common.js

/**
 * This is the common logic for both the Node.js and web browser
 * implementations of `debug()`.
 */

module.exports = function setup(env) {
  createDebug.debug = createDebug['default'] = createDebug;
  createDebug.coerce = coerce;
  createDebug.disable = disable;
  createDebug.enable = enable;
  createDebug.enabled = enabled;
  createDebug.humanize = require('ms');

  Object.keys(env).forEach(function(key) {
    createDebug[key] = env[key];
  });

  /**
   * Active `debug` instances.
   */
  createDebug.instances = [];

  /**
   * The currently active debug mode names, and names to skip.
   */

  createDebug.names = [];
  createDebug.skips = [];

  /**
   * Map of special "%n" handling functions, for the debug "format" argument.
   *
   * Valid key names are a single, lower or upper-case letter, i.e. "n" and "N".
   */

  createDebug.formatters = {};

  /**
   * Select a color.
   * @param {String} namespace
   * @return {Number}
   * @api private
   */

  function selectColor(namespace) {
    var hash = 0, i;

    for (i in namespace) {
      hash  = ((hash << 5) - hash) + namespace.charCodeAt(i);
      hash |= 0; // Convert to 32bit integer
    }

    return createDebug.colors[Math.abs(hash) % createDebug.colors.length];
  }
  createDebug.selectColor = selectColor;

  /**
   * Create a debugger with the given `namespace`.
   *
   * @param {String} namespace
   * @return {Function}
   * @api public
   */

  function createDebug(namespace) {
    var prevTime;

    function debug() {
      // disabled?
      if (!debug.enabled) return;

      var self = debug;

      // set `diff` timestamp
      var curr = +new Date();
      var ms = curr - (prevTime || curr);
      self.diff = ms;
      self.prev = prevTime;
      self.curr = curr;
      prevTime = curr;

      // turn the `arguments` into a proper Array
      var args = new Array(arguments.length);
      for (var i = 0; i < args.length; i++) {
        args[i] = arguments[i];
      }

      args[0] = createDebug.coerce(args[0]);

      if ('string' !== typeof args[0]) {
        // anything else let's inspect with %O
        args.unshift('%O');
      }

      // apply any `formatters` transformations
      var index = 0;
      args[0] = args[0].replace(/%([a-zA-Z%])/g, function(match, format) {
        // if we encounter an escaped % then don't increase the array index
        if (match === '%%') return match;
        index++;
        var formatter = createDebug.formatters[format];
        if ('function' === typeof formatter) {
          var val = args[index];
          match = formatter.call(self, val);

          // now we need to remove `args[index]` since it's inlined in the `format`
          args.splice(index, 1);
          index--;
        }
        return match;
      });

      // apply env-specific formatting (colors, etc.)
      createDebug.formatArgs.call(self, args);

      var logFn = self.log || createDebug.log;
      logFn.apply(self, args);
    }

    debug.namespace = namespace;
    debug.enabled = createDebug.enabled(namespace);
    debug.useColors = createDebug.useColors();
    debug.color = selectColor(namespace);
    debug.destroy = destroy;
    debug.extend = extend;
    //debug.formatArgs = formatArgs;
    //debug.rawLog = rawLog;

    // env-specific initialization logic for debug instances
    if ('function' === typeof createDebug.init) {
      createDebug.init(debug);
    }

    createDebug.instances.push(debug);

    return debug;
  }

  function destroy () {
    var index = createDebug.instances.indexOf(this);
    if (index !== -1) {
      createDebug.instances.splice(index, 1);
      return true;
    } else {
      return false;
    }
  }

  function extend (namespace, delimiter) {
    return createDebug(this.namespace + (typeof delimiter !== 'undefined' ? delimiter : ':') + namespace);
  }

  /**
   * Enables a debug mode by namespaces. This can include modes
   * separated by a colon and wildcards.
   *
   * @param {String} namespaces
   * @api public
   */

  function enable(namespaces) {
    createDebug.save(namespaces);

    createDebug.names = [];
    createDebug.skips = [];

    var i;
    var split = (typeof namespaces === 'string' ? namespaces : '').split(/[\s,]+/);
    var len = split.length;

    for (i = 0; i < len; i++) {
      if (!split[i]) continue; // ignore empty strings
      namespaces = split[i].replace(/\*/g, '.*?');
      if (namespaces[0] === '-') {
        createDebug.skips.push(new RegExp('^' + namespaces.substr(1) + '$'));
      } else {
        createDebug.names.push(new RegExp('^' + namespaces + '$'));
      }
    }

    for (i = 0; i < createDebug.instances.length; i++) {
      var instance = createDebug.instances[i];
      instance.enabled = createDebug.enabled(instance.namespace);
    }
  }

  /**
   * Disable debug output.
   *
   * @api public
   */

  function disable() {
    createDebug.enable('');
  }

  /**
   * Returns true if the given mode name is enabled, false otherwise.
   *
   * @param {String} name
   * @return {Boolean}
   * @api public
   */

  function enabled(name) {
    if (name[name.length - 1] === '*') {
      return true;
    }
    var i, len;
    for (i = 0, len = createDebug.skips.length; i < len; i++) {
      if (createDebug.skips[i].test(name)) {
        return false;
      }
    }
    for (i = 0, len = createDebug.names.length; i < len; i++) {
      if (createDebug.names[i].test(name)) {
        return true;
      }
    }
    return false;
  }

  /**
   * Coerce `val`.
   *
   * @param {Mixed} val
   * @return {Mixed}
   * @api private
   */

  function coerce(val) {
    if (val instanceof Error) return val.stack || val.message;
    return val;
  }

  createDebug.enable(createDebug.load());

  return createDebug;
}