app/node_modules/markdown-it/lib/rules_block/list.mjs

// Lists

import { isSpace } from '../common/utils.mjs'

// Search `[-+*][\n ]`, returns next pos after marker on success
// or -1 on fail.
function skipBulletListMarker (state, startLine) {
  const max = state.eMarks[startLine]
  let pos = state.bMarks[startLine] + state.tShift[startLine]

  const marker = state.src.charCodeAt(pos++)
  // Check bullet
  if (marker !== 0x2A/* * */ &&
      marker !== 0x2D/* - */ &&
      marker !== 0x2B/* + */) {
    return -1
  }

  if (pos < max) {
    const ch = state.src.charCodeAt(pos)

    if (!isSpace(ch)) {
      // " -test " - is not a list item
      return -1
    }
  }

  return pos
}

// Search `\d+[.)][\n ]`, returns next pos after marker on success
// or -1 on fail.
function skipOrderedListMarker (state, startLine) {
  const start = state.bMarks[startLine] + state.tShift[startLine]
  const max = state.eMarks[startLine]
  let pos = start

  // List marker should have at least 2 chars (digit + dot)
  if (pos + 1 >= max) { return -1 }

  let ch = state.src.charCodeAt(pos++)

  if (ch < 0x30/* 0 */ || ch > 0x39/* 9 */) { return -1 }

  for (;;) {
    // EOL -> fail
    if (pos >= max) { return -1 }

    ch = state.src.charCodeAt(pos++)

    if (ch >= 0x30/* 0 */ && ch <= 0x39/* 9 */) {
      // List marker should have no more than 9 digits
      // (prevents integer overflow in browsers)
      if (pos - start >= 10) { return -1 }

      continue
    }

    // found valid marker
    if (ch === 0x29/* ) */ || ch === 0x2e/* . */) {
      break
    }

    return -1
  }

  if (pos < max) {
    ch = state.src.charCodeAt(pos)

    if (!isSpace(ch)) {
      // " 1.test " - is not a list item
      return -1
    }
  }
  return pos
}

function markTightParagraphs (state, idx) {
  const level = state.level + 2

  for (let i = idx + 2, l = state.tokens.length - 2; i < l; i++) {
    if (state.tokens[i].level === level && state.tokens[i].type === 'paragraph_open') {
      state.tokens[i + 2].hidden = true
      state.tokens[i].hidden = true
      i += 2
    }
  }
}

export default function list (state, startLine, endLine, silent) {
  let max, pos, start, token
  let nextLine = startLine
  let tight = true

  // if it's indented more than 3 spaces, it should be a code block
  if (state.sCount[nextLine] - state.blkIndent >= 4) { return false }

  // Special case:
  //  - item 1
  //   - item 2
  //    - item 3
  //     - item 4
  //      - this one is a paragraph continuation
  if (state.listIndent >= 0 &&
      state.sCount[nextLine] - state.listIndent >= 4 &&
      state.sCount[nextLine] < state.blkIndent) {
    return false
  }

  let isTerminatingParagraph = false

  // limit conditions when list can interrupt
  // a paragraph (validation mode only)
  if (silent && state.parentType === 'paragraph') {
    // Next list item should still terminate previous list item;
    //
    // This code can fail if plugins use blkIndent as well as lists,
    // but I hope the spec gets fixed long before that happens.
    //
    if (state.sCount[nextLine] >= state.blkIndent) {
      isTerminatingParagraph = true
    }
  }

  // Detect list type and position after marker
  let isOrdered
  let markerValue
  let posAfterMarker
  if ((posAfterMarker = skipOrderedListMarker(state, nextLine)) >= 0) {
    isOrdered = true
    start = state.bMarks[nextLine] + state.tShift[nextLine]
    markerValue = Number(state.src.slice(start, posAfterMarker - 1))

    // If we're starting a new ordered list right after
    // a paragraph, it should start with 1.
    if (isTerminatingParagraph && markerValue !== 1) return false
  } else if ((posAfterMarker = skipBulletListMarker(state, nextLine)) >= 0) {
    isOrdered = false
  } else {
    return false
  }

  // If we're starting a new unordered list right after
  // a paragraph, first line should not be empty.
  if (isTerminatingParagraph) {
    if (state.skipSpaces(posAfterMarker) >= state.eMarks[nextLine]) return false
  }

  // For validation mode we can terminate immediately
  if (silent) { return true }

  // We should terminate list on style change. Remember first one to compare.
  const markerCharCode = state.src.charCodeAt(posAfterMarker - 1)

  // Start list
  const listTokIdx = state.tokens.length

  if (isOrdered) {
    token       = state.push('ordered_list_open', 'ol', 1)
    if (markerValue !== 1) {
      token.attrs = [['start', markerValue]]
    }
  } else {
    token       = state.push('bullet_list_open', 'ul', 1)
  }

  const listLines = [nextLine, 0]
  token.map    = listLines
  token.markup = String.fromCharCode(markerCharCode)

