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# This file is a part of Julia. License is MIT: https://julialang.org/license
# OffsetArrays (arrays with indexing that doesn't start at 1)
# This test file is designed to exercise support for generic indexing,
# even though offset arrays aren't implemented in Base.
module OffsetArrays
using Base: Indices, IndexCartesian, IndexLinear, tail
export OffsetArray
struct OffsetArray{T,N,AA<:AbstractArray} <: AbstractArray{T,N}
parent::AA
offsets::NTuple{N,Int}
end
OffsetVector{T,AA<:AbstractArray} = OffsetArray{T,1,AA}
OffsetArray(A::AbstractArray{T,N}, offsets::NTuple{N,Int}) where {T,N} = OffsetArray{T,N,typeof(A)}(A, offsets)
OffsetArray(A::AbstractArray{T,N}, offsets::Vararg{Int,N}) where {T,N} = OffsetArray(A, offsets)
OffsetArray{T,N}(::UndefInitializer, inds::Indices{N}) where {T,N} =
OffsetArray{T,N,Array{T,N}}(Array{T,N}(undef, map(length, inds)), map(indsoffset, inds))
OffsetArray{T}(::UndefInitializer, inds::Indices{N}) where {T,N} =
OffsetArray{T,N}(undef, inds)
Base.IndexStyle(::Type{T}) where {T<:OffsetArray} = Base.IndexStyle(parenttype(T))
parenttype(::Type{OffsetArray{T,N,AA}}) where {T,N,AA} = AA
parenttype(A::OffsetArray) = parenttype(typeof(A))
Base.parent(A::OffsetArray) = A.parent
Base.size(A::OffsetArray) = size(A.parent)
Base.size(A::OffsetArray, d) = size(A.parent, d)
Base.eachindex(::IndexCartesian, A::OffsetArray) = CartesianIndices(axes(A))
Base.eachindex(::IndexLinear, A::OffsetVector) = axes(A, 1)
# Implementations of indices and axes1. Since bounds-checking is
# performance-critical and relies on indices, these are usually worth
# optimizing thoroughly.
@inline Base.axes(A::OffsetArray, d) = 1 <= d <= length(A.offsets) ? Base.IdentityUnitRange(axes(parent(A))[d] .+ A.offsets[d]) : Base.IdentityUnitRange(1:1)
@inline Base.axes(A::OffsetArray) = _indices(axes(parent(A)), A.offsets) # would rather use ntuple, but see #15276
@inline _indices(inds, offsets) = (Base.IdentityUnitRange(inds[1] .+ offsets[1]), _indices(tail(inds), tail(offsets))...)
_indices(::Tuple{}, ::Tuple{}) = ()
Base.axes1(A::OffsetArray{T,0}) where {T} = Base.IdentityUnitRange(1:1) # we only need to specialize this one
const OffsetAxis = Union{Integer, UnitRange, Base.IdentityUnitRange{<:UnitRange}, Base.OneTo}
function Base.similar(A::OffsetArray, T::Type, dims::Dims)
B = similar(parent(A), T, dims)
end
function Base.similar(A::AbstractArray, T::Type, inds::Tuple{OffsetAxis,Vararg{OffsetAxis}})
B = similar(A, T, map(indslength, inds))
OffsetArray(B, map(indsoffset, inds))
end
Base.similar(::Type{T}, shape::Tuple{OffsetAxis,Vararg{OffsetAxis}}) where {T<:AbstractArray} =
OffsetArray(T(undef, map(indslength, shape)), map(indsoffset, shape))
Base.reshape(A::AbstractArray, inds::Tuple{OffsetAxis,Vararg{OffsetAxis}}) = OffsetArray(reshape(A, map(indslength, inds)), map(indsoffset, inds))
Base.fill(v, inds::NTuple{N, Union{Integer, AbstractUnitRange}}) where {N} =
fill!(OffsetArray(Array{typeof(v), N}(undef, map(indslength, inds)), map(indsoffset, inds)), v)
Base.zeros(::Type{T}, inds::NTuple{N, Union{Integer, AbstractUnitRange}}) where {T, N} =
fill!(OffsetArray(Array{T, N}(undef, map(indslength, inds)), map(indsoffset, inds)), zero(T))
Base.ones(::Type{T}, inds::NTuple{N, Union{Integer, AbstractUnitRange}}) where {T, N} =
fill!(OffsetArray(Array{T, N}(undef, map(indslength, inds)), map(indsoffset, inds)), one(T))
Base.trues(inds::NTuple{N, Union{Integer, AbstractUnitRange}}) where {N} =
fill!(OffsetArray(BitArray{N}(undef, map(indslength, inds)), map(indsoffset, inds)), true)
Base.falses(inds::NTuple{N, Union{Integer, AbstractUnitRange}}) where {N} =
fill!(OffsetArray(BitArray{N}(undef, map(indslength, inds)), map(indsoffset, inds)), false)
@inline function Base.getindex(A::OffsetArray{T,N}, I::Vararg{Int,N}) where {T,N}
checkbounds(A, I...)
