Java Code Examples for com.google.javascript.rhino.Token#OBJECTLIT

/**
 * Gets the function's name. This method recognizes the forms:
 * <ul>
 * <li>{@code {'name': function() ...}}</li>
 * <li>{@code {name: function() ...}}</li>
 * <li>{@code function name() ...}</li>
 * <li>{@code var name = function() ...}</li>
 * <li>{@code qualified.name = function() ...}</li>
 * <li>{@code var name2 = function name1() ...}</li>
 * <li>{@code qualified.name2 = function name1() ...}</li>
 * </ul>
 *
 * @param n a node whose type is {@link Token#FUNCTION}
 * @return the function's name, or {@code null} if it has no name
 */
static String getNearestFunctionName(Node n) {
  String name = getFunctionName(n);
  if (name != null) {
    return name;
  }

  // Check for the form { 'x' : function() { } }
  Node parent = n.getParent();
  switch (parent.getType()) {
    case Token.OBJECTLIT:
      // Return the name of the literal's key.
      return getStringValue(parent.getFirstChild());
  }

  return null;
}
 

@Override
public ObjectLiteralCast getObjectLiteralCast(NodeTraversal t,
    Node callNode) {
  Preconditions.checkArgument(callNode.getType() == Token.CALL);
  Node callName = callNode.getFirstChild();
  if (!"goog.reflect.object".equals(callName.getQualifiedName()) ||
      callNode.getChildCount() != 3) {
    return null;
  }

  Node typeNode = callName.getNext();
  if (!typeNode.isQualifiedName()) {
    return null;
  }

  Node objectNode = typeNode.getNext();
  if (objectNode.getType() != Token.OBJECTLIT) {
    // TODO(johnlenz): The coding convention should not be performing checks.
    t.getCompiler().report(JSError.make(t.getSourceName(), callNode,
                                        OBJECTLIT_EXPECTED));
    return null;
  }

  return new ObjectLiteralCast(typeNode.getQualifiedName(),
                               typeNode.getNext());
}
 

@Override
public void remove() {
  // Setters have VAR, FUNCTION, or ASSIGN parent nodes. CALL parent
  // nodes are global refs, and are handled later in this function.
  Node containingNode = parent.getParent();
  switch (parent.getType()) {
    case Token.VAR:
      Preconditions.checkState(parent.hasOneChild());
      replaceWithRhs(containingNode, parent);
      break;
    case Token.FUNCTION:
      replaceWithRhs(containingNode, parent);
      break;
    case Token.ASSIGN:
      if (containingNode.isExprResult()) {
        replaceWithRhs(containingNode.getParent(), containingNode);
      } else {
        replaceWithRhs(containingNode, parent);
      }
      break;
    case Token.OBJECTLIT:
      // TODO(nicksantos): Come up with a way to remove this.
      // If we remove object lit keys, then we will need to also
      // create dependency scopes for them.
      break;
  }
}
 

/**
 * Determines whether a node represents an object literal key
 * (e.g. key1 in {key1: value1, key2: value2}).
 *
 * @param node A node
 * @param parent The node's parent
 */
static boolean isObjectLitKey(Node node, Node parent) {
  switch (node.getType()) {
    case Token.STRING:
      return parent.getType() == Token.OBJECTLIT;
    case Token.GET:
    case Token.SET:
      return true;
  }
  return false;
}
 

@Override
public void visit(NodeTraversal t, Node n, Node parent) {
  switch (n.getType()) {
    case Token.VAR:
      removeVarDeclarationsByNameOrRvalue(t, n, parent);
      break;

    case Token.NAME:
      maybeRemoveReferenceToRemovedVariable(t, n, parent);
      break;

    case Token.ASSIGN:
    case Token.ASSIGN_BITOR:
    case Token.ASSIGN_BITXOR:
    case Token.ASSIGN_BITAND:
    case Token.ASSIGN_LSH:
    case Token.ASSIGN_RSH:
    case Token.ASSIGN_URSH:
    case Token.ASSIGN_ADD:
    case Token.ASSIGN_SUB:
    case Token.ASSIGN_MUL:
    case Token.ASSIGN_DIV:
    case Token.ASSIGN_MOD:
      maybeEliminateAssignmentByLvalueName(t, n, parent);
      break;

    case Token.CALL:
    case Token.NEW:
      maybeRemoveCall(t, n, parent);
      break;

    case Token.OBJECTLIT:
      eliminateKeysWithStripNamesFromObjLit(t, n);
      break;

    case Token.EXPR_RESULT:
      maybeEliminateExpressionByName(t, n, parent);
      break;
  }
}
 

