/**
+ * Provides console log capability and exposes a custom event for
+ * console implementations.
+ * @module yui
+ * @submodule yui-log
+ */
+(function() {
+
+var INSTANCE = Y,
+ LOGEVENT = 'yui:log',
+ UNDEFINED = 'undefined',
+ LEVELS = { debug: 1, info: 1, warn: 1, error: 1 },
+ _published;
+
+/**
+ * If the 'debug' config is true, a 'yui:log' event will be
+ * dispatched, which the Console widget and anything else
+ * can consume. If the 'useBrowserConsole' config is true, it will
+ * write to the browser console if available. YUI-specific log
+ * messages will only be present in the -debug versions of the
+ * JS files. The build system is supposed to remove log statements
+ * from the raw and minified versions of the files.
+ *
+ * @method log
+ * @for YUI
+ * @param {String} msg The message to log.
+ * @param {String} cat The log category for the message. Default
+ * categories are "info", "warn", "error", time".
+ * Custom categories can be used as well. (opt)
+ * @param {String} src The source of the the message (opt)
+ * @param {boolean} silent If true, the log event won't fire
+ * @return {YUI} YUI instance
+ */
+INSTANCE.log = function(msg, cat, src, silent) {
+ var Y = INSTANCE, c = Y.config, bail = false, excl, incl, m, f;
+ // suppress log message if the config is off or the event stack
+ // or the event call stack contains a consumer of the yui:log event
+ if (c.debug) {
+ // apply source filters
+ if (src) {
+ excl = c.logExclude;
+ incl = c.logInclude;
+
+ if (incl && !(src in incl)) {
+ bail = 1;
+ } else if (excl && (src in excl)) {
+ bail = 1;
+ }
+ }
+
+ if (!bail) {
+
+ if (c.useBrowserConsole) {
+ m = (src) ? src + ': ' + msg : msg;
+ if (typeof console != UNDEFINED && console.log) {
+ f = (cat && console[cat] && (cat in LEVELS)) ? cat : 'log';
+ console[f](m);
+ } else if (typeof opera != UNDEFINED) {
+ opera.postError(m);
+ }
+ }
+
+ if (Y.fire && !silent) {
+ if (!_published) {
+ Y.publish(LOGEVENT, {
+ broadcast: 2,
+ emitFacade: 1
+ });
+
+ _published = 1;
+
+ }
+ Y.fire(LOGEVENT, {
+ msg: msg,
+ cat: cat,
+ src: src
+ });
+ }
+ }
+ }
+
+ return Y;
+};
+
+/**
+ * Write a system message. This message will be preserved in the
+ * minified and raw versions of the YUI files, unlike log statements.
+ * @method message
+ * @for YUI
+ * @param {String} msg The message to log.
+ * @param {String} cat The log category for the message. Default
+ * categories are "info", "warn", "error", time".
+ * Custom categories can be used as well. (opt)
+ * @param {String} src The source of the the message (opt)
+ * @param {boolean} silent If true, the log event won't fire
+ * @return {YUI} YUI instance
+ */
+INSTANCE.message = function() {
+ return INSTANCE.log.apply(INSTANCE, arguments);
+};
+
+})();
+