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

/**
 * Gets the condition of an ON_TRUE / ON_FALSE CFG edge.
 * @param n a node with an outgoing conditional CFG edge
 * @return the condition node or null if the condition is not obviously a node
 */
static Node getConditionExpression(Node n) {
  switch (n.getType()) {
    case Token.IF:
    case Token.WHILE:
      return n.getFirstChild();
    case Token.DO:
      return n.getLastChild();
    case Token.FOR:
      switch (n.getChildCount()) {
        case 3:
          return null;
        case 4:
          return n.getFirstChild().getNext();
      }
      throw new IllegalArgumentException("malformed 'for' statement " + n);
    case Token.CASE:
      return null;
  }
  throw new IllegalArgumentException(n + " does not have a condition.");
}
 

/**
 * Determines whether the given node is a FOR, DO, WHILE, WITH, or IF node.
 */
static boolean isControlStructure(Node n) {
  switch (n.getType()) {
    case Token.FOR:
    case Token.DO:
    case Token.WHILE:
    case Token.WITH:
    case Token.IF:
    case Token.LABEL:
    case Token.TRY:
    case Token.CATCH:
    case Token.SWITCH:
    case Token.CASE:
    case Token.DEFAULT_CASE:
      return true;
    default:
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

/**
 * Determines whether the given node is a FOR, DO, WHILE, WITH, or IF node.
 */
static boolean isControlStructure(Node n) {
  switch (n.getType()) {
    case Token.FOR:
    case Token.DO:
    case Token.WHILE:
    case Token.WITH:
    case Token.IF:
    case Token.LABEL:
    case Token.TRY:
    case Token.CATCH:
    case Token.SWITCH:
    case Token.CASE:
    case Token.DEFAULT_CASE:
      return true;
    default:
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

/**
 * Determines whether the given node is a FOR, DO, WHILE, WITH, or IF node.
 */
static boolean isControlStructure(Node n) {
  switch (n.getType()) {
    case Token.FOR:
    case Token.DO:
    case Token.WHILE:
    case Token.WITH:
    case Token.IF:
    case Token.LABEL:
    case Token.TRY:
    case Token.CATCH:
    case Token.SWITCH:
    case Token.CASE:
    case Token.DEFAULT_CASE:
      return true;
    default:
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT_CASE:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT_CASE:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

/**
 * Determines whether the given node is a FOR, DO, WHILE, WITH, or IF node.
 */
static boolean isControlStructure(Node n) {
  switch (n.getType()) {
    case Token.FOR:
    case Token.DO:
    case Token.WHILE:
    case Token.WITH:
    case Token.IF:
    case Token.LABEL:
    case Token.TRY:
    case Token.CATCH:
    case Token.SWITCH:
    case Token.CASE:
    case Token.DEFAULT:
      return true;
    default:
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

/**
 * Determines whether the given node is code node for FOR, DO,
 * WHILE, WITH, or IF node.
 */
static boolean isControlStructureCodeBlock(Node parent, Node n) {
  switch (parent.getType()) {
    case Token.FOR:
    case Token.WHILE:
    case Token.LABEL:
    case Token.WITH:
      return parent.getLastChild() == n;
    case Token.DO:
      return parent.getFirstChild() == n;
    case Token.IF:
      return parent.getFirstChild() != n;
    case Token.TRY:
      return parent.getFirstChild() == n || parent.getLastChild() == n;
    case Token.CATCH:
      return parent.getLastChild() == n;
    case Token.SWITCH:
    case Token.CASE:
      return parent.getFirstChild() != n;
    case Token.DEFAULT_CASE:
      return true;
    default:
      Preconditions.checkState(isControlStructure(parent));
      return false;
  }
}
 

private void handleStmtList(Node node) {
  Node parent = node.getParent();
  // Special case, don't add a block of empty CATCH block to the graph.
  if (node.isBlock() && parent != null &&
      parent.isTry() &&
      NodeUtil.getCatchBlock(parent) == node &&
      !NodeUtil.hasCatchHandler(node)) {
    return;
  }

  // A block transfer control to its first child if it is not empty.
  Node child = node.getFirstChild();

