40 lines
1.2 KiB
Julia
40 lines
1.2 KiB
Julia
# This file is a part of Julia. License is MIT: https://julialang.org/license
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struct Pair{A,B}
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first::A
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second::B
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end
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const => = Pair
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start(p::Pair) = 1
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done(p::Pair, i) = i>2
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next(p::Pair, i) = (getfield(p,i), i+1)
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eltype(p::Pair{A,B}) where {A,B} = Union{A,B}
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indexed_next(p::Pair, i::Int, state) = (getfield(p,i), i+1)
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hash(p::Pair, h::UInt) = hash(p.second, hash(p.first, h))
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==(p::Pair, q::Pair) = (p.first==q.first) & (p.second==q.second)
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isequal(p::Pair, q::Pair) = isequal(p.first,q.first) & isequal(p.second,q.second)
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isless(p::Pair, q::Pair) = ifelse(!isequal(p.first,q.first), isless(p.first,q.first),
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isless(p.second,q.second))
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getindex(p::Pair,i::Int) = getfield(p,i)
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getindex(p::Pair,i::Real) = getfield(p, convert(Int, i))
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reverse{A,B}(p::Pair{A,B}) = Pair{B,A}(p.second, p.first)
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endof(p::Pair) = 2
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length(p::Pair) = 2
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first(p::Pair) = p.first
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last(p::Pair) = p.second
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convert(::Type{Pair{A,B}}, x::Pair{A,B}) where {A,B} = x
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function convert(::Type{Pair{A,B}}, x::Pair) where {A,B}
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Pair{A,B}(convert(A, x[1]), convert(B, x[2]))
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end
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promote_rule(::Type{Pair{A1,B1}}, ::Type{Pair{A2,B2}}) where {A1,B1,A2,B2} =
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Pair{promote_type(A1, A2), promote_type(B1, B2)}
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