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RFC: use first/last as endpoints for Range indexing #15750

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RFC: use first/last as endpoints for Range indexing #15750

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4 changes: 4 additions & 0 deletions base/abstractarray.jl
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Expand Up @@ -130,6 +130,10 @@ end
checkbounds(::Type{Bool}, sz::Integer, i) = throw(ArgumentError("unable to check bounds for indices of type $(typeof(i))"))
checkbounds(::Type{Bool}, sz::Integer, i::Real) = 1 <= i <= sz
checkbounds(::Type{Bool}, sz::Integer, ::Colon) = true
checkbounds(::Type{Bool}, sz::Integer, i::EndpointRange{typeof(first),typeof(last)}) = true
checkbounds(::Type{Bool}, sz::Integer, i::EndpointRange{typeof(first),Int}) = 1 <= i.stop <= sz
checkbounds(::Type{Bool}, sz::Integer, i::EndpointRange{Int,typeof(last)}) = 1 <= i.start <= sz

function checkbounds(::Type{Bool}, sz::Integer, r::Range)
@_propagate_inbounds_meta
isempty(r) || (checkbounds(Bool, sz, minimum(r)) && checkbounds(Bool, sz, maximum(r)))
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8 changes: 4 additions & 4 deletions base/multidimensional.jl
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Expand Up @@ -210,15 +210,15 @@ index_shape_dim(A, dim, ::Colon) = (trailingsize(A, dim),)
# ambiguities for AbstractArray subtypes. See the note in abstractarray.jl

# Note that it's most efficient to call checkbounds first, and then to_index
@inline function _getindex(l::LinearIndexing, A::AbstractArray, I::Union{Real, AbstractArray, Colon}...)
@inline function _getindex(l::LinearIndexing, A::AbstractArray, I::Union{Real, AbstractArray, Colon, EndpointRange}...)
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Shouldn't be necessary if EndpointRange <: Range{Int}.

@boundscheck checkbounds(A, I...)
_unsafe_getindex(l, A, I...)
end
@generated function _unsafe_getindex(::LinearIndexing, A::AbstractArray, I::Union{Real, AbstractArray, Colon}...)
@generated function _unsafe_getindex(::LinearIndexing, A::AbstractArray, I::Union{Real, AbstractArray, Colon, EndpointRange}...)
N = length(I)
quote
# This is specifically *not* inlined.
@nexprs $N d->(I_d = to_index(I[d]))
@nexprs $N d->(I_d = to_index(A, d, I[d]))
dest = similar(A, @ncall $N index_shape A I)
@ncall $N checksize dest I
@ncall $N _unsafe_getindex! dest A I
Expand Down Expand Up @@ -305,7 +305,7 @@ _iterable(v) = repeated(v)
_unsafe_setindex!(l, A, x, J...)
end
@inline function _unsafe_setindex!(::LinearIndexing, A::AbstractArray, x, J::Union{Real,AbstractArray,Colon}...)
_unsafe_batchsetindex!(A, _iterable(x), to_indexes(J...)...)
_unsafe_batchsetindex!(A, _iterable(x), to_array_indexes(A, J...)...)
end

# 1-d logical indexing: override the above to avoid calling find (in to_index)
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21 changes: 21 additions & 0 deletions base/operators.jl
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Expand Up @@ -414,11 +414,32 @@ to_index(A::AbstractArray) = A
to_index{T<:AbstractArray}(A::AbstractArray{T}) = throw(ArgumentError("invalid index: $A"))
to_index(A::AbstractArray{Colon}) = throw(ArgumentError("invalid index: $A"))
to_index(i) = throw(ArgumentError("invalid index: $i"))
to_index(A::AbstractArray, d, idx) = to_index(idx)

# EndpointRanges (2:last, first:5, first:last)
typealias EndPoint Union{typeof(first), typeof(last)}

immutable EndpointRange{F<:Union{Int,EndPoint},L<:Union{Int,EndPoint}} <: Range{Int}
start::F
stop::L
end

colon(start::EndPoint, stop::EndPoint) = EndpointRange(start, stop)
colon(start::EndPoint, stop::Int) = EndpointRange(start, stop)
colon(start::Int, stop::EndPoint) = EndpointRange(start, stop)

to_index(A::AbstractArray, d, idx::EndpointRange{typeof(first),typeof(last)}) = 1:size(A,d)
to_index(A::AbstractArray, d, idx::EndpointRange{typeof(first),Int}) = 1:idx.stop
to_index(A::AbstractArray, d, idx::EndpointRange{Int,typeof(last)}) = idx.start:size(A,d)

to_indexes() = ()
to_indexes(i1) = (to_index(i1),)
to_indexes(i1, I...) = (to_index(i1), to_indexes(I...)...)

to_array_indexes(A, I...) = _to_array_indexes(A, (), I...)
_to_array_indexes(A, out) = out
_to_array_indexes(A, out, i1, I...) = _to_array_indexes(A, (out..., to_index(A, length(out)+1, i1)), I...)

# Addition/subtraction of ranges
for f in (:+, :-)
@eval begin
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