/**
* Connects cfgNode to the proper CATCH block if target subtree might throw an exception. If there
* are FINALLY blocks reached before a CATCH, it will make the corresponding entry in finallyMap.
*/
private void connectToPossibleExceptionHandler(Node cfgNode, Node target) {
if (mayThrowException(target) && !exceptionHandler.isEmpty()) {
Node lastJump = cfgNode;
for (Node handler : exceptionHandler) {
if (NodeUtil.isFunction(handler)) {
return;
}
Preconditions.checkState(handler.getType() == Token.TRY);
Node catchBlock = NodeUtil.getCatchBlock(handler);
if (!NodeUtil.hasCatchHandler(catchBlock)) { // No catch but a FINALLY.
if (lastJump == cfgNode) {
createEdge(cfgNode, Branch.ON_EX, handler.getLastChild());
} else {
finallyMap.put(lastJump, handler.getLastChild());
}
} else { // Has a catch.
if (lastJump == cfgNode) {
createEdge(cfgNode, Branch.ON_EX, catchBlock);
return;
} else {
finallyMap.put(lastJump, catchBlock);
}
}
lastJump = handler;
}
}
}
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;
}
}
}
/**
* Computes the follow() node of a given node and its parent. There is a side effect when calling
* this function. If this function computed an edge that exists a FINALLY, it'll attempt to
* connect the fromNode to the outer FINALLY according to the finallyMap.
*
* @param fromNode The original source node since {@code node} is changed during recursion.
* @param node The node that follow() should compute.
*/
private Node computeFollowNode(Node fromNode, Node node) {
/*
* This is the case where:
*
* 1. Parent is null implies that we are transferring control to the end of
* the script.
*
* 2. Parent is a function implies that we are transferring control back to
* the caller of the function.
*
* 3. If the node is a return statement, we should also transfer control
* back to the caller of the function.
*
* 4. If the node is root then we have reached the end of what we have been
* asked to traverse.
*
* In all cases we should transfer control to a "symbolic return" node.
* This will make life easier for DFAs.
*/
Node parent = node.getParent();
if (parent == null || parent.getType() == Token.FUNCTION || node == root) {
return null;
}
// If we are just before a IF/WHILE/DO/FOR:
switch (parent.getType()) {
// The follow() of any of the path from IF would be what follows IF.
case Token.IF:
return computeFollowNode(fromNode, parent);
case Token.CASE:
case Token.DEFAULT:
// After the body of a CASE, the control goes to the body of the next
// case, without having to go to the case condition.
if (parent.getNext() != null) {
if (parent.getNext().getType() == Token.CASE) {
return parent.getNext().getFirstChild().getNext();
} else if (parent.getNext().getType() == Token.DEFAULT) {
return parent.getNext().getFirstChild();
} else {
Preconditions.checkState(false, "Not reachable");
}
} else {
return computeFollowNode(fromNode, parent);
}
break;
case Token.FOR:
if (NodeUtil.isForIn(parent)) {
return parent;
} else {
return parent.getFirstChild().getNext().getNext();
}
case Token.WHILE:
case Token.DO:
return parent;
case Token.TRY:
// If we are coming out of the TRY block...
if (parent.getFirstChild() == node) {
if (NodeUtil.hasFinally(parent)) { // and have FINALLY block.
return computeFallThrough(parent.getLastChild());
} else { // and have no FINALLY.
return computeFollowNode(fromNode, parent);
}
// CATCH block.
} else if (NodeUtil.getCatchBlock(parent) == node) {
if (NodeUtil.hasFinally(parent)) { // and have FINALLY block.
return computeFallThrough(node.getNext());
} else {
return computeFollowNode(fromNode, parent);
}
// If we are coming out of the FINALLY block...
} else if (parent.getLastChild() == node) {
for (Node finallyNode : finallyMap.get(parent)) {
createEdge(fromNode, Branch.UNCOND, finallyNode);
}
return computeFollowNode(fromNode, parent);
}
}
// Now that we are done with the special cases follow should be its
// immediate sibling, unless its sibling is a function
Node nextSibling = node.getNext();
// Skip function declarations because control doesn't get pass into it.
while (nextSibling != null && nextSibling.getType() == Token.FUNCTION) {
nextSibling = nextSibling.getNext();
}
if (nextSibling != null) {
return computeFallThrough(nextSibling);
} else {
// If there are no more siblings, control is transfered up the AST.
return computeFollowNode(fromNode, parent);
}
}
