Remove the "experimental" status from non-1 indexing

NEWS.md

@@ -226,6 +226,10 @@ Language changes
   * `try` blocks without `catch` or `finally` are no longer allowed. An explicit empty
     `catch` block should be written instead ([#27554]).
 
+  * `AbstractArray` types that use unconventional (not 1-based) indexing can now support
+    `size`, `length`, and `@inbounds`. To optionally enforce conventional indices,
+    you can `@assert !has_offset_axes(A)`.
+
 Breaking changes
 ----------------
 

base/abstractarray.jl

@@ -83,12 +83,23 @@ function axes(A)
     map(OneTo, size(A))
 end
 
+"""
+    has_offset_axes(A)
+    has_offset_axes(A, B, ...)
+
+Return `true` if the indices of `A` start with something other than 1 along any axis.
+If multiple arguments are passed, equivalent to `has_offset_axes(A) | has_offset_axes(B) | ...`.
+"""
+has_offset_axes(A)    = _tuple_any(x->first(x)!=1, axes(A))
+has_offset_axes(A...) = _tuple_any(has_offset_axes, A)
+has_offset_axes(::Colon) = false
+
 # Performance optimization: get rid of a branch on `d` in `axes(A, d)`
 # for d=1. 1d arrays are heavily used, and the first dimension comes up
 # in other applications.
-indices1(A::AbstractArray{<:Any,0}) = OneTo(1)
-indices1(A::AbstractArray) = (@_inline_meta; axes(A)[1])
-indices1(iter) = OneTo(length(iter))
+axes1(A::AbstractArray{<:Any,0}) = OneTo(1)
+axes1(A::AbstractArray) = (@_inline_meta; axes(A)[1])
+axes1(iter) = OneTo(length(iter))
 
