SequenceGenerator

SequenceGenerator = Class.new()

function SequenceGenerator.new.default()
    local self = setmetatable({}, SequenceGenerator)

    self.outputSequence = ""
    self.buffer = ""

    return self
end

function SequenceGenerator:append(s)
    self.outputSequence = self.outputSequence .. s
    return self
end

function SequenceGenerator:push()
    self.outputSequence = self.outputSequence .. self.buffer
    self.buffer = ""
end

function SequenceGenerator:rem()
    local buffer
    buffer, self.buffer = self.buffer, ""
    return buffer
end

function SequenceGenerator:forward(n)
    return self:append((n or "") .. "f");
end

function SequenceGenerator:left(n)
    return self:append((n or "") .. "l");
end

function SequenceGenerator:right(n)
    return self:append((n or "") .. "r");
end

function SequenceGenerator:basicLayer(n)
    return self:append("UD")
end

function SequenceGenerator:digUp()
    return self:append("U")
end

function SequenceGenerator:digDown()
    return self:append("D")
end

function SequenceGenerator:startBlock(n)
    return self:append((n or 1) .. "[")
end

function SequenceGenerator:endBlock()
    return self:append("]")
end

function SequenceGenerator:generate3by3BranchMiningPattern(length)
    self:forward():right():basicLayer():forward():basicLayer():right(2):forward(2):right():basicLayer()
    self:forward():right();
    self:startBlock(length)
    self:startBlock(2):basicLayer():forward():endBlock():left():basicLayer():forward():left()
    self:startBlock(2):basicLayer():forward():endBlock():right():basicLayer()
    self:endBlock()
    return self:getOutput()
end

function SequenceGenerator:getOutput()
    return self.outputSequence
end