/**
* Updates the first initialization (a.k.a "declaration") of a global name. This involves
* flattening the global name (if it's not just a global variable name already), collapsing object
* literal keys into global variables, declaring stub global variables for properties added later
* in a local scope.
*
* <p>It may seem odd that this function also takes care of declaring stubs for direct children.
* The ultimate goal of this function is to eliminate the global name entirely (when possible), so
* that "middlemen" namespaces disappear, and to do that we need to make sure that all the direct
* children will be collapsed as well.
*
* @param n An object representing a global name (e.g. "a", "a.b.c")
* @param alias The flattened name for {@code n} (e.g. "a", "a$b$c")
* @param canCollapseChildNames Whether it's possible to collapse children of this name. (This is
* mostly passed for convenience; it's equivalent to n.canCollapseChildNames()).
*/
private void updateObjLitOrFunctionDeclaration(
Name n, String alias, boolean canCollapseChildNames) {
Ref decl = n.getDeclaration();
if (decl == null) {
// Some names do not have declarations, because they
// are only defined in local scopes.
return;
}
if (decl.getTwin() != null) {
// Twin declarations will get handled when normal references
// are handled.
return;
}
switch (decl.node.getParent().getType()) {
case Token.ASSIGN:
updateObjLitOrFunctionDeclarationAtAssignNode(n, alias, canCollapseChildNames);
break;
case Token.VAR:
updateObjLitOrFunctionDeclarationAtVarNode(n, canCollapseChildNames);
break;
case Token.FUNCTION:
updateFunctionDeclarationAtFunctionNode(n, canCollapseChildNames);
break;
}
}
/**
* Flattens all occurrences of a name as a prefix of subnames beginning with a particular subname.
*
* @param n A global property name (e.g. "a.b.c.d")
* @param alias A flattened prefix name (e.g. "a$b")
* @param depth The difference in depth between the property name and the prefix name (e.g. 2)
*/
private void flattenPrefixes(String alias, Name n, int depth) {
// Only flatten the prefix of a name declaration if the name being
// initialized is fully qualified (i.e. not an object literal key).
String originalName = n.getFullName();
Ref decl = n.getDeclaration();
if (decl != null && decl.node != null && decl.node.isGetProp()) {
flattenNameRefAtDepth(alias, decl.node, depth, originalName);
}
for (Ref r : n.getRefs()) {
if (r == decl) {
// Declarations are handled separately.
continue;
}
// References inside a complex assign (a = x.y = 0)
// have twins. We should only flatten one of the twins.
if (r.getTwin() == null || r.isSet()) {
flattenNameRefAtDepth(alias, r.node, depth, originalName);
}
}
if (n.props != null) {
for (Name p : n.props) {
flattenPrefixes(alias, p, depth + 1);
}
}
}
/**
* Flattens all references to a collapsible property of a global name except its initial
* definition.
*
* @param n A global property name (e.g. "a.b" or "a.b.c.d")
* @param alias The flattened name (e.g. "a$b" or "a$b$c$d")
*/
private void flattenReferencesTo(Name n, String alias) {
String originalName = n.getFullName();
for (Ref r : n.getRefs()) {
if (r == n.getDeclaration()) {
// Declarations are handled separately.
continue;
}
Node rParent = r.node.getParent();
// There are two cases when we shouldn't flatten a reference:
// 1) Object literal keys, because duplicate keys show up as refs.
// 2) References inside a complex assign. (a = x.y = 0). These are
// called TWIN references, because they show up twice in the
// reference list. Only collapse the set, not the alias.
if (!NodeUtil.isObjectLitKey(r.node) && (r.getTwin() == null || r.isSet())) {
flattenNameRef(alias, r.node, rParent, originalName);
}
}
// Flatten all occurrences of a name as a prefix of its subnames. For
// example, if {@code n} corresponds to the name "a.b", then "a.b" will be
// replaced with "a$b" in all occurrences of "a.b.c", "a.b.c.d", etc.
if (n.props != null) {
for (Name p : n.props) {
flattenPrefixes(alias, p, 1);
}
}
}
/**
* For each qualified name N in the global scope, we check if: (a) No ancestor of N is ever
* aliased or assigned an unknown value type. (If N = "a.b.c", "a" and "a.b" are never aliased).
