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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2006 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import static com.google.javascript.rhino.jstype.JSTypeNative.GLOBAL_THIS;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.javascript.jscomp.CodingConvention.SubclassRelationship;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticSourceFile;
import com.google.javascript.rhino.StaticSymbolTable;
import com.google.javascript.rhino.TokenStream;
import com.google.javascript.rhino.TypeI;
import com.google.javascript.rhino.jstype.StaticTypedRef;
import com.google.javascript.rhino.jstype.StaticTypedScope;
import com.google.javascript.rhino.jstype.StaticTypedSlot;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import javax.annotation.Nullable;
/**
* Builds a global namespace of all the objects and their properties in
* the global scope. Also builds an index of all the references to those names.
*
* @author [email protected] (Nick Santos)
*/
class GlobalNamespace
implements StaticTypedScope,
StaticSymbolTable {
private AbstractCompiler compiler;
private final Node root;
private final Node externsRoot;
private boolean inExterns;
private Scope externsScope;
private boolean generated = false;
/**
* Each reference has an index in post-order.
* Notice that some nodes are represented by 2 Ref objects, so
* this index is not necessarily unique.
*/
private int currentPreOrderIndex = 0;
/** Global namespace tree */
private List globalNames = new ArrayList<>();
/** Maps names (e.g. "a.b.c") to nodes in the global namespace tree */
private Map nameMap = new HashMap<>();
/**
* Creates an instance that may emit warnings when building the namespace.
*
* @param compiler The AbstractCompiler, for reporting code changes
* @param root The root of the rest of the code to build a namespace for.
*/
GlobalNamespace(AbstractCompiler compiler, Node root) {
this(compiler, null, root);
}
/**
* Creates an instance that may emit warnings when building the namespace.
*
* @param compiler The AbstractCompiler, for reporting code changes
* @param externsRoot The root of the externs to build a namespace for. If
* this is null, externs and properties defined on extern types will not
* be included in the global namespace. If non-null, it allows
* user-defined function on extern types to be included in the global
* namespace. E.g. String.foo.
* @param root The root of the rest of the code to build a namespace for.
*/
GlobalNamespace(AbstractCompiler compiler, Node externsRoot, Node root) {
this.compiler = compiler;
this.externsRoot = externsRoot;
this.root = root;
}
boolean hasExternsRoot() {
return externsRoot != null;
}
@Override
public Node getRootNode() {
return root.getParent();
}
@Override
public StaticTypedScope getParentScope() {
return null;
}
@Override
public Name getSlot(String name) {
return getOwnSlot(name);
}
@Override
public Name getOwnSlot(String name) {
ensureGenerated();
return nameMap.get(name);
}
@Override
public TypeI getTypeOfThis() {
return compiler.getTypeIRegistry().getNativeObjectType(GLOBAL_THIS);
}
@Override
public Iterable getReferences(Name slot) {
ensureGenerated();
return Collections.unmodifiableList(slot.getRefs());
}
@Override
public StaticTypedScope getScope(Name slot) {
return this;
}
@Override
public Iterable getAllSymbols() {
ensureGenerated();
return Collections.unmodifiableCollection(getNameIndex().values());
}
private void ensureGenerated() {
if (!generated) {
process();
}
}
/**
* Gets a list of the roots of the forest of the global names, where the
* roots are the top-level names.
*/
List getNameForest() {
ensureGenerated();
return globalNames;
}
/**
* Gets an index of all the global names, indexed by full qualified name
* (as in "a", "a.b.c", etc.).
*/
Map getNameIndex() {
ensureGenerated();
return nameMap;
}
/**
* A simple data class that contains the information necessary to inspect
* a node for changes to the global namespace.
