Merge pull request #1058 from JuliaSymbolics/fb/morestructs

store more useful information in symbolic struct

src/struct.jl

@@ -68,9 +68,31 @@ function decodetyp(typ::TypeT)
 end
 
 struct Struct
+    juliatype::DataType
     v::Vector{StructElement}
 end
 
+
+"""
+    symstruct(T)
+
+Create a symbolic struct from a given type `T`.
+"""
+function symstruct(T)
+    elems = map(fieldnames(T)) do fieldname
+        StructElement(fieldtype(T, fieldname), fieldname)
+    end |> collect
+    Struct(T, elems)
+end
+
+"""
+    juliatype(s::Struct)
+
+Get the Julia type that `s` is representing.
+"""
+juliatype(s::Struct) = getfield(s, :juliatype)
+getelements(s::Struct) = getfield(s, :v)
+
 function Base.getproperty(s::Struct, name::Symbol)
     v = getfield(s, :v)
     idx = findfirst(x -> nameof(x) == name, v)

test/struct.jl

@@ -1,5 +1,5 @@
 using Test, Symbolics
-using Symbolics: StructElement, Struct, operation, arguments
+using Symbolics: StructElement, Struct, operation, arguments, symstruct, juliatype
 
 handledtypes = [Int8,
     Int16,
@@ -17,17 +17,25 @@ for t in handledtypes
 end
 
 @variables t x(t)
+struct Fisk
+    a::Int8
+    b::Int
+end
 a = StructElement(Int8, :a)
 b = StructElement(Int, :b)
-s = Struct([a, b])
-sa = s.a
-sb = s.b
-@test operation(sa) === getfield
-@test arguments(sa) == Any[s, 1]
-@test arguments(sa) isa Any
-@test operation(sb) === getfield
-@test arguments(sb) == Any[s, 2]
-@test arguments(sb) isa Any
+for s in [Struct(Fisk, [a, b]), symstruct(Fisk)]
+    sa = s.a
+    sb = s.b
+    @test operation(sa) === getfield
+    @test arguments(sa) == Any[s, 1]
+    @test arguments(sa) isa Any
+    @test operation(sb) === getfield
+    @test arguments(sb) == Any[s, 2]
+    @test arguments(sb) isa Any
+    @test juliatype(s) == Fisk
+end
+
+s = Struct(Fisk, [a, b])
 
 sa1 = (setproperty!(s, :a, UInt8(1)))
 @test operation(sa1) === setfield!
@@ -38,3 +46,12 @@ sb1 = (setproperty!(s, :b, "hi"))
 @test operation(sb1) === setfield!
 @test arguments(sb1) == Any[s, 2, "hi"]
 @test arguments(sb1) isa Any
+
+struct Jörgen
+    a::Int
+    b::Float64
+end
+
+ss = symstruct(Jörgen)
+
+@test getfield(ss, :v) == [StructElement(Int, :a), StructElement(Float64, :b)]