Review

6

com/google/javascript/jscomp/TightenTypes.java

visit(NodeTraversal, Node, Node)

class TightenTypes.CreateScope {
    // TODO(user): handle object literals like { a: new Foo };
    public void visit(NodeTraversal t, Node n, Node parent) {
      switch (n.getType()) {
        case Token.VAR:
          // Variable declaration, e.g. var a = b;
          Node name;
          for (name = n.getFirstChild(); name != null; name = name.getNext()) {
            if (inExterns) {
              // In externs, we have to trust the type information because there
              // are not necessarily assignments to the variables, calls to the
              // functions, etc.
              scope.declareSlot(name.getString(), n, createType(name, scope));
            } else {
              scope.declareSlot(name.getString(), n);
              if (name.getFirstChild() != null) {
                addActions(createAssignmentActions(
                    name, name.getFirstChild(), n));
              }
            }
          }
          break;

        case Token.GETPROP:
          // Property access, e.g. a.b = c;
          if (inExterns) {
            ConcreteType type = inferConcreteType(getTopScope(), n);
            // We only need to set a type if one hasn't been assigned by
            // something else, e.g. an ASSIGN node.
            if (type.isNone()) {
              ConcreteScope scope =
                  (ConcreteScope) inferConcreteType(getTopScope(),
                      n.getFirstChild()).getScope();
              if (scope != null) {
                type = createType(n.getJSType());
                if (type.isNone() || type.isAll()) {
                  break;
                }
                type = createUnionWithSubTypes(type);
                Node nameNode = n.getLastChild();
                scope.declareSlot(nameNode.getString(), n, type);
              }
            }
          }
          break;

        case Token.FUNCTION:
          // Function declaration, e.g. function Foo() {};
          if (NodeUtil.isFunctionDeclaration(n)) {
            if (!n.getJSType().isNoObjectType()) {
              ConcreteFunctionType type = createConcreteFunction(n, scope);
              scope.declareSlot(n.getFirstChild().getString(), n, type);

              if (inExterns && type.getInstanceType() != null) {
                // We must assume all extern types are instantiated since they
                // can be created by the browser itself.
                allInstantiatedTypes.add(type.getInstanceType());
              }
            }
          }
          break;

        case Token.ASSIGN:
          // Variable assignment, e.g. a = b;
          Node lhs = n.getFirstChild();
          if (inExterns) {
            // Again, we have to trust the externs.
            ConcreteScope scope;
            if (lhs.getType() == Token.GETPROP) {
              ConcreteType type = inferConcreteType(getTopScope(),
                  lhs.getFirstChild());
              scope = (ConcreteScope) type.getScope();
            } else {
              scope = getTopScope();
            }

            if (scope == null) break;

            ConcreteType type = inferConcreteType(getTopScope(), n);
            if (type.isNone() || type.isAll()) {
              break;
            }

            if (type.isFunction()) {
              if (lhs.getJSType() == null
                  || !(lhs.getJSType() instanceof FunctionType)) {
                break;
              }
              ConcreteType retType = createType(((FunctionType)
                  lhs.getJSType().restrictByNotNullOrUndefined())
                  .getReturnType());
              retType = createUnionWithSubTypes(retType);
              ConcreteType newret = type.toFunction().getReturnSlot()
                  .getType().unionWith(retType);
              ((ConcreteScope) type.getScope()).declareSlot(
                  ConcreteFunctionType.RETURN_SLOT_NAME, n, newret);
            }
            scope.declareSlot(lhs.getLastChild().getString(), n, type);
          } else {
            addActions(createAssignmentActions(lhs, n.getLastChild(), n));
          }
          break;

        case Token.NEW:
        case Token.CALL:
          Node receiver = n.getFirstChild();
          if (receiver.getType() == Token.GETPROP) {
            Node first = receiver.getFirstChild();
            // Special case the call() function.
            if ("call".equals(first.getNext().getString())) {
              if (first.getType() == Token.GETPROP) {
                // foo.bar.call()
                addAction(new FunctionCallBuilder(first, receiver.getNext())
                    .setPropName(first.getFirstChild().getNext().getString())
                    .setIsCallFunction()
                    .build());
              } else {
                // bar.call()
                addAction(new FunctionCallBuilder(
                    first, receiver.getNext()).setIsCallFunction()
                          .build());
              }
            } else {
              // foo.bar()
              addAction(new FunctionCallBuilder(first, receiver.getNext())
                  .setPropName(first.getNext().getString())
                  .build());
            }
          } else {
            // foo() or new Foo()
            addAction(new FunctionCallBuilder(receiver, receiver.getNext())
                      .setIsNewCall(n.getType() == Token.NEW)
                      .build());
          }
          break;

        case Token.NAME:
          if (parent.getType() == Token.CATCH && parent.getFirstChild() == n) {
            // The variable in a catch statement gets defined in the scope of
            // the catch block. We approximate that, as does the normal type
            // sytem, by declaring a variable for it in the scope in which the
            // catch is declared.
            scope.declareSlot(n.getString(), n,
                createUnionWithSubTypes(
                  createType(getTypeRegistry().getType("Error")).toInstance()));
          }
          break;

        case Token.RETURN:
          if (n.getFirstChild() != null) {
            addAction(new VariableAssignAction(
                (ConcreteSlot) scope.getOwnSlot(
                    ConcreteFunctionType.RETURN_SLOT_NAME), n.getFirstChild()));
          }
          break;
      }

      Collection<Action> actions = getImplicitActions(n);
      if (actions != null) {
        for (Action action : actions) {
          addAction(action);
        }
      }
    }

}