faster sampling from singletons

src/Utils/samples.jl

@@ -88,6 +88,7 @@ _default_sampler(::LineSegment{N}) where {N} =
 _default_sampler(::HalfSpace) = HalfSpaceSampler()
 _default_sampler(::Hyperplane) = HyperplaneSampler()
 _default_sampler(::Line2D) = HyperplaneSampler()
+_default_sampler(::AbstractSingleton) = SingletonSampler()
 
 # =====================
 # Uniform distribution
@@ -530,6 +531,28 @@ function sample!(D::Vector{VN}, hp::Union{Hyperplane, Line2D},
     end
 end
 
+# ==================
+# Singleton sampler
+# ==================
+
+"""
+    SingletonSampler <: AbstractSampler
+
+Type used for sampling from a singleton.
+"""
+struct SingletonSampler <: AbstractSampler
+end
+
+function sample!(D::Vector{VN}, S::AbstractSingleton,
+                 sampler::SingletonSampler;
+                 rng::AbstractRNG=GLOBAL_RNG,
+                 seed::Union{Int, Nothing}=nothing) where {N, VN<:AbstractVector{N}}
+    x = element(S)
+    @inbounds for i in 1:length(D)
+        D[i] = copy(x)
+    end
+end
+
 # =============================
 # Code requiring Distributions
 # =============================

test/Sets/Singleton.jl

@@ -60,6 +60,9 @@ for N in [Float64, Rational{Int}, Float32]
     answer, w = isuniversal(s, true)
     @test !isuniversal(s) && !answer && w ∉ s
 
+    # sampling
+    @test sample(s, 2) == [element(s), element(s)]
+
     # membership
     S = Singleton(N[1, 1])
     @test N[0.9, 1.1] ∉ S