function onSIGINT() {
		var isEmpty;

		debug( 'Received a SIGINT event.' );

		// If the REPL is currently busy executing a command, stop waiting for it to finish:
		if ( self._busy ) {
			self._done( new Error( 'unexpected error. Command execution terminated.' ) );
			return;
		}
		// Check whether the user has entered any characters:
		isEmpty = ( self._rli.line.length === 0 );

		// Close the completer engine:
		self._completerEngine.closeCompleter();

		// Clear the current line:
		self.clearLine();

		// In the absence of any entered partial and/or unevaluated commands, determine whether we should close the REPL...
		if ( self._cmd.length === 0 && isEmpty ) {
			if ( self._SIGINT ) {
				self._SIGINT = false;
				self.close();
				return;
			}
			self._ostream.write( 'To exit, enter ^D or ^C again or enter quit().\n' );
			self._SIGINT = true;
		} else {
			self._SIGINT = false;
		}
		// Reset the command queue:
		self._queue.clear();

		// Clear any command which has been buffered but not yet executed:
		self.clearCommand();

		// Display a new prompt:
		displayPrompt( self, false );
	}
Callback invoked upon receiving a "SIGINT" event (e.g., Ctrl-C).

@private
@returns {void}