traitdispatch.jl

# ###############
# # recreate manual-traitdispatch.jl: f2

# @traitfn ttf2{X,Y<:Integer; D1{Y}, D4{X,Y}}(x::X,y::Y) = x + sin(y)
# @traitfn ttf2{S,T<:Integer; D1{S}, D1{T}  }(s::S,t::T) = sin(s) - sin(t)
# @traitfn ttf2{X,Y<:FloatingPoint; D1{X}, D1{Y}  }(x::X,y::Y) = cos(x) - cos(y)

# @test ttf2(4,5)==(4 + sin(5))
# @test ttf2(4,5.) == cos(4)-cos(5.)

# @test ttf2(MTT1(5),4) == sin(5)-sin(4)
# @test ttf2(MTT2(5),3) == sin(3)+5

# @test length(methods(f2))==length(methods(ttf2))



# note that some of below functions are also tested in perf/perf.jl.
# So a update here might need an update there.

################
@traitfn ft1{X,Y; Eq{X,Y}}(x::X,y::Y) = x==y
ff1(x,y) = x==y
@test ff1(4,5)==ft1(4,5)

#################
@traitfn function ft2{X,Y; Arith{X,Y}}(x::X,y::Y) 
    out = zero(promote(x,y)[1])
    for xe in 1:round(Int,x)
        out += xe + y
    end
    out
end
function ff2{X,Y}(x::X,y::Y) 
    out = zero(promote(x,y)[1])
    for xe in 1:round(Int,x)
        out += xe + y
    end
    out
end
        
@test ff2(7.3,5.)==ft2(7.3,5.)

##################

@traitfn ft3{X1,X2; IsIterable{X1}}(x::X1,y::X2) = (out=X2[]; for i in x; push!(out,i+y) end; out)
ff3{Y}(x,y::Y) = Y[i+y for i in x]

@test ff3([1:10;],5)==ft3([1:10;],5)
@test ff3(BigFloat[1:10;],BigInt(5))==ft3(BigFloat[1:10;],BigInt(5))

###############
@traitdef MyTr{X,Y} begin
    foobar(X,Y) -> Bool
end
type A
    a::Int
end
foobar(a::A, b::A) = a.a==b.a
@test istrait(MyTr{A,A})  # true
@test istrait(MyTr{Int,Int})==false

# make a function which dispatches on traits:
@traitfn ft111{X,Y; Cmp{X,Y}}(x::X,y::Y)  = x>y ? 5 : 6
@traitfn ft111{X,Y; MyTr{X,Y}}(x::X,y::Y) = foobar(x,y) ? -99 : -999

@test ft111(4,5)==6
@test ft111(A(5), A(6))==-999

@test_throws TraitException ft111("asdf", 5)
foobar(a::String, b::Int) = length(a)==b
@test ft111("asdf", 4)==-99

## dispatch using subtraits
@traitdef MyTr2{X,Y} <: MyTr{X,Y} begin
    bar(X,Y) -> Bool
end

@traitfn gt1{X,Y; MyTr2{X,Y}}(x::X,y::Y)  = "MyTr2"
@traitfn gt1{X,Y; MyTr{X,Y}}(x::X,y::Y)   = "MyTr"

type B1
    a::Int
end
foobar(a::B1, b::B1) = a.a==b.a
type B2
    a::Int
end
foobar(a::B2, b::B2) = a.a==b.a
bar(a::B2, b::B2) = a.a==b.a
@test istrait(MyTr{B1,B1})  # true
@test istrait(MyTr2{B1,B1})==false
@test istrait(MyTr2{B2,B2})

@test gt1(B1(1), B1(1))=="MyTr"
@test gt1(B2(1), B2(1))=="MyTr2" 


##########
## adding trait methods to existing functions:
@traitdef MyTr7{X} begin
    bobo(X) -> String
end

abstract AMTyp7
type MTyp71 <: AMTyp7
end
type MTyp72 <: AMTyp7
end
# add to above trait
@traitimpl MyTr7{MTyp71} begin
    bobo(X::MTyp71) = "Yeah"
end

import Base.sin
@traitfn sin{X; MyTr7{X}}(x::X) = bobo(x)
@test sin(MTyp71())=="Yeah"
@test_throws TraitException sin(MTyp72())