/**
 * Gets the value of a node as a Number, or null if it cannot be converted.
 * When it returns a non-null Double, this method effectively emulates the
 * <code>Number()</code> JavaScript cast function.
 */
static Double getNumberValue(Node n) {
  switch (n.getType()) {
    case Token.TRUE:
      return 1.0;

    case Token.FALSE:
    case Token.NULL:
      return 0.0;

    case Token.NUMBER:
      return n.getDouble();

    case Token.VOID:
      if (mayHaveSideEffects(n.getFirstChild())) {
        return null;
      } else {
        return Double.NaN;
      }

    case Token.NAME:
      // Check for known constants
      String name = n.getString();
      if (name.equals("undefined")) {
        return Double.NaN;
      }
      if (name.equals("NaN")) {
        return Double.NaN;
      }
      if (name.equals("Infinity")) {
        return Double.POSITIVE_INFINITY;
      }
      return null;

    case Token.NEG:
      if (n.getChildCount() == 1 && n.getFirstChild().getType() == Token.NAME
          && n.getFirstChild().getString().equals("Infinity")) {
        return Double.NEGATIVE_INFINITY;
      }
      return null;

    case Token.NOT:
      TernaryValue child = getPureBooleanValue(n.getFirstChild());
      if (child != TernaryValue.UNKNOWN) {
        return child.toBoolean(true) ? 0.0 : 1.0; // reversed.
      }
      break;

    case Token.STRING:
      return getStringNumberValue(n.getString());

    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      String value = getStringValue(n);
      return value != null ? getStringNumberValue(value) : null;
  }

  return null;
}
 

/**
 * Updates the first initialization (a.k.a "declaration") of a global name
 * that occurs at an ASSIGN node. See comment for
 * {@link #updateObjLitOrFunctionDeclaration}.
 *
 * @param n An object representing a global name (e.g. "a", "a.b.c")
 * @param alias The flattened name for {@code n} (e.g. "a", "a$b$c")
 */
private void updateObjLitOrFunctionDeclarationAtAssignNode(
    Name n, String alias) {
  // NOTE: It's important that we don't add additional nodes
  // (e.g. a var node before the exprstmt) because the exprstmt might be
  // the child of an if statement that's not inside a block).

  Ref ref = n.declaration;
  Node rvalue = ref.node.getNext();
  Node varNode = new Node(Token.VAR);
  Node varParent = ref.node.getAncestor(3);
  Node gramps = ref.node.getAncestor(2);
  boolean isObjLit = rvalue.getType() == Token.OBJECTLIT;

  if (isObjLit && n.canEliminate()) {
    // Eliminate the object literal altogether.
    varParent.replaceChild(gramps, varNode);
    ref.node = null;

  } else {
    if (rvalue.getType() == Token.FUNCTION) {
      checkForHosedThisReferences(rvalue, n.docInfo, n);
    }

    ref.node.getParent().removeChild(rvalue);

    Node nameNode = NodeUtil.newName(
        compiler.getCodingConvention(),
        alias, ref.node.getAncestor(2), n.fullName());

    if (ref.node.getLastChild().getBooleanProp(Node.IS_CONSTANT_NAME)) {
      nameNode.putBooleanProp(Node.IS_CONSTANT_NAME, true);
    }

    varNode.addChildToBack(nameNode);
    nameNode.addChildToFront(rvalue);
    varParent.replaceChild(gramps, varNode);

    // Update the node ancestry stored in the reference.
    ref.node = nameNode;
  }

  if (isObjLit) {
    declareVarsForObjLitValues(
        n, alias, rvalue,
        varNode, varParent.getChildBefore(varNode), varParent);
  }

  addStubsForUndeclaredProperties(n, alias, varParent, varNode);

  if (!varNode.hasChildren()) {
    varParent.removeChild(varNode);
  }

  compiler.reportCodeChange();
}
 

/**
 * Gets the boolean value of a node that represents a literal. This method
 * effectively emulates the <code>Boolean()</code> JavaScript cast function
 * except it return UNKNOWN for known values with side-effects, use
 * getExpressionBooleanValue if you don't care about side-effects.
 */
static TernaryValue getPureBooleanValue(Node n) {
  switch (n.getType()) {
    case Token.STRING:
      return TernaryValue.forBoolean(n.getString().length() > 0);