 unsafe_indices(A) = axes(A)
 unsafe_indices(r::AbstractRange) = (OneTo(unsafe_length(r)),) # Ranges use checked_sub for size
@@ -154,14 +165,12 @@ julia> length([1 2; 3 4])
 ```
 """
 length(t::AbstractArray) = (@_inline_meta; prod(size(t)))
-_length(A::AbstractArray) = (@_inline_meta; prod(map(unsafe_length, axes(A)))) # circumvent missing size
-_length(A) = (@_inline_meta; length(A))
 
 # `eachindex` is mostly an optimization of `keys`
 eachindex(itrs...) = keys(itrs...)
 
 # eachindex iterates over all indices. IndexCartesian definitions are later.
-eachindex(A::AbstractVector) = (@_inline_meta(); indices1(A))
+eachindex(A::AbstractVector) = (@_inline_meta(); axes1(A))
 
 """
     eachindex(A...)
@@ -209,8 +218,8 @@ function eachindex(A::AbstractArray, B::AbstractArray...)
     @_inline_meta
     eachindex(IndexStyle(A,B...), A, B...)
 end
-eachindex(::IndexLinear, A::AbstractArray) = (@_inline_meta; OneTo(_length(A)))
-eachindex(::IndexLinear, A::AbstractVector) = (@_inline_meta; indices1(A))
+eachindex(::IndexLinear, A::AbstractArray) = (@_inline_meta; OneTo(length(A)))
+eachindex(::IndexLinear, A::AbstractVector) = (@_inline_meta; axes1(A))
 function eachindex(::IndexLinear, A::AbstractArray, B::AbstractArray...)
     @_inline_meta
     indsA = eachindex(IndexLinear(), A)
@@ -509,7 +518,7 @@ function checkindex(::Type{Bool}, inds::AbstractUnitRange, r::AbstractRange)
     @_propagate_inbounds_meta
     isempty(r) | (checkindex(Bool, inds, first(r)) & checkindex(Bool, inds, last(r)))
 end
-checkindex(::Type{Bool}, indx::AbstractUnitRange, I::AbstractVector{Bool}) = indx == indices1(I)
+checkindex(::Type{Bool}, indx::AbstractUnitRange, I::AbstractVector{Bool}) = indx == axes1(I)
 checkindex(::Type{Bool}, indx::AbstractUnitRange, I::AbstractArray{Bool}) = false
 function checkindex(::Type{Bool}, inds::AbstractUnitRange, I::AbstractArray)
     @_inline_meta
@@ -744,7 +753,7 @@ function copyto!(::IndexStyle, dest::AbstractArray, ::IndexCartesian, src::Abstr
 end
 
 function copyto!(dest::AbstractArray, dstart::Integer, src::AbstractArray)
-    copyto!(dest, dstart, src, first(LinearIndices(src)), _length(src))
+    copyto!(dest, dstart, src, first(LinearIndices(src)), length(src))
 end
 
 function copyto!(dest::AbstractArray, dstart::Integer, src::AbstractArray, sstart::Integer)
@@ -837,7 +846,7 @@ function iterate(A::AbstractArray, state=(eachindex(A),))
     A[y[1]], (state[1], tail(y)...)
 end
 
-isempty(a::AbstractArray) = (_length(a) == 0)
+isempty(a::AbstractArray) = (length(a) == 0)
 
 
 ## range conversions ##
@@ -1148,9 +1157,9 @@ get(A::AbstractArray, I::Dims, default) = checkbounds(Bool, A, I...) ? A[I...] :
 
 function get!(X::AbstractVector{T}, A::AbstractVector, I::Union{AbstractRange,AbstractVector{Int}}, default::T) where T
     # 1d is not linear indexing
-    ind = findall(in(indices1(A)), I)
+    ind = findall(in(axes1(A)), I)
     X[ind] = A[I[ind]]
-    Xind = indices1(X)
+    Xind = axes1(X)
     X[first(Xind):first(ind)-1] = default
     X[last(ind)+1:last(Xind)] = default
     X
@@ -1776,9 +1785,9 @@ _sub2ind(inds::Union{DimsInteger,Indices}, I1::AbstractVector{T}, I::AbstractVec
     _sub2ind_vecs(inds, I1, I...)
 function _sub2ind_vecs(inds, I::AbstractVector...)
     I1 = I[1]
-    Iinds = indices1(I1)
+    Iinds = axes1(I1)
     for j = 2:length(I)
-        indices1(I[j]) == Iinds || throw(DimensionMismatch("indices of I[1] ($(Iinds)) does not match indices of I[$j] ($(indices1(I[j])))"))
+        axes1(I[j]) == Iinds || throw(DimensionMismatch("indices of I[1] ($(Iinds)) does not match indices of I[$j] ($(axes1(I[j])))"))
     end
     Iout = similar(I1)
     _sub2ind!(Iout, inds, Iinds, I)

base/abstractarraymath.jl

@@ -39,7 +39,7 @@ julia> vec(1:3)
 
 See also [`reshape`](@ref).
 """
-vec(a::AbstractArray) = reshape(a,_length(a))
+vec(a::AbstractArray) = reshape(a,length(a))
 vec(a::AbstractVector) = a
 
 _sub(::Tuple{}, ::Tuple{}) = ()