  // Function declarations are skipped since control doesn't go into that
  // function (unless it is called)
  while (child != null && child.isFunction()) {
    child = child.getNext();
  }

  if (child != null) {
    createEdge(node, Branch.UNCOND, computeFallThrough(child));
  } else {
    createEdge(node, Branch.UNCOND, computeFollowNode(node, this));
  }

  // Synthetic blocks
  if (parent != null) {
    switch (parent.getType()) {
      case Token.DEFAULT_CASE:
      case Token.CASE:
      case Token.TRY:
        break;
      default:
        if (node.isBlock() && node.isSyntheticBlock()) {
          createEdge(node, Branch.SYN_BLOCK, computeFollowNode(node, this));
        }
        break;
    }
  }
}
 

private void handleStmtList(Node node) {
  Node parent = node.getParent();
  // Special case, don't add a block of empty CATCH block to the graph.
  if (node.isBlock() && parent != null &&
      parent.isTry() &&
      NodeUtil.getCatchBlock(parent) == node &&
      !NodeUtil.hasCatchHandler(node)) {
    return;
  }

  // A block transfer control to its first child if it is not empty.
  Node child = node.getFirstChild();

  // Function declarations are skipped since control doesn't go into that
  // function (unless it is called)
  while (child != null && child.isFunction()) {
    child = child.getNext();
  }

  if (child != null) {
    createEdge(node, Branch.UNCOND, computeFallThrough(child));
  } else {
    createEdge(node, Branch.UNCOND, computeFollowNode(node, this));
  }

  // Synthetic blocks
  if (parent != null) {
    switch (parent.getType()) {
      case Token.DEFAULT_CASE:
      case Token.CASE:
      case Token.TRY:
        break;
      default:
        if (node.isBlock() && node.isSyntheticBlock()) {
          createEdge(node, Branch.SYN_BLOCK, computeFollowNode(node, this));
        }
        break;
    }
  }
}
 

/**
 * Try to remove useless assignments from a control flow graph that has been
 * annotated with liveness information.
 *
 * @param t The node traversal.
 * @param cfg The control flow graph of the program annotated with liveness
 *        information.
 */
private void tryRemoveDeadAssignments(NodeTraversal t,
    ControlFlowGraph<Node> cfg) {
  Iterable<DiGraphNode<Node, Branch>> nodes = cfg.getDirectedGraphNodes();

  for (DiGraphNode<Node, Branch> cfgNode : nodes) {
    FlowState<LiveVariableLattice> state =
        cfgNode.getAnnotation();
    Node n = cfgNode.getValue();
    if (n == null) {
      continue;
    }
    switch (n.getType()) {
      case Token.IF:
      case Token.WHILE:
      case Token.DO:
        tryRemoveAssignment(t, NodeUtil.getConditionExpression(n), state);
        continue;
      case Token.FOR:
        if (!NodeUtil.isForIn(n)) {
          tryRemoveAssignment(
              t, NodeUtil.getConditionExpression(n), state);
        }
        continue;
      case Token.SWITCH:
      case Token.CASE:
      case Token.RETURN:
        if (n.hasChildren()) {
          tryRemoveAssignment(t, n.getFirstChild(), state);
        }
        continue;
      // TODO(user): case Token.VAR: Remove var a=1;a=2;.....
    }

    tryRemoveAssignment(t, n, state);
  }
}
 

private void handleStmtList(Node node) {
  Node parent = node.getParent();
  // Special case, don't add a block of empty CATCH block to the graph.
  if (node.getType() == Token.BLOCK && parent != null &&
      parent.getType() == Token.TRY &&
      NodeUtil.getCatchBlock(parent) == node &&
      !NodeUtil.hasCatchHandler(node)) {
    return;
  }

  // A block transfer control to its first child if it is not empty.
  Node child = node.getFirstChild();

  // Function declarations are skipped since control doesn't go into that
  // function (unless it is called)
  while (child != null && child.getType() == Token.FUNCTION) {
    child = child.getNext();
  }

  if (child != null) {
    createEdge(node, Branch.UNCOND, computeFallThrough(child));
  } else {
    createEdge(node, Branch.UNCOND, computeFollowNode(node));
  }

