/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Rhino code, released
* May 6, 1999.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1997-1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Norris Boyd
* Igor Bukanov
* Bob Jervis
* Roger Lawrence
* Mike McCabe
*
* Alternatively, the contents of this file may be used under the terms of
* the GNU General Public License Version 2 or later (the "GPL"), in which
* case the provisions of the GPL are applicable instead of those above. If
* you wish to allow use of your version of this file only under the terms of
* the GPL and not to allow others to use your version of this file under the
* MPL, indicate your decision by deleting the provisions above and replacing
* them with the notice and other provisions required by the GPL. If you do
* not delete the provisions above, a recipient may use your version of this
* file under either the MPL or the GPL.
*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.javascript;
/**
* This class transforms a tree to a lower-level representation for codegen.
*
* @see Node
* @author Norris Boyd
*/
public class NodeTransformer
{
public NodeTransformer()
{
}
public final void transform(ScriptOrFnNode tree)
{
transformCompilationUnit(tree);
for (int i = 0; i != tree.getFunctionCount(); ++i) {
FunctionNode fn = tree.getFunctionNode(i);
transform(fn);
}
}
private void transformCompilationUnit(ScriptOrFnNode tree)
{
loops = new ObjArray();
loopEnds = new ObjArray();
// to save against upchecks if no finally blocks are used.
hasFinally = false;
transformCompilationUnit_r(tree, tree);
}
private void transformCompilationUnit_r(final ScriptOrFnNode tree,
final Node parent)
{
Node node = null;
siblingLoop:
for (;;) {
Node previous = null;
if (node == null) {
node = parent.getFirstChild();
} else {
previous = node;
node = node.getNext();
}
if (node == null) {
break;
}
int type = node.getType();
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.getNext();
if (leave.getType() != Token.LEAVEWITH) {
Kit.codeBug();
}
loopEnds.push(leave);
break;
}
case Token.TRY:
{
Node.Jump jump = (Node.Jump)node;
Node finallytarget = jump.getFinally();
if (finallytarget != null) {
hasFinally = true;
loops.push(node);
loopEnds.push(finallytarget);
}
break;
}
case Token.TARGET:
case Token.LEAVEWITH:
if (!loopEnds.isEmpty() && 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.getType();
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).getFinally();
jsrnode.target = jsrtarget;
unwind = jsrnode;
} else {
unwind = new Node(Token.LEAVEWITH);
}
if (unwindBlock == null) {
unwindBlock = new Node(Token.BLOCK,
node.getLineno());
}
unwindBlock.addChildToBack(unwind);
}
}
if (unwindBlock != null) {
Node returnNode = node;
Node returnExpr = returnNode.getFirstChild();
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
continue siblingLoop;
}
break;
}
case Token.BREAK:
case Token.CONTINUE:
{
Node.Jump jump = (Node.Jump)node;
Node.Jump jumpStatement = jump.getJumpStatement();
if (jumpStatement == null) Kit.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 Kit.codeBug();
}
--i;
Node n = (Node) loops.get(i);
if (n == jumpStatement) {
break;
}
int elemtype = n.getType();
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.getFinally();
previous = addBeforeCurrent(parent, previous, node,
jsrFinally);
}
}
if (type == Token.BREAK) {
jump.target = jumpStatement.target;
} else {
jump.target = jumpStatement.getContinue();
}
jump.setType(Token.GOTO);
break;
}
case Token.CALL:
visitCall(node, tree);
break;
case Token.NEW:
visitNew(node, tree);
break;
case Token.CONST:
case Token.VAR:
{
Node result = new Node(Token.BLOCK);
for (Node cursor = node.getFirstChild(); cursor != null;) {
// Move cursor to next before createAssignment get chance
// to change n.next
Node n = cursor;
if (n.getType() != Token.NAME) Kit.codeBug();
cursor = cursor.getNext();
if (!n.hasChildren())
continue;
Node init = n.getFirstChild();
n.removeChild(init);
n.setType(Token.BINDNAME);
n = new Node(type == Token.VAR ?
Token.SETNAME :
Token.SETCONST,
n, init);
Node pop = new Node(Token.EXPR_VOID, n, node.getLineno());
result.addChildToBack(pop);
}
node = replaceCurrent(parent, previous, node, result);
break;
}
case Token.NAME:
case Token.SETNAME:
case Token.SETCONST:
case Token.DELPROP:
{
// Turn name to var for faster access if possible
if (tree.getType() != Token.FUNCTION
|| ((FunctionNode)tree).requiresActivation())
{
break;
}
Node nameSource;
if (type == Token.NAME) {
nameSource = node;
} else {
nameSource = node.getFirstChild();
if (nameSource.getType() != Token.BINDNAME) {
if (type == Token.DELPROP) {
break;
}
throw Kit.codeBug();
}
}
String name = nameSource.getString();
if (tree.hasParamOrVar(name)) {
if (type == Token.NAME) {
node.setType(Token.GETVAR);
} else if (type == Token.SETNAME) {
node.setType(Token.SETVAR);
nameSource.setType(Token.STRING);
} else if (type == Token.SETCONST) {
node.setType(Token.SETCONSTVAR);
nameSource.setType(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 Kit.codeBug();
}
}
break;
}
}
transformCompilationUnit_r(tree, node);
}
}
protected void visitNew(Node node, ScriptOrFnNode tree) {
}
protected void visitCall(Node node, ScriptOrFnNode tree) {
}
private static Node addBeforeCurrent(Node parent, Node previous,
Node current, Node toAdd)
{
if (previous == null) {
if (!(current == parent.getFirstChild())) Kit.codeBug();
parent.addChildToFront(toAdd);
} else {
if (!(current == previous.getNext())) Kit.codeBug();
parent.addChildAfter(toAdd, previous);
}
return toAdd;
}
private static Node replaceCurrent(Node parent, Node previous,
Node current, Node replacement)
{
if (previous == null) {
if (!(current == parent.getFirstChild())) Kit.codeBug();
parent.replaceChild(current, replacement);
} else if (previous.next == current) {
// Check cachedPrev.next == current is necessary due to possible
// tree mutations
parent.replaceChildAfter(previous, replacement);
} else {
parent.replaceChild(current, replacement);
}
return replacement;
}
private ObjArray loops;
private ObjArray loopEnds;
private boolean hasFinally;
}