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Add Base.hash(::Quaternion, ::UInt) #136

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merged 4 commits into from
Feb 5, 2024
Merged

Add Base.hash(::Quaternion, ::UInt) #136

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0ed1893
add `Base.hash(::Quaternion)`
hyrodium Nov 9, 2023
e2dd7b3
add tests for `hash`
hyrodium Nov 9, 2023
859d0f5
update hash for more readability
hyrodium Nov 9, 2023
eab2f56
replace `==` with `===` in hash test
hyrodium Feb 3, 2024
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11 changes: 11 additions & 0 deletions src/Quaternion.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -236,6 +236,17 @@ function Base.isequal(q::Quaternion, w::Quaternion)
isequal(q.s, w.s) & isequal(q.v1, w.v1) & isequal(q.v2, w.v2) & isequal(q.v3, w.v3)
end

if UInt === UInt64
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Would this be better?

Suggested change
if UInt === UInt64
@static if UInt === UInt64

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The @static macro brings better performance if it is used inside a function, but this case is not, so it seems there would not be better performance here.

julia> f() = @static Sys.iswindows() ? 1 : 2
f (generic function with 1 method)

julia> @code_lowered f()
CodeInfo(
1 ─     return 2
)

julia> g() = Sys.iswindows() ? 1 : 2
g (generic function with 1 method)

julia> @code_lowered g()
CodeInfo(
1 ─ %1 = Base.Sys.iswindows
│   %2 = (%1)()
└──      goto #3 if not %2
2 ─      return 1
3 ─      return 2
)

const h_imags = 0xfa29df508725c1bf, 0x5e6c4b26a400626d, 0x8dfd375bac9f9403
else
const h_imags = 0x62802719, 0x5a9b072e, 0x209019b1
end
const hash_0_imags = hash.(0, h_imags)

function Base.hash(z::Quaternion, h::UInt)
hash(real(z), h ⊻ xor(xor.(hash.(imag_part(z), h_imags), hash_0_imags)...))
end

"""
extend_analytic(f, q::Quaternion)

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10 changes: 10 additions & 0 deletions test/Quaternion.jl
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Expand Up @@ -66,6 +66,16 @@ end
@test !isequal(Quaternion(NaN, 0.0, Inf, -Inf), Quaternion(NaN, -0.0, Inf, -Inf))
end

@testset "hash" begin
# https://github.com/JuliaGeometry/Quaternions.jl/issues/135
@test hash(0) == hash(quat(0)) == hash(0.0) == hash(quat(0.0))
@test hash(1) == hash(quat(1)) == hash(1.0) == hash(quat(1.0))
@test hash(quat(-0.0)) ≠ hash(quat(+0.0))
@test allunique([hash(quat(1,0,0,0)), hash(quat(0,1,0,0)), hash(quat(0,0,1,0)), hash(quat(0,0,0,1))])
@test hash(57, UInt(42)) == hash(quat(57), UInt(42))
@test length(unique(Quaternion[quat(2), quat(big"2")])) == 1
end

@testset "convert" begin
@test convert(Quaternion{Float64}, 1) === Quaternion(1.0)
@test convert(Quaternion{Float64}, Quaternion(1, 2, 3, 4)) ===
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