/**
* If we haven't found a return value yet, try to look at the "return" statements in the function.
*/
FunctionTypeBuilder inferReturnStatementsAsLastResort(@Nullable Node functionBlock) {
if (functionBlock == null || compiler.getInput(sourceName).isExtern()) {
return this;
}
Preconditions.checkArgument(functionBlock.getType() == Token.BLOCK);
if (returnType == null) {
boolean hasNonEmptyReturns = false;
List<Node> worklist = Lists.newArrayList(functionBlock);
while (!worklist.isEmpty()) {
Node current = worklist.remove(worklist.size() - 1);
int cType = current.getType();
if (cType == Token.RETURN && current.getFirstChild() != null || cType == Token.THROW) {
hasNonEmptyReturns = true;
break;
} else if (NodeUtil.isStatementBlock(current) || NodeUtil.isControlStructure(current)) {
for (Node child = current.getFirstChild(); child != null; child = child.getNext()) {
worklist.add(child);
}
}
}
if (!hasNonEmptyReturns) {
returnType = typeRegistry.getNativeType(VOID_TYPE);
returnTypeInferred = true;
}
}
return this;
}
public void testLinenoCharnoObjectLiteral() throws Exception {
Node n = parse("\n\n var a = {a:0\n,b :1};").getFirstChild().getFirstChild().getFirstChild();
assertEquals(Token.OBJECTLIT, n.getType());
assertEquals(3, n.getLineno());
assertEquals(9, n.getCharno());
Node key = n.getFirstChild();
assertEquals(Token.STRING_KEY, key.getType());
assertEquals(3, key.getLineno());
assertEquals(10, key.getCharno());
Node value = key.getFirstChild();
assertEquals(Token.NUMBER, value.getType());
assertEquals(3, value.getLineno());
assertEquals(12, value.getCharno());
key = key.getNext();
assertEquals(Token.STRING_KEY, key.getType());
assertEquals(4, key.getLineno());
assertEquals(1, key.getCharno());
value = key.getFirstChild();
assertEquals(Token.NUMBER, value.getType());
assertEquals(4, value.getLineno());
assertEquals(4, value.getCharno());
}
/**
* Gets whether a node is a CALL node whose return value should be stripped. A call's return
* value should be stripped if the function getting called is a static method in a class that
* gets stripped. For example, if "goog.debug.Logger" is a strip name, then this function
* returns true for a call such as "goog.debug.Logger.getLogger(...)". It may also simply be a
* function that is getting stripped. For example, if "getLogger" is a strip name, but not
* "goog.debug.Logger", this will still return true.
*
* @param n A node (typically a CALL node)
* @return Whether the call's return value should be stripped
*/
boolean isCallWhoseReturnValueShouldBeStripped(@Nullable Node n) {
return n != null
&& (n.getType() == Token.CALL || n.getType() == Token.NEW)
&& n.hasChildren()
&& (qualifiedNameBeginsWithStripType(n.getFirstChild())
|| nameEndsWithFieldNameToStrip(n.getFirstChild()));
}
public void testJSDocAttachment18() {
Node fn =
parse("function f() { " + " var x = /** @type {string} */ (y);" + "};").getFirstChild();
assertEquals(Token.FUNCTION, fn.getType());
Node cast = fn.getLastChild().getFirstChild().getFirstChild().getFirstChild();
assertEquals(Token.CAST, cast.getType());
}
/** If this is an assign to a variable or its property, return it. Otherwise, return null. */
static Assign maybeCreateAssign(Node assignNode) {
Preconditions.checkState(NodeUtil.isAssignmentOp(assignNode));
// Skip one level of GETPROPs or GETELEMs.