    case Token.NUMBER:
      return TernaryValue.forBoolean(n.getDouble() != 0);

    case Token.NOT:
      return getPureBooleanValue(n.getLastChild()).not();

    case Token.NULL:
    case Token.FALSE:
      return TernaryValue.FALSE;

    case Token.VOID:
      if (!mayHaveSideEffects(n.getFirstChild())) {
        return TernaryValue.FALSE;
      }
      break;

    case Token.NAME:
      String name = n.getString();
      if ("undefined".equals(name)
          || "NaN".equals(name)) {
        // We assume here that programs don't change the value of the keyword
        // undefined to something other than the value undefined.
        return TernaryValue.FALSE;
      } else if ("Infinity".equals(name)) {
        return TernaryValue.TRUE;
      }
      break;

    case Token.TRUE:
    case Token.REGEXP:
      return TernaryValue.TRUE;

    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      if (!mayHaveSideEffects(n)) {
        return TernaryValue.TRUE;
      }
      break;
  }

  return TernaryValue.UNKNOWN;
}
 

/**
 * Gets the value of a node as a Number, or null if it cannot be converted.
 * When it returns a non-null Double, this method effectively emulates the
 * <code>Number()</code> JavaScript cast function.
 */
static Double getNumberValue(Node n) {
  switch (n.getType()) {
    case Token.TRUE:
      return 1.0;

    case Token.FALSE:
    case Token.NULL:
      return 0.0;

    case Token.NUMBER:
      return n.getDouble();

    case Token.VOID:
      if (mayHaveSideEffects(n.getFirstChild())) {
        return null;
      } else {
        return Double.NaN;
      }

    case Token.NAME:
      // Check for known constants
      String name = n.getString();
      if (name.equals("undefined")) {
        return Double.NaN;
      }
      if (name.equals("NaN")) {
        return Double.NaN;
      }
      if (name.equals("Infinity")) {
        return Double.POSITIVE_INFINITY;
      }
      return null;

    case Token.NEG:
      if (n.getChildCount() == 1 && n.getFirstChild().isName()
          && n.getFirstChild().getString().equals("Infinity")) {
        return Double.NEGATIVE_INFINITY;
      }
      return null;

    case Token.NOT:
      TernaryValue child = getPureBooleanValue(n.getFirstChild());
      if (child != TernaryValue.UNKNOWN) {
        return child.toBoolean(true) ? 0.0 : 1.0; // reversed.
      }
      break;

    case Token.STRING:
      return getStringNumberValue(n.getString());

    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      String value = getStringValue(n);
      return value != null ? getStringNumberValue(value) : null;
  }

  return null;
}
 

private void attachLiteralTypes(NodeTraversal t, Node n) {
  switch (n.getType()) {
    case Token.NULL:
      n.setJSType(getNativeType(NULL_TYPE));
      break;

    case Token.VOID:
      n.setJSType(getNativeType(VOID_TYPE));
      break;

    case Token.STRING:
      // Defer keys to the Token.OBJECTLIT case
      if (!NodeUtil.isObjectLitKey(n, n.getParent())) {
        n.setJSType(getNativeType(STRING_TYPE));
      }
      break;

    case Token.NUMBER:
      n.setJSType(getNativeType(NUMBER_TYPE));
      break;

    case Token.TRUE:
    case Token.FALSE:
      n.setJSType(getNativeType(BOOLEAN_TYPE));
      break;

    case Token.REGEXP:
      n.setJSType(getNativeType(REGEXP_TYPE));
      break;

    case Token.REF_SPECIAL:
      n.setJSType(getNativeType(UNKNOWN_TYPE));
      break;

    case Token.OBJECTLIT:
      defineObjectLiteral(t, n);
      break;

      // NOTE(nicksantos): If we ever support Array tuples,
      // we will need to put ARRAYLIT here as well.
  }
}
 

