// nanoquery has no function to get just a character
// so we have to implement our own
def get_char()
    c = ""
    while len(c)=0
        c = input()
    end
    return c[0]
end

// a function to handle fatal errors
def fatal_error(errtext)
    println "%" + errtext
    println "usage: " + args[1] + " [filename.bf]"
    exit
end

// get a filename from the command line and read the file in
fname = null
source = null
try
    fname = args[2]
    source = new(Nanoquery.IO.File, fname).readAll()
catch
    fatal_error("error while trying to read from specified file")
end

// start with one hundred cells and the pointer at 0
cells = {0} * 100
ptr   = 0

// loop through the instructions
loc = 0
while loc < len(source)
        instr = source[loc]

        if instr = ">"
                ptr += 1
                if ptr = len(cells)
                        cells.append(0)
                end
        else if instr = "<"
                ptr -= 1
                if ptr < 0
                        ptr = 0
                end
        else if instr = "+"
                cells[ptr] += 1
        else if instr = "-"
                cells[ptr] -= 1
        else if instr = "."
                print chr(cells[ptr])
        else if instr = ","
                cells[ptr] = ord(get_char())
        else if instr = "["
                if cells[ptr] = 0
                        while source[loc] != "]"
                                loc += 1
                        end
                end
        else if instr = "]"
                if cells[ptr] != 0
                        while source[loc] != "["
                                loc -= 1
                        end
                end
        else
                // do nothing
        end

        loc += 1
end