//
// Don't skip more than one level, because then we get into
// situations where assigns to properties of properties will always
// trigger side-effects, and the variable they're on cannot be removed.
boolean isPropAssign = false;
Node current = assignNode.getFirstChild();
if (NodeUtil.isGet(current)) {
current = current.getFirstChild();
isPropAssign = true;
if (current.getType() == Token.GETPROP
&& current.getLastChild().getString().equals("prototype")) {
// Prototype properties sets should be considered like normal
// property sets.
current = current.getFirstChild();
}
}
if (current.getType() == Token.NAME) {
return new Assign(assignNode, current, isPropAssign);
}
return null;
}
/** Replace the current assign with its right hand side. */
void remove() {
Node parent = assignNode.getParent();
if (mayHaveSecondarySideEffects) {
Node replacement = assignNode.getLastChild().detachFromParent();
// Aggregate any expressions in GETELEMs.
for (Node current = assignNode.getFirstChild();
current.getType() != Token.NAME;
current = current.getFirstChild()) {
if (current.getType() == Token.GETELEM) {
replacement =
new Node(Token.COMMA, current.getLastChild().detachFromParent(), replacement);
replacement.copyInformationFrom(current);
}
}
parent.replaceChild(assignNode, replacement);
} else {
Node gramps = parent.getParent();
if (parent.getType() == Token.EXPR_RESULT) {
gramps.removeChild(parent);
} else {
parent.replaceChild(assignNode, assignNode.getLastChild().detachFromParent());
}
}
}
private void scanRoot(Node n, Scope parent) {
if (n.getType() == Token.FUNCTION) {
sourceName = (String) n.getProp(Node.SOURCENAME_PROP);
final Node fnNameNode = n.getFirstChild();
final Node args = fnNameNode.getNext();
final Node body = args.getNext();
// Bleed the function name into the scope, if it hasn't
// been declared in the outer scope.
String fnName = fnNameNode.getString();
if (!fnName.isEmpty() && NodeUtil.isFunctionExpression(n)) {
declareVar(fnName, fnNameNode, n, null, null, n);
}
// Args: Declare function variables
Preconditions.checkState(args.getType() == Token.LP);
for (Node a = args.getFirstChild(); a != null; a = a.getNext()) {
Preconditions.checkState(a.getType() == Token.NAME);
declareVar(a.getString(), a, args, n, null, n);
}
// Body
scanVars(body, n);
} else {
// It's the global block
Preconditions.checkState(scope.getParent() == null);
scanVars(n, null);
}
}
public void onRedeclaration(
Scope s, String name, Node n, Node parent, Node gramps, Node nodeWithLineNumber) {
// Don't allow multiple variables to be declared at the top level scope
if (scope.isGlobal()) {
Scope.Var origVar = scope.getVar(name);
Node origParent = origVar.getParentNode();
if (origParent.getType() == Token.CATCH && parent.getType() == Token.CATCH) {
// Okay, both are 'catch(x)' variables.
return;
}
boolean allowDupe = false;
JSDocInfo info = n.getJSDocInfo();
if (info == null) {
info = parent.getJSDocInfo();
}
allowDupe = info != null && info.getSuppressions().contains("duplicate");
if (!allowDupe) {
compiler.report(
JSError.make(
sourceName,
nodeWithLineNumber,
VAR_MULTIPLY_DECLARED_ERROR,
name,
(origVar.input != null ? origVar.input.getName() : "??")));
}
} else if (name.equals(ARGUMENTS) && !NodeUtil.isVarDeclaration(n)) {
// Disallow shadowing "arguments" as we can't handle with our current
// scope modeling.
compiler.report(JSError.make(sourceName, nodeWithLineNumber, VAR_ARGUMENTS_SHADOWED_ERROR));
}
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.getType() == Token.GETPROP) {
handleGetProp(t, n);
} else if (n.getType() == Token.OBJECTLIT) {
handleObjectLit(t, n);
}
}
/**
* Gets whether a name ends with a field name that should be stripped. For example, this
* function would return true when passed "this.logger" or "a.b.c.myLogger" if "logger" is a
* strip name.
*
* @param n A node (typically a GETPROP node)
* @return Whether the name ends with a field name that should be stripped
*/
boolean nameEndsWithFieldNameToStrip(@Nullable Node n) {
if (n != null && n.getType() == Token.GETPROP) {
Node propNode = n.getLastChild();
return propNode != null
&& propNode.getType() == Token.STRING
&& isStripName(propNode.getString());
}
return false;
}
public void testObjectLiteralDoc1() {
Node n = parse("var x = {/** @type {number} */ 1: 2};");
Node objectLit = n.getFirstChild().getFirstChild().getFirstChild();
assertEquals(Token.OBJECTLIT, objectLit.getType());
Node number = objectLit.getFirstChild();
assertEquals(Token.STRING_KEY, number.getType());
assertNotNull(number.getJSDocInfo());
}
/** Scans and gather variables declarations under a Node */
private void scanVars(Node n, Node parent) {
switch (n.getType()) {
case Token.VAR:
// Declare all variables. e.g. var x = 1, y, z;
for (Node child = n.getFirstChild(); child != null; ) {
Node next = child.getNext();
Preconditions.checkState(child.getType() == Token.NAME);
String name = child.getString();
declareVar(name, child, n, parent, null, n);
child = next;
}
return;
case Token.FUNCTION:
if (NodeUtil.isFunctionExpression(n)) {
return;
}
String fnName = n.getFirstChild().getString();
if (fnName.isEmpty()) {
// This is invalid, but allow it so the checks can catch it.