@@ -72,7 +72,7 @@ squeeze(A; dims) = _squeeze(A, dims)
 function _squeeze(A::AbstractArray, dims::Dims)
     for i in 1:length(dims)
         1 <= dims[i] <= ndims(A) || throw(ArgumentError("squeezed dims must be in range 1:ndims(A)"))
-        _length(axes(A, dims[i])) == 1 || throw(ArgumentError("squeezed dims must all be size 1"))
+        length(axes(A, dims[i])) == 1 || throw(ArgumentError("squeezed dims must all be size 1"))
         for j = 1:i-1
             dims[j] == dims[i] && throw(ArgumentError("squeezed dims must be unique"))
         end
@@ -158,7 +158,7 @@ function reverse(A::AbstractArray; dims::Integer)
     B = similar(A)
     nnd = 0
     for i = 1:nd
-        nnd += Int(_length(inds[i])==1 || i==d)
+        nnd += Int(length(inds[i])==1 || i==d)
     end
     indsd = inds[d]
     sd = first(indsd)+last(indsd)

base/array.jl

@@ -445,6 +445,7 @@ for (fname, felt) in ((:zeros, :zero), (:ones, :one))
 end
 
 function _one(unit::T, x::AbstractMatrix) where T
+    @assert !has_offset_axes(x)
     m,n = size(x)
     m==n || throw(DimensionMismatch("multiplicative identity defined only for square matrices"))
     # Matrix{T}(I, m, m)
@@ -547,9 +548,9 @@ end
 
 _collect_indices(::Tuple{}, A) = copyto!(Array{eltype(A),0}(undef), A)
 _collect_indices(indsA::Tuple{Vararg{OneTo}}, A) =
-    copyto!(Array{eltype(A)}(undef, _length.(indsA)), A)
+    copyto!(Array{eltype(A)}(undef, length.(indsA)), A)
 function _collect_indices(indsA, A)
-    B = Array{eltype(A)}(undef, _length.(indsA))
+    B = Array{eltype(A)}(undef, length.(indsA))
     copyto!(B, CartesianIndices(axes(B)), A, CartesianIndices(indsA))
 end
 
@@ -748,6 +749,7 @@ function setindex! end
 function setindex!(A::Array, X::AbstractArray, I::AbstractVector{Int})
     @_propagate_inbounds_meta
     @boundscheck setindex_shape_check(X, length(I))
+    @assert !has_offset_axes(X)
     X′ = unalias(A, X)
     I′ = unalias(A, I)
     count = 1
@@ -866,7 +868,7 @@ themselves in another collection. The result is of the preceding example is equi
 """
 function append!(a::Array{<:Any,1}, items::AbstractVector)
     itemindices = eachindex(items)
-    n = _length(itemindices)
+    n = length(itemindices)
     _growend!(a, n)
     copyto!(a, length(a)-n+1, items, first(itemindices), n)
     return a
@@ -876,6 +878,7 @@ append!(a::Vector, iter) = _append!(a, IteratorSize(iter), iter)
 push!(a::Vector, iter...) = append!(a, iter)
 
 function _append!(a, ::Union{HasLength,HasShape}, iter)
+    @assert !has_offset_axes(a)
     n = length(a)
     resize!(a, n+length(iter))
     @inbounds for (i,item) in zip(n+1:length(a), iter)
@@ -909,7 +912,7 @@ function prepend! end
 
 function prepend!(a::Array{<:Any,1}, items::AbstractVector)
     itemindices = eachindex(items)
-    n = _length(itemindices)
+    n = length(itemindices)
     _growbeg!(a, n)
     if a === items
         copyto!(a, 1, items, n+1, n)
@@ -923,6 +926,7 @@ prepend!(a::Vector, iter) = _prepend!(a, IteratorSize(iter), iter)
 pushfirst!(a::Vector, iter...) = prepend!(a, iter)
 
 function _prepend!(a, ::Union{HasLength,HasShape}, iter)
+    @assert !has_offset_axes(a)
     n = length(iter)
     _growbeg!(a, n)
     i = 0

base/arrayshow.jl

@@ -78,7 +78,7 @@ function alignment(io::IO, X::AbstractVecOrMat,
             break
         end
     end
-    if 1 < length(a) < _length(axes(X,2))
+    if 1 < length(a) < length(axes(X,2))
         while sum(map(sum,a)) + sep*length(a) >= cols_otherwise
             pop!(a)
         end
@@ -168,7 +168,7 @@ function print_matrix(io::IO, X::AbstractVecOrMat,
     @assert textwidth(hdots) == textwidth(ddots)
     sepsize = length(sep)
     rowsA, colsA = axes(X,1), axes(X,2)
-    m, n = _length(rowsA), _length(colsA)
+    m, n = length(rowsA), length(colsA)
     # To figure out alignments, only need to look at as many rows as could
     # fit down screen. If screen has at least as many rows as A, look at A.