*/
static class AstChange {
final JSModule module;
final Scope scope;
final Node node;
AstChange(JSModule module, Scope scope, Node node) {
this.module = module;
this.scope = scope;
this.node = node;
}
@Override
public boolean equals(Object obj) {
Preconditions.checkState(obj instanceof AstChange);
AstChange other = (AstChange) obj;
return Objects.equals(this.module, other.module)
&& Objects.equals(this.scope, other.scope)
&& Objects.equals(this.node, other.node);
}
@Override
public int hashCode() {
return Objects.hash(this.module, this.scope, this.node);
}
}
/**
* If the client adds new nodes to the AST, scan these new nodes
* to see if they've added any references to the global namespace.
* @param newNodes New nodes to check.
*/
void scanNewNodes(Set newNodes) {
BuildGlobalNamespace builder = new BuildGlobalNamespace();
for (AstChange info : newNodes) {
if (!info.node.isQualifiedName() && !NodeUtil.isObjectLitKey(info.node)) {
continue;
}
scanFromNode(builder, info.module, info.scope, info.node);
}
}
private void scanFromNode(
BuildGlobalNamespace builder, JSModule module, Scope scope, Node n) {
// Check affected parent nodes first.
if (n.isName() || n.isGetProp()) {
scanFromNode(builder, module, scope, n.getParent());
}
builder.collect(module, scope, n);
}
/**
* Builds the namespace lazily.
*/
private void process() {
if (externsRoot != null) {
inExterns = true;
NodeTraversal.traverseEs6(compiler, externsRoot, new BuildGlobalNamespace());
}
inExterns = false;
NodeTraversal.traverseEs6(compiler, root, new BuildGlobalNamespace());
generated = true;
}
/**
* Determines whether a name reference in a particular scope is a global name
* reference.
*
* @param name A variable or property name (e.g. "a" or "a.b.c.d")
* @param s The scope in which the name is referenced
* @return Whether the name reference is a global name reference
*/
private boolean isGlobalNameReference(String name, Scope s) {
String topVarName = getTopVarName(name);
return isGlobalVarReference(topVarName, s);
}
/**
* Gets the top variable name from a possibly namespaced name.
*
* @param name A variable or qualified property name (e.g. "a" or "a.b.c.d")
* @return The top variable name (e.g. "a")
*/
private static String getTopVarName(String name) {
int firstDotIndex = name.indexOf('.');
return firstDotIndex == -1 ? name : name.substring(0, firstDotIndex);
}
/**
* Determines whether a variable name reference in a particular scope is a
* global variable reference.
*
* @param name A variable name (e.g. "a")
* @param s The scope in which the name is referenced
* @return Whether the name reference is a global variable reference
*/
private boolean isGlobalVarReference(String name, Scope s) {
Var v = s.getVar(name);
if (v == null && externsScope != null) {
v = externsScope.getVar(name);
}
return v != null && !v.isLocal();
}
// -------------------------------------------------------------------------
/** Builds a tree representation of the global namespace. Omits prototypes. */
private class BuildGlobalNamespace extends NodeTraversal.AbstractPreOrderCallback {
/** Collect the references in pre-order. */
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
// If we are traversing the externs, then we save a pointer to the scope
// generated by them, so that we can do lookups in it later.
if (externsRoot != null && n == externsRoot) {
externsScope = t.getScope();
}
collect(t.getModule(), t.getScope(), n);
return true;
}
public void collect(JSModule module, Scope scope, Node n) {
Node parent = n.getParent();
String name;
boolean isSet = false;
Name.Type type = Name.Type.OTHER;
boolean isPropAssign = false;
switch (n.getToken()) {
case GETTER_DEF:
case SETTER_DEF:
case STRING_KEY:
case MEMBER_FUNCTION_DEF:
// This may be a key in an object literal declaration.
name = null;
if (parent != null && parent.isObjectLit()) {
name = getNameForObjLitKey(n);
} else if (parent != null && parent.isClassMembers()) {
name = getNameForClassMembers(n);
}
if (name == null) {
return;
}
isSet = true;
switch (n.getToken()) {
case MEMBER_FUNCTION_DEF:
case STRING_KEY:
type = getValueType(n.getFirstChild());
break;
case GETTER_DEF:
type = Name.Type.GET;
break;
case SETTER_DEF:
type = Name.Type.SET;
break;
default:
throw new IllegalStateException("unexpected:" + n);
}
break;
case NAME:
// This may be a variable get or set.