* (b) N has exactly one write, and it lives in the global scope. (c) N is aliased in a local
* scope. (d) N is aliased in global scope
*
* <p>If (a) is true, then GlobalNamespace must know all the writes to N. If (a) and (b) are true,
* then N cannot change during the execution of a local scope. If (a) and (b) and (c) are true,
* then the alias can be inlined if the alias obeys the usual rules for how we decide whether a
* variable is inlineable. If (a) and (b) and (d) are true, then inline the alias if possible (if
* it is assigned exactly once unconditionally).
*
* @see InlineVariables
*/
private void inlineAliases(GlobalNamespace namespace) {
// Invariant: All the names in the worklist meet condition (a).
Deque<Name> workList = new ArrayDeque<>(namespace.getNameForest());
while (!workList.isEmpty()) {
Name name = workList.pop();
// Don't attempt to inline a getter or setter property as a variable.
if (name.type == Name.Type.GET || name.type == Name.Type.SET) {
continue;
}
if (!name.inExterns && name.globalSets == 1 && name.localSets == 0 && name.aliasingGets > 0) {
// {@code name} meets condition (b). Find all of its local aliases
// and try to inline them.
List<Ref> refs = new ArrayList<>(name.getRefs());
for (Ref ref : refs) {
if (ref.type == Type.ALIASING_GET && ref.scope.isLocal()) {
// {@code name} meets condition (c). Try to inline it.
// TODO(johnlenz): consider picking up new aliases at the end
// of the pass instead of immediately like we do for global
// inlines.
if (inlineAliasIfPossible(name, ref, namespace)) {
name.removeRef(ref);
}
} else if (ref.type == Type.ALIASING_GET
&& ref.scope.isGlobal()
&& ref.getTwin() == null) { // ignore aliases in chained assignments
if (inlineGlobalAliasIfPossible(name, ref, namespace)) {
name.removeRef(ref);
}
}
}
}
// Check if {@code name} has any aliases left after the
// local-alias-inlining above.
if ((name.type == Name.Type.OBJECTLIT || name.type == Name.Type.FUNCTION)
&& name.aliasingGets == 0
&& name.props != null) {
// All of {@code name}'s children meet condition (a), so they can be
// added to the worklist.
workList.addAll(name.props);
}
}
}
/**
* Updates the first initialization (a.k.a "declaration") of a global name that occurs at a VAR
* node. See comment for {@link #updateObjLitOrFunctionDeclaration}.
*
* @param n An object representing a global name (e.g. "a")
*/
private void updateObjLitOrFunctionDeclarationAtVarNode(Name n, boolean canCollapseChildNames) {
if (!canCollapseChildNames) {
return;
}
Ref ref = n.getDeclaration();
String name = ref.node.getString();
Node rvalue = ref.node.getFirstChild();
Node varNode = ref.node.getParent();
Node grandparent = varNode.getParent();
boolean isObjLit = rvalue.isObjectLit();
int numChanges = 0;
if (isObjLit) {
numChanges +=
declareVarsForObjLitValues(
n, name, rvalue, varNode, grandparent.getChildBefore(varNode), grandparent);
}
numChanges += addStubsForUndeclaredProperties(n, name, grandparent, varNode);
if (isObjLit && n.canEliminate()) {
varNode.removeChild(ref.node);
if (!varNode.hasChildren()) {
grandparent.removeChild(varNode);
}
numChanges++;
// Clear out the object reference, since we've eliminated it from the
// parse tree.
ref.node = null;
}
if (numChanges > 0) {
compiler.reportCodeChange();
}
}
/**
* Declares global variables to serve as aliases for the values in an object literal, optionally
* removing all of the object literal's keys and values.
