refactor to make the common code be a setup function

This is so that we can make both a Node.js instance and
web browser instance for when `--inspect` is used in Node.js.

src/browser.js

@@ -1,10 +1,7 @@
 /**
  * This is the web browser implementation of `debug()`.
- *
- * Expose `debug()` as the module.
  */
 
-exports = module.exports = require('./debug');
 exports.log = log;
 exports.formatArgs = formatArgs;
 exports.save = save;
@@ -66,19 +63,6 @@ function useColors() {
     (typeof navigator !== 'undefined' && navigator.userAgent && navigator.userAgent.toLowerCase().match(/applewebkit\/(\d+)/));
 }
 
-/**
- * Map %j to `JSON.stringify()`, since no Web Inspectors do that by default.
- */
-
-exports.formatters.j = function(v) {
-  try {
-    return JSON.stringify(v);
-  } catch (err) {
-    return '[UnexpectedJSONParseError]: ' + err.message;
-  }
-};
-
-
 /**
  * Colorize log arguments if enabled.
  *
@@ -93,7 +77,7 @@ function formatArgs(args) {
     + (useColors ? ' %c' : ' ')
     + args[0]
     + (useColors ? '%c ' : ' ')
-    + '+' + exports.humanize(this.diff);
+    + '+' + module.exports.humanize(this.diff);
 
   if (!useColors) return;
 
@@ -171,12 +155,6 @@ function load() {
   return r;
 }
 
-/**
- * Enable namespaces listed in `localStorage.debug` initially.
- */
-
-exports.enable(load());
-
 /**
  * Localstorage attempts to return the localstorage.
  *
@@ -193,3 +171,19 @@ function localstorage() {
     return window.localStorage;
   } catch (e) {}
 }
+
+module.exports = require('./common')(exports);
+
+var formatters = module.exports.formatters;
+
+/**
+ * Map %j to `JSON.stringify()`, since no Web Inspectors do that by default.
+ */
+
+formatters.j = function(v) {
+  try {
+    return JSON.stringify(v);
+  } catch (err) {
+    return '[UnexpectedJSONParseError]: ' + err.message;
+  }
+};

src/common.js

@@ -0,0 +1,235 @@
+
+/**
+ * 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.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;
+    }
+  }
+
+  /**
+   * 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;
+}