From b43750b555aea13f7579b18f109056270e72371a Mon Sep 17 00:00:00 2001
From: mohamed82008 <mohamed82008@gmail.com>
Date: Thu, 23 Jan 2020 16:38:46 +1100
Subject: [PATCH] flatten all multi of univariate by default

---
 src/flatten.jl | 107 +++++++++++++++++++++++++++----------------------
 src/multi.jl   |  17 +++++---
 2 files changed, 71 insertions(+), 53 deletions(-)

diff --git a/src/flatten.jl b/src/flatten.jl
index 16372a89..acd862ad 100644
--- a/src/flatten.jl
+++ b/src/flatten.jl
@@ -1,3 +1,9 @@
+macro register(dist)
+    return quote
+        DistributionsAD.eval(getexpr($(esc(dist))))
+        DistributionsAD.toflatten(::$(esc(dist))) = true
+    end
+end
 function getexpr(Tdist)
     x = gensym()
     fnames = fieldnames(Tdist)
@@ -13,53 +19,58 @@ function getexpr(Tdist)
             )
     return :(flatten(dist::$Tdist) = ($func, $flattened_args))
 end
-for T in (  Bernoulli,
-            BetaBinomial,
-            Binomial,
-            Geometric,
-            NegativeBinomial,
-            Poisson,
-            Skellam,
-            PoissonBinomial,
-            Arcsine,
-            Beta,
-            BetaPrime,
-            Biweight,
-            Cauchy,
-            Chernoff,
-            Chi,
-            Chisq,
-            Cosine,
-            Epanechnikov,
-            Erlang,
-            Exponential,
-            FDist,
-            Frechet,
-            Gamma,
-            GeneralizedExtremeValue,
-            GeneralizedPareto,
-            Gumbel,
-            InverseGamma,
-            InverseGaussian,
-            Kolmogorov,
-            Laplace,
-            Levy,
-            LocationScale,
-            Logistic,
-            LogitNormal,
-            LogNormal,
-            Normal,
-            NormalCanon,
-            NormalInverseGaussian,
-            Pareto,
-            PGeneralizedGaussian,
-            Rayleigh,
-            SymTriangularDist,
-            TDist,
-            TriangularDist,
-            Triweight,
-            Categorical,
-            Truncated,
-        )
+const flattened_dists = [   Bernoulli,
+                            BetaBinomial,
+                            Binomial,
+                            Geometric,
+                            NegativeBinomial,
+                            Poisson,
+                            Skellam,
+                            PoissonBinomial,
+                            Arcsine,
+                            Beta,
+                            BetaPrime,
+                            Biweight,
+                            Cauchy,
+                            Chernoff,
+                            Chi,
+                            Chisq,
+                            Cosine,
+                            Epanechnikov,
+                            Erlang,
+                            Exponential,
+                            FDist,
+                            Frechet,
+                            Gamma,
+                            GeneralizedExtremeValue,
+                            GeneralizedPareto,
+                            Gumbel,
+                            InverseGamma,
+                            InverseGaussian,
+                            Kolmogorov,
+                            Laplace,
+                            Levy,
+                            LocationScale,
+                            Logistic,
+                            LogitNormal,
+                            LogNormal,
+                            Normal,
+                            NormalCanon,
+                            NormalInverseGaussian,
+                            Pareto,
+                            PGeneralizedGaussian,
+                            Rayleigh,
+                            SymTriangularDist,
+                            TDist,
+                            TriangularDist,
+                            Triweight,
+                            Categorical,
+                            Truncated,
+                        ]
+for T in flattened_dists
+    @eval toflatten(::T) = true
+end
+toflatten(::Distribution) = false
+for T in flattened_dists
     eval(getexpr(T))
 end
diff --git a/src/multi.jl b/src/multi.jl
index 35aacbcf..03a04ee7 100644
--- a/src/multi.jl
+++ b/src/multi.jl
@@ -61,12 +61,19 @@ function Distributions.logpdf(
     dist::MultipleContinuousUnivariate,
     x::AbstractVector{<:Real},
 )
-    f, args = flatten(dist.dist)
-    return sum(f.(args..., x))
+    return _flat_logpdf(dist.dist, x)
 end
 function Distributions.rand(rng::Random.AbstractRNG, dist::MultipleContinuousUnivariate)
     return rand(rng, dist.dist, dist.N)
 end
+function _flat_logpdf(dist, x)
+    if toflatten(dist)
+        f, args = flatten(dist)
+        return sum(f.(args..., x))
+    else
+        return sum(logpdf.(dist, x))
+    end
+end
 
 struct MatrixContinuousUnivariate{
     Tdist <: ContinuousUnivariateDistribution,
@@ -83,7 +90,7 @@ function Distributions.logpdf(
     dist::MatrixContinuousUnivariate,
     x::AbstractMatrix{<:Real}
 )
-    return sum(logpdf.(dist.dist, x))
+    return _flat_logpdf(dist.dist, x)
 end
 function Distributions.rand(rng::Random.AbstractRNG, dist::MatrixContinuousUnivariate)
     return rand(rng, dist.dist, dist.S)
@@ -106,7 +113,7 @@ function Distributions.logpdf(
     dist::MultipleDiscreteUnivariate,
     x::AbstractVector{<:Integer}
 )
-    return sum(logpdf.(dist.dist, x))
+    return _flat_logpdf(dist.dist, x)
 end
 function Distributions.rand(rng::Random.AbstractRNG, dist::MultipleDiscreteUnivariate)
     return rand(rng, dist.dist, dist.N)
@@ -127,7 +134,7 @@ function Distributions.logpdf(
     dist::MatrixDiscreteUnivariate,
     x::AbstractMatrix{<:Real}
 )
-    return sum(logpdf.(dist.dist, x))
+    return _flat_logpdf(dist.dist, x)
 end
 function Distributions.rand(rng::Random.AbstractRNG, dist::MatrixDiscreteUnivariate)
     return rand(rng, dist.dist, dist.S)