Crawler, second version

lib/logger.js

+/**
+ * Logging service. This is not the log function itself, but rather provide a factory for making such.
+ *
+ * @param {String} module
+ *      The name identifying the main module.
+ * @constructor
+ */
+var Logger = function( module )
+{
+  /**
+   * The module name
+   * @type {String}
+   */
+  this.module = module;
+
+  /**
+   * Global flag to suppress all output.
+   * @type {boolean}
+   * @private
+   */
+  this._suppressed = false;
+
+  /**
+   * The console service used to report messages. This instance is used to get access to logMessage, which
+   * we use as a static function.
+   */
+  this.console_service =
+    Components.classes["@mozilla.org/consoleservice;1"].getService( Components.interfaces.nsIConsoleService );
+};
+exports.Logger = Logger;
+
+Logger.prototype.suppress = function( suppressed )
+{
+  this._suppressed = suppressed;
+};
+
+/**
+ * Create an ordinary log function with a consistent naming convention.
+ *
+ * @param {String} [submodule]
+ *      The name identifying some piece of the main module.
+ * @return {Function}
+ *      A two-argument function with the ordinary signature for a log message.
+ */
+Logger.prototype.make_log = function( submodule )
+{
+  var prefix = this.module;
+  if ( submodule && submodule.length > 0 )
+  {
+    prefix += "/" + submodule;
+  }
+  prefix += ": ";
+  return this.log.bind( this, prefix );
+};
+
+/**
+ * Display a log message whose location is reported as the source line of the caller, rather than some line within
+ * the log function itself.
+ * <p/>
+ * Note that this function would ordinarily be called from a function returned from make_log(), which computes the
+ * prefix argument. This is not a hard requirement, but rather a recommended practice.
+ *
+ * @param {String} prefix
+ *      String to be prepended before the message argument.
+ * @param {String} message
+ *      The main error message.
+ * @param {Boolean} [allow]
+ *      If present and false, suppresses the message. Allows disabling a log message by arbitrary category,
+ *      as implemented by the caller.
+ */
+Logger.prototype.log = function( prefix, message, allow )
+{
+  if ( ( arguments.length >= 3 && !allow ) || this._suppressed )
+  {
+    // Assert we have an explicit argument to disallow the message
+    return;
+  }
+  var error_report =
+    Components.classes["@mozilla.org/scripterror;1"].createInstance( Components.interfaces.nsIScriptError );
+  var caller = Components.stack.caller;
+
+  /*
+   * Remove the beginning of any filename value that contains a text arrow. This notation is used to indicate the
+   * complete link path by which the source came into context. While complete, it makes the links presented in
+   * the error console non-clickable.
+   */
+  var filename = caller.filename;
+  var n = filename.lastIndexOf( " -> " );
+  if ( n > -1 )
+  {
+    filename = filename.substr( n + 4 );
+  }
+
+  error_report.init( prefix + message, filename, null, caller.lineNumber, null, 1, "javascript" );
+  this.console_service.logMessage( error_report );
+
+  /*
+   * This line was used during development to see just what was in the scripterror object. Unfortunately, making a
+   * string message that exactly matches this format does not display as an error. In particular there is no
+   * clickable link displayed. Thus the best we can do is to display a warning with a link, rather than an ordinary
+   * console message, which doesn't display a clickable location.
+   */
+  //Cu.reportError( "ScriptError=" + scriptError.toString() );
+};
+
+/**
+ * Emit a stack trace to the log.
+ */
+Logger.prototype.stack_trace = function()
+{
+  var e = new Error();
+  this.log( "", e.stack );
+};
+
+
+function pad2( n )
+{
+  var s = String( n );
+  if ( n < 10 )
+    s = "0" + s;
+  return s;
+}
+
+function pad3( n )
+{
+  var s = String( n );
+  if ( n < 100 )
+  {
+    s = "0" + s;
+    if ( n < 10 )
+      s = "0" + s;
+  }
+  return s;
+}
+
+Logger.timestamp = function()
+{
+  let date = new Date();
+  return date.getUTCFullYear() + "-" + pad2( date.getUTCMonth() + 1 ) + "-" + pad2( date.getUTCDate() )
+    + " " + pad2( date.getUTCHours() ) + ":" + pad2( date.getUTCMinutes() ) + ":" + pad2( date.getUTCSeconds() )
+    + "." + pad3( date.getUTCMilliseconds() );
+};