/** Try to fold {@code left instanceof right} into {@code true} or {@code false}. */
private Node tryFoldInstanceof(Node n, Node left, Node right) {
Preconditions.checkArgument(n.isInstanceOf());
// TODO(johnlenz) Use type information if available to fold
// instanceof.
if (NodeUtil.isLiteralValue(left, true) && !mayHaveSideEffects(right)) {
Node replacementNode = null;
if (NodeUtil.isImmutableValue(left)) {
// Non-object types are never instances.
replacementNode = IR.falseNode();
} else if (right.isName() && "Object".equals(right.getString())) {
replacementNode = IR.trueNode();
}
if (replacementNode != null) {
n.getParent().replaceChild(n, replacementNode);
reportCodeChange();
return replacementNode;
}
}
return n;
}
private Node tryFoldInForcedStringContext(Node n) {
// For now, we only know how to fold ctors.
Preconditions.checkArgument(n.isNew());
Node objectType = n.getFirstChild();
if (!objectType.isName()) {
return n;
}
if (objectType.getString().equals("String")) {
Node value = objectType.getNext();
String stringValue = null;
if (value == null) {
stringValue = "";
} else {
if (!NodeUtil.isImmutableValue(value)) {
return n;
}
stringValue = NodeUtil.getStringValue(value);
}
if (stringValue == null) {
return n;
}
Node parent = n.getParent();
Node newString = IR.string(stringValue);
parent.replaceChild(n, newString);
newString.useSourceInfoIfMissingFrom(parent);
reportCodeChange();
return newString;
}
return n;
}