rebber/src/escaper.js

/* Dependencies. */
const has = require('has')
const xtend = require('xtend')

/* Expose. */
module.exports = encode

encode.escape = escape

/* List of enforced escapes. */
const defaultEscapes = {
  '#': '\\#',
  '$': '\\$',
  '%': '\\%',
  '&': '\\&',
  '\\': '\\textbackslash{}',
  '^': '\\textasciicircum{}',
  '_': '\\_',
  '{': '\\{',
  '}': '\\}',
  '~': '\\textasciitilde{}',
}

/* Encode special characters in `value`. */
function encode (value, opts = {}) {
  const escapes = xtend(defaultEscapes, opts)
  const set = toExpression(Object.keys(escapes))

  value = value.replace(set, function (char, pos, val) {
    return one(char, val.charAt(pos + 1), escapes)
  })

  return value
}

/* Encode `char` according to `options`. */
function one (char, next, escapes) {
  if (has(escapes, char)) {
    return escapes[char]
  }

  return char
}

/* Create an expression for `characters`. */
function toExpression (characters) {
  const pattern = characters.map(escapeRegExp).join('|')

  return new RegExp(`[${pattern}]`, 'g')
}

function escapeRegExp (str) {
  return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, '\\$&') // eslint-disable-line no-useless-escape
}