@traitfn Base.cos{X; MyTr7{X}}(x::X) = bobo(x)
@test cos(MTyp71())=="Yeah"
@test_throws TraitException cos(MTyp72())

######
# Ambiguities
######
@traitdef TrTr1{X} begin
    len1(X) 
end

@traitfn tf7465{X<:Integer,Y; TrTr1{X}}(x::X,y::Y) = x-y
@traitfn tf7465{X<:Integer,Y; TrTr1{Y}}(x::X,y::Y) = x+y

@traitimpl TrTr1{Int} begin
    len1(x::Int) = 5
end

# now ambiguous:
@test_throws Traits.TraitException tf7465(5,6)
# resolve
@traitfn tf7465{X<:Integer,Y; TrTr1{X}, TrTr1{Y}}(x::X,y::Y) = x*y
@test tf7465(5,6)==5*6

@traitdef TrTr22{X,Y} <: TrTr1{X}, TrTr1{Y} begin
    # empty
end

@traitfn tf7465{X<:Integer,Y; TrTr22{X,Y}}(x::X,y::Y) = x*y*1000
# errors again because ambigours again
@test_throws Traits.TraitException tf7465(5,6)

## single argument ambiguities
####
@traitdef TrTr2{X} begin
    len2(X) 
end

@traitfn tttf{X; TrTr1{X}}(x::X) = len1(x)
@traitfn tttf{X; TrTr2{X}}(x::X) = len2(x)

@test tttf(5)==len1(5)  # works as TrTr2{Int} is not a trait

@traitimpl TrTr1{Float64} begin
    len1(x::Float64) = 5
end
@traitimpl TrTr2{Float64} begin
    len2(x::Float64) = 55
end

@test_throws Traits.TraitException tttf(5.)  # errors

@traitfn tttf{X; TrTr1{X}, TrTr2{X}}(x::X) = len2(x) # pick len2 over len1
@test tttf(5.)==len2(5.)

# # this can also be resolved by using a sub-trait, essentially equivalent:
# @traitdef STrTr{X} <: TrTr1{X}, TrTr2{X} begin
#     # empty
# end
# # no need to implement it for Float64: it's already a member:
# @test istrait(STrTr{Float64})


## test resolution of single argument ambiguities with subtraits
####
# came up here: https://github.com/mauro3/Traits.jl/pull/4#issuecomment-69742371
@traitdef U1{X} begin
    u1(X)
end
@traitdef U2{X} <: U1{X} begin
    u2(X)
end

@traitdef UU1{X} <: U1{X} begin
    uu1(X)
end
@traitdef UU2{X} <: U2{X} begin
    uu2(X)
end

@traitimpl U1{Int} begin
    u1(x::Int) = 1
end
@traitimpl U2{Int} begin
    u2(x::Int) = 2
end
@traitimpl UU1{Int} begin
    uu1(x::Int) = 11
end
@traitimpl UU2{Int} begin
    uu2(x::Int) = 12
end

@traitfn tttf238{X; UU1{X}}(x::X) = "this should loose"
@traitfn tttf238{X; UU2{X}}(x::X) = "this should win"  

# This test in traitdispatch.jl should probably pass:
if dispatch_bug1
    @test_throws Traits.TraitException tttf238(5)=="this should win"
else
    @test tttf238(5)=="this should win"
end

# however if U2 were a subtrait of something else but U1 then dispatch should be ambiguous:
@traitdef V1{X} begin
    v1(X)
end
@traitdef Other1{X} begin
    other1(X)
end

@traitdef V2{X} <: Other1{X} begin
    v2(X)
end

@traitdef VV1{X} <: V1{X} begin
    vv1(X)
end
@traitdef VV2{X} <: V2{X} begin
    vv2(X)
end

@traitimpl V1{Int} begin
    v1(x::Int) = 1
end
@traitimpl Other1{Int} begin
    other1(x::Int) = -1
end
@traitimpl V2{Int} begin
    v2(x::Int) = 2
end
@traitimpl VV1{Int} begin
    vv1(x::Int) = 11
end
@traitimpl VV2{Int} begin
    vv2(x::Int) = 12
end

@traitfn tttf240{X; VV1{X}}(x::X) = "neither should win 1"
@traitfn tttf240{X; VV2{X}}(x::X) = "neither should win 2"
@test_throws Traits.TraitException tttf240(5)