Type-stability in 2d tensorizer iteration (#374)

* type-stability in 2d tensorizer iteration

* version bump to v0.7.69

Author: jishnub

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.7.68"
+version = "0.7.69"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/LinearAlgebra/helper.jl

@@ -546,7 +546,7 @@ end
 CachedIterator{T,IT}(it::IT, state) where {T,IT} = CachedIterator{T,IT}(it,T[],state,0)
 CachedIterator(it::IT) where IT = CachedIterator{eltype(it),IT}(it, ())
 
-function resize!(it::CachedIterator,n::Integer)
+function resize!(it::CachedIterator{T},n::Integer) where {T}
     m = it.length
     if n > m
         if n > length(it.storage)
@@ -559,10 +559,10 @@ function resize!(it::CachedIterator,n::Integer)
                 it.length = k-1
                 return it
             end
-            it.storage[k] = xst[1]
-            it.state = (xst[2],)
+            v::T, st = xst
+            it.storage[k] = v
+            it.state = (st,)
         end
-
         it.length = n
     end
     it
@@ -579,7 +579,7 @@ Base.keys(c::CachedIterator) = oneto(length(c))
 
 iterate(it::CachedIterator) = iterate(it,1)
 function iterate(it::CachedIterator,st::Int)
-    if  st == it.length + 1 && iterate(it.iterator,it.state...) === nothing
+    if  st > it.length && iterate(it.iterator,it.state...) === nothing
         nothing
     else
         (it[st],st+1)

src/Multivariate/TensorSpace.jl

@@ -17,11 +17,11 @@ factor(d::AbstractProductSpace,k) = factors(d)[k]
 # tensor entry of a tensor product of d spaces
 # findfirst is overriden to get efficient inverse
 # blocklengths is a tuple of block lengths, e.g., Chebyshev()^2
-# would be Tensorizer((1:∞,1:∞))
+# would be Tensorizer((Ones{Int}(∞), Ones{Int}(∞)))
 # ConstantSpace() ⊗ Chebyshev()
-# would be Tensorizer((1:1,1:∞))
+# would be Tensorizer((1:1,Ones{Int}(∞)))
 # and Chebyshev() ⊗ ArraySpace([Chebyshev(),Chebyshev()])
-# would be Tensorizer((1:∞,2:2:∞))
+# would be Tensorizer((Ones{Int}(∞), Fill(2,∞)))
 
 
 struct Tensorizer{DMS<:Tuple}
@@ -79,7 +79,7 @@ function next(a::TrivialTensorizer{d}, iterator_tuple) where {d}
 end
 
 
-function done(a::TrivialTensorizer, iterator_tuple)
+function done(a::TrivialTensorizer, iterator_tuple)::Bool
     i, tot = last(iterator_tuple)
     return i ≥ tot
 end
@@ -89,12 +89,13 @@ end
 start(a::Tensorizer2D) = _start(a)
 start(a::TrivialTensorizer{2}) = _start(a)
 
-_start(a) = (1,1), (1,1), (0,0), (a.blocks[1][1],a.blocks[2][1]), (0,length(a))
+_start(a) = (1,1, 1,1, 0,0, a.blocks[1][1],a.blocks[2][1]), (0,length(a))
 
-next(a::Tensorizer2D, state) = _next(a, state)
-next(a::TrivialTensorizer{2}, state) = _next(a, state)
+next(a::Tensorizer2D, state) = _next(a, state::typeof(_start(a)))
+next(a::TrivialTensorizer{2}, state) = _next(a, state::typeof(_start(a)))
 
-function _next(a, ((K,J), (k,j), (rsh,csh), (n,m), (i,tot)))
+function _next(a, st)
+    (K,J, k,j, rsh,csh, n,m), (i,tot) = st
     ret = k+rsh,j+csh
     if k==n && j==m  # end of block
         if J == 1 || K == length(a.blocks[1])   # end of new block
@@ -115,13 +116,16 @@ function _next(a, ((K,J), (k,j), (rsh,csh), (n,m), (i,tot)))
     else
         k += 1
     end
-    ret, ((K,J), (k,j), (rsh,csh), (n,m), (i+1,tot))
+    ret, ((K,J, k,j, rsh,csh, n,m), (i+1,tot))
 end
 
-done(a::Tensorizer2D, state) = _done(a, state)
-done(a::TrivialTensorizer{2}, state) = _done(a, state)
+done(a::Tensorizer2D, state) = _done(a, state::typeof(_start(a)))
+done(a::TrivialTensorizer{2}, state) = _done(a, state::typeof(_start(a)))
 
-_done(a, (_, _, _, _, (i,tot))) = i ≥ tot
+function _done(a, st)::Bool
+    i, tot = last(st)
+    i ≥ tot
+end
 
 iterate(a::Tensorizer) = next(a, start(a))
 function iterate(a::Tensorizer, st)