2048 for humans

2048.jl

# 2048 for humans
# ---------------
# controls:
# w: up
# a: left
# s: down
# d: right
# press enter

mutable struct Board{T,N} <: AbstractArray{T,N}
    cells::Array{T,N}
    dir
end

Board() = Board(4)
Board(n) = Board(zeros(Int, n, n), Val(:l))
dir(x) = Val(:l)
dir(b::Board) = b.dir
cells(b::Board) = b.cells

Base.size(b::Board) = size(b.cells)
Base.getindex(b::Board{T,N}, i...) where {T,N} =
    Base.getindex(cells(b), inv(dir(b), size(b)[1], i...)...)
Base.setindex!(b::Board{T,N}, x, i...) where {T,N} =
    Base.setindex!(cells(b), x, inv(dir(b), size(b)[1], i...)...)

Base.inv(dir, n, c::CartesianIndex{2}) = inv(dir, n, Tuple(c)...)
Base.inv(dir::Val{:l}, n, i, j) = tuple(i, j)
Base.inv(dir::Val{:r}, n, i, j) = tuple(i, n + 1 - j)
Base.inv(dir::Val{:u}, n, i, j) = tuple(j, i)
Base.inv(dir::Val{:d}, n, i, j) = tuple(n + 1 - j, i)

Base.display(b::Board) = display(cells(b))
function shift(arr::AbstractArray{T, 2}, default=zero(T)) where T
    shifted = -1
    r, c = size(arr)
    @inbounds for i=1:r
        k = 1
        can_merge = true
        @inbounds for j=1:c
            if arr[i, j] == default
            elseif k > 1 && arr[i, j] == arr[i, k-1] && can_merge
                shifted = 1
                arr[i, k-1] *= 2
                arr[i, j] = default
                can_merge = false
            elseif j == k
                k += 1
                can_merge = true
            else
                shifted = 1
                arr[i, k] = arr[i, j]
                arr[i, j] = default
                k += 1
                can_merge = true
            end
        end
    end
    return shifted
end

function drop(arr::AbstractArray{T,2}) where {T}
    s = findall(iszero, arr)
    (length(s) == 0) && return -1
    arr[Tuple(rand(s))...] = rand([2, 2, 4])
end

m = Dict("w"=> :u, "a"=>:l, "s"=>:d, "d"=>:r)
function input!(b::Board)
    inp = () -> (println("w/a/s/d? ");readline())
    d = inp();
    while !haskey(m, d)
        d = inp()
    end
    b.dir = Val(m[d])
end

function play()
    b = Board()
    v = drop(b)
    while v != -1
        display(b)
        input!(b)
        if  shift(b) != -1
            v = drop(b)
        end
    end
    println("Game Over!")
end

play()