use Base implementation for compute_offset1 (#135)

* Fix #133: compute_offset1 for an IdOffsetRange axis

* [compat] use Base implementation for compute_offset1 for Julia >= 1.6

Julia < 1.6 still need this for correctness

closes #100
closes #133
closes #134

Co-authored-by: jishnub <jishnuonline@gmail.com>

Author: johnnychen94

src/axes.jl

@@ -129,9 +129,6 @@ offset_coerce(::Type{I}, r::AbstractUnitRange) where I<:AbstractUnitRange{T} whe
 @inline Base.axes1(r::IdOffsetRange) = IdOffsetRange(Base.axes1(r.parent), r.offset)
 @inline Base.unsafe_indices(r::IdOffsetRange) = (r,)
 @inline Base.length(r::IdOffsetRange) = length(r.parent)
-# issue 100: IdOffsetRange as another index-preserving case shouldn't comtribute offsets
-@inline Base.compute_offset1(parent, stride1::Integer, dims::Tuple{Int}, inds::Tuple{IdOffsetRange}, I::Tuple) =
-    Base.compute_linindex(parent, I) - stride1*first(axes(parent, dims[1]))
 Base.reduced_index(i::IdOffsetRange) = typeof(i)(first(i):first(i))
 # Workaround for #92 on Julia < 1.4
 Base.reduced_index(i::IdentityUnitRange{<:IdOffsetRange}) = typeof(i)(first(i):first(i))
@@ -170,3 +167,9 @@ Base.show(io::IO, r::IdOffsetRange) = print(io, first(r), ':', last(r))
 
 # Optimizations
 @inline Base.checkindex(::Type{Bool}, inds::IdOffsetRange, i::Real) = Base.checkindex(Bool, inds.parent, i - inds.offset)
+
+if VERSION < v"1.6.0-DEV.762"
+    # issue 100, 133: IdOffsetRange as another index-preserving case shouldn't comtribute offsets
+    @inline Base.compute_offset1(parent, stride1::Integer, dims::Tuple{Int}, inds::Tuple{IdOffsetRange}, I::Tuple) =
+        Base.compute_linindex(parent, I) - stride1*first(inds[1])
+end

test/runtests.jl

@@ -335,6 +335,35 @@ end
     @test_throws BoundsError S[1]
     @test axes(S) == (OffsetArrays.IdOffsetRange(3:4), )
 
+    # issue 133
+    r = OffsetArrays.IdOffsetRange(1:2, -1)
+    v1 = view(A, r, 3)
+    @test v1[0] == 1
+    @test v1[1] == 2
+    @test axes(v1, 1) == axes(r, 1)
+    v2 = view(A, UnitRange(r), 3)
+    for (indflat, indoffset) in enumerate(r)
+        @test v1[indoffset] == v2[indflat]
+    end
+
+    # issue 133
+    r = OffsetArrays.IdOffsetRange(1:2, 2)
+    v1 = view(A, 1, r)
+    @test v1[3] == 2
+    @test v1[4] == 4
+    @test axes(v1, 1) == axes(r, 1)
+    v2 = view(A, 1, UnitRange(r))
+    for (indflat, indoffset) in enumerate(r)
+        @test v1[indoffset] == v2[indflat]
+    end
+
+    # issue 133
+    a12 = zeros(3:8, 3:4)
+    r = OffsetArrays.IdOffsetRange(Base.OneTo(3), 5)
+    a12[r, 4] .= 3
+    @test all(a12[r, 4] .== 3)
+    @test all(a12[UnitRange(r), 4] .== 3)
+
     A0 = collect(reshape(1:24, 2, 3, 4))
     A = OffsetArray(A0, (-1,2,1))
     S = view(A, axes(A, 1), 3:4, axes(A, 3))