  // Synthetic blocks
  if (parent != null) {
    switch (parent.getType()) {
      case Token.DEFAULT:
      case Token.CASE:
      case Token.TRY:
        break;
      default:
        if (node.getType() == Token.BLOCK && node.isSyntheticBlock()) {
          Node next = node.getLastChild();
          if (next != null) {
            createEdge(node, Branch.SYN_BLOCK, computeFallThrough(next));
          }
        }
        break;
    }
  }
}
 

/**
 * @param n The expression to check.
 * @return Whether the expression is unconditionally executed only once in the
 *     containing execution scope.
 */
static boolean isExecutedExactlyOnce(Node n) {
  inspect: do {
    Node parent = n.getParent();
    switch (parent.getType()) {
      case Token.IF:
      case Token.HOOK:
      case Token.AND:
      case Token.OR:
        if (parent.getFirstChild() != n) {
          return false;
        }
        // other ancestors may be conditional
        continue inspect;
      case Token.FOR:
        if (NodeUtil.isForIn(parent)) {
          if (parent.getChildAtIndex(1) != n) {
            return false;
          }
        } else {
          if (parent.getFirstChild() != n) {
            return false;
          }
        }
        // other ancestors may be conditional
        continue inspect;
      case Token.WHILE:
      case Token.DO:
        return false;
      case Token.TRY:
        // Consider all code under a try/catch to be conditionally executed.
        if (!hasFinally(parent) || parent.getLastChild() != n) {
          return false;
        }
        continue inspect;
      case Token.CASE:
      case Token.DEFAULT_CASE:
        return false;
      case Token.SCRIPT:
      case Token.FUNCTION:
        // Done, we've reached the scope root.
        break inspect;
    }
  } while ((n = n.getParent()) != null);
  return true;
}
 

@Override
public boolean shouldTraverse(
    NodeTraversal nodeTraversal, Node n, Node parent) {
  astPosition.put(n, astPositionCounter++);

  switch (n.getType()) {
    case Token.FUNCTION:
      if (shouldTraverseFunctions || n == cfg.getEntry().getValue()) {
        exceptionHandler.push(n);
        return true;
      }
      return false;
    case Token.TRY:
      exceptionHandler.push(n);
      return true;
  }

  /*
   * We are going to stop the traversal depending on what the node's parent
   * is.
   *
   * We are only interested in adding edges between nodes that change control
   * flow. The most obvious ones are loops and IF-ELSE's. A statement
   * transfers control to its next sibling.
   *
   * In case of an expression tree, there is no control flow within the tree
   * even when there are short circuited operators and conditionals. When we
   * are doing data flow analysis, we will simply synthesize lattices up the
   * expression tree by finding the meet at each expression node.
   *
   * For example: within a Token.SWITCH, the expression in question does not
   * change the control flow and need not to be considered.
   */
  if (parent != null) {
    switch (parent.getType()) {
      case Token.FOR:
        // Only traverse the body of the for loop.
        return n == parent.getLastChild();

      // Skip the conditions.
      case Token.IF:
      case Token.WHILE:
      case Token.WITH:
        return n != parent.getFirstChild();
      case Token.DO:
        return n != parent.getFirstChild().getNext();
      // Only traverse the body of the cases
      case Token.SWITCH:
      case Token.CASE:
      case Token.CATCH:
      case Token.LABEL:
        return n != parent.getFirstChild();
      case Token.FUNCTION:
        return n == parent.getFirstChild().getNext().getNext();
      case Token.CONTINUE:
      case Token.BREAK:
      case Token.EXPR_RESULT:
      case Token.VAR:
      case Token.RETURN:
      case Token.THROW:
        return false;
      case Token.TRY:
        /* Just before we are about to visit the second child of the TRY node,
         * we know that we will be visiting either the CATCH or the FINALLY.
         * In other words, we know that the post order traversal of the TRY
         * block has been finished, no more exceptions can be caught by the
         * handler at this TRY block and should be taken out of the stack.
         */
        if (n == parent.getFirstChild().getNext()) {
          Preconditions.checkState(exceptionHandler.peek() == parent);
          exceptionHandler.pop();
        }
    }
  }
  return true;
}
 

