TimeTail.df

class TimeTail
    // Utilities for obtaining sections of channel history.
    
    function Span(string channelName, timeInterval)
        private channelData = Evaluate(channelName)
        
        private endTime = SysTime()
        private startIndex = 0
        
        while (startIndex < NumRows(channelData))
            if (endTime - GetTime(channelData[startIndex]) > timeInterval)
                break
            else
                startIndex++
            endif
        endwhile
        
        return channelData[0, startIndex]
    endfunction
    
    function From(string channelName, startTime)
        private channelData = Evaluate(channelName)
        
        private startIndex = 0
        
        while (startIndex < NumRows(channelData))
            if (startTime >= GetTime(channelData[startIndex]))
                break
            else
                startIndex++
            endif
        endwhile
        
        return channelData[0, startIndex]
    endfunction
endclass

global TimeTail = new(TimeTail)