# This file is a part of Julia. License is MIT: https://julialang.org/license ## type join (closest common ancestor, or least upper bound) ## """ typejoin(T, S) Return the closest common ancestor of `T` and `S`, i.e. the narrowest type from which they both inherit. """ typejoin() = Bottom typejoin(@nospecialize(t)) = t typejoin(@nospecialize(t), ts...) = (@_pure_meta; typejoin(t, typejoin(ts...))) function typejoin(@nospecialize(a), @nospecialize(b)) @_pure_meta if isa(a, TypeVar) return typejoin(a.ub, b) elseif isa(b, TypeVar) return typejoin(a, b.ub) elseif a <: b return b elseif b <: a return a elseif isa(a, UnionAll) return UnionAll(a.var, typejoin(a.body, b)) elseif isa(b, UnionAll) return UnionAll(b.var, typejoin(a, b.body)) elseif isa(a, Union) return typejoin(typejoin(a.a, a.b), b) elseif isa(b, Union) return typejoin(a, typejoin(b.a, b.b)) elseif a <: Tuple if !(b <: Tuple) return Any end ap, bp = a.parameters::Core.SimpleVector, b.parameters::Core.SimpleVector lar = length(ap) lbr = length(bp) if lar == 0 return Tuple{Vararg{tailjoin(bp, 1)}} end if lbr == 0 return Tuple{Vararg{tailjoin(ap, 1)}} end laf, afixed = full_va_len(ap) lbf, bfixed = full_va_len(bp) if laf < lbf if isvarargtype(ap[lar]) && !afixed c = Vector{Any}(undef, laf) c[laf] = Vararg{typejoin(unwrapva(ap[lar]), tailjoin(bp, laf))} n = laf-1 else c = Vector{Any}(undef, laf+1) c[laf+1] = Vararg{tailjoin(bp, laf+1)} n = laf end elseif lbf < laf if isvarargtype(bp[lbr]) && !bfixed c = Vector{Any}(undef, lbf) c[lbf] = Vararg{typejoin(unwrapva(bp[lbr]), tailjoin(ap, lbf))} n = lbf-1 else c = Vector{Any}(undef, lbf+1) c[lbf+1] = Vararg{tailjoin(ap, lbf+1)} n = lbf end else c = Vector{Any}(undef, laf) n = laf end for i = 1:n ai = ap[min(i,lar)]; bi = bp[min(i,lbr)] ci = typejoin(unwrapva(ai), unwrapva(bi)) c[i] = i == length(c) && (isvarargtype(ai) || isvarargtype(bi)) ? Vararg{ci} : ci end return Tuple{c...} elseif b <: Tuple return Any end a, b = a::DataType, b::DataType while b !== Any if a <: b.name.wrapper while a.name !== b.name a = supertype(a)::DataType end if a.name === Type.body.name ap = a.parameters[1] bp = b.parameters[1] if ((isa(ap,TypeVar) && ap.lb === Bottom && ap.ub === Any) || (isa(bp,TypeVar) && bp.lb === Bottom && bp.ub === Any)) # handle special Type{T} supertype return Type end end aprimary = a.name.wrapper # join on parameters n = length(a.parameters) if n == 0 return aprimary end vars = [] for i = 1:n ai, bi = a.parameters[i], b.parameters[i] if ai === bi || (isa(ai,Type) && isa(bi,Type) && ai <: bi && bi <: ai) aprimary = aprimary{ai} else # pushfirst!(vars, aprimary.var) _growbeg!(vars, 1) arrayset(false, vars, aprimary.var, 1) aprimary = aprimary.body end end for v in vars aprimary = UnionAll(v, aprimary) end return aprimary end b = supertype(b)::DataType end return Any end # return an upper-bound on type `a` with type `b` removed # such that `return <: a` && `Union{return, b} == Union{a, b}` # WARNING: this is wrong for some objects for which subtyping is broken # (Core.Compiler.isnotbrokensubtype), use only simple types for `b` function typesplit(@nospecialize(a), @nospecialize(b)) @_pure_meta if a <: b return Bottom end if isa(a, Union) return Union{typesplit(a.a, b), typesplit(a.b, b)} end return a end """ promote_typejoin(T, S) Compute a type that contains both `T` and `S`, which could be either a parent of both types, or a `Union` if appropriate. Falls back to [`typejoin`](@ref). See instead [`promote`](@ref), [`promote_type`](@ref). # Examples ```jldoctest julia> Base.promote_typejoin(Int, Float64) Real julia> Base.promote_type(Int, Float64) Float64 ``` """ function promote_typejoin(@nospecialize(a), @nospecialize(b)) c = typejoin(_promote_typesubtract(a), _promote_typesubtract(b)) return Union{a, b, c}::Type end _promote_typesubtract(@nospecialize(a)) = typesplit(a, Union{Nothing, Missing}) # Returns length, isfixed function full_va_len(p) isempty(p) && return 0, true last = p[end] if isvarargtype(last) if isdefined(last, :N) && isa(last.N, Int) return length(p)::Int + last.N - 1, true end return length(p)::Int, false end return length(p)::Int, true end # reduce typejoin over A[i:end] function tailjoin(A, i) if i > length(A) return unwrapva(A[end]) end t = Bottom for j = i:length(A) t = typejoin(t, unwrapva(A[j])) end return t end ## promotion mechanism ## """ promote_type(type1, type2) Promotion refers to converting values of mixed types to a single common type. `promote_type` represents the default promotion behavior in Julia when operators (usually mathematical) are given arguments of differing types. `promote_type` generally tries to return a type which can at least approximate most values of either input type without excessively widening. Some loss is tolerated; for example, `promote_type(Int64, Float64)` returns [`Float64`](@ref) even though strictly, not all [`Int64`](@ref) values can be represented exactly as `Float64` values. See also: [`promote`](@ref), [`promote_typejoin`](@ref), [`promote_rule`](@ref). # Examples ```jldoctest julia> promote_type(Int64, Float64) Float64 julia> promote_type(Int32, Int64) Int64 julia> promote_type(Float32, BigInt) BigFloat julia> promote_type(Int16, Float16) Float16 julia> promote_type(Int64, Float16) Float16 julia> promote_type(Int8, UInt16) UInt16 ``` !!! warning "Don't overload this directly" To overload promotion for your own types you should overload [`promote_rule`](@ref). `promote_type` calls `promote_rule` internally to determine the type. Overloading `promote_type` directly can cause ambiguity errors. """ function promote_type end promote_type() = Bottom promote_type(T) = T promote_type(T, S, U, V...) = (@_inline_meta; promote_type(T, promote_type(S, U, V...))) promote_type(::Type{Bottom}, ::Type{Bottom}) = Bottom promote_type(::Type{T}, ::Type{T}) where {T} = T promote_type(::Type{T}, ::Type{Bottom}) where {T} = T promote_type(::Type{Bottom}, ::Type{T}) where {T} = T function promote_type(::Type{T}, ::Type{S}) where {T,S} @_inline_meta # Try promote_rule in both orders. Typically only one is defined, # and there is a fallback returning Bottom below, so the common case is # promote_type(T, S) => # promote_result(T, S, result, Bottom) => # typejoin(result, Bottom) => result promote_result(T, S, promote_rule(T,S), promote_rule(S,T)) end """ promote_rule(type1, type2) Specifies what type should be used by [`promote`](@ref) when given values of types `type1` and `type2`. This function should not be called directly, but should have definitions added to it for new types as appropriate. """ function promote_rule end promote_rule(::Type{<:Any}, ::Type{<:Any}) = Bottom promote_result(::Type{<:Any},::Type{<:Any},::Type{T},::Type{S}) where {T,S} = (@_inline_meta; promote_type(T,S)) # If no promote_rule is defined, both directions give Bottom. In that # case use typejoin on the original types instead. promote_result(::Type{T},::Type{S},::Type{Bottom},::Type{Bottom}) where {T,S} = (@_inline_meta; typejoin(T, S)) """ promote(xs...) Convert all arguments to a common type, and return them all (as a tuple). If no arguments can be converted, an error is raised. See also: [`promote_type`], [`promote_rule`]. # Examples ```jldoctest julia> promote(Int8(1), Float16(4.5), Float32(4.1)) (1.0f0, 4.5f0, 4.1f0) ``` """ function promote end function _promote(x::T, y::S) where {T,S} @_inline_meta R = promote_type(T, S) return (convert(R, x), convert(R, y)) end promote_typeof(x) = typeof(x) promote_typeof(x, xs...) = (@_inline_meta; promote_type(typeof(x), promote_typeof(xs...))) function _promote(x, y, z) @_inline_meta R = promote_typeof(x, y, z) return (convert(R, x), convert(R, y), convert(R, z)) end function _promote(x, y, zs...) @_inline_meta R = promote_typeof(x, y, zs...) return (convert(R, x), convert(R, y), convert(Tuple{Vararg{R}}, zs)...) end # TODO: promote(x::T, ys::T...) where {T} here to catch all circularities? ## promotions in arithmetic, etc. ## promote() = () promote(x) = (x,) function promote(x, y) @_inline_meta px, py = _promote(x, y) not_sametype((x,y), (px,py)) px, py end function