return;
}
declareVar(fnName, n.getFirstChild(), n, parent, null, n);
return; // should not examine function's children
case Token.CATCH:
Preconditions.checkState(n.getChildCount() == 2);
Preconditions.checkState(n.getFirstChild().getType() == Token.NAME);
// the first child is the catch var and the third child
// is the code block
final Node var = n.getFirstChild();
final Node block = var.getNext();
declareVar(var.getString(), var, n, parent, null, n);
scanVars(block, n);
return; // only one child to scan
case Token.SCRIPT:
sourceName = (String) n.getProp(Node.SOURCENAME_PROP);
break;
}
// Variables can only occur in statement-level nodes, so
// we only need to traverse children in a couple special cases.
if (NodeUtil.isControlStructure(n) || NodeUtil.isStatementBlock(n)) {
for (Node child = n.getFirstChild(); child != null; ) {
Node next = child.getNext();
scanVars(child, n);
child = next;
}
}
}
/**
* Locates the array literal specified by the <code>array</code> node, in the source using the
* source location information provided by the node, and inserts <code>str</code> as a string
* literal (quoted) in the source at the end of the array.
*
* @param array Node with source position information
* @param str the string to insert into the source at the end of the specified array
*/
public void appendToArrayLit(Node array, String str) {
final String sourceMethod = "appendToArrayLit"; // $NON-NLS-1$
if (isTraceLogging) {
log.entering(JSSource.class.getName(), sourceMethod, new Object[] {array, str});
}
// Get the node for the last element in the array
Node lastChild = array.getLastChild();
// If token is not a string, then punt
if (lastChild.getType() != Token.STRING && lastChild.getType() != Token.NAME) {
if (log.isLoggable(Level.WARNING)) {
log.warning(
"Last element of array at "
+ mid
+ "("
+ array.getLineno()
+ ","
+ array.getCharno()
+ ") is type "
+ array.getType()); // $NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
}
if (isTraceLogging) {
log.exiting(JSSource.class.getName(), sourceMethod);
}
return;
}
int len =
lastChild.getString().length()
+ (lastChild.getType() == Token.STRING ? 2 : 0); // add 2 for string quotes
// Search the source for the closing array bracket ']', skipping over
// whitespace and comments. In order to be valid javascript, the next
// token must be the closing bracket.
int lineno = lastChild.getLineno();
int charno = lastChild.getCharno() + len;
PositionLocator pos = new PositionLocator(lineno, charno);
if (pos.findNextJSToken() == ']') {
insert(",\"" + str + "\"", pos.getLineno(), pos.getCharno()); // $NON-NLS-1$ //$NON-NLS-2$
} else {
if (log.isLoggable(Level.WARNING)) {
log.warning(
"Closing array bracket not found in "
+ mid
+ "("
+ lineno
+ ","
+ charno
+ ")"); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
}
}
if (isTraceLogging) {
log.exiting(JSSource.class.getName(), sourceMethod);
}
}
public void testJSDocAttachment10() {
Node varNode = parse("/** x\n */var a;").getFirstChild();
// VAR
assertEquals(Token.VAR, varNode.getType());
// NAME
Node nameNode = varNode.getFirstChild();
assertEquals(Token.NAME, nameNode.getType());
assertNull(nameNode.getJSDocInfo());
}
public void testLinenoCharnoGetProp2() throws Exception {
Node getprop = parse("\n foo.\nbar").getFirstChild().getFirstChild();
assertEquals(Token.GETPROP, getprop.getType());
assertEquals(2, getprop.getLineno());
assertEquals(1, getprop.getCharno());
Node name = getprop.getFirstChild().getNext();
assertEquals(Token.STRING, name.getType());
assertEquals(3, name.getLineno());
assertEquals(0, name.getCharno());
}
private void validateSwitchMember(Node n) {
switch (n.getType()) {
case Token.CASE:
validateCase(n);
return;
case Token.DEFAULT_CASE:
validateDefaultCase(n);
return;
default:
violation("Expected switch member but was " + Token.name(n.getType()), n);
}
}
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.getType() != Token.FUNCTION) {
return;
}
int id = functionNames.getFunctionId(n);
if (id < 0) {
// Function node was added during compilation; don't instrument.