/**
 * Gets the value of a node as a String, or null if it cannot be converted.
 * When it returns a non-null String, this method effectively emulates the
 * <code>String()</code> JavaScript cast function.
 */
static String getStringValue(Node n) {
  // TODO(user): regex literals as well.
  switch (n.getType()) {
    case Token.STRING:
    case Token.STRING_KEY:
      return n.getString();

    case Token.NAME:
      String name = n.getString();
      if ("undefined".equals(name)
          || "Infinity".equals(name)
          || "NaN".equals(name)) {
        return name;
      }
      break;

    case Token.NUMBER:
      return getStringValue(n.getDouble());

    case Token.FALSE:
      return "false";

    case Token.TRUE:
      return "true";

    case Token.NULL:
      return "null";

    case Token.VOID:
      return "undefined";

    case Token.NOT:
      TernaryValue child = getPureBooleanValue(n.getFirstChild());
      if (child != TernaryValue.UNKNOWN) {
        return child.toBoolean(true) ? "false" : "true"; // reversed.
      }
      break;

    case Token.ARRAYLIT:
      return arrayToString(n);

    case Token.OBJECTLIT:
      return "[object Object]";
  }
  return null;
}
 

private void attachLiteralTypes(NodeTraversal t, Node n) {
  switch (n.getType()) {
    case Token.NULL:
      n.setJSType(getNativeType(NULL_TYPE));
      break;

    case Token.VOID:
      n.setJSType(getNativeType(VOID_TYPE));
      break;

    case Token.STRING:
      n.setJSType(getNativeType(STRING_TYPE));
      break;

    case Token.NUMBER:
      n.setJSType(getNativeType(NUMBER_TYPE));
      break;

    case Token.TRUE:
    case Token.FALSE:
      n.setJSType(getNativeType(BOOLEAN_TYPE));
      break;

    case Token.REGEXP:
      n.setJSType(getNativeType(REGEXP_TYPE));
      break;

    case Token.OBJECTLIT:
      JSDocInfo info = n.getJSDocInfo();
      if (info != null &&
          info.getLendsName() != null) {
        if (lentObjectLiterals == null) {
          lentObjectLiterals = Lists.newArrayList();
        }
        lentObjectLiterals.add(n);
      } else {
        defineObjectLiteral(n);
      }
      break;

      // NOTE(nicksantos): If we ever support Array tuples,
      // we will need to put ARRAYLIT here as well.
  }
}
 

/**
 * Gets the boolean value of a node that represents a literal. This method
 * effectively emulates the <code>Boolean()</code> JavaScript cast function
 * except it return UNKNOWN for known values with side-effects, use
 * getExpressionBooleanValue if you don't care about side-effects.
 */
static TernaryValue getPureBooleanValue(Node n) {
  switch (n.getType()) {
    case Token.STRING:
      return TernaryValue.forBoolean(n.getString().length() > 0);

    case Token.NUMBER:
      return TernaryValue.forBoolean(n.getDouble() != 0);

    case Token.NOT:
      return getPureBooleanValue(n.getLastChild()).not();

    case Token.NULL:
    case Token.FALSE:
    case Token.VOID:
      return TernaryValue.FALSE;

    case Token.NAME:
      String name = n.getString();
      if ("undefined".equals(name)
          || "NaN".equals(name)) {
        // We assume here that programs don't change the value of the keyword
        // undefined to something other than the value undefined.
        return TernaryValue.FALSE;
      } else if ("Infinity".equals(name)) {
        return TernaryValue.TRUE;
      }
      break;

    case Token.TRUE:
    case Token.REGEXP:
      return TernaryValue.TRUE;

    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      if (!mayHaveSideEffects(n)) {
        return TernaryValue.TRUE;
      }
  }

  return TernaryValue.UNKNOWN;
}
 

/**
 * @param locals A predicate to apply to unknown local values.
 * @return Whether the node is known to be a value that is not a reference
 *     outside the expression scope.
 */
static boolean evaluatesToLocalValue(Node value, Predicate<Node> locals) {
  switch (value.getType()) {
    case Token.ASSIGN:
      // A result that is aliased by a non-local name, is the effectively the
      // same as returning a non-local name, but this doesn't matter if the
      // value is immutable.
      return NodeUtil.isImmutableValue(value.getLastChild())
          || (locals.apply(value)
              && evaluatesToLocalValue(value.getLastChild(), locals));
    case Token.COMMA:
      return evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.AND:
    case Token.OR:
      return evaluatesToLocalValue(value.getFirstChild(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.HOOK:
      return evaluatesToLocalValue(value.getFirstChild().getNext(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.INC:
    case Token.DEC:
      if (value.getBooleanProp(Node.INCRDECR_PROP)) {
        return evaluatesToLocalValue(value.getFirstChild(), locals);
      } else {
        return true;
      }
    case Token.THIS:
      return locals.apply(value);
    case Token.NAME:
      return isImmutableValue(value) || locals.apply(value);
    case Token.GETELEM:
    case Token.GETPROP:
      // There is no information about the locality of object properties.
      return locals.apply(value);
    case Token.CALL:
      return callHasLocalResult(value)
          || isToStringMethodCall(value)
          || locals.apply(value);
    case Token.NEW:
      return newHasLocalResult(value)
             || locals.apply(value);
    case Token.FUNCTION:
    case Token.REGEXP:
    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      // Literals objects with non-literal children are allowed.
      return true;
    case Token.DELPROP:
    case Token.IN:
      // TODO(johnlenz): should IN operator be included in #isSimpleOperator?
      return true;
    default:
      // Other op force a local value:
      //  x = '' + g (x is now an local string)
      //  x -= g (x is now an local number)
      if (isAssignmentOp(value)
          || isSimpleOperator(value)
          || isImmutableValue(value)) {
        return true;
      }