promote(x, y, z) @_inline_meta px, py, pz = _promote(x, y, z) not_sametype((x,y,z), (px,py,pz)) px, py, pz end function promote(x, y, z, a...) p = _promote(x, y, z, a...) not_sametype((x, y, z, a...), p) p end promote(x::T, y::T, zs::T...) where {T} = (x, y, zs...) not_sametype(x::T, y::T) where {T} = sametype_error(x) not_sametype(x, y) = nothing function sametype_error(input) @_noinline_meta error("promotion of types ", join(map(x->string(typeof(x)), input), ", ", " and "), " failed to change any arguments") end +(x::Number, y::Number) = +(promote(x,y)...) *(x::Number, y::Number) = *(promote(x,y)...) -(x::Number, y::Number) = -(promote(x,y)...) /(x::Number, y::Number) = /(promote(x,y)...) """ ^(x, y) Exponentiation operator. If `x` is a matrix, computes matrix exponentiation. If `y` is an `Int` literal (e.g. `2` in `x^2` or `-3` in `x^-3`), the Julia code `x^y` is transformed by the compiler to `Base.literal_pow(^, x, Val(y))`, to enable compile-time specialization on the value of the exponent. (As a default fallback we have `Base.literal_pow(^, x, Val(y)) = ^(x,y)`, where usually `^ == Base.^` unless `^` has been defined in the calling namespace.) If `y` is a negative integer literal, then `Base.literal_pow` transforms the operation to `inv(x)^-y` by default, where `-y` is positive. # Examples ```jldoctest julia> 3^5 243 julia> A = [1 2; 3 4] 2×2 Matrix{Int64}: 1 2 3 4 julia> A^3 2×2 Matrix{Int64}: 37 54 81 118 ``` """ ^(x::Number, y::Number) = ^(promote(x,y)...) fma(x::Number, y::Number, z::Number) = fma(promote(x,y,z)...) muladd(x::Number, y::Number, z::Number) = muladd(promote(x,y,z)...) ==(x::Number, y::Number) = (==)(promote(x,y)...) <( x::Real, y::Real) = (< )(promote(x,y)...) <=(x::Real, y::Real) = (<=)(promote(x,y)...) rem(x::Real, y::Real) = rem(promote(x,y)...) mod(x::Real, y::Real) = mod(promote(x,y)...) mod1(x::Real, y::Real) = mod1(promote(x,y)...) fld1(x::Real, y::Real) = fld1(promote(x,y)...) max(x::Real, y::Real) = max(promote(x,y)...) min(x::Real, y::Real) = min(promote(x,y)...) minmax(x::Real, y::Real) = minmax(promote(x, y)...) if isdefined(Core, :Compiler) const _return_type = Core.Compiler.return_type else _return_type(@nospecialize(f), @nospecialize(t)) = Any end """ promote_op(f, argtypes...) Guess what an appropriate container eltype would be for storing results of `f(::argtypes...)`. The guess is in part based on type inference, so can change any time. !!! warning Due to its fragility, use of `promote_op` should be avoided. It is preferable to base the container eltype on the type of the actual elements. Only in the absence of any elements (for an empty result container), it may be unavoidable to call `promote_op`. """ promote_op(f, S::Type...) = _return_type(f, Tuple{S...}) ## catch-alls to prevent infinite recursion when definitions are missing ## no_op_err(name, T) = error(name," not defined for ",T) (+)(x::T, y::T) where {T<:Number} = no_op_err("+", T) (*)(x::T, y::T) where {T<:Number} = no_op_err("*", T) (-)(x::T, y::T) where {T<:Number} = no_op_err("-", T) (/)(x::T, y::T) where {T<:Number} = no_op_err("/", T) (^)(x::T, y::T) where {T<:Number} = no_op_err("^", T) fma(x::T, y::T, z::T) where {T<:Number} = no_op_err("fma", T) fma(x::Integer, y::Integer, z::Integer) = x*y+z muladd(x::T, y::T, z::T) where {T<:Number} = x*y+z (&)(x::T, y::T) where {T<:Integer} = no_op_err("&", T) (|)(x::T, y::T) where {T<:Integer} = no_op_err("|", T) xor(x::T, y::T) where {T<:Integer} = no_op_err("xor", T) (==)(x::T, y::T) where {T<:Number} = x === y (< )(x::T, y::T) where {T<:Real} = no_op_err("<" , T) (<=)(x::T, y::T) where {T<:Real} = no_op_err("<=", T) rem(x::T, y::T) where {T<:Real} = no_op_err("rem", T) mod(x::T, y::T) where {T<:Real} = no_op_err("mod", T) min(x::Real) = x max(x::Real) = x minmax(x::Real) = (x, x) max(x::T, y::T) where {T<:Real} = ifelse(y < x, x, y) min(x::T, y::T) where {T<:Real} = ifelse(y < x, y, x) minmax(x::T, y::T) where {T<:Real} = y < x ? (y, x) : (x, y) flipsign(x::T, y::T) where {T<:Signed} = no_op_err("flipsign", T)