return;
}
if (reportFunctionName.length() != 0) {
Node body = n.getFirstChild().getNext().getNext();
Node call =
new Node(
Token.CALL, Node.newString(Token.NAME, reportFunctionName), Node.newNumber(id));
Node expr = new Node(Token.EXPR_RESULT, call);
body.addChildToFront(expr);
compiler.reportCodeChange();
}
if (reportFunctionExitName.length() != 0) {
Node body = n.getFirstChild().getNext().getNext();
(new InstrumentReturns(id)).process(body);
}
if (definedFunctionName.length() != 0) {
Node call =
new Node(
Token.CALL, Node.newString(Token.NAME, definedFunctionName), Node.newNumber(id));
Node expr = NodeUtil.newExpr(call);
Node addingRoot = null;
if (NodeUtil.isFunctionDeclaration(n)) {
JSModule module = t.getModule();
addingRoot = compiler.getNodeForCodeInsertion(module);
addingRoot.addChildToFront(expr);
} else {
Node beforeChild = n;
for (Node ancestor : n.getAncestors()) {
int type = ancestor.getType();
if (type == Token.BLOCK || type == Token.SCRIPT) {
addingRoot = ancestor;
break;
}
beforeChild = ancestor;
}
addingRoot.addChildBefore(expr, beforeChild);
}
compiler.reportCodeChange();
}
}
// Looks at the type AST without evaluating it
private boolean isUnionWithUndefined(Node n) {
if (n == null || n.getType() != Token.PIPE) {
return false;
}
for (Node child : n.children()) {
if (child.getType() == Token.VOID
|| child.getType() == Token.STRING
&& (child.getString().equals("void") || child.getString().equals("undefined"))) {
return true;
}
}
return false;
}
/**
* Traverses a function, which creates a new scope in javascript.
*
* <p>Note that CATCH blocks also create a new scope, but only for the catch variable.
* Declarations within the block actually belong to the enclosing scope. Because we don't remove
* catch variables, there's no need to treat CATCH blocks differently like we do functions.
*/
private void traverseFunction(Node n, Scope parentScope) {
Preconditions.checkState(n.getChildCount() == 3);
Preconditions.checkState(n.getType() == Token.FUNCTION);
final Node body = n.getLastChild();
Preconditions.checkState(body.getNext() == null && body.getType() == Token.BLOCK);
Scope fnScope = new SyntacticScopeCreator(compiler).createScope(n, parentScope);
traverseNode(body, n, fnScope);
collectMaybeUnreferencedVars(fnScope);
allFunctionScopes.add(fnScope);
}
private void fillInFunTypeBuilder(
Node jsdocNode,
RawNominalType ownerType,
DeclaredTypeRegistry registry,
ImmutableList<String> typeParameters,
FunctionTypeBuilder builder)
throws UnknownTypeException {
Node child = jsdocNode.getFirstChild();
if (child.getType() == Token.THIS) {
if (ownerType == null) {
builder.addReceiverType(getThisOrNewType(child.getFirstChild(), registry, typeParameters));
}
child = child.getNext();
} else if (child.getType() == Token.NEW) {
Node newTypeNode = child.getFirstChild();
JSType t = getThisOrNewType(newTypeNode, registry, typeParameters);
if (!t.isSubtypeOf(JSType.TOP_OBJECT) && (!t.hasTypeVariable() || t.hasScalar())) {
warnings.add(JSError.make(newTypeNode, NEW_EXPECTS_OBJECT_OR_TYPEVAR, t.toString()));
}
builder.addNominalType(t);
child = child.getNext();
}
if (child.getType() == Token.PARAM_LIST) {
for (Node arg = child.getFirstChild(); arg != null; arg = arg.getNext()) {
try {
switch (arg.getType()) {
case Token.EQUALS:
builder.addOptFormal(