/** Whether the node is part of a switch statement. */
static boolean isSwitchCase(Node n) {
  return n.getType() == Token.CASE || n.getType() == Token.DEFAULT;
}
 

@Override
public void visit(NodeTraversal t, Node n, Node parent) {
  switch (n.getType()) {
    case Token.IF:
      handleIf(n);
      return;
    case Token.WHILE:
      handleWhile(n);
      return;
    case Token.DO:
      handleDo(n);
      return;
    case Token.FOR:
      handleFor(n);
      return;
    case Token.SWITCH:
      handleSwitch(n);
      return;
    case Token.CASE:
      handleCase(n);
      return;
    case Token.DEFAULT_CASE:
      handleDefault(n);
      return;
    case Token.BLOCK:
    case Token.SCRIPT:
      handleStmtList(n);
      return;
    case Token.FUNCTION:
      handleFunction(n);
      return;
    case Token.EXPR_RESULT:
      handleExpr(n);
      return;
    case Token.THROW:
      handleThrow(n);
      return;
    case Token.TRY:
      handleTry(n);
      return;
    case Token.CATCH:
      handleCatch(n);
      return;
    case Token.BREAK:
      handleBreak(n);
      return;
    case Token.CONTINUE:
      handleContinue(n);
      return;
    case Token.RETURN:
      handleReturn(n);
      return;
    case Token.WITH:
      handleWith(n);
      return;
    case Token.LABEL:
      return;
    default:
      handleStmt(n);
      return;
  }
}
 

@Override
public boolean shouldTraverse(
    NodeTraversal nodeTraversal, Node n, Node parent) {
  astPosition.put(n, astPositionCounter++);

  switch (n.getType()) {
    case Token.FUNCTION:
      if (shouldTraverseFunctions || n == cfg.getEntry().getValue()) {
        exceptionHandler.push(n);
        return true;
      }
      return false;
    case Token.TRY:
      exceptionHandler.push(n);
      return true;
  }

  /*
   * We are going to stop the traversal depending on what the node's parent
   * is.
   *
   * We are only interested in adding edges between nodes that change control
   * flow. The most obvious ones are loops and IF-ELSE's. A statement
   * transfers control to its next sibling.
   *
   * In case of an expression tree, there is no control flow within the tree
   * even when there are short circuited operators and conditionals. When we
   * are doing data flow analysis, we will simply synthesize lattices up the
   * expression tree by finding the meet at each expression node.
   *
   * For example: within a Token.SWITCH, the expression in question does not
   * change the control flow and need not to be considered.
   */
  if (parent != null) {
    switch (parent.getType()) {
      case Token.FOR:
        // Only traverse the body of the for loop.
        return n == parent.getLastChild();

      // Skip the conditions.
      case Token.IF:
      case Token.WHILE:
      case Token.WITH:
        return n != parent.getFirstChild();
      case Token.DO:
        return n != parent.getFirstChild().getNext();
      // Only traverse the body of the cases
      case Token.SWITCH:
      case Token.CASE:
      case Token.CATCH:
      case Token.LABEL:
        return n != parent.getFirstChild();
      case Token.FUNCTION:
        return n == parent.getFirstChild().getNext().getNext();
      case Token.CONTINUE:
      case Token.BREAK:
      case Token.EXPR_RESULT:
      case Token.VAR:
      case Token.RETURN:
      case Token.THROW:
        return false;
      case Token.TRY:
        /* Just before we are about to visit the second child of the TRY node,
         * we know that we will be visiting either the CATCH or the FINALLY.
         * In other words, we know that the post order traversal of the TRY
         * block has been finished, no more exceptions can be caught by the
         * handler at this TRY block and should be taken out of the stack.
         */
        if (n == parent.getFirstChild().getNext()) {
          Preconditions.checkState(exceptionHandler.peek() == parent);
          exceptionHandler.pop();
        }
    }
  }
  return true;
}