Test for cartesian iteration using tuples

cartitertuple.jl

function sumtuple{T}(A::AbstractArray{T,3}, iter)
    s = zero(typeof(one(T)+one(T)))
    for k = 1:iter
        I = (1,1,1)
        while I[3] <= size(A,3)
            s += A[I...]
            if I[1] < size(A,1)
                I = (I[1]+1,I[2],I[3])
            elseif I[2] < size(A,2)
                I = (1,I[2]+1,I[3])
            else
                I = (1,1,I[3]+1)
            end
        end
    end
    s
end

function sumloop{T}(A::AbstractArray{T,3}, iter)
    s = zero(typeof(one(T)+one(T)))
    for k = 1:iter
        for i3 = 1:size(A,3)
            for i2 = 1:size(A,2)
                for i1 = 1:size(A,1)
                    s += A[i1,i2,i3]
                end
            end
        end
    end
    s
end

import Base: getindex, start, done, next
import Base.Cartesian: @nexprs, @ntuple, @ngenerate

immutable TupleIter{N}
    I::NTuple{N,Int}
end
getindex(I::TupleIter, n) = I.I[n]
TupleIter(A::Array) = TupleIter(size(A))

# start{N}(lim::TupleIter{N}) = ntuple(N, d->1)
@ngenerate N NTuple{N,Int} start{N}(lim::TupleIter{N}) = @ntuple N d->1
done{N}(lim::TupleIter{N}, I::NTuple{N,Int}) = I[N] > lim[N]
@ngenerate N (NTuple{N,Int},NTuple{N,Int}) function next{N}(lim::TupleIter{N}, I::NTuple{N,Int})
    @nexprs N i->begin
        if I[i] < lim[i]
            newI = @ntuple N d->((d < i)  ? 1 :
                                 (d == i) ? I[d]+1 : I[d])
            return I, newI
        end
    end
    newI = @ntuple N d->((d<N) ? 1 : lim[N]+1)
    I, newI
end

# function next{N}(lim::TupleIter{N}, I::NTuple{N,Int})
#     for i = 1:N
#         if I[i] < lim[i]
#             newI = ntuple(N, d->(d < i)  ? 1 :
#                                 (d == i) ? I[d]+1 : I[d])
#             return I, newI
#         end
#     end
#     newI = ntuple(N, d->(d<N) ? 1 : lim[N]+1)
#     I, newI
# end


function sumtuple_gen{T}(A::AbstractArray{T}, iter)
    s = zero(typeof(one(T)+one(T)))
    for k = 1:iter
        for I = TupleIter(A)
            s += A[I...]
        end
    end
    s
end

function sumtuple_inlined_cartesian{T}(A::AbstractArray{T,3}, iter)
    s = zero(typeof(one(T)+one(T)))
    for k = 1:iter
        I = (1,1,1)
        while I[3] <= size(A,3)
            s += A[I...]
            isdone = false
            @nexprs 3 i->begin
                if !isdone && I[i] < size(A, i)
                    I = @ntuple 3 d->((d < i)  ? 1 :
                                      (d == i) ? I[d]+1 : I[d])
                    isdone = true
                end
            end
            if !isdone
                I = @ntuple 3 d->((d<3) ? 1 : size(A,3)+1)
            end
        end
    end
    s
end

function sumtuple_inlined_anon{T}(A::AbstractArray{T,3}, iter)
    s = zero(typeof(one(T)+one(T)))
    for k = 1:iter
        I = (1,1,1)
        while I[3] <= size(A,3)
            s += A[I...]
            isdone = false
            for i = 1:3
                if !isdone && I[i] < size(A, i)
                    I = ntuple(3, d->(d < i)  ? 1 :
                                     (d == i) ? I[d]+1 : I[d])
                    isdone = true
                end
            end
            if !isdone
                I = ntuple(3, d->(d<3) ? 1 : size(A,3)+1)
            end
        end
    end
    s
end