markdown-it/lib/rules_inline/escape.mjs

// Process escaped chars and hardbreaks

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

const ESCAPED = []

for (let i = 0; i < 256; i++) { ESCAPED.push(0) }

'\\!"#$%&\'()*+,./:;<=>?@[]^_`{|}~-'
  .split('').forEach(function (ch) { ESCAPED[ch.charCodeAt(0)] = 1 })

export default function escape (state, silent) {
  let pos = state.pos
  const max = state.posMax

  if (state.src.charCodeAt(pos) !== 0x5C/* \ */) return false
  pos++

  // '\' at the end of the inline block
  if (pos >= max) return false

  let ch1 = state.src.charCodeAt(pos)

  if (ch1 === 0x0A) {
    if (!silent) {
      state.push('hardbreak', 'br', 0)
    }

    pos++
    // skip leading whitespaces from next line
    while (pos < max) {
      ch1 = state.src.charCodeAt(pos)
      if (!isSpace(ch1)) break
      pos++
    }

    state.pos = pos
    return true
  }

  let escapedStr = state.src[pos]

  if (ch1 >= 0xD800 && ch1 <= 0xDBFF && pos + 1 < max) {
    const ch2 = state.src.charCodeAt(pos + 1)

    if (ch2 >= 0xDC00 && ch2 <= 0xDFFF) {
      escapedStr += state.src[pos + 1]
      pos++
    }
  }

  const origStr = '\\' + escapedStr

  if (!silent) {
    const token = state.push('text_special', '', 0)

    if (ch1 < 256 && ESCAPED[ch1] !== 0) {
      token.content = escapedStr
    } else {
      token.content = origStr
    }

    token.markup = origStr
    token.info   = 'escape'
  }

  state.pos = pos + 1
  return true
}