property-expr-csp/index.js

tiny util for getting and setting deep object props safely

/**
 * Based on Kendo UI Core expression code <https://github.com/telerik/kendo-ui-core#license-information>
 * And on the original property-expr package <https://github.com/jquense/expr>
 */
'use strict'
var SPLIT_REGEX = /[^.^\]^[]+|(?=\[\]|\.\.)/g,
  DIGIT_REGEX = /^\d+$/,
  LEAD_DIGIT_REGEX = /^\d/,
  SPEC_CHAR_REGEX = /[~`!#$%\^&*+=\-\[\]\\';,/{}|\\":<>\?]/g,
  NO_QUOTES_REGEX = /^\s*(['"])(.*)(\1)\s*$/,
  BREAK_FOR_EACH_SYMBOL = {}

module.exports = {
  forEach: forEach,

  setter: function(path) {
    return function(data, value) {
      return setter(path, data, value)
    }
  },

  getter: function(path, safe) {
    return function(data) {
      return getter(path, data, safe)
    }
  },

  split: function(path) {
    return path.match(SPLIT_REGEX)
  },

  join: function(segments) {
    return segments.reduce(function(path, part) {
      return (
        path +
        (isQuoted(part) || DIGIT_REGEX.test(part)
          ? '[' + part + ']'
          : (path ? '.' : '') + part)
      )
    }, '')
  }
}

function setter(path, data, value) {
  forEach(path, function(part, isBracket, isArray, idx, parts) {
    part = normalizePropertyName(part, isBracket, isArray)
    if (idx === parts.length - 1) {
      data[part] = value
    } else {
      data = data[part]
    }
  })
}

function getter(path, data, safe) {
  var value
  forEach(path, function(part, isBracket, isArray, idx, parts) {
    if (safe && !data) {
      return BREAK_FOR_EACH_SYMBOL
    }
    part = normalizePropertyName(part, isBracket, isArray)
    data = data[part]
    if (idx === parts.length - 1) {
      value = data
    } else if (safe) {
      data = data || {}
    }
  })
  return value
}

function forEach(path, cb, thisArg) {
  forEachPart(path.match(SPLIT_REGEX), cb, thisArg)
}

function forEachPart(parts, iter, thisArg) {
  var len = parts.length,
    part,
    idx,
    isArray,
    isBracket

  for (idx = 0; idx < len; idx++) {
    part = parts[idx]

    if (part) {
      if (shouldBeQuoted(part)) {
        part = '"' + part + '"'
      }

      isBracket = isQuoted(part)
      isArray = !isBracket && /^\d+$/.test(part)

      if (iter.call(thisArg, part, isBracket, isArray, idx, parts) === BREAK_FOR_EACH_SYMBOL) {
        break
      }
    }
  }
}

function isQuoted(str) {
  return (
    typeof str === 'string' && str && ["'", '"'].indexOf(str.charAt(0)) !== -1
  )
}

function normalizePropertyName(part, isBracket, isArray) {
  if (isBracket && !isArray) {
    part = part.replace(NO_QUOTES_REGEX, '$2')
  } else {
    part = part.trim()
  }
  return part
}

function hasLeadingNumber(part) {
  return part.match(LEAD_DIGIT_REGEX) && !part.match(DIGIT_REGEX)
}

function hasSpecialChars(part) {
  return SPEC_CHAR_REGEX.test(part)
}

function shouldBeQuoted(part) {
  return !isQuoted(part) && (hasLeadingNumber(part) || hasSpecialChars(part))
}