/// <summary> Try/Catch/Finally
///
/// The IRFactory tries to express as much as possible in the tree;
/// the responsibilities remaining for Codegen are to add the Java
/// handlers: (Either (but not both) of TARGET and FINALLY might not
/// be defined)
/// - a catch handler for javascript exceptions that unwraps the
/// exception onto the stack and GOTOes to the catch target
/// - a finally handler
/// ... and a goto to GOTO around these handlers.
/// </summary>
internal Node CreateTryCatchFinally(Node tryBlock, Node catchBlocks, Node finallyBlock, int lineno)
{
bool hasFinally = (finallyBlock != null) && (finallyBlock.Type != Token.BLOCK || finallyBlock.hasChildren ());
// short circuit
if (tryBlock.Type == Token.BLOCK && !tryBlock.hasChildren () && !hasFinally) {
return tryBlock;
}
bool hasCatch = catchBlocks.hasChildren ();
// short circuit
if (!hasFinally && !hasCatch) {
// bc finally might be an empty block...
return tryBlock;
}
Node handlerBlock = new Node (Token.LOCAL_BLOCK);
Node.Jump pn = new Node.Jump (Token.TRY, tryBlock, lineno);
pn.putProp (Node.LOCAL_BLOCK_PROP, handlerBlock);
if (hasCatch) {
// jump around catch code
Node endCatch = Node.newTarget ();
pn.addChildToBack (makeJump (Token.GOTO, endCatch));
// make a TARGET for the catch that the tcf node knows about
Node catchTarget = Node.newTarget ();
pn.target = catchTarget;
// mark it
pn.addChildToBack (catchTarget);
//
// Given
//
// try {
// tryBlock;
// } catch (e if condition1) {
// something1;
// ...
//
// } catch (e if conditionN) {
// somethingN;
// } catch (e) {
// somethingDefault;
// }
//
// rewrite as
//
// try {
// tryBlock;
// goto after_catch:
// } catch (x) {
// with (newCatchScope(e, x)) {
// if (condition1) {
// something1;
// goto after_catch;
// }
// }
// ...
// with (newCatchScope(e, x)) {
// if (conditionN) {
// somethingN;
// goto after_catch;
// }
// }
// with (newCatchScope(e, x)) {
// somethingDefault;
// goto after_catch;
// }
// }
// after_catch:
//
// If there is no default catch, then the last with block
// arround "somethingDefault;" is replaced by "rethrow;"
// It is assumed that catch handler generation will store
// exeception object in handlerBlock register
// Block with local for exception scope objects
Node catchScopeBlock = new Node (Token.LOCAL_BLOCK);
// expects catchblocks children to be (cond block) pairs.
Node cb = catchBlocks.FirstChild;
bool hasDefault = false;
int scopeIndex = 0;
while (cb != null) {
int catchLineNo = cb.Lineno;
Node name = cb.FirstChild;
Node cond = name.Next;
Node catchStatement = cond.Next;
cb.removeChild (name);
cb.removeChild (cond);
cb.removeChild (catchStatement);
// Add goto to the catch statement to jump out of catch
// but prefix it with LEAVEWITH since try..catch produces
// "with"code in order to limit the scope of the exception
// object.
catchStatement.addChildToBack (new Node (Token.LEAVEWITH));
catchStatement.addChildToBack (makeJump (Token.GOTO, endCatch));
// Create condition "if" when present
Node condStmt;
if (cond.Type == Token.EMPTY) {
condStmt = catchStatement;
hasDefault = true;
}
else {
condStmt = CreateIf (cond, catchStatement, null, catchLineNo);
}
// Generate code to Create the scope object and store
// it in catchScopeBlock register
Node catchScope = new Node (Token.CATCH_SCOPE, name, CreateUseLocal (handlerBlock));
catchScope.putProp (Node.LOCAL_BLOCK_PROP, catchScopeBlock);
catchScope.putIntProp (Node.CATCH_SCOPE_PROP, scopeIndex);
catchScopeBlock.addChildToBack (catchScope);
// Add with statement based on catch scope object
catchScopeBlock.addChildToBack (CreateWith (CreateUseLocal (catchScopeBlock), condStmt, catchLineNo));
// move to next cb
cb = cb.Next;
++scopeIndex;
}
pn.addChildToBack (catchScopeBlock);
if (!hasDefault) {
// Generate code to rethrow if no catch clause was executed
Node rethrow = new Node (Token.RETHROW);
rethrow.putProp (Node.LOCAL_BLOCK_PROP, handlerBlock);
pn.addChildToBack (rethrow);
}
pn.addChildToBack (endCatch);
}
if (hasFinally) {
Node finallyTarget = Node.newTarget ();
pn.Finally = finallyTarget;
// add jsr finally to the try block
pn.addChildToBack (makeJump (Token.JSR, finallyTarget));
// jump around finally code
Node finallyEnd = Node.newTarget ();
pn.addChildToBack (makeJump (Token.GOTO, finallyEnd));
pn.addChildToBack (finallyTarget);
Node fBlock = new Node (Token.FINALLY, finallyBlock);
fBlock.putProp (Node.LOCAL_BLOCK_PROP, handlerBlock);
pn.addChildToBack (fBlock);
pn.addChildToBack (finallyEnd);
}
handlerBlock.addChildToBack (pn);
return handlerBlock;
}
private void transformCompilationUnit_r(ScriptOrFnNode tree, Node parent)
{
Node node = null;
using (Helpers.StackOverflowVerifier sov = new Helpers.StackOverflowVerifier(1024)) {
for (; ;)
{
Node previous = null;
if (node == null)
{
node = parent.FirstChild;
}
else
{
previous = node;
node = node.Next;
}
if (node == null)
{
break;
}
int type = node.Type;
switch (type)
{
case Token.LABEL:
case Token.SWITCH:
case Token.LOOP:
loops.push(node);
loopEnds.push(((Node.Jump)node).target);
break;
case Token.WITH: {
loops.push(node);
Node leave = node.Next;
if (leave.Type != Token.LEAVEWITH)
{
Context.CodeBug();
}
loopEnds.push(leave);
break;
}
case Token.TRY: {
Node.Jump jump = (Node.Jump)node;
Node finallytarget = jump.Finally;
if (finallytarget != null)
{
hasFinally = true;
loops.push(node);
loopEnds.push(finallytarget);
}
break;
}
case Token.TARGET:
case Token.LEAVEWITH:
if (!loopEnds.Empty && loopEnds.peek() == node)
{
loopEnds.pop();
loops.pop();
}
break;
case Token.RETURN: {
/* If we didn't support try/finally, it wouldn't be
* necessary to put LEAVEWITH nodes here... but as
* we do need a series of JSR FINALLY nodes before
* each RETURN, we need to ensure that each finally
* block gets the correct scope... which could mean
* that some LEAVEWITH nodes are necessary.