getTypeFromCommentHelper(arg.getFirstChild(), registry, typeParameters));
break;
case Token.ELLIPSIS:
Node restNode = arg.getFirstChild();
builder.addRestFormals(
restNode == null
? JSType.UNKNOWN
: getTypeFromCommentHelper(restNode, registry, typeParameters));
break;
default:
builder.addReqFormal(getTypeFromCommentHelper(arg, registry, typeParameters));
break;
}
} catch (FunctionTypeBuilder.WrongParameterOrderException e) {
warnings.add(JSError.make(jsdocNode, WRONG_PARAMETER_ORDER));
builder.addPlaceholderFormal();
}
}
child = child.getNext();
}
builder.addRetType(getTypeFromCommentHelper(child, registry, typeParameters));
}
public void testJSDocAttachment1() {
Node varNode = parse("/** @type number */var a;").getFirstChild();
// VAR
assertEquals(Token.VAR, varNode.getType());
JSDocInfo info = varNode.getJSDocInfo();
assertNotNull(info);
assertTypeEquals(NUMBER_TYPE, info.getType());
// NAME
Node nameNode = varNode.getFirstChild();
assertEquals(Token.NAME, nameNode.getType());
assertNull(nameNode.getJSDocInfo());
}
/**
* Gets all the control flow edges from some node with the first token to
* some node with the second token.
*/
private static List<DiGraphEdge<Node, Branch>> getAllEdges(
ControlFlowGraph<Node> cfg, int startToken, int endToken) {
List<DiGraphEdge<Node, Branch>> edges = getAllEdges(cfg);
Iterator<DiGraphEdge<Node, Branch>> it = edges.iterator();
while (it.hasNext()) {
DiGraphEdge<Node, Branch> edge = it.next();
Node startNode = edge.getSource().getValue();
Node endNode = edge.getDestination().getValue();
if (startNode == null || endNode == null ||
startNode.getType() != startToken || endNode.getType() != endToken) {
it.remove();
}
}
return edges;
}
/**
* 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 handleContinue(Node node) {
String label = null;
if (node.hasChildren()) {
label = node.getFirstChild().getString();
}
Node cur;
Node lastJump;
// Similar to handBreak's logic with a few minor variation.
Node parent = node.getParent();
for (cur = node, lastJump = node;
!isContinueTarget(cur, parent, label);
cur = parent, parent = parent.getParent()) {
if (cur.getType() == Token.TRY && NodeUtil.hasFinally(cur)) {
if (lastJump == node) {
createEdge(lastJump, Branch.UNCOND, cur.getLastChild());
} else {
finallyMap.put(lastJump, computeFallThrough(cur.getLastChild()));
}
lastJump = cur;
}
Preconditions.checkState(parent != null, "Cannot find continue target.");
}
Node iter = cur;
if (cur.getChildCount() == 4) {
iter = cur.getFirstChild().getNext().getNext();
}
if (lastJump == node) {
createEdge(node, Branch.UNCOND, iter);
} else {
finallyMap.put(lastJump, iter);
}
}
/** @return true if this node marks the start of a new basic block */
private static boolean isBlockBoundary(Node n, Node parent) {
if (parent != null) {
switch (parent.getType()) {
case Token.DO:
case Token.FOR:
case Token.FOR_OF:
case Token.TRY:
case Token.WHILE:
case Token.WITH:
// NOTE: TRY has up to 3 child blocks:
// TRY
// BLOCK
// BLOCK
// CATCH
// BLOCK
// Note that there is an explicit CATCH token but no explicit
// FINALLY token. For simplicity, we consider each BLOCK
// a separate basic BLOCK.
return true;
case Token.AND:
case Token.HOOK:
case Token.IF:
case Token.OR:
// The first child of a conditional is not a boundary,
// but all the rest of the children are.