if (parent != null) {
switch (parent.getToken()) {
case VAR:
case LET:
case CONST:
isSet = true;
Node rvalue = n.getFirstChild();
type = rvalue == null ? Name.Type.OTHER : getValueType(rvalue);
break;
case ASSIGN:
if (parent.getFirstChild() == n) {
isSet = true;
type = getValueType(n.getNext());
}
break;
case GETPROP:
return;
case FUNCTION:
Node grandparent = parent.getParent();
if (grandparent == null || NodeUtil.isFunctionExpression(parent)) {
return;
}
isSet = true;
type = Name.Type.FUNCTION;
break;
case CATCH:
case INC:
case DEC:
isSet = true;
type = Name.Type.OTHER;
break;
case CLASS:
isSet = true;
type = Name.Type.CLASS;
break;
default:
if (NodeUtil.isAssignmentOp(parent) && parent.getFirstChild() == n) {
isSet = true;
type = Name.Type.OTHER;
}
}
}
name = n.getString();
break;
case GETPROP:
// This may be a namespaced name get or set.
if (parent != null) {
switch (parent.getToken()) {
case ASSIGN:
if (parent.getFirstChild() == n) {
isSet = true;
type = getValueType(n.getNext());
isPropAssign = true;
}
break;
case INC:
case DEC:
isSet = true;
type = Name.Type.OTHER;
break;
case GETPROP:
return;
default:
if (NodeUtil.isAssignmentOp(parent) && parent.getFirstChild() == n) {
isSet = true;
type = Name.Type.OTHER;
}
}
}
name = n.getQualifiedName();
if (name == null) {
return;
}
break;
default:
return;
}
// We are only interested in global names.
if (!isGlobalNameReference(name, scope)) {
return;
}
scope = scope.getClosestHoistScope();
if (isSet) {
if (scope.isGlobal()) {
handleSetFromGlobal(module, scope, n, parent, name, isPropAssign, type);
} else {
handleSetFromLocal(module, scope, n, parent, name);
}
} else {
handleGet(module, scope, n, parent, name);
}
}
/**
* Gets the fully qualified name corresponding to an object literal key,
* as long as it and its prefix property names are valid JavaScript
* identifiers. The object literal may be nested inside of other object
* literals.
*
* For example, if called with node {@code n} representing "z" in any of
* the following expressions, the result would be "w.x.y.z":
* var w = {x: {y: {z: 0}}};
* w.x = {y: {z: 0}};
* w.x.y = {'a': 0, 'z': 0};
*
* @param n A child of an OBJLIT node
* @return The global name, or null if {@code n} doesn't correspond to the
* key of an object literal that can be named
*/
String getNameForObjLitKey(Node n) {
Node parent = n.getParent();
Preconditions.checkState(parent.isObjectLit());
Node grandparent = parent.getParent();
if (grandparent == null) {
return null;
}
Node greatGrandparent = grandparent.getParent();
String name;
switch (grandparent.getToken()) {
case NAME:
// VAR
// NAME (grandparent)
// OBJLIT (parent)
// STRING (n)
if (greatGrandparent == null || !NodeUtil.isNameDeclaration(greatGrandparent)) {
return null;
}
name = grandparent.getString();
break;
case ASSIGN:
// ASSIGN (grandparent)
// NAME|GETPROP
// OBJLIT (parent)
// STRING (n)
Node lvalue = grandparent.getFirstChild();
name = lvalue.getQualifiedName();
break;
case STRING_KEY:
// OBJLIT
// STRING (grandparent)
// OBJLIT (parent)
// STRING (n)
if (greatGrandparent != null && greatGrandparent.isObjectLit()) {
name = getNameForObjLitKey(grandparent);
} else {
return null;
}
break;
default:
return null;
}
if (name != null) {
String key = n.getString();
if (TokenStream.isJSIdentifier(key)) {
return name + '.' + key;
}
}
return null;
}
/**
* Gets the fully qualified name corresponding to an class member function,
* as long as it and its prefix property names are valid JavaScript
* identifiers.
