rebase on master

Author: jishnub

src/axes.jl

@@ -179,16 +179,21 @@ for f in [:first, :last]
     @eval @inline Base.$f(r::IdOffsetRange) = eltype(r)($f(r.parent) + r.offset)
 end
 
-@inline function Base.iterate(r::IdOffsetRange)
-    ret = iterate(r.parent)
-    ret === nothing && return nothing
-    return (eltype(r)(ret[1] + r.offset), ret[2])
-end
-@inline function Base.iterate(r::IdOffsetRange, i)
-    ret = iterate(r.parent, i)
+# Iteration for an IdOffsetRange
+@inline Base.iterate(r::IdOffsetRange, i...) = _iterate(r, i...)
+# In general we iterate over the parent term by term and add the offset.
+# This might have some performance degradation when coupled with bounds-checking
+# See https://github.com/JuliaArrays/OffsetArrays.jl/issues/214
+@inline function _iterate(r::IdOffsetRange, i...)
+    ret = iterate(r.parent, i...)
     ret === nothing && return nothing
     return (eltype(r)(ret[1] + r.offset), ret[2])
 end
+# Base.OneTo(n) is known to be exactly equivalent to the range 1:n,
+# and has no specialized iteration defined for it,
+# so we may add the offset to the range directly and iterate over the result
+# This gets around the performance issue described in issue #214
+@inline _iterate(r::IdOffsetRange{<:Integer, <:Base.OneTo}, i...) = iterate(r.parent .+ r.offset, i...)
 
 @inline function Base.getindex(r::IdOffsetRange, i::Integer)
     i isa Bool && throw(ArgumentError("invalid index: $i of type Bool"))

test/runtests.jl

@@ -221,7 +221,6 @@ end
             @test OrdinalRange{BigInt,BigInt}(r2) === r2
         end
     end
-<<<<<<< HEAD
 
     @testset "Bool IdOffsetRange (issue #223)" begin
         for b1 in [false, true], b2 in [false, true]
@@ -345,7 +344,8 @@ end
             @test_throws BoundsError r[true:true:false]
             @test_throws BoundsError r[false:true:false]
         end
-=======
+    end
+
     @testset "iteration" begin
         # parent has Base.OneTo axes
         A = ones(4:10)
@@ -363,7 +363,6 @@ end
         @test C[ind] == C[4]
         ind, st = iterate(ax, st)
         @test C[ind] == C[5]
->>>>>>> df172e1... specialize for Base.OneTo
     end
 end