wip closures: dedupliacation of upvalue references

src/ndspkg/compiler.nim

@@ -407,22 +407,30 @@ proc addUpvalue(comp: Compiler, index: int): int =
   ## and creates an upvalue in every function up until the one
   ## including this local so that all of the function scopes in between
   ## have the right upvalue in them (compile time)
-  
+  ## 
+  ## does not create duplicates: at each layer it will first find existing ones
+  ## and create references to that further down the line
+    
   template lenCheck(scope: Scope, blk: untyped) =
     if scope.upvalues.len() >= argMax:
       comp.error("Too many closure variables in function.")
       blk
 
-  let local = comp.locals[index]
-  var scopeIndex = local.depth
+  var scopeIndex = comp.locals[index].depth
   var isLocal = true
-  var upvalIndex: int
+  var upvalIndex: int = index
   while scopeIndex < comp.scopes.len():
     let scope = comp.scopes[scopeIndex]
     if scope.function:
       scope.lenCheck():
         return 0
-      scope.upvalues.add(Upvalue(index: if isLocal: index else: upvalIndex, isLocal: isLocal))
+      block ensure: # exiting this block means that the upvalueIndex is updated and points to the upvalue within scope
+        for i in countup(0, scope.upvalues.high()):
+          let upval = scope.upvalues[i]
+          if upval.index == upvalIndex and upval.isLocal == isLocal:
+            upvalIndex = i
+            break ensure
+        scope.upvalues.add(Upvalue(index: upvalIndex, isLocal: isLocal))
       isLocal = false
       upvalIndex = scope.upvalues.high()
     scopeIndex.inc