      throw new IllegalStateException(
          "Unexpected expression node" + value +
          "\n parent:" + value.getParent());
  }
}
 

@Override
public void visit(NodeTraversal t, Node n, Node parent) {
  if (nodeFilter != null && !nodeFilter.apply(n)) {
    return;
  }

  // If we are traversing the externs, then we save a pointer to the scope
  // generated by them, so that we can do lookups in it later.
  if (externsRoot != null && n == externsRoot) {
    externsScope = t.getScope();
  }

  String name;
  boolean isSet = false;
  Name.Type type = Name.Type.OTHER;
  boolean isPropAssign = false;

  switch (n.getType()) {
    case Token.STRING:
      // This may be a key in an object literal declaration.
      name = null;
      if (parent != null && parent.getType() == Token.OBJECTLIT) {
        name = getNameForObjLitKey(n);
      }
      if (name == null) return;
      isSet = true;
      type = getValueType(n.getFirstChild());
      break;
    case Token.NAME:
      // This may be a variable get or set.
      if (parent != null) {
        switch (parent.getType()) {
          case Token.VAR:
            isSet = true;
            Node rvalue = n.getFirstChild();
            type = rvalue == null ? Name.Type.OTHER : getValueType(rvalue);
            break;
          case Token.ASSIGN:
            if (parent.getFirstChild() == n) {
              isSet = true;
              type = getValueType(n.getNext());
            }
            break;
          case Token.GETPROP:
            return;
          case Token.FUNCTION:
            Node gramps = parent.getParent();
            if (gramps == null ||
                NodeUtil.isFunctionExpression(parent)) return;
            isSet = true;
            type = Name.Type.FUNCTION;
            break;
        }
      }
      name = n.getString();
      break;
    case Token.GETPROP:
      // This may be a namespaced name get or set.
      if (parent != null) {
        switch (parent.getType()) {
          case Token.ASSIGN:
            if (parent.getFirstChild() == n) {
              isSet = true;
              type = getValueType(n.getNext());
              isPropAssign = true;
            }
            break;
          case Token.GETPROP:
            return;
        }
      }
      name = n.getQualifiedName();
      if (name == null) return;
      break;
    default:
      return;
  }

  // We are only interested in global names.
  Scope scope = t.getScope();
  if (!isGlobalNameReference(name, scope)) {
    return;
  }

  if (isSet) {
    if (isGlobalScope(scope)) {
      handleSetFromGlobal(t, n, parent, name, isPropAssign, type);
    } else {
      handleSetFromLocal(t, n, parent, name);
    }
  } else {
    handleGet(t, n, parent, name);
  }
}
 

@Override
public void visit(NodeTraversal t, Node n, Node parent) {
  switch (n.getType()) {
    case Token.GETPROP:
    case Token.GETELEM:
      Node dest = n.getFirstChild().getNext();

      if (dest.isString()) {
        if (dest.getString().equals("prototype")) {
          processPrototypeParent(t, parent);
        } else {
          // Static methods of the form Foo.bar = function() {} or
          // Static methods of the form Foo.bar = baz (where baz is a
          // function name). Parse tree looks like:
          // assign                 <- parent
          //      getprop           <- n
          //          name Foo
          //          string bar
          //      function or name  <- n.getNext()
          if (parent.isAssign() &&
              parent.getFirstChild() == n) {
            addPossibleSignature(dest.getString(), n.getNext(), t);
          }
        }
      }
      break;

    case Token.OBJECTLIT:
      for (Node key = n.getFirstChild(); key != null; key = key.getNext()) {
        switch(key.getType()) {
          case Token.STRING_KEY:
            addPossibleSignature(key.getString(), key.getFirstChild(), t);
            break;
          case Token.SETTER_DEF:
          case Token.GETTER_DEF:
            nonMethodProperties.add(key.getString());
            break;
          default:
            throw new IllegalStateException(
                "unexpect OBJECTLIT key: " + key);
        }
      }
      break;
  }
}
 