     # If not, then we only need to look at the first and last chunks of A,
@@ -266,10 +266,10 @@ function show_nd(io::IO, a::AbstractArray, print_matrix::Function, label_slices:
             for i = 1:nd
                 ii = idxs[i]
                 ind = tailinds[i]
-                if _length(ind) > 10
+                if length(ind) > 10
                     if ii == ind[firstindex(ind)+3] && all(d->idxs[d]==first(tailinds[d]),1:i-1)
                         for j=i+1:nd
-                            szj = _length(axes(a, j+2))
+                            szj = length(axes(a, j+2))
                             indj = tailinds[j]
                             if szj>10 && first(indj)+2 < idxs[j] <= last(indj)-3
                                 @goto skip
@@ -313,7 +313,7 @@ print_array(io::IO, X::AbstractArray) = show_nd(io, X, print_matrix, true)
 # implements: show(io::IO, ::MIME"text/plain", X::AbstractArray)
 function show(io::IO, ::MIME"text/plain", X::AbstractArray)
     # 0) compute new IOContext
-    if !haskey(io, :compact) && _length(axes(X, 2)) > 1
+    if !haskey(io, :compact) && length(axes(X, 2)) > 1
         io = IOContext(io, :compact => true)
     end
     if get(io, :limit, false) && eltype(X) === Method
@@ -359,7 +359,7 @@ function _show_nonempty(io::IO, X::AbstractMatrix, prefix::String)
     @assert !isempty(X)
     limit = get(io, :limit, false)::Bool
     indr, indc = axes(X,1), axes(X,2)
-    nr, nc = _length(indr), _length(indc)
+    nr, nc = length(indr), length(indc)
     rdots, cdots = false, false
     rr1, rr2 = UnitRange{Int}(indr), 1:0
     cr1, cr2 = UnitRange{Int}(indc), 1:0
@@ -432,8 +432,8 @@ function show_vector(io::IO, v, opn='[', cls=']')
     # directly or indirectly, the context now knows about eltype(v)
     io = IOContext(io, :typeinfo => eltype(v), :compact => get(io, :compact, true))
     limited = get(io, :limit, false)
-    if limited && _length(v) > 20
-        inds = indices1(v)
+    if limited && length(v) > 20
+        inds = axes1(v)
         show_delim_array(io, v, opn, ",", "", false, inds[1], inds[1]+9)
         print(io, "  …  ")
         show_delim_array(io, v, "", ",", cls, false, inds[end-9], inds[end])

base/broadcast.jl

@@ -504,7 +504,7 @@ Base.@propagate_inbounds _newindex(ax::Tuple{}, I::Tuple{}) = ()
 @inline function _newindexer(indsA::Tuple)
     ind1 = indsA[1]
     keep, Idefault = _newindexer(tail(indsA))
-    (Base._length(ind1)!=1, keep...), (first(ind1), Idefault...)
+    (Base.length(ind1)!=1, keep...), (first(ind1), Idefault...)
 end
 
 @inline function Base.getindex(bc::Broadcasted, I::Union{Integer,CartesianIndex})

base/c.jl

@@ -267,6 +267,7 @@ transcode(T, src::String) = transcode(T, codeunits(src))
 transcode(::Type{String}, src) = String(transcode(UInt8, src))
 
 function transcode(::Type{UInt16}, src::AbstractVector{UInt8})
+    @assert !has_offset_axes(src)
     dst = UInt16[]
     i, n = 1, length(src)
     n > 0 || return dst
@@ -317,6 +318,7 @@ function transcode(::Type{UInt16}, src::AbstractVector{UInt8})
 end
 
 function transcode(::Type{UInt8}, src::AbstractVector{UInt16})
+    @assert !has_offset_axes(src)
     n = length(src)
     n == 0 && return UInt8[]
 

base/combinatorics.jl

@@ -64,6 +64,7 @@ isperm(p::Tuple{Int}) = p[1] == 1
 isperm(p::Tuple{Int,Int}) = ((p[1] == 1) & (p[2] == 2)) | ((p[1] == 2) & (p[2] == 1))
 
 function permute!!(a, p::AbstractVector{<:Integer})
+    @assert !has_offset_axes(a, p)
     count = 0
     start = 0
     while count < length(a)
@@ -114,6 +115,7 @@ julia> A
 permute!(a, p::AbstractVector) = permute!!(a, copymutable(p))
 
 function invpermute!!(a, p::AbstractVector{<:Integer})
+    @assert !has_offset_axes(a, p)
     count = 0
     start = 0
     while count < length(a)
@@ -194,6 +196,7 @@ julia> B[invperm(v)]
 ```
 """
 function invperm(a::AbstractVector)
+    @assert !has_offset_axes(a)
     b = zero(a) # similar vector of zeros
     n = length(a)
     @inbounds for (i, j) in enumerate(a)

