first commit

src/services/markdownTable.ts

@@ -0,0 +1,147 @@
+function isEscaped(value: string, index: number): boolean {
+  let backslashCount = 0
+
+  for (let cursor = index - 1; cursor >= 0 && value[cursor] === '\\'; cursor--) {
+    backslashCount++
+  }
+
+  return backslashCount % 2 === 1
+}
+
+function hasMatchingCodeFence(
+  value: string,
+  start: number,
+  fenceLength: number,
+): boolean {
+  for (let index = start + fenceLength; index < value.length; ) {
+    if (value[index] !== '`') {
+      index++
+      continue
+    }
+
+    let runLength = 1
+
+    while (value[index + runLength] === '`') {
+      runLength++
+    }
+
+    if (!isEscaped(value, index) && runLength === fenceLength) {
+      return true
+    }
+
+    index += runLength
+  }
+
+  return false
+}
+
+export interface MarkdownTable {
+  start: number
+  end: number
+  header: string[]
+  rows: string[][]
+}
+
+export function splitMarkdownRow(row: string): string[] {
+  const cells: string[] = []
+  let cell = ''
+  let codeFenceLength = 0
+
+  for (let index = 0; index < row.length; ) {
+    const character = row[index]!
+
+    if (character === '`' && !isEscaped(row, index)) {
+      let runLength = 1
+
+      while (row[index + runLength] === '`') {
+        runLength++
+      }
+
+      cell += row.slice(index, index + runLength)
+
+      if (
+        codeFenceLength === 0 &&
+        hasMatchingCodeFence(row, index, runLength)
+      ) {
+        codeFenceLength = runLength
+      } else if (codeFenceLength === runLength) {
+        codeFenceLength = 0
+      }
+
+      index += runLength
+      continue
+    }
+
+    if (
+      character === '|' &&
+      codeFenceLength === 0 &&
+      !isEscaped(row, index)
+    ) {
+      cells.push(cell.trim())
+      cell = ''
+      index++
+      continue
+    }
+
+    cell += character
+    index++
+  }
+
+  cells.push(cell.trim())
+
+  if (cells[0] === '') {
+    cells.shift()
+  }
+  if (cells.at(-1) === '') {
+    cells.pop()
+  }
+
+  return cells
+}
+
+const dividerCellPattern = /^:?-{3,}:?$/
+
+function startsWithPipe(line: string): boolean {
+  return line.trimStart().startsWith('|')
+}
+
+export function extractMarkdownTable(
+  lines: readonly string[],
+  fromIndex = 0,
+): MarkdownTable | null {
+  for (
+    let start = Math.max(0, fromIndex);
+    start < lines.length - 1;
+    start++
+  ) {
+    const headerLine = lines[start]!
+    const dividerLine = lines[start + 1]!
+
+    if (!startsWithPipe(headerLine) || !startsWithPipe(dividerLine)) {
+      continue
+    }
+
+    const header = splitMarkdownRow(headerLine)
+    const divider = splitMarkdownRow(dividerLine)
+
+    if (
+      header.length === 0 ||
+      divider.length !== header.length ||
+      !divider.every((cell) => dividerCellPattern.test(cell))
+    ) {
+      continue
+    }
+
+    const rows: string[][] = []
+    let end = start + 1
+
+    while (end + 1 < lines.length && startsWithPipe(lines[end + 1]!)) {
+      end++
+      rows.push(splitMarkdownRow(lines[end]!))
+    }
+
+    return { start, end, header, rows }
+  }
+
+  return null
+}