined) break
     if (!opened) closeContainers(walk, depth)
     opened = true
@@ -102,11 +112,15 @@ function containerStart(line: string, paragraphOpen: boolean, enclosing: OpenCon
   const opener = removeColumns(line, largestOpenerIndentation)
   if (opener.startsWith('>')) return { kind: 'blockquote', rest: removeColumns(opener.slice(1), 1) }
   if (isThematicBreak(opener) || (paragraphOpen && setextHeadingLevel(opener) !== undefined)) return undefined
+  return itemStart(line, opener, paragraphOpen, enclosing)
+}
+
+function itemStart(line: string, opener: string, paragraphOpen: boolean, enclosing: OpenContainer | undefined): ContainerStart | undefined {
   const marker = itemMarker(opener)
   if (marker === undefined) return undefined
   const after = opener.slice(marker.width)
   const blank = blankLine.test(after)
-  if (paragraphOpen && (blank || (marker.list.kind === 'orderedList' && marker.list.start !== 1))) return undefined
+  if (paragraphOpen && !markerInterruptsParagraph(marker.list.kind === 'orderedList' ? marker.list.start : undefined, blank)) return undefined
   const spaces = leadingColumns(after)
   const padding = blank || spaces > indentedCodeColumns ? 1 : spaces
   const continued = enclosing?.kind === 'item' && enclosing.list.kind === marker.list.kind && enclosing.marker === marker.marker

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

@@ -197,6 +197,7 @@ test('opens a list beside a paragraph only where the marker interrupts it', () =
   assert.deepEqual(content(markdownToAdf('Part.\n- - -\n')), [paragraph('Part.'), { type: 'rule' }])
   assert.deepEqual(content(markdownToAdf('Part.\n-\n')), [{ attrs: { level: 2 }, content: [text('Part.')], type: 'heading' }])
   assert.deepEqual(content(markdownToAdf('- a\n  2. b\n')), [bulletList(item(paragraph('a 2. b')))])
+  assert.deepEqual(content(markdownToAdf('- a\n  1. b\n')), [bulletList(item(paragraph('a'), orderedList(1, item(paragraph('b')))))])
 })
 
 test('folds a lazy continuation into the paragraph the container holds', () => {

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

@@ -22,16 +22,28 @@ function blockNodes(blocks: readonly Block[], path: ConvertErrorPath, depth: num
   return success(content)
 }
 
+// Switched, not chained: `noImplicitReturns` then refuses the kind a later milestone adds and forgets.
 function blockNode(block: Block, path: ConvertErrorPath, depth: number): Result<AdfNode> {
-  if (block.kind === 'blockquote') return containerNode({ type: 'blockquote' }, block.blocks, path, depth)
-  if (block.kind === 'bulletList') return listNode({ type: 'bulletList' }, block.items, path, depth)
-  if (block.kind === 'claim') return claimFailure(block.construct, path)
-  if (block.kind === 'code') return success(codeBlockNode(block.language, block.text))
-  if (block.kind === 'heading') return success(withContent({ attrs: { level: block.level }, type: 'heading' }, block.text))
-  if (block.kind === 'html') return failure('unmappable-html', `no ADF node carries ${block.construct}`, path)
-  if (block.kind === 'orderedList') return listNode({ attrs: { order: block.start }, type: 'orderedList' }, block.items, path, depth)
-  if (block.kind === 'paragraph') return success(withContent({ type: 'paragraph' }, block.text))
-  return success({ type: 'rule' })
+  switch (block.kind) {
+    case 'blockquote':
+      return containerNode({ type: 'blockquote' }, block.blocks, path, depth)
+    case 'bulletList':
+      return listNode({ type: 'bulletList' }, block.items, path, depth)
+    case 'claim':
+      return claimFailure(block.construct, path)
+    case 'code':
+      return success(codeBlockNode(block.language, block.text))
+    case 'heading':
+      return success(withContent({ attrs: { level: block.level }, type: 'heading' }, block.text))
+    case 'html':
+      return failure('unmappable-html', `no ADF node carries ${block.construct}`, path)
+    case 'orderedList':
+      return listNode({ attrs: { order: block.start }, type: 'orderedList' }, block.items, path, depth)
+    case 'paragraph':
+      return success(withContent({ type: 'paragraph' }, block.text))
+    case 'rule':
+      return success({ type: 'rule' })
+  }
 }
 
 function containerNode(node: AdfNode, blocks: readonly Block[], path: ConvertErrorPath, depth: number): Result<AdfNode> {
@@ -51,8 +63,12 @@ function listNode(node: AdfNode, items: readonly Block[][], path: ConvertErrorPa
 }
 
 function claimFailure(construct: ClaimedConstruct, path: ConvertErrorPath): Result<AdfNode> {
-  if (construct === 'directive') return failure('malformed-directive', 'the line claims a directive and parses as none', path)
-  return failure('malformed-pipe-table', 'the line claims a pipe table and parses as none', path)
+  switch (construct) {
+    case 'directive':
+      return failure('malformed-directive', 'the line claims a directive and parses as none', path)
+    case 'pipe-table':
+      return failure('malformed-pipe-table', 'the line claims a pipe table and parses as none', path)
+  }
 }
 
 function codeBlockNode(language: string, text: string): AdfNode {