base/deprecated.jl

@@ -1747,6 +1747,7 @@ end
 @deprecate mapfoldl(f, op, v0, itr) mapfoldl(f, op, itr; init=v0)
 @deprecate mapfoldr(f, op, v0, itr) mapfoldr(f, op, itr; init=v0)
 
+
 @deprecate startswith(a::Vector{UInt8}, b::Vector{UInt8}) length(a) >= length(b) && view(a, 1:length(b)) == b
 
 # PR #27859
@@ -1759,6 +1760,9 @@ function print(io::IO, ::Nothing)
     show(io, nothing)
 end
 
+@deprecate indices1 axes1
+@deprecate _length length
+
 # END 0.7 deprecations
 
 # BEGIN 1.0 deprecations

base/indices.jl

@@ -179,16 +179,16 @@ function setindex_shape_check(X::AbstractArray, I::Integer...)
 end
 
 setindex_shape_check(X::AbstractArray) =
-    (_length(X)==1 || throw_setindex_mismatch(X,()))
+    (length(X)==1 || throw_setindex_mismatch(X,()))
 
 setindex_shape_check(X::AbstractArray, i::Integer) =
-    (_length(X)==i || throw_setindex_mismatch(X, (i,)))
+    (length(X)==i || throw_setindex_mismatch(X, (i,)))
 
 setindex_shape_check(X::AbstractArray{<:Any,1}, i::Integer) =
-    (_length(X)==i || throw_setindex_mismatch(X, (i,)))
+    (length(X)==i || throw_setindex_mismatch(X, (i,)))
 
 setindex_shape_check(X::AbstractArray{<:Any,1}, i::Integer, j::Integer) =
-    (_length(X)==i*j || throw_setindex_mismatch(X, (i,j)))
+    (length(X)==i*j || throw_setindex_mismatch(X, (i,j)))
 
 function setindex_shape_check(X::AbstractArray{<:Any,2}, i::Integer, j::Integer)
     if length(X) != i*j
@@ -282,17 +282,15 @@ end
 Slice(S::Slice) = S
 axes(S::Slice) = (S,)
 unsafe_indices(S::Slice) = (S,)
-indices1(S::Slice) = S
+axes1(S::Slice) = S
 axes(S::Slice{<:OneTo}) = (S.indices,)
 unsafe_indices(S::Slice{<:OneTo}) = (S.indices,)
-indices1(S::Slice{<:OneTo}) = S.indices
+axes1(S::Slice{<:OneTo}) = S.indices
 
 first(S::Slice) = first(S.indices)
 last(S::Slice) = last(S.indices)
-errmsg(A) = error("size not supported for arrays with indices $(axes(A)); see https://docs.julialang.org/en/latest/devdocs/offset-arrays/")
-size(S::Slice) = first(S.indices) == 1 ? (length(S.indices),) : errmsg(S)
-length(S::Slice) = first(S.indices) == 1 ? length(S.indices) : errmsg(S)
-_length(S::Slice) = length(S.indices)
+size(S::Slice) = (length(S.indices),)
+length(S::Slice) = length(S.indices)
 unsafe_length(S::Slice) = unsafe_length(S.indices)
 getindex(S::Slice, i::Int) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
 getindex(S::Slice, i::AbstractUnitRange{<:Integer}) = (@_inline_meta; @boundscheck checkbounds(S, i); i)
@@ -361,7 +359,7 @@ LinearIndices(A::Union{AbstractArray,SimpleVector}) = LinearIndices(axes(A))
 
 # AbstractArray implementation
 IndexStyle(::Type{<:LinearIndices}) = IndexLinear()
-axes(iter::LinearIndices) = map(indices1, iter.indices)
+axes(iter::LinearIndices) = map(axes1, iter.indices)
 size(iter::LinearIndices) = map(unsafe_length, iter.indices)
 function getindex(iter::LinearIndices, i::Int)
     @_inline_meta