Specialize literal_pow for Fun (#115)

* specialize literal_pow for Fun

* better inference in f^0

* version bump to v0.6.11

Project.toml

@@ -1,6 +1,6 @@
 name = "ApproxFunBase"
 uuid = "fbd15aa5-315a-5a7d-a8a4-24992e37be05"
-version = "0.6.10"
+version = "0.6.11"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"

src/Fun.jl

@@ -368,6 +368,12 @@ function intpow(f::Fun,k::Integer)
 end
 
 ^(f::Fun, k::Integer) = intpow(f,k)
+# some common cases
+Base.literal_pow(::typeof(^), x::Fun, ::Val{0}) = ones(cfstype(x), space(x))
+Base.literal_pow(::typeof(^), x::Fun, ::Val{1}) = x
+Base.literal_pow(::typeof(^), x::Fun, ::Val{2}) = x * x
+Base.literal_pow(::typeof(^), x::Fun, ::Val{3}) = x * x * x
+Base.literal_pow(::typeof(^), x::Fun, ::Val{4}) = x * x * x * x
 
 inv(f::Fun) = 1/f
 

test/SpacesTest.jl

@@ -94,6 +94,23 @@ using ApproxFunOrthogonalPolynomials
         M2 = M + M
         infty = ApproxFunBase.InfiniteCardinal{0}()
         @test (@inferred size(M2)) == (infty, infty)
+
+        @testset "literal pow" begin
+            local f = Fun(PointSpace(1:3), Float64[1:3;])
+            @test (@inferred (x -> x^0)(f)) == ApproxFunBase.intpow(f,0)
+            @test (@inferred (x -> x^1)(f)) == ApproxFunBase.intpow(f,1)
+            @test (@inferred (x -> x^2)(f)) == ApproxFunBase.intpow(f,2)
+            @test (@inferred (x -> x^3)(f)) == ApproxFunBase.intpow(f,3)
+            @test (@inferred (x -> x^4)(f)) == ApproxFunBase.intpow(f,4)
+
+            local f = Fun(PointSpace(Float32[1:3;]), Float32[1:3;])
+            g = @inferred (x -> x^0)(f)
+            @test eltype(coefficients(g)) == Float32
+            g = @inferred (x -> x^1)(f)
+            @test eltype(coefficients(g)) == Float32
+            g = @inferred (x -> x^2)(f)
+            @test eltype(coefficients(g)) == Float32
+        end
     end
 
     @testset "Derivative operator for HeavisideSpace" begin