/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript;
import org.mozilla.javascript.ast.AstRoot;
import org.mozilla.javascript.ast.FunctionNode;
import org.mozilla.javascript.ast.Jump;
import org.mozilla.javascript.ast.Scope;
import org.mozilla.javascript.ast.ScriptNode;
import java.util.ArrayList;
import java.util.List;
/**
* 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(ScriptNode tree)
{
transformCompilationUnit(tree);
for (int i = 0; i != tree.getFunctionCount(); ++i) {
FunctionNode fn = tree.getFunctionNode(i);
transform(fn);
}
}
private void transformCompilationUnit(ScriptNode tree)
{
loops = new ObjArray();
loopEnds = new ObjArray();
// to save against upchecks if no finally blocks are used.
hasFinally = false;
// Flatten all only if we are not using scope objects for block scope
boolean createScopeObjects = tree.getType() != Token.FUNCTION ||
((FunctionNode)tree).requiresActivation();
tree.flattenSymbolTable(!createScopeObjects);
//uncomment to print tree before transformation
if (Token.printTrees) System.out.println(tree.toStringTree(tree));
boolean inStrictMode = tree instanceof AstRoot &&
((AstRoot)tree).isInStrictMode();
transformCompilationUnit_r(tree, tree, tree, createScopeObjects,
inStrictMode);
}
private void transformCompilationUnit_r(final ScriptNode tree,
final Node parent,
Scope scope,
boolean createScopeObjects,
boolean inStrictMode)
{
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();
if (createScopeObjects &&
(type == Token.BLOCK || type == Token.LOOP ||
type == Token.ARRAYCOMP) &&
(node instanceof Scope))
{
Scope newScope = (Scope) node;
if (newScope.getSymbolTable() != null) {
// transform to let statement so we get a with statement
// created to contain scoped let variables
Node let = new Node(type == Token.ARRAYCOMP ? Token.LETEXPR
: Token.LET);
Node innerLet = new Node(Token.LET);
let.addChildToBack(innerLet);
for (String name: newScope.getSymbolTable().keySet()) {
innerLet.addChildToBack(Node.newString(Token.NAME, name));
}
newScope.setSymbolTable(null); // so we don't transform again
Node oldNode = node;
node = replaceCurrent(parent, previous, node, let);
type = node.getType();
let.addChildToBack(oldNode);
}
}
switch (type) {
case Token.LABEL:
case Token.SWITCH:
case Token.LOOP:
loops.push(node);
loopEnds.push(((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:
{
Jump jump = (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.YIELD:
((FunctionNode)tree).addResumptionPoint(node);
break;
case Token.RETURN:
{
boolean isGenerator = tree.getType() == Token.FUNCTION
&& ((FunctionNode)tree).isGenerator();
if (isGenerator) {
node.putIntProp(Node.GENERATOR_END_PROP, 1);
}
/* 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) {
Jump jsrnode = new Jump(Token.JSR);
Node jsrtarget = ((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 || isGenerator) {
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, scope,
createScopeObjects,
inStrictMode);
}
// skip transformCompilationUnit_r to avoid infinite loop
continue siblingLoop;
}
break;
}
case Token.BREAK:
case Token.CONTINUE:
{
Jump jump = (Jump)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) {
Jump tryNode = (Jump)n;
Jump jsrFinally = new 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.LETEXPR:
case Token.LET: {
Node child = node.getFirstChild();
if (child.getType() == Token.LET) {
// We have a let statement or expression rather than a
// let declaration
boolean createWith = tree.getType() != Token.FUNCTION
|| ((FunctionNode)tree).requiresActivation();
node = visitLet(createWith, parent, previous, node);
break;
} else {
// fall through to process let declaration...
}
}
/* fall through */
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 gets chance
// to change n.next
Node n = cursor;
cursor = cursor.getNext();
if (n.getType() == Token.NAME) {
if (!n.hasChildren())
continue;
Node init = n.getFirstChild();
n.removeChild(init);
n.setType(Token.BINDNAME);
n = new Node(type == Token.CONST ?