/**
 * Try to fold array-element. e.g [1, 2, 3][10];
 */
private Node tryFoldGetElem(Node n, Node left, Node right) {
  Preconditions.checkArgument(n.getType() == Token.GETELEM);

  if (left.getType() == Token.OBJECTLIT) {
    return tryFoldObjectPropAccess(n, left, right);
  }

  if (left.getType() == Token.ARRAYLIT) {
    if (right.getType() != Token.NUMBER) {
      // Sometimes people like to use complex expressions to index into
      // arrays, or strings to index into array methods.
      return n;
    }

    double index = right.getDouble();
    int intIndex = (int) index;
    if (intIndex != index) {
      error(INVALID_GETELEM_INDEX_ERROR, right);
      return n;
    }

    if (intIndex < 0) {
      error(INDEX_OUT_OF_BOUNDS_ERROR, right);
      return n;
    }

    Node elem = left.getFirstChild();
    for (int i = 0; elem != null && i < intIndex; i++) {
      elem = elem.getNext();
    }

    if (elem == null) {
      error(INDEX_OUT_OF_BOUNDS_ERROR, right);
      return n;
    }

    if (elem.getType() == Token.EMPTY) {
      elem = NodeUtil.newUndefinedNode(elem);
    } else {
      left.removeChild(elem);
    }

    // Replace the entire GETELEM with the value
    n.getParent().replaceChild(n, elem);
    reportCodeChange();
    return elem;
  }
  return n;
}
 

/**
 * @param locals A predicate to apply to unknown local values.
 * @return Whether the node is known to be a value that is not a reference
 *     outside the expression scope.
 */
static boolean evaluatesToLocalValue(Node value, Predicate<Node> locals) {
  switch (value.getType()) {
    case Token.ASSIGN:
      // A result that is aliased by a non-local name, is the effectively the
      // same as returning a non-local name, but this doesn't matter if the
      // value is immutable.
      return NodeUtil.isImmutableValue(value.getLastChild())
          || (locals.apply(value)
              && evaluatesToLocalValue(value.getLastChild(), locals));
    case Token.COMMA:
      return evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.AND:
    case Token.OR:
      return evaluatesToLocalValue(value.getFirstChild(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.HOOK:
      return evaluatesToLocalValue(value.getFirstChild().getNext(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.INC:
    case Token.DEC:
      if (value.getBooleanProp(Node.INCRDECR_PROP)) {
        return evaluatesToLocalValue(value.getFirstChild(), locals);
      } else {
        return true;
      }
    case Token.THIS:
      return locals.apply(value);
    case Token.NAME:
      return isImmutableValue(value) || locals.apply(value);
    case Token.GETELEM:
    case Token.GETPROP:
      // There is no information about the locality of object properties.
      return locals.apply(value);
    case Token.CALL:
      return callHasLocalResult(value)
          || isToStringMethodCall(value)
          || locals.apply(value);
    case Token.NEW:
      return newHasLocalResult(value)
             || locals.apply(value);
    case Token.FUNCTION:
    case Token.REGEXP:
    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      // Literals objects with non-literal children are allowed.
      return true;
    case Token.DELPROP:
    case Token.IN:
      // TODO(johnlenz): should IN operator be included in #isSimpleOperator?
      return true;
    default:
      // Other op force a local value:
      //  x = '' + g (x is now an local string)
      //  x -= g (x is now an local number)
      if (isAssignmentOp(value)
          || isSimpleOperator(value)
          || isImmutableValue(value)) {
        return true;
      }

      throw new IllegalStateException(
          "Unexpected expression node" + value +
          "\n parent:" + value.getParent());
  }
}
 

