Piercing Line automatic finding script

////////////////////////////////////////////////////////////
//  Copyright by HPotter v1.0 10/04/2014
//    This is a bullish reversal pattern formed by two candlesticks. Following a downtrend, 
//    an up candlestick with a long real body is followed by a lower open on the next 
//    candlestick. This session finishes as an up candlestick and closes above the midpoint 
//    of the prior candlestick's real body. It is the reverse of the Dark Cloud.
////////////////////////////////////////////////////////////

study(title = "Piercing Line", overlay = true)
upper = highest(10)[1]
barcolor(close[1] < open[1] ?  open < low[1] ? close > close[1] + ((open[1] - close[1])/2) ? close < open[1] ? yellow :na :na  : na : na)