Token.SETCONST :
Token.SETNAME,
n, init);
} else {
// May be a destructuring assignment already transformed
// to a LETEXPR
if (n.getType() != Token.LETEXPR)
throw Kit.codeBug();
}
Node pop = new Node(Token.EXPR_VOID, n, node.getLineno());
result.addChildToBack(pop);
}
node = replaceCurrent(parent, previous, node, result);
break;
}
case Token.TYPEOFNAME: {
Scope defining = scope.getDefiningScope(node.getString());
if (defining != null) {
node.setScope(defining);
}
}
break;
case Token.TYPEOF:
case Token.IFNE: {
/* We want to suppress warnings for undefined property o.p
* for the following constructs: typeof o.p, if (o.p),
* if (!o.p), if (o.p == undefined), if (undefined == o.p)
*/
Node child = node.getFirstChild();
if (type == Token.IFNE) {
while (child.getType() == Token.NOT) {
child = child.getFirstChild();
}
if (child.getType() == Token.EQ ||
child.getType() == Token.NE)
{
Node first = child.getFirstChild();
Node last = child.getLastChild();
if (first.getType() == Token.NAME &&
first.getString().equals("undefined"))
child = last;
else if (last.getType() == Token.NAME &&
last.getString().equals("undefined"))
child = first;
}
}
if (child.getType() == Token.GETPROP)
child.setType(Token.GETPROPNOWARN);
break;
}
case Token.SETNAME:
if (inStrictMode) {
node.setType(Token.STRICT_SETNAME);
}
/* fall through */
case Token.NAME:
case Token.SETCONST:
case Token.DELPROP:
{
// Turn name to var for faster access if possible
if (createScopeObjects) {
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();
}
}
if (nameSource.getScope() != null) {
break; // already have a scope set
}
String name = nameSource.getString();
Scope defining = scope.getDefiningScope(name);
if (defining != null) {
nameSource.setScope(defining);
if (type == Token.NAME) {
node.setType(Token.GETVAR);
} else if (type == Token.SETNAME ||
type == Token.STRICT_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,
node instanceof Scope ? (Scope)node : scope,
createScopeObjects, inStrictMode);
}
}
protected void visitNew(Node node, ScriptNode tree) {
}
protected void visitCall(Node node, ScriptNode tree) {
}
protected Node visitLet(boolean createWith, Node parent, Node previous,
Node scopeNode)
{
Node vars = scopeNode.getFirstChild();
Node body = vars.getNext();
scopeNode.removeChild(vars);
scopeNode.removeChild(body);
boolean isExpression = scopeNode.getType() == Token.LETEXPR;
Node result;
Node newVars;
if (createWith) {
result = new Node(isExpression ? Token.WITHEXPR : Token.BLOCK);
result = replaceCurrent(parent, previous, scopeNode, result);
ArrayList<Object> list = new ArrayList<Object>();
Node objectLiteral = new Node(Token.OBJECTLIT);
for (Node v=vars.getFirstChild(); v != null; v = v.getNext()) {
Node current = v;
if (current.getType() == Token.LETEXPR) {
// destructuring in let expr, e.g. let ([x, y] = [3, 4]) {}
List<?> destructuringNames = (List<?>)
current.getProp(Node.DESTRUCTURING_NAMES);
Node c = current.getFirstChild();
if (c.getType() != Token.LET) throw Kit.codeBug();
// Add initialization code to front of body
if (isExpression) {
body = new Node(Token.COMMA, c.getNext(), body);
} else {
body = new Node(Token.BLOCK,
new Node(Token.EXPR_VOID, c.getNext()),
body);
}
// Update "list" and "objectLiteral" for the variables
// defined in the destructuring assignment
if (destructuringNames != null) {
list.addAll(destructuringNames);
for (int i=0; i < destructuringNames.size(); i++) {
objectLiteral.addChildToBack(
new Node(Token.VOID, Node.newNumber(0.0)));
}
}
current = c.getFirstChild(); // should be a NAME, checked below
}
if (current.getType() != Token.NAME) throw Kit.codeBug();
list.add(ScriptRuntime.getIndexObject(current.getString()));
Node init = current.getFirstChild();
if (init == null) {
init = new Node(Token.VOID, Node.newNumber(0.0));
}
objectLiteral.addChildToBack(init);
}
objectLiteral.putProp(Node.OBJECT_IDS_PROP, list.toArray());
newVars = new Node(Token.ENTERWITH, objectLiteral);
result.addChildToBack(newVars);
result.addChildToBack(new Node(Token.WITH, body));
result.addChildToBack(new Node(Token.LEAVEWITH));
} else {
result = new Node(isExpression ? Token.COMMA : Token.BLOCK);
result = replaceCurrent(parent, previous, scopeNode, result);
newVars = new Node(Token.COMMA);
for (Node v=vars.getFirstChild(); v != null; v = v.getNext()) {
Node current = v;
if (current.getType() == Token.LETEXPR) {
// destructuring in let expr, e.g. let ([x, y] = [3, 4]) {}
Node c = current.getFirstChild();
if (c.getType() != Token.LET) throw Kit.codeBug();
// Add initialization code to front of body
if (isExpression) {
body = new Node(Token.COMMA, c.getNext(), body);
} else {
body = new Node(Token.BLOCK,
new Node(Token.EXPR_VOID, c.getNext()),
body);
}
// We're removing the LETEXPR, so move the symbols
Scope.joinScopes((Scope)current,
(Scope)scopeNode);
current = c.getFirstChild(); // should be a NAME, checked below
}
if (current.getType() != Token.NAME) throw Kit.codeBug();
Node stringNode = Node.newString(current.getString());
stringNode.setScope((Scope)scopeNode);
Node init = current.getFirstChild();
if (init == null) {
init = new Node(Token.VOID, Node.newNumber(0.0));
}
newVars.addChildToBack(new Node(Token.SETVAR, stringNode, init));
}
if (isExpression) {
result.addChildToBack(newVars);
scopeNode.setType(Token.COMMA);
result.addChildToBack(scopeNode);
scopeNode.addChildToBack(body);
if (body instanceof Scope) {
Scope scopeParent = ((Scope) body).getParentScope();
((Scope) body).setParentScope((Scope)scopeNode);
((Scope) scopeNode).setParentScope(scopeParent);
}
} else {
result.addChildToBack(new Node(Token.EXPR_VOID, newVars));
scopeNode.setType(Token.BLOCK);
result.addChildToBack(scopeNode);
scopeNode.addChildrenToBack(body);
if (body instanceof Scope) {
Scope scopeParent = ((Scope) body).getParentScope();
((Scope) body).setParentScope((Scope)scopeNode);
((Scope) scopeNode).setParentScope(scopeParent);
}
}
}
return result;
}
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;
}