*
* @param alias The object literal's flattened name (e.g. "a$b$c")
* @param objlit The OBJLIT node
* @param varNode The VAR node to which new global variables should be added as children
* @param nameToAddAfter The child of {@code varNode} after which new variables should be added
* (may be null)
* @param varParent {@code varNode}'s parent
* @return The number of variables added
*/
private int declareVarsForObjLitValues(
Name objlitName,
String alias,
Node objlit,
Node varNode,
Node nameToAddAfter,
Node varParent) {
int numVars = 0;
int arbitraryNameCounter = 0;
boolean discardKeys = !objlitName.shouldKeepKeys();
for (Node key = objlit.getFirstChild(), nextKey; key != null; key = nextKey) {
Node value = key.getFirstChild();
nextKey = key.getNext();
// A get or a set can not be rewritten as a VAR.
if (key.isGetterDef() || key.isSetterDef()) {
continue;
}
// We generate arbitrary names for keys that aren't valid JavaScript
// identifiers, since those keys are never referenced. (If they were,
// this object literal's child names wouldn't be collapsible.) The only
// reason that we don't eliminate them entirely is the off chance that
// their values are expressions that have side effects.
boolean isJsIdentifier = !key.isNumber() && TokenStream.isJSIdentifier(key.getString());
String propName = isJsIdentifier ? key.getString() : String.valueOf(++arbitraryNameCounter);
// If the name cannot be collapsed, skip it.
String qName = objlitName.getFullName() + '.' + propName;
Name p = nameMap.get(qName);
if (p != null && !p.canCollapse()) {
continue;
}
String propAlias = appendPropForAlias(alias, propName);
Node refNode = null;
if (discardKeys) {
objlit.removeChild(key);
value.detachFromParent();
} else {
// Substitute a reference for the value.
refNode = IR.name(propAlias);
if (key.getBooleanProp(Node.IS_CONSTANT_NAME)) {
refNode.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
key.replaceChild(value, refNode);
}
// Declare the collapsed name as a variable with the original value.
Node nameNode = IR.name(propAlias);
nameNode.addChildToFront(value);
if (key.getBooleanProp(Node.IS_CONSTANT_NAME)) {
nameNode.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
Node newVar = IR.var(nameNode).useSourceInfoIfMissingFromForTree(key);
if (nameToAddAfter != null) {
varParent.addChildAfter(newVar, nameToAddAfter);
} else {
varParent.addChildBefore(newVar, varNode);
}
compiler.reportCodeChange();
nameToAddAfter = newVar;
// Update the global name's node ancestry if it hasn't already been
// done. (Duplicate keys in an object literal can bring us here twice
// for the same global name.)
if (isJsIdentifier && p != null) {
if (!discardKeys) {
Ref newAlias = p.getDeclaration().cloneAndReclassify(Ref.Type.ALIASING_GET);
newAlias.node = refNode;
p.addRef(newAlias);
}
p.getDeclaration().node = nameNode;
if (value.isFunction()) {
checkForHosedThisReferences(value, key.getJSDocInfo(), p);
}
}
numVars++;
}
return numVars;
}
/**
* Updates the first initialization (a.k.a "declaration") of a global name that occurs at an
* ASSIGN node. See comment for {@link #updateObjLitOrFunctionDeclaration}.
*
* @param n An object representing a global name (e.g. "a", "a.b.c")
* @param alias The flattened name for {@code n} (e.g. "a", "a$b$c")
*/
private void updateObjLitOrFunctionDeclarationAtAssignNode(
Name n, String alias, boolean canCollapseChildNames) {
// NOTE: It's important that we don't add additional nodes
// (e.g. a var node before the exprstmt) because the exprstmt might be
// the child of an if statement that's not inside a block).