*
* For example, if called with node {@code n} representing "y" in any of
* the following expressions, the result would be "x.y":
* class x{y(){}};
* var x = class{y(){}};
* var x; x = class{y(){}};
*
* @param n A child of an CLASS_MEMBERS node
* @return The global name, or null if {@code n} doesn't correspond to
* a class member function that can be named
*/
String getNameForClassMembers(Node n) {
Node parent = n.getParent();
Preconditions.checkState(parent.isClassMembers());
String className = NodeUtil.getName(parent.getParent());
return className == null ? null : className + '.' + n.getString();
}
/**
* Gets the type of a value or simple expression.
*
* @param n An r-value in an assignment or variable declaration (not null)
* @return A {@link Name.Type}
*/
Name.Type getValueType(Node n) {
// Shorthand assignment of extended object literal
if (n == null) {
return Name.Type.OTHER;
}
switch (n.getToken()) {
case CLASS:
return Name.Type.CLASS;
case OBJECTLIT:
return Name.Type.OBJECTLIT;
case FUNCTION:
return Name.Type.FUNCTION;
case OR:
// Recurse on the second value. If the first value were an object
// literal or function, then the OR would be meaningless and the
// second value would be dead code. Assume that if the second value
// is an object literal or function, then the first value will also
// evaluate to one when it doesn't evaluate to false.
return getValueType(n.getLastChild());
case HOOK:
// The same line of reasoning used for the OR case applies here.
Node second = n.getSecondChild();
Name.Type t = getValueType(second);
if (t != Name.Type.OTHER) {
return t;
}
Node third = second.getNext();
return getValueType(third);
default:
break;
}
return Name.Type.OTHER;
}
/**
* Updates our representation of the global namespace to reflect an
* assignment to a global name in global scope.
*
* @param module the current module
* @param scope the current scope
* @param n The node currently being visited
* @param parent {@code n}'s parent
* @param name The global name (e.g. "a" or "a.b.c.d")
* @param isPropAssign Whether this set corresponds to a property
* assignment of the form a.b.c = ...;
* @param type The type of the value that the name is being assigned
*/
void handleSetFromGlobal(JSModule module, Scope scope,
Node n, Node parent, String name,
boolean isPropAssign, Name.Type type) {
if (maybeHandlePrototypePrefix(module, scope, n, parent, name)) {
return;
}
Name nameObj = getOrCreateName(name);
nameObj.type = type;
Ref set = new Ref(module, scope, n, nameObj, Ref.Type.SET_FROM_GLOBAL,
currentPreOrderIndex++);
nameObj.addRef(set);
if (isNestedAssign(parent)) {
// This assignment is both a set and a get that creates an alias.
Ref get = new Ref(module, scope, n, nameObj, Ref.Type.ALIASING_GET,
currentPreOrderIndex++);
nameObj.addRef(get);
Ref.markTwins(set, get);
} else if (isTypeDeclaration(n)) {
// Names with a @constructor or @enum annotation are always collapsed
nameObj.setDeclaredType();
}
}
/**
* Determines whether a set operation is a constructor or enumeration
* or interface declaration. The set operation may either be an assignment
* to a name, a variable declaration, or an object literal key mapping.
