system.locals is now a plugin for education

compiler/plugins/active.nim

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+#
+#
+#           The Nim Compiler
+#        (c) Copyright 2015 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Include file that imports all plugins that are active.
+
+import
+  locals.locals

compiler/plugins/locals/locals.nim

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+#
+#
+#           The Nim Compiler
+#        (c) Copyright 2015 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## The builtin 'system.locals' implemented as a plugin.
+
+import plugins, ast, astalgo, magicsys, lookups, semdata, lowerings
+
+proc semLocals(c: PContext, n: PNode): PNode =
+  var counter = 0
+  var tupleType = newTypeS(tyTuple, c)
+  result = newNodeIT(nkPar, n.info, tupleType)
+  tupleType.n = newNodeI(nkRecList, n.info)
+  # for now we skip openarrays ...
+  for scope in walkScopes(c.currentScope):
+    if scope == c.topLevelScope: break
+    for it in items(scope.symbols):
+      # XXX parameters' owners are wrong for generics; this caused some pain
+      # for closures too; we should finally fix it.
+      #if it.owner != c.p.owner: return result
+      if it.kind in skLocalVars and
+          it.typ.skipTypes({tyGenericInst, tyVar}).kind notin
+            {tyVarargs, tyOpenArray, tyTypeDesc, tyStatic, tyExpr, tyStmt, tyEmpty}:
+
+        var field = newSym(skField, it.name, getCurrOwner(), n.info)
+        field.typ = it.typ.skipTypes({tyGenericInst, tyVar})
+        field.position = counter
+        inc(counter)
+
+        addSon(tupleType.n, newSymNode(field))
+        addSonSkipIntLit(tupleType, field.typ)
+
+        var a = newSymNode(it, result.info)
+        if it.typ.skipTypes({tyGenericInst}).kind == tyVar: a = newDeref(a)
+        result.add(a)
+
+registerPlugin("stdlib", "system", "locals", semLocals)