Add Visit iterator and speed up enumerate for LinearSlow arrays

Author: timholy

base/exports.jl

@@ -125,6 +125,7 @@ export
     VecOrMat,
     Vector,
     VersionNumber,
+    Visit,
     WeakKeyDict,
     WorkerConfig,
     WString,
@@ -981,6 +982,7 @@ export
     enumerate,
     next,
     start,
+    visit,
     zip,
     rest,
     countfrom,

base/iterator.jl

@@ -21,18 +21,43 @@ enumerate(itr) = Enumerate(itr)
 
 length(e::Enumerate) = length(e.itr)
 size(e::Enumerate) = size(e.itr)
-start(e::Enumerate) = (1, start(e.itr))
-function next(e::Enumerate, state)
+@inline start(e::Enumerate) = (1, start(e.itr))
+@inline function next(e::Enumerate, state)
     n = next(e.itr,state[2])
     (state[1],n[1]), (state[1]+1,n[2])
 end
-done(e::Enumerate, state) = done(e.itr, state[2])
+@inline done(e::Enumerate, state) = done(e.itr, state[2])
 
 eltype{I}(::Type{Enumerate{I}}) = Tuple{Int, eltype(I)}
 
 iteratorsize{I}(::Type{Enumerate{I}}) = iteratorsize(I)
 iteratoreltype{I}(::Type{Enumerate{I}}) = iteratoreltype(I)
 
+# visit
+# visit is like enumerate, except rather than counting entries it
+# returns the index associated with each entry
+
+immutable Visit{I,A<:AbstractArray}
+    data::A
+    itr::I
+end
+visit(A::AbstractArray) = Visit(A, eachindex(A))
+
+Base.length(v::Visit) = length(v.itr)
+Base.size(v::Visit) = size(v.itr)
+@inline Base.start(v::Visit) = start(v.itr)
+@inline function Base.next(v::Visit, state)
+    indx, n = next(v.itr, state)
+    @inbounds item = v.data[indx]
+    (indx, item), n
+end
+@inline Base.done(v::Visit, state) = done(v.itr, state)
+
+Base.eltype{I,A}(::Type{Visit{I,A}}) = Tuple{eltype(I), eltype(A)}
+
+Base.iteratorsize{I}(::Type{Visit{I}}) = iteratorsize(I)
+Base.iteratoreltype{I}(::Type{Visit{I}}) = iteratoreltype(I)
+
 # zip
 
 abstract AbstractZipIterator

test/arrayops.jl

@@ -936,6 +936,13 @@ let a36 = boo32_64()
 end
 @test isequal([1,2,3], [a for (a,b) in enumerate(2:4)])
 @test isequal([2,3,4], [b for (a,b) in enumerate(2:4)])
+A14 = [11 13; 12 14]
+B14 = sub(A14, 1:2, 1:2)
+@test isa(Base.linearindexing(B14), Base.LinearSlow)
+@test isequal([1,2,3,4], [a for (a,b) in visit(A14)])
+@test isequal(vec(collect(eachindex(B14))), [a for (a,b) in visit(B14)])
+@test isequal([11,12,13,14], [b for (a,b) in visit(A14)])
+@test isequal([11,12,13,14], [b for (a,b) in visit(B14)])
 
 # comprehension in let-bound function
 let x⊙y = sum([x[i]*y[i] for i=1:length(x)])