/**
* The scope that we should declare this function in, if it needs to be declared in a scope.
* Notice that TypedScopeCreator takes care of most scope-declaring.
*/
private Scope getScopeDeclaredIn() {
int dotIndex = fnName.indexOf(".");
if (dotIndex != -1) {
String rootVarName = fnName.substring(0, dotIndex);
Var rootVar = scope.getVar(rootVarName);
if (rootVar != null) {
return rootVar.getScope();
}
}
return scope;
}
@Override
public void enterScope(NodeTraversal t) {
if (t.inGlobalScope()) return;
Iterator<Var> it = t.getScope().getVars();
while (it.hasNext()) {
Var current = it.next();
if (current.isBleedingFunction()) {
localBleedingFunctions.add(current);
localBleedingFunctionsPerScope.put(t.getScope().getParent(), current);
}
}
}
private boolean isRemovableVar(Var var) {
// Global variables are off-limits if the user might be using them.
if (!removeGlobals && var.isGlobal()) {
return false;
}
// Referenced variables are off-limits.
if (referenced.contains(var)) {
return false;
}
// Exported variables are off-limits.
if (codingConvention.isExported(var.getName())) {
return false;
}
return true;
}
/**
* Look at all the property assigns to all variables. These may or may not count as references.
* For example, <code>
* var x = {};
* x.foo = 3; // not a reference.
* var y = foo();
* y.foo = 3; // is a reference.
* </code> Interpreting assigments could mark a variable as referenced that wasn't referenced
* before, in order to keep it alive. Because we find references by lazily traversing subtrees,
* marking a variable as referenced could trigger new traversals of new subtrees, which could find
* new references.
*
* <p>Therefore, this interpretation needs to be run to a fixed point.
*/
private void interpretAssigns() {
boolean changes = false;
do {
changes = false;
// We can't use traditional iterators and iterables for this list,
// because our lazily-evaluated continuations will modify it while
// we traverse it.
for (int current = 0; current < maybeUnreferenced.size(); current++) {
Var var = maybeUnreferenced.get(current);
if (referenced.contains(var)) {
maybeUnreferenced.remove(current);
current--;
} else {
boolean assignedToUnknownValue = false;
boolean hasPropertyAssign = false;
if (var.getParentNode().getType() == Token.VAR
&& !NodeUtil.isForIn(var.getParentNode().getParent())) {
Node value = var.getInitialValue();
assignedToUnknownValue = value != null && !NodeUtil.isLiteralValue(value, true);
} else {
// This was initialized to a function arg or a catch param
// or a for...in variable.
assignedToUnknownValue = true;
}
for (Assign assign : assignsByVar.get(var)) {
if (assign.isPropertyAssign) {
hasPropertyAssign = true;
} else if (!NodeUtil.isLiteralValue(assign.assignNode.getLastChild(), true)) {
assignedToUnknownValue = true;
}
}
if (assignedToUnknownValue && hasPropertyAssign) {
changes = markReferencedVar(var) || changes;
maybeUnreferenced.remove(current);
current--;
}
}
}
} while (changes);
}
private boolean isParameter(Var v) {
return v.getParentNode().getType() == Token.LP;
}
/**
* Traverses everything in the current scope and marks variables that are referenced.
*
* <p>During traversal, we identify subtrees that will only be referenced if their enclosing
* variables are referenced. Instead of traversing those subtrees, we create a continuation for
* them, and traverse them lazily.
*/
private void traverseNode(Node n, Node parent, Scope scope) {
int type = n.getType();
Var var = null;
switch (type) {
case Token.FUNCTION:
// If this function is a removable var, then create a continuation
// for it instead of traversing immediately.
if (NodeUtil.isFunctionDeclaration(n)) {
var = scope.getVar(n.getFirstChild().getString());
}
if (var != null && isRemovableVar(var)) {
continuations.put(var, new Continuation(n, scope));
} else {
traverseFunction(n, scope);
}
return;
case Token.ASSIGN:
Assign maybeAssign = Assign.maybeCreateAssign(n);
if (maybeAssign != null) {
// Put this in the assign map. It might count as a reference,
// but we won't know that until we have an index of all assigns.
var = scope.getVar(maybeAssign.nameNode.getString());
if (var != null) {
assignsByVar.put(var, maybeAssign);
assignsByNode.put(maybeAssign.nameNode, maybeAssign);
if (isRemovableVar(var) && !maybeAssign.mayHaveSecondarySideEffects) {
// If the var is unreferenced and performing this assign has
// no secondary side effects, then we can create a continuation
// for it instead of traversing immediately.
continuations.put(var, new Continuation(n, scope));
return;
}
}
}
break;
case Token.CALL:
// Look for calls to inheritance-defining calls (such as goog.inherits).
SubclassRelationship subclassRelationship = codingConvention.getClassesDefinedByCall(n);
if (subclassRelationship != null) {
Var subclassVar = scope.getVar(subclassRelationship.subclassName);
// Don't try to track the inheritance calls for non-globals. It would
// be more correct to only not track when the subclass does not
// reference a constructor, but checking that it is a global is
// easier and mostly the same.
if (subclassVar != null && subclassVar.isGlobal() && !referenced.contains(subclassVar)) {
// Save a reference to the EXPR node.
inheritsCalls.put(subclassVar, parent);
continuations.put(subclassVar, new Continuation(n, scope));
return;
}
}
break;
case Token.NAME:
var = scope.getVar(n.getString());
if (parent.getType() == Token.VAR) {
Node value = n.getFirstChild();
if (value != null
&& var != null
&& isRemovableVar(var)
&& !NodeUtil.mayHaveSideEffects(value)) {
// If the var is unreferenced and creating its value has no side
// effects, then we can create a continuation for it instead
// of traversing immediately.
continuations.put(var, new Continuation(n, scope));
return;
}
} else {
// If arguments is escaped, we just assume the worst and continue
// on all the parameters.
if ("arguments".equals(n.getString()) && scope.isLocal()) {
Node lp = scope.getRootNode().getFirstChild().getNext();
for (Node a = lp.getFirstChild(); a != null; a = a.getNext()) {
markReferencedVar(scope.getVar(a.getString()));
}
}
// All name references that aren't declarations or assigns
// are references to other vars.
if (var != null) {
// If that var hasn't already been marked referenced, then
// start tracking it. If this is an assign, do nothing
// for now.
if (isRemovableVar(var)) {
if (!assignsByNode.containsKey(n)) {
markReferencedVar(var);
}
} else {
markReferencedVar(var);
}
}
}
break;
}
for (Node c = n.getFirstChild(); c != null; c = c.getNext()) {
traverseNode(c, n, scope);
}
}
