WIP: add IteratorAccess trait: for indexing capabilities #22489
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@@ -108,11 +108,50 @@ Base.HasEltype() | |
| iteratoreltype(x) = iteratoreltype(typeof(x)) | ||
| iteratoreltype(::Type) = HasEltype() # HasEltype is the default | ||
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| abstract type IteratorAccess end | ||
| struct ForwardAccess <: IteratorAccess end | ||
| struct RandomAccess <: IteratorAccess end | ||
| struct WritableRandomAccess <: IteratorAccess end | ||
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| """ | ||
| iteratoraccess(itertype::Type) -> IteratorAccess | ||
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| Given the type of an iterator, returns one of the following values: | ||
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| * `ForwardAccess()` if the iterator can be iterated over. | ||
| * `RandomAccess()` if the iterator supports read-only indexing. | ||
| * `WritableRandomAccess()` if the iterator supports read-write indexing. | ||
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| The default value (for iterators that do not define this function) is `ForwardAccess()`. | ||
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| ```jldoctest | ||
| julia> Base.iteratoraccess(1:5) | ||
| Base.RandomAccess() | ||
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| julia> Base.iteratoraccess([1, 2, 3]) | ||
| Base.WritableRandomAccess() | ||
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| julia> Base.iteratoraccess(drop([1, 2, 3], 1)) | ||
| Base.WritableRandomAccess() | ||
| ``` | ||
| """ | ||
| iteratoraccess(x) = iteratoraccess(typeof(x)) | ||
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There was a problem hiding this comment. You could spell There was a problem hiding this comment. This follows There was a problem hiding this comment. Iteratortraits are also spelled in camel case by now, #25402 |
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| iteratoraccess(::Type) = ForwardAccess() # ForwardAccess is the default | ||
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| removewritable(::ForwardAccess) = ForwardAccess() | ||
| removewritable(::Union{RandomAccess,WritableRandomAccess}) = RandomAccess() | ||
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| iteratorsize(::Type{<:AbstractArray}) = HasShape() | ||
| iteratorsize(::Type{Generator{I,F}}) where {I,F} = iteratorsize(I) | ||
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| iteratoraccess(::Type{<:AbstractArray}) = RandomAccess() | ||
| iteratoraccess(::Type{<:Array}) = WritableRandomAccess() | ||
| iteratoraccess(::Type{Generator{I,F}}) where{I,F} = removewritable(iteratoraccess(I)) | ||
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| length(g::Generator) = length(g.iter) | ||
| size(g::Generator) = size(g.iter) | ||
| indices(g::Generator) = indices(g.iter) | ||
| ndims(g::Generator) = ndims(g.iter) | ||
| getindex(g::Generator, key...) = map(g.f, g.iter[key...]) | ||
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| iteratoreltype(::Type{Generator{I,T}}) where {I,T} = EltypeUnknown() | ||
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@@ -2,7 +2,7 @@ | |
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| module Sort | ||
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| using Base: Order, Checked, copymutable, linearindices, IndexStyle, viewindexing, IndexLinear, _length, WritableRandomAccess | ||
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| import | ||
| Base.sort, | ||
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@@ -244,7 +244,7 @@ const DEFAULT_STABLE = MergeSort | |
| const SMALL_ALGORITHM = InsertionSort | ||
| const SMALL_THRESHOLD = 20 | ||
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| function sort!(v, lo::Int, hi::Int, ::InsertionSortAlg, o::Ordering) | ||
| @inbounds for i = lo+1:hi | ||
| j = i | ||
| x = v[i] | ||
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@@ -269,7 +269,7 @@ end | |
| # Upon return, the pivot is in v[lo], and v[hi] is guaranteed to be | ||
| # greater than the pivot | ||
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| @inline function selectpivot!(v, lo::Int, hi::Int, o::Ordering) | ||
| @inbounds begin | ||
| mi = (lo+hi)>>>1 | ||
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@@ -299,7 +299,7 @@ end | |
| # | ||
| # select a pivot, and partition v according to the pivot | ||
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| function partition!(v, lo::Int, hi::Int, o::Ordering) | ||
| pivot = selectpivot!(v, lo, hi, o) | ||
| # pivot == v[lo], v[hi] > pivot | ||
| i, j = lo, hi | ||
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@@ -318,7 +318,7 @@ function partition!(v::AbstractVector, lo::Int, hi::Int, o::Ordering) | |
| return j | ||
| end | ||
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| function sort!(v, lo::Int, hi::Int, a::QuickSortAlg, o::Ordering) | ||
| @inbounds while lo < hi | ||
| hi-lo <= SMALL_THRESHOLD && return sort!(v, lo, hi, SMALL_ALGORITHM, o) | ||
| j = partition!(v, lo, hi, o) | ||
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@@ -336,7 +336,7 @@ function sort!(v::AbstractVector, lo::Int, hi::Int, a::QuickSortAlg, o::Ordering | |
| return v | ||
| end | ||
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| function sort!(v, lo::Int, hi::Int, a::MergeSortAlg, o::Ordering, t=similar(v,0)) | ||
| @inbounds if lo < hi | ||
| hi-lo <= SMALL_THRESHOLD && return sort!(v, lo, hi, SMALL_ALGORITHM, o) | ||
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@@ -401,7 +401,7 @@ end | |
| # end | ||
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| function sort!(v, lo::Int, hi::Int, a::PartialQuickSort, | ||
| o::Ordering) | ||
| @inbounds while lo < hi | ||
| hi-lo <= SMALL_THRESHOLD && return sort!(v, lo, hi, SMALL_ALGORITHM, o) | ||
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@@ -427,11 +427,16 @@ end | |
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| ## generic sorting methods ## | ||
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| defalg(v) = defalg(eltype(v)) | ||
| defalg(::Type) = DEFAULT_STABLE | ||
| defalg(::Type{<:Number}) = DEFAULT_UNSTABLE | ||
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| sort!(v, alg::Algorithm, order::Ordering) = sort!(v, Base.iteratoraccess(v), alg, order) | ||
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| sort!(v, access, alg::Algorithm, order::Ordering) = throw(ArgumentError("the collection must have setindex! defined")) | ||
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| function sort!(v, ::WritableRandomAccess, alg::Algorithm, order::Ordering) | ||
| inds = linearindices(v) | ||
| sort!(v,first(inds),last(inds),alg,order) | ||
| end | ||
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@@ -473,7 +478,7 @@ julia> v = [(1, "c"), (3, "a"), (2, "b")]; sort!(v, by = x -> x[2]); v | |
| (1, "c") | ||
| ``` | ||
| """ | ||
| function sort!(v; | ||
| alg::Algorithm=defalg(v), | ||
| lt=isless, | ||
| by=identity, | ||
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@@ -538,7 +543,7 @@ julia> v | |
| 2 | ||
| ``` | ||
| """ | ||
| sort(v; kws...) = sort!(copymutable(v); kws...) | ||
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| ## selectperm: the permutation to sort the first k elements of an array ## | ||
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Will folks want
ReverseAccess? In other words, is this intended to collect all supported/efficient ways of iterating over an object? If so we may need to think about traits for iterator arithmetic, etc.There was a problem hiding this comment.
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The idea was indeed to also support
ReverseAccess(although I can't read my mind from almost 3y ago!) and this was definitely inspired by the c++ traits. Cf. my comment,ReverseAccessis probably "orthogonal" to the three access patterns currently included here.