return n != parent.getFirstChild();
}
}
return n.isCase();
}
/** Creates an instance for a function that might be a constructor. */
FunctionType(
JSTypeRegistry registry,
String name,
Node source,
ArrowType arrowType,
JSType typeOfThis,
TemplateTypeMap templateTypeMap,
boolean isConstructor,
boolean nativeType) {
super(
registry,
name,
registry.getNativeObjectType(JSTypeNative.FUNCTION_INSTANCE_TYPE),
nativeType,
templateTypeMap);
setPrettyPrint(true);
Preconditions.checkArgument(source == null || Token.FUNCTION == source.getType());
Preconditions.checkNotNull(arrowType);
this.source = source;
if (isConstructor) {
this.kind = Kind.CONSTRUCTOR;
this.propAccess = PropAccess.ANY;
this.typeOfThis =
typeOfThis != null ? typeOfThis : new InstanceObjectType(registry, this, nativeType);
} else {
this.kind = Kind.ORDINARY;
this.typeOfThis =
typeOfThis != null ? typeOfThis : registry.getNativeObjectType(JSTypeNative.UNKNOWN_TYPE);
}
this.call = arrowType;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getType()) {
// Function calls
case Token.CALL:
Node child = n.getFirstChild();
String name = null;
// NOTE: The normalization pass insures that local names do not
// collide with global names.
if (child.isName()) {
name = child.getString();
} else if (child.isFunction()) {
name = anonFunctionMap.get(child);
} else if (NodeUtil.isFunctionObjectCall(n)) {
Preconditions.checkState(NodeUtil.isGet(child));
Node fnIdentifingNode = child.getFirstChild();
if (fnIdentifingNode.isName()) {
name = fnIdentifingNode.getString();
} else if (fnIdentifingNode.isFunction()) {
name = anonFunctionMap.get(fnIdentifingNode);
}
}
if (name != null) {
FunctionState fs = functionMap.get(name);
// Only visit call-sites for functions that can be inlined.
if (fs != null) {
callback.visitCallSite(t, n, fs);
}
}
break;
}
}
public void findNamedFunctions(NodeTraversal t, Node n, Node parent) {
if (!NodeUtil.isStatement(n)) {
// There aren't any interesting functions here.
return;
}
switch (n.getType()) {
// Functions expressions in the form of:
// var fooFn = function(x) { return ... }
case Token.VAR:
Preconditions.checkState(n.hasOneChild());
Node nameNode = n.getFirstChild();
if (nameNode.isName()
&& nameNode.hasChildren()
&& nameNode.getFirstChild().isFunction()) {
maybeAddFunction(new FunctionVar(n), t.getModule());
}
break;
// Named functions
// function Foo(x) { return ... }
case Token.FUNCTION:
Preconditions.checkState(NodeUtil.isStatementBlock(parent) || parent.isLabel());
if (!NodeUtil.isFunctionExpression(n)) {
Function fn = new NamedFunction(n);
maybeAddFunction(fn, t.getModule());
}
break;
}
}
@Override
Node optimizeSubtree(Node subtree) {
switch (subtree.getType()) {
case CALL:
return tryFoldCall(subtree);
case NEW:
return tryFoldCtorCall(subtree);
case TYPEOF:
return tryFoldTypeof(subtree);
case NOT:
case POS:
case NEG:
case BITNOT:
tryReduceOperandsForOp(subtree);
return tryFoldUnaryOperator(subtree);
case VOID:
return tryReduceVoid(subtree);
default:
tryReduceOperandsForOp(subtree);
return tryFoldBinaryOperator(subtree);
}
}
/** Try to fold array-length. e.g [1, 2, 3].length ==> 3, [x, y].length ==> 2 */
private Node tryFoldGetProp(Node n, Node left, Node right) {
Preconditions.checkArgument(n.isGetProp());
if (left.isObjectLit()) {
return tryFoldObjectPropAccess(n, left, right);
}
if (right.isString() && right.getString().equals("length")) {
int knownLength = -1;
switch (left.getType()) {
case ARRAYLIT:
if (mayHaveSideEffects(left)) {
// Nope, can't fold this, without handling the side-effects.
return n;
}
knownLength = left.getChildCount();
break;
case STRING:
knownLength = left.getString().length();
break;
default:
// Not a foldable case, forget it.
return n;
}
Preconditions.checkState(knownLength != -1);
Node lengthNode = IR.number(knownLength);
n.getParent().replaceChild(n, lengthNode);
reportCodeChange();
return lengthNode;
}
return n;
}