Ref ref = n.getDeclaration();
Node rvalue = ref.node.getNext();
Node varNode = new Node(Token.VAR);
Node varParent = ref.node.getAncestor(3);
Node grandparent = ref.node.getAncestor(2);
boolean isObjLit = rvalue.isObjectLit();
boolean insertedVarNode = false;
if (isObjLit && n.canEliminate()) {
// Eliminate the object literal altogether.
varParent.replaceChild(grandparent, varNode);
ref.node = null;
insertedVarNode = true;
} else if (!n.isSimpleName()) {
// Create a VAR node to declare the name.
if (rvalue.isFunction()) {
checkForHosedThisReferences(rvalue, n.docInfo, n);
}
ref.node.getParent().removeChild(rvalue);
Node nameNode = NodeUtil.newName(compiler, alias, ref.node.getAncestor(2), n.getFullName());
JSDocInfo info = NodeUtil.getBestJSDocInfo(ref.node.getParent());
if (ref.node.getLastChild().getBooleanProp(Node.IS_CONSTANT_NAME)
|| (info != null && info.isConstant())) {
nameNode.putBooleanProp(Node.IS_CONSTANT_NAME, true);
}
if (info != null) {
varNode.setJSDocInfo(info);
}
varNode.addChildToBack(nameNode);
nameNode.addChildToFront(rvalue);
varParent.replaceChild(grandparent, varNode);
// Update the node ancestry stored in the reference.
ref.node = nameNode;
insertedVarNode = true;
}
if (canCollapseChildNames) {
if (isObjLit) {
declareVarsForObjLitValues(
n, alias, rvalue, varNode, varParent.getChildBefore(varNode), varParent);
}
addStubsForUndeclaredProperties(n, alias, varParent, varNode);
}
if (insertedVarNode) {
if (!varNode.hasChildren()) {
varParent.removeChild(varNode);
}
compiler.reportCodeChange();
}
}
/**
* Updates the initial assignment to a collapsible property at global scope by changing it to a
* variable declaration (e.g. a.b = 1 -> var a$b = 1). The property's value may either be a
* primitive or an object literal or function whose properties aren't collapsible.
*
* @param alias The flattened property name (e.g. "a$b")
* @param refName The name for the reference being updated.
* @param ref An object containing information about the assignment getting updated
*/
private void updateSimpleDeclaration(String alias, Name refName, Ref ref) {
Node rvalue = ref.node.getNext();
Node parent = ref.node.getParent();
Node grandparent = parent.getParent();
Node greatGrandparent = grandparent.getParent();
if (rvalue != null && rvalue.isFunction()) {
checkForHosedThisReferences(rvalue, refName.docInfo, refName);
}
// Create the new alias node.
Node nameNode =
NodeUtil.newName(compiler, alias, grandparent.getFirstChild(), refName.getFullName());
NodeUtil.copyNameAnnotations(ref.node.getLastChild(), nameNode);
if (grandparent.isExprResult()) {
// BEFORE: a.b.c = ...;
// exprstmt
// assign
// getprop
// getprop
// name a
// string b
// string c
// NODE
// AFTER: var a$b$c = ...;
// var
// name a$b$c
// NODE
// Remove the r-value (NODE).
parent.removeChild(rvalue);
nameNode.addChildToFront(rvalue);
Node varNode = IR.var(nameNode);
greatGrandparent.replaceChild(grandparent, varNode);
} else {
// This must be a complex assignment.
Preconditions.checkNotNull(ref.getTwin());
// BEFORE:
// ... (x.y = 3);
//
// AFTER:
// var x$y;
// ... (x$y = 3);
Node current = grandparent;
Node currentParent = grandparent.getParent();
for (;
!currentParent.isScript() && !currentParent.isBlock();
current = currentParent, currentParent = currentParent.getParent()) {}
// Create a stub variable declaration right
// before the current statement.
