inspect.mjs

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

import nodejsCustomInspectSymbol from './nodejsCustomInspectSymbol';
var MAX_ARRAY_LENGTH = 10;
var MAX_RECURSIVE_DEPTH = 2;
/**
 * Used to print values in error messages.
 */

export default function inspect(value) {
  return formatValue(value, []);
}

function formatValue(value, seenValues) {
  switch (_typeof(value)) {
    case 'string':
      return JSON.stringify(value);

    case 'function':
      return value.name ? "[function ".concat(value.name, "]") : '[function]';

    case 'object':
      if (value === null) {
        return 'null';
      }

      return formatObjectValue(value, seenValues);

    default:
      return String(value);
  }
}

function formatObjectValue(value, previouslySeenValues) {
  if (previouslySeenValues.indexOf(value) !== -1) {
    return '[Circular]';
  }

  var seenValues = [].concat(previouslySeenValues, [value]);
  var customInspectFn = getCustomFn(value);

  if (customInspectFn !== undefined) {
    // $FlowFixMe(>=0.90.0)
    var customValue = customInspectFn.call(value); // check for infinite recursion

    if (customValue !== value) {
      return typeof customValue === 'string' ? customValue : formatValue(customValue, seenValues);
    }
  } else if (Array.isArray(value)) {
    return formatArray(value, seenValues);
  }

  return formatObject(value, seenValues);
}

function formatObject(object, seenValues) {
  var keys = Object.keys(object);

  if (keys.length === 0) {
    return '{}';
  }

  if (seenValues.length > MAX_RECURSIVE_DEPTH) {
    return '[' + getObjectTag(object) + ']';
  }

  var properties = keys.map(function (key) {
    var value = formatValue(object[key], seenValues);
    return key + ': ' + value;
  });
  return '{ ' + properties.join(', ') + ' }';
}

function formatArray(array, seenValues) {
  if (array.length === 0) {
    return '[]';
  }

  if (seenValues.length > MAX_RECURSIVE_DEPTH) {
    return '[Array]';
  }

  var len = Math.min(MAX_ARRAY_LENGTH, array.length);
  var remaining = array.length - len;
  var items = [];

  for (var i = 0; i < len; ++i) {
    items.push(formatValue(array[i], seenValues));
  }

  if (remaining === 1) {
    items.push('... 1 more item');
  } else if (remaining > 1) {
    items.push("... ".concat(remaining, " more items"));
  }

  return '[' + items.join(', ') + ']';
}

function getCustomFn(object) {
  var customInspectFn = object[String(nodejsCustomInspectSymbol)];

  if (typeof customInspectFn === 'function') {
    return customInspectFn;
  }

  if (typeof object.inspect === 'function') {
    return object.inspect;
  }
}

function getObjectTag(object) {
  var tag = Object.prototype.toString.call(object).replace(/^\[object /, '').replace(/]$/, '');

  if (tag === 'Object' && typeof object.constructor === 'function') {
    var name = object.constructor.name;

    if (typeof name === 'string' && name !== '') {
      return name;
    }
  }

  return tag;
}