5b3: merge the code list's duplicate causes, spell the list separator, claim the bare pipe table

src/markdown/pipe-table-syntax.ts

@@ -4,6 +4,21 @@ import { backslashEscape, claimsPipeLine, trimSpace } from './commonmark-grammar
 const alignmentCell = /^:-+:?$|^-+:$/
 const delimiterCell = /^-+$/
 
+// spec/flavour.md, Tables: the cells of a row the leading `|` no claim read, GFM's form without it.
+export function barePipeCells(line: string): string[] | undefined {
+  const cells = splitPipeCells(line, 0)
+  return cells.length > 1 ? cells : undefined
+}
+
+export function isBareDelimiterRow(line: string): boolean {
+  const cells = barePipeCells(line)
+  return cells !== undefined && isDelimiterRow(cells)
+}
+
+export function isDelimiterRow(cells: readonly string[]): boolean {
+  return cells.every((cell) => isPipeDelimiter(cell) || isPipeAlignment(cell))
+}
+
 export function isPipeAlignment(cell: string): boolean {
   return alignmentCell.test(cell)
 }
@@ -18,24 +33,7 @@ export function malformedPipeTable(message: string): ConvertFault {
 
 // spec/flavour.md, Tables: the cells of a claimed row, the closing `|` the spelling writes optional here.
 export function pipeCells(line: string): string[] | undefined {
-  if (!claimsPipeLine(line)) return undefined
-  const cells: string[] = []
-  let start = 1
-  let index = 1
-  while (index < line.length) {
-    if (backslashEscape(line, index) !== undefined) {
-      index += 2
-      continue
-    }
-    if (line.charAt(index) === '|') {
-      cells.push(trimSpace(line.slice(start, index)))
-      start = index + 1
-    }
-    index += 1
-  }
-  cells.push(trimSpace(line.slice(start)))
-  if (cells.length > 1 && cells.at(-1) === '') cells.pop()
-  return cells
+  return claimsPipeLine(line) ? splitPipeCells(line, 1) : undefined
 }
 
 export function spellPipeDelimiter(columns: number): string {
@@ -45,3 +43,23 @@ export function spellPipeDelimiter(columns: number): string {
 export function spellPipeRow(cells: readonly string[]): string {
   return `| ${cells.join(' | ')} |`
 }
+
+function splitPipeCells(line: string, start: number): string[] {
+  const cells: string[] = []
+  let cellStart = start
+  let index = start
+  while (index < line.length) {
+    if (backslashEscape(line, index) !== undefined) {
+      index += 2
+      continue
+    }
+    if (line.charAt(index) === '|') {
+      cells.push(trimSpace(line.slice(cellStart, index)))
+      cellStart = index + 1
+    }
+    index += 1
+  }
+  cells.push(trimSpace(line.slice(cellStart)))
+  if (cells.length > 1 && cells.at(-1) === '') cells.pop()
+  return cells
+}