Immutable assignment support (#44)

* Fixed build script
* Supporting MetaModelica assignment semantics

Project.toml

@@ -8,6 +8,7 @@ DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 ExportAll = "ad2082ca-a69e-11e9-38fa-e96309a31fe4"
 ImmutableList = "4a558cac-c1ed-11e9-20da-3584bcd8709a"
 MacroTools = "1914dd2f-81c6-5fcd-8719-6d5c9610ff09"
+Setfield = "efcf1570-3423-57d1-acb7-fd33fddbac46"
 
 [compat]
 julia = "1.1"

src/MetaModelica.jl

@@ -3,7 +3,9 @@ module MetaModelica
 import MacroTools
 import MacroTools: @capture
 import ExportAll
-  #=
+import Setfield: @set!
+import Setfield: @set
+#=
   Have to treat the types slightly different.
   Precompilation of the types need to occur before everything else
 =#
@@ -18,17 +20,16 @@ include("matchcontinue.jl")
 include("functionInheritance.jl")
 include("metaRuntime.jl")
 include("shouldFail.jl")
+include("utilityMacros.jl")
 
 export @match, @matchcontinue, MatchFailure, ModelicaReal, ModelicaInteger
 export @Uniontype, @Record, @UniontypeDecl, @ExtendedFunction, @ExtendedAnonFunction
 export List, list, Nil, nil, Cons, cons, =>, Option, SOME, NONE, SourceInfo, SOURCEINFO
 export @do_threaded_for, <|, @shouldFail, sourceInfo, _cons, @importDBG
+export @assign
 
 include("exportmetaRuntime.jl")
 include("dangerous.jl")
 include("array.jl")
 
-
-#=============================#
 end
-

src/matchcontinue.jl

@@ -15,9 +15,10 @@
   limitations under the License.
 
   The code is based on https://github.com/RelationalAI-oss/Rematch.jl with
-  changed to allow keyword argument matching on a struct as well as
-  supporting @matchcontinue (try the next case when any exception is thrown).
-  """
+  changed to allow keyword argument matching on a struct, matching on the immutable list construct
+  accompanying MetaModelica.
+  It also provides  @matchcontinue macro (try the next case when any exception is thrown).
+"""
 
 include("fixLines.jl")
 
@@ -421,7 +422,7 @@ end
       end
 
   Return `result` for the first matching `pattern`. If there are no matches, throw `MatchFailure`.
-  """
+"""
 macro match(value, cases)
   res = handle_match_cases(value, cases ; mathcontinue = false)
   replaceLineNum(res, @__FILE__, __source__)

src/utilityMacros.jl

@@ -0,0 +1,35 @@
+import Setfield
+"""
+  Helper function for the assignmacro, see @assign
+  We have one case where we assign a immutable structure to an immutable structure or something to a primitive variable.
+  If it is not a primitive we assign to a subcomponent of that structure. We then clone the structure with that particular field changed.
+"""
+function assignFunc(expr)
+  res = if @capture(expr, lhs_._= rhs_)
+    if !isprimitivetype(typeof(lhs))
+      Setfield.setmacro(identity, expr, overwrite=true)
+    else
+      quote
+        $(esc(expr))
+      end
+    end
+  else
+    quote
+      $(esc(expr))
+    end
+  end
+  return res
+end
+
+"""
+  This macro reimplements the MetaModelica assignment semantics using
+  setfield to assign to variables.
+  For assignments using primitives, the regular Julia assignment is generated.
+  For cases where deeply nested immutable structures are manipulated we use setfield
+E.g.:
+  a.b.c = 5
+  Where a is a nested immutable struct
+"""
+macro assign(expr)
+  assignFunc(expr)
+end

test/runtimeTest.jl

@@ -198,5 +198,24 @@ end
   @test "AB" == "A" + "B"
 end
 
+@testset "Testing MetaModelica assignment semantics" begin
+  struct A
+    a
+  end
+  struct B
+    b
+  end
+  struct C
+    c
+  end
+  nested = A(B(C(1)))
+  @assign nested.a.b.c = 4
+  @test nested.a.b.c == 4
+  @assign a = 4
+  @test a == 4
+  @assign simple = 4
+  @test simple == 4
+end
+
 end #=End runtime tests=#
 end #=End module=#