@inbounds ret = parent(A)[offset(A.offsets, I)...]
ret
end
# Vectors don't support one-based linear indexing; they always use the offsets
@inline function Base.getindex(A::OffsetVector, i::Int)
checkbounds(A, i)
@inbounds ret = parent(A)[offset(A.offsets, (i,))[1]]
ret
end
# But multidimensional arrays allow one-based linear indexing
@inline function Base.getindex(A::OffsetArray, i::Int)
checkbounds(A, i)
@inbounds ret = parent(A)[i]
ret
end
@inline function Base.setindex!(A::OffsetArray{T,N}, val, I::Vararg{Int,N}) where {T,N}
checkbounds(A, I...)
@inbounds parent(A)[offset(A.offsets, I)...] = val
val
end
@inline function Base.setindex!(A::OffsetVector, val, i::Int)
checkbounds(A, i)
@inbounds parent(A)[offset(A.offsets, (i,))[1]] = val
val
end
@inline function Base.setindex!(A::OffsetArray, val, i::Int)
checkbounds(A, i)
@inbounds parent(A)[i] = val
val
end
@inline function Base.deleteat!(A::OffsetArray, i::Int)
checkbounds(A, i)
@inbounds deleteat!(parent(A), offset(A.offsets, (i,))[1])
end
@inline function Base.deleteat!(A::OffsetArray{T,N}, I::Vararg{Int, N}) where {T,N}
checkbounds(A, I...)
@inbounds deleteat!(parent(A), offset(A.offsets, I)...)
end
@inline function Base.deleteat!(A::OffsetArray, i::UnitRange{Int})
checkbounds(A, first(i))
checkbounds(A, last(i))
first_idx = offset(A.offsets, (first(i),))[1]
last_idx = offset(A.offsets, (last(i),))[1]
@inbounds deleteat!(parent(A), first_idx:last_idx)
end
function Base.push!(a::OffsetArray{T,1}, item) where T
# convert first so we don't grow the array if the assignment won't work
itemT = convert(T, item)
resize!(a, length(a)+1)
a[end] = itemT
return a
end
# Computing a shifted index (subtracting the offset)
offset(offsets::NTuple{N,Int}, inds::NTuple{N,Int}) where {N} = _offset((), offsets, inds)
_offset(out, ::Tuple{}, ::Tuple{}) = out
@inline _offset(out, offsets, inds) = _offset((out..., inds[1]-offsets[1]), Base.tail(offsets), Base.tail(inds))
indsoffset(r::AbstractRange) = first(r) - 1
indsoffset(i::Integer) = 0
indslength(r::AbstractRange) = length(r)
indslength(i::Integer) = i
Base.resize!(A::OffsetVector, nl::Integer) = (resize!(A.parent, nl); A)
end
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