hanoi_ascii.py

class Disc:
    def __init__(self, size):
        self.size = size
    def __str__(self):
        return self.size * "#"

class HanoiState:
    """Draws Hanoi Towers in  ASCII art style.
    This does not check for illegal moves nor does it implement error handling.
    """
    line_width = 99
    centers = (17, 17 + 33, 17 + 2*33)
    smallest_size = 3
    max_n = 10
    labels = ("A", "B", "C")
    label2index = {"A" : 0, "B" : 1, "C" : 2}

    def __init__(self, n):
        if n > HanoiState.max_n:
            raise ValueError("Max {} discs allowed!".format(HanoiState.max_n))
        else:
            self.n = n
            self.pegs = [self._init_discs(), [], []]

    def _init_discs(self):
        discs = []
        size = HanoiState.smallest_size
        for i in range(self.n):
            discs.append(Disc(size))
            size += 2
        return list(reversed(discs))

    def draw(self):
        line_width, centers = HanoiState.line_width, HanoiState.centers
        lines = [ list(line_width*" ") for _i in range(self.n + 3) ]
        for i in range(len(lines)):
            line = lines[i]
            for j, peg in enumerate(self.pegs):
                if i < len(peg):
                    disc = str(peg[i])
                    # TODO factor out center text to function
                    r = range(centers[j] - len(disc) // 2, centers[j] + len(disc)//2 + 1)
                    assert len(r) == len(disc)
                    line[r.start:r.stop] = list(disc)
                else:
                    line[centers[j]] = '|'

        for line in reversed(lines):
            print("".join(line))

        label_line = list(99*" ")
        for l, c in zip(HanoiState.labels, centers):
            label_line[c] = l
        print("".join(label_line))

        print(HanoiState.line_width * "-")


    def move(self, f, t):
        f, t = tuple(map(lambda x: HanoiState.label2index[x.strip()], (f, t)))
        disc = self.pegs[f].pop()
        self.pegs[t].append(disc)


    def move_and_draw(self, f, t):
        print(HanoiState.line_width * "-")
        print("{}{} -> {}".format(47*" ", f, t))
        self.move(f, t)
        print(HanoiState.line_width * "-")
        self.draw()