static int precedence(int type) {
  switch (type) {
    case Token.COMMA:  return 0;
    case Token.ASSIGN_BITOR:
    case Token.ASSIGN_BITXOR:
    case Token.ASSIGN_BITAND:
    case Token.ASSIGN_LSH:
    case Token.ASSIGN_RSH:
    case Token.ASSIGN_URSH:
    case Token.ASSIGN_ADD:
    case Token.ASSIGN_SUB:
    case Token.ASSIGN_MUL:
    case Token.ASSIGN_DIV:
    case Token.ASSIGN_MOD:
    case Token.ASSIGN: return 1;
    case Token.HOOK:   return 2;  // ?: operator
    case Token.OR:     return 3;
    case Token.AND:    return 4;
    case Token.BITOR:  return 5;
    case Token.BITXOR: return 6;
    case Token.BITAND: return 7;
    case Token.EQ:
    case Token.NE:
    case Token.SHEQ:
    case Token.SHNE:   return 8;
    case Token.LT:
    case Token.GT:
    case Token.LE:
    case Token.GE:
    case Token.INSTANCEOF:
    case Token.IN:     return 9;
    case Token.LSH:
    case Token.RSH:
    case Token.URSH:   return 10;
    case Token.SUB:
    case Token.ADD:    return 11;
    case Token.MUL:
    case Token.MOD:
    case Token.DIV:    return 12;
    case Token.INC:
    case Token.DEC:
    case Token.NEW:
    case Token.DELPROP:
    case Token.TYPEOF:
    case Token.VOID:
    case Token.NOT:
    case Token.BITNOT:
    case Token.POS:
    case Token.NEG:    return 13;

    case Token.CALL:
    case Token.GETELEM:
    case Token.GETPROP:
    // Data values
    case Token.ARRAYLIT:
    case Token.EMPTY:  // TODO(johnlenz): remove this.
    case Token.FALSE:
    case Token.FUNCTION:
    case Token.NAME:
    case Token.NULL:
    case Token.NUMBER:
    case Token.OBJECTLIT:
    case Token.REGEXP:
    case Token.STRING:
    case Token.THIS:
    case Token.TRUE:
      return 15;

    default: throw new Error("Unknown precedence for " +
                             Node.tokenToName(type) +
                             " (type " + type + ")");
  }
}
 

/**
 * @param locals A predicate to apply to unknown local values.
 * @return Whether the node is known to be a value that is not a reference
 *     outside the expression scope.
 */
static boolean evaluatesToLocalValue(Node value, Predicate<Node> locals) {
  switch (value.getType()) {
    case Token.ASSIGN:
      // A result that is aliased by a non-local name, is the effectively the
      // same as returning a non-local name, but this doesn't matter if the
      // value is immutable.
      return NodeUtil.isImmutableValue(value.getLastChild())
          || (locals.apply(value)
              && evaluatesToLocalValue(value.getLastChild(), locals));
    case Token.COMMA:
      return evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.AND:
    case Token.OR:
      return evaluatesToLocalValue(value.getFirstChild(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.HOOK:
      return evaluatesToLocalValue(value.getFirstChild().getNext(), locals)
         && evaluatesToLocalValue(value.getLastChild(), locals);
    case Token.INC:
    case Token.DEC:
      if (value.getBooleanProp(Node.INCRDECR_PROP)) {
        return evaluatesToLocalValue(value.getFirstChild(), locals);
      } else {
        return true;
      }
    case Token.THIS:
      return locals.apply(value);
    case Token.NAME:
      return isImmutableValue(value) || locals.apply(value);
    case Token.GETELEM:
    case Token.GETPROP:
      // There is no information about the locality of object properties.
      return locals.apply(value);
    case Token.CALL:
      return callHasLocalResult(value)
          || isToStringMethodCall(value)
          || locals.apply(value);
    case Token.NEW:
      return newHasLocalResult(value)
             || locals.apply(value);
    case Token.FUNCTION:
    case Token.REGEXP:
    case Token.ARRAYLIT:
    case Token.OBJECTLIT:
      // Literals objects with non-literal children are allowed.
      return true;
    case Token.DELPROP:
    case Token.IN:
      // TODO(johnlenz): should IN operator be included in #isSimpleOperator?
      return true;
    default:
      // Other op force a local value:
      //  x = '' + g (x is now an local string)
      //  x -= g (x is now an local number)
      if (isAssignmentOp(value)
          || isSimpleOperator(value)
          || isImmutableValue(value)) {
        return true;
      }

      throw new IllegalStateException(
          "Unexpected expression node" + value +
          "\n parent:" + value.getParent());
  }
}