Costa, Premier Inn and restaurant owner Whitbread should be a 'buy' ahead of its full-year results, according to Galvan Research and Trading.Galvan said that the stock has been in a "steady, rising trend channel" since September 2013, trading well above the rising 100- and 200-day moving averages.However, there has been a period of consolidation after the shares hit a 52-week high in March; the stock has fallen nearly 5% over the past month despite Whitbread saying in late February that full-year results will come in at the top-end of current expectations.Galvan expects the shares to revisit a level of 4,476p by its annual results announcement on April 29th."As the UK's largest hotel, restaurant and coffee shop operator, Whitbread occupies a unique but enviable position as it's two key brands - Premier Inns and Costa Coffee - continue their rapid expansion," said Ed Woolfitt, Head of Trading at Galvan."Costa in particular is benefitting from the UK's apparently insatiable appetite for coffee shops, and with a clear strategy for growth providing plenty of visibility, Galvan Research believe that the current dip in the share price warrants an investor alert call to pick the stock up in the run up to the full-year results at the end of the month."The stock was under more selling pressure on Tuesday, falling 2.5% to 4,062p by 11:17.BC