Node stubVar = IR.var(nameNode.cloneTree()).useSourceInfoIfMissingFrom(nameNode);
currentParent.addChildBefore(stubVar, current);
parent.replaceChild(ref.node, nameNode);
}
compiler.reportCodeChange();
}
/**
* Extracts all Behaviors from an array recursively. The array must be an array literal whose
* value is known at compile-time. Entries in the array can be object literals or array literals
* (of other behaviors). Behavior names must be global, fully qualified names.
*
* @see https://github.com/Polymer/polymer/blob/0.8-preview/PRIMER.md#behaviors
* @return A list of all {@code BehaviorDefinitions} in the array.
*/
private List<BehaviorDefinition> extractBehaviors(Node behaviorArray) {
if (behaviorArray == null) {
return ImmutableList.of();
}
if (!behaviorArray.isArrayLit()) {
compiler.report(JSError.make(behaviorArray, POLYMER_INVALID_BEHAVIOR_ARRAY));
return ImmutableList.of();
}
ImmutableList.Builder<BehaviorDefinition> behaviors = ImmutableList.builder();
for (Node behaviorName : behaviorArray.children()) {
if (behaviorName.isObjectLit()) {
this.switchDollarSignPropsToBrackets(behaviorName);
this.quoteListenerAndHostAttributeKeys(behaviorName);
behaviors.add(
new BehaviorDefinition(
extractProperties(behaviorName),
getBehaviorFunctionsToCopy(behaviorName),
getNonPropertyMembersToCopy(behaviorName),
!NodeUtil.isInFunction(behaviorName)));
continue;
}
Name behaviorGlobalName = globalNames.getSlot(behaviorName.getQualifiedName());
boolean isGlobalDeclaration = true;
if (behaviorGlobalName == null) {
compiler.report(JSError.make(behaviorName, POLYMER_UNQUALIFIED_BEHAVIOR));
continue;
}
Ref behaviorDeclaration = behaviorGlobalName.getDeclaration();
// Use any set as a backup declaration, even if it's local.
if (behaviorDeclaration == null) {
List<Ref> behaviorRefs = behaviorGlobalName.getRefs();
for (Ref ref : behaviorRefs) {
if (ref.isSet()) {
isGlobalDeclaration = false;
behaviorDeclaration = ref;
break;
}
}
}
if (behaviorDeclaration == null) {
compiler.report(JSError.make(behaviorName, POLYMER_UNQUALIFIED_BEHAVIOR));
continue;
}
Node behaviorDeclarationNode = behaviorDeclaration.getNode();
JSDocInfo behaviorInfo = NodeUtil.getBestJSDocInfo(behaviorDeclarationNode);
if (behaviorInfo == null || !behaviorInfo.isPolymerBehavior()) {
compiler.report(JSError.make(behaviorDeclarationNode, POLYMER_UNANNOTATED_BEHAVIOR));
}
Node behaviorValue = NodeUtil.getRValueOfLValue(behaviorDeclarationNode);
if (behaviorValue == null) {
compiler.report(JSError.make(behaviorName, POLYMER_UNQUALIFIED_BEHAVIOR));
} else if (behaviorValue.isArrayLit()) {
// Individual behaviors can also be arrays of behaviors. Parse them recursively.
behaviors.addAll(extractBehaviors(behaviorValue));
} else if (behaviorValue.isObjectLit()) {
this.switchDollarSignPropsToBrackets(behaviorValue);
this.quoteListenerAndHostAttributeKeys(behaviorValue);
behaviors.add(
new BehaviorDefinition(
extractProperties(behaviorValue),
getBehaviorFunctionsToCopy(behaviorValue),
getNonPropertyMembersToCopy(behaviorValue),
isGlobalDeclaration));
} else {
compiler.report(JSError.make(behaviorName, POLYMER_UNQUALIFIED_BEHAVIOR));
}
}
return behaviors.build();
}