*/
if (!hasFinally)
{
break; // skip the whole mess.
}
Node unwindBlock = null;
for (int i = loops.size() - 1; i >= 0; i--)
{
Node n = (Node)loops.Get(i);
int elemtype = n.Type;
if (elemtype == Token.TRY || elemtype == Token.WITH)
{
Node unwind;
if (elemtype == Token.TRY)
{
Node.Jump jsrnode = new Node.Jump(Token.JSR);
Node jsrtarget = ((Node.Jump)n).Finally;
jsrnode.target = jsrtarget;
unwind = jsrnode;
}
else
{
unwind = new Node(Token.LEAVEWITH);
}
if (unwindBlock == null)
{
unwindBlock = new Node(Token.BLOCK, node.Lineno);
}
unwindBlock.addChildToBack(unwind);
}
}
if (unwindBlock != null)
{
Node returnNode = node;
Node returnExpr = returnNode.FirstChild;
node = replaceCurrent(parent, previous, node, unwindBlock);
if (returnExpr == null)
{
unwindBlock.addChildToBack(returnNode);
}
else
{
Node store = new Node(Token.EXPR_RESULT, returnExpr);
unwindBlock.addChildToFront(store);
returnNode = new Node(Token.RETURN_RESULT);
unwindBlock.addChildToBack(returnNode);
// transform return expression
transformCompilationUnit_r(tree, store);
}
// skip transformCompilationUnit_r to avoid infinite loop
goto siblingLoop;
}
break;
}
case Token.BREAK:
case Token.CONTINUE: {
Node.Jump jump = (Node.Jump)node;
Node.Jump jumpStatement = jump.JumpStatement;
if (jumpStatement == null)
{
Context.CodeBug();
}
for (int i = loops.size(); ;)
{
if (i == 0)
{
// Parser/IRFactory ensure that break/continue
// always has a jump statement associated with it
// which should be found
throw Context.CodeBug();
}
--i;
Node n = (Node)loops.Get(i);
if (n == jumpStatement)
{
break;
}
int elemtype = n.Type;
if (elemtype == Token.WITH)
{
Node leave = new Node(Token.LEAVEWITH);
previous = addBeforeCurrent(parent, previous, node, leave);
}
else if (elemtype == Token.TRY)
{
Node.Jump tryNode = (Node.Jump)n;
Node.Jump jsrFinally = new Node.Jump(Token.JSR);
jsrFinally.target = tryNode.Finally;
previous = addBeforeCurrent(parent, previous, node, jsrFinally);
}
}
if (type == Token.BREAK)
{
jump.target = jumpStatement.target;
}
else
{
jump.target = jumpStatement.Continue;
}
jump.Type = Token.GOTO;
break;
}
case Token.CALL:
visitCall(node, tree);
break;
case Token.NEW:
visitNew(node, tree);
break;
case Token.VAR: {
Node result = new Node(Token.BLOCK);
for (Node cursor = node.FirstChild; cursor != null;)
{
// Move cursor to next before createAssignment get chance
// to change n.next
Node n = cursor;
if (n.Type != Token.NAME)
{
Context.CodeBug();
}
cursor = cursor.Next;
if (!n.hasChildren())
{
continue;
}
Node init = n.FirstChild;
n.removeChild(init);
n.Type = Token.BINDNAME;
n = new Node(Token.SETNAME, n, init);
Node pop = new Node(Token.EXPR_VOID, n, node.Lineno);
result.addChildToBack(pop);
}
node = replaceCurrent(parent, previous, node, result);
break;
}
case Token.NAME:
case Token.SETNAME:
case Token.DELPROP: {
// Turn name to var for faster access if possible
if (tree.Type != Token.FUNCTION || ((FunctionNode)tree).RequiresActivation)
{
break;
}
Node nameSource;
if (type == Token.NAME)
{
nameSource = node;
}
else
{
nameSource = node.FirstChild;
if (nameSource.Type != Token.BINDNAME)
{
if (type == Token.DELPROP)
{
break;
}
throw Context.CodeBug();
}
}
string name = nameSource.String;
if (tree.hasParamOrVar(name))
{
if (type == Token.NAME)
{
node.Type = Token.GETVAR;
}
else if (type == Token.SETNAME)
{
node.Type = Token.SETVAR;
nameSource.Type = Token.STRING;
}
else if (type == Token.DELPROP)
{
// Local variables are by definition permanent
Node n = new Node(Token.FALSE);
node = replaceCurrent(parent, previous, node, n);
}
else
{
throw Context.CodeBug();
}
}
break;
}
}
transformCompilationUnit_r(tree, node);
siblingLoop:
;
}
}
}
