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Edit File: splat.js

'use strict';

/**
 * Captures the number of format (i.e. %s strings) in a given string.
 * Based on `util.format`, see Node.js source:
 * https://github.com/nodejs/node/blob/b1c8f15c5f169e021f7c46eb7b219de95fe97603/lib/util.js#L201-L230
 * @type {RegExp}
 */
var formatRegExp = /%[scdjifoO%]/g;

/**
 * Captures the number of escaped % signs in a format string (i.e. %s strings).
 * @type {RegExp}
 */
var escapedPercent = /%%/g;
var Splatter = /*#__PURE__*/function () {
  function Splatter(opts) {
    _classCallCheck(this, Splatter);
    this.options = opts;
  }

/**
     * Check to see if tokens <= splat.length, assign { splat, meta } into the
     * `info` accordingly, and write to this instance.
     *
     * @param  {Info} info Logform info message.
     * @param  {String[]} tokens Set of string interpolation tokens.
     * @returns {Info} Modified info message
     * @private
     */
  _createClass(Splatter, [{
    key: "_splat",
    value: function _splat(info, tokens) {
      var msg = info.message;
      var splat = info[SPLAT] || info.splat || [];
      var percents = msg.match(escapedPercent);
      var escapes = percents && percents.length || 0;

// The expected splat is the number of tokens minus the number of escapes
      // e.g.
      // - { expectedSplat: 3 } '%d %s %j'
      // - { expectedSplat: 5 } '[%s] %d%% %d%% %s %j'
      //
      // Any "meta" will be arugments in addition to the expected splat size
      // regardless of type. e.g.
      //
      // logger.log('info', '%d%% %s %j', 100, 'wow', { such: 'js' }, { thisIsMeta: true });
      // would result in splat of four (4), but only three (3) are expected. Therefore:
      //
      // extraSplat = 3 - 4 = -1
      // metas = [100, 'wow', { such: 'js' }, { thisIsMeta: true }].splice(-1, -1 * -1);
      // splat = [100, 'wow', { such: 'js' }]
      var expectedSplat = tokens.length - escapes;
      var extraSplat = expectedSplat - splat.length;
      var metas = extraSplat < 0 ? splat.splice(extraSplat, -1 * extraSplat) : [];

/**
      * Transforms the `info` message by using `util.format` to complete
      * any `info.message` provided it has string interpolation tokens.
      * If no tokens exist then `info` is immutable.
      *
      * @param  {Info} info Logform info message.
      * @param  {Object} opts Options for this instance.
      * @returns {Info} Modified info message
      */
  }, {
    key: "transform",
    value: function transform(info) {
      var msg = info.message;
      var splat = info[SPLAT] || info.splat;

// No need to process anything if splat is undefined
      if (!splat || !splat.length) {
        return info;
      }

// Extract tokens, if none available default to empty array to
      // ensure consistancy in expected results
      var tokens = msg && msg.match && msg.match(formatRegExp);

// This condition will take care of inputs with info[SPLAT]
      // but no tokens present
      if (!tokens && (splat || splat.length)) {
        var metas = splat.length > 1 ? splat.splice(0) : splat;

// Now that { splat } has been separated from any potential { meta }. we
        // can assign this to the `info` object and write it to our format stream.
        // If the additional metas are **NOT** objects or **LACK** enumerable properties
        // you are going to have a bad time.
        var metalen = metas.length;
        if (metalen) {
          for (var i = 0; i < metalen; i++) {
            Object.assign(info, metas[i]);
          }
        }
        return info;
      }
      if (tokens) {
        return this._splat(info, tokens);
      }
      return info;
    }
  }]);
  return Splatter;
}();
/*
 * function splat (info)
 * Returns a new instance of the splat format TransformStream
 * which performs string interpolation from `info` objects. This was
 * previously exposed implicitly in `winston < 3.0.0`.
 */
module.exports = function (opts) {
  return new Splatter(opts);
};

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