  //
  // Iterate list items
  //

  let prevEmptyEnd = false
  const terminatorRules = state.md.block.ruler.getRules('list')

  const oldParentType = state.parentType
  state.parentType = 'list'

  while (nextLine < endLine) {
    pos = posAfterMarker
    max = state.eMarks[nextLine]

    const initial = state.sCount[nextLine] + posAfterMarker - (state.bMarks[nextLine] + state.tShift[nextLine])
    let offset = initial

    while (pos < max) {
      const ch = state.src.charCodeAt(pos)

      if (ch === 0x09) {
        offset += 4 - (offset + state.bsCount[nextLine]) % 4
      } else if (ch === 0x20) {
        offset++
      } else {
        break
      }

      pos++
    }

    const contentStart = pos
    let indentAfterMarker

    if (contentStart >= max) {
      // trimming space in "-    \n  3" case, indent is 1 here
      indentAfterMarker = 1
    } else {
      indentAfterMarker = offset - initial
    }

    // If we have more than 4 spaces, the indent is 1
    // (the rest is just indented code block)
    if (indentAfterMarker > 4) { indentAfterMarker = 1 }

    // "  -  test"
    //  ^^^^^ - calculating total length of this thing
    const indent = initial + indentAfterMarker

    // Run subparser & write tokens
    token        = state.push('list_item_open', 'li', 1)
    token.markup = String.fromCharCode(markerCharCode)
    const itemLines = [nextLine, 0]
    token.map    = itemLines
    if (isOrdered) {
      token.info = state.src.slice(start, posAfterMarker - 1)
    }

    // change current state, then restore it after parser subcall
    const oldTight = state.tight
    const oldTShift = state.tShift[nextLine]
    const oldSCount = state.sCount[nextLine]

    //  - example list
    // ^ listIndent position will be here
    //   ^ blkIndent position will be here
    //
    const oldListIndent = state.listIndent
    state.listIndent = state.blkIndent
    state.blkIndent = indent

    state.tight = true
    state.tShift[nextLine] = contentStart - state.bMarks[nextLine]
    state.sCount[nextLine] = offset

    if (contentStart >= max && state.isEmpty(nextLine + 1)) {
      // workaround for this case
      // (list item is empty, list terminates before "foo"):
      // ~~~~~~~~
      //   -
      //
      //     foo
      // ~~~~~~~~
      state.line = Math.min(state.line + 2, endLine)
    } else {
      state.md.block.tokenize(state, nextLine, endLine, true)
    }

    // If any of list item is tight, mark list as tight
    if (!state.tight || prevEmptyEnd) {
      tight = false
    }
    // Item become loose if finish with empty line,
    // but we should filter last element, because it means list finish
    prevEmptyEnd = (state.line - nextLine) > 1 && state.isEmpty(state.line - 1)

    state.blkIndent = state.listIndent
    state.listIndent = oldListIndent
    state.tShift[nextLine] = oldTShift
    state.sCount[nextLine] = oldSCount
    state.tight = oldTight

    token        = state.push('list_item_close', 'li', -1)
    token.markup = String.fromCharCode(markerCharCode)

    nextLine = state.line
    itemLines[1] = nextLine

    if (nextLine >= endLine) { break }

    //
    // Try to check if list is terminated or continued.
    //
    if (state.sCount[nextLine] < state.blkIndent) { break }

    // if it's indented more than 3 spaces, it should be a code block
    if (state.sCount[nextLine] - state.blkIndent >= 4) { break }

    // fail if terminating block found
    let terminate = false
    for (let i = 0, l = terminatorRules.length; i < l; i++) {
      if (terminatorRules[i](state, nextLine, endLine, true)) {
        terminate = true
        break
      }
    }
    if (terminate) { break }

    // fail if list has another type
    if (isOrdered) {
      posAfterMarker = skipOrderedListMarker(state, nextLine)
      if (posAfterMarker < 0) { break }
      start = state.bMarks[nextLine] + state.tShift[nextLine]
    } else {
      posAfterMarker = skipBulletListMarker(state, nextLine)
      if (posAfterMarker < 0) { break }
    }

    if (markerCharCode !== state.src.charCodeAt(posAfterMarker - 1)) { break }
  }

  // Finalize list
  if (isOrdered) {
    token = state.push('ordered_list_close', 'ol', -1)
  } else {
    token = state.push('bullet_list_close', 'ul', -1)
  }
  token.markup = String.fromCharCode(markerCharCode)

  listLines[1] = nextLine
  state.line = nextLine

  state.parentType = oldParentType

  // mark paragraphs tight if needed
  if (tight) {
    markTightParagraphs(state, listTokIdx)
  }

  return true
}