*
* @param n The node that represents the name being set
* @return Whether the set operation is either a constructor or enum
* declaration
*/
private boolean isTypeDeclaration(Node n) {
Node valueNode = NodeUtil.getRValueOfLValue(n);
JSDocInfo info = NodeUtil.getBestJSDocInfo(n);
// Heed the annotations only if they're sensibly used.
return info != null
&& valueNode != null
&& ((info.isConstructor() && valueNode.isFunction())
|| (info.isInterface() && valueNode.isFunction())
|| (info.hasEnumParameterType() && valueNode.isObjectLit()));
}
/**
* Updates our representation of the global namespace to reflect an
* assignment to a global name in a local scope.
*
* @param module The current module
* @param scope The current scope
* @param n The node currently being visited
* @param parent {@code n}'s parent
* @param name The global name (e.g. "a" or "a.b.c.d")
*/
void handleSetFromLocal(JSModule module, Scope scope, Node n, Node parent,
String name) {
if (maybeHandlePrototypePrefix(module, scope, n, parent, name)) {
return;
}
Name nameObj = getOrCreateName(name);
Ref set = new Ref(module, scope, n, nameObj,
Ref.Type.SET_FROM_LOCAL, currentPreOrderIndex++);
nameObj.addRef(set);
if (isNestedAssign(parent)) {
// This assignment is both a set and a get that creates an alias.
Ref get = new Ref(module, scope, n, nameObj,
Ref.Type.ALIASING_GET, currentPreOrderIndex++);
nameObj.addRef(get);
Ref.markTwins(set, get);
}
}
/**
* Updates our representation of the global namespace to reflect a read
* of a global name.
*
* @param module The current module
* @param scope The current scope
* @param n The node currently being visited
* @param parent {@code n}'s parent
* @param name The global name (e.g. "a" or "a.b.c.d")
*/
void handleGet(JSModule module, Scope scope,
Node n, Node parent, String name) {
if (maybeHandlePrototypePrefix(module, scope, n, parent, name)) {
return;
}
Ref.Type type;
switch (parent.getToken()) {
case EXPR_RESULT:
case IF:
case INSTANCEOF:
case TYPEOF:
case VOID:
case NOT:
case BITNOT:
case POS:
case NEG:
type = Ref.Type.DIRECT_GET;
break;
case CALL:
if (n == parent.getFirstChild()) {
// It is a call target
type = Ref.Type.CALL_GET;
} else if (isClassDefiningCall(parent)) {
type = Ref.Type.DIRECT_GET;
} else {
type = Ref.Type.ALIASING_GET;
}
break;
case NEW:
type = n == parent.getFirstChild() ? Ref.Type.DIRECT_GET : Ref.Type.ALIASING_GET;
break;
case OR:
case AND:
// This node is x or y in (x||y) or (x&&y). We only know that an
// alias is not getting created for this name if the result is used
// in a boolean context or assigned to the same name
// (e.g. var a = a || {}).
type = determineGetTypeForHookOrBooleanExpr(module, scope, parent, name);
break;
case HOOK:
if (n != parent.getFirstChild()) {
// This node is y or z in (x?y:z). We only know that an alias is
// not getting created for this name if the result is assigned to
// the same name (e.g. var a = a ? a : {}).
type = determineGetTypeForHookOrBooleanExpr(module, scope, parent, name);
} else {
type = Ref.Type.DIRECT_GET;
}
break;
case DELPROP:
type = Ref.Type.DELETE_PROP;
break;
default:
type = Ref.Type.ALIASING_GET;
break;
}
handleGet(module, scope, n, parent, name, type);
}
private boolean isClassDefiningCall(Node callNode) {
CodingConvention convention = compiler.getCodingConvention();
// Look for goog.inherits, goog.mixin
SubclassRelationship classes =
convention.getClassesDefinedByCall(callNode);
if (classes != null) {
return true;
}
// Look for calls to goog.addSingletonGetter calls.
String className = convention.getSingletonGetterClassName(callNode);
return className != null;
}
/**
* Determines whether the result of a hook (x?y:z) or boolean expression
* (x||y) or (x&&y) is assigned to a specific global name.
*
* @param module The current module
* @param scope The current scope
* @param parent The parent of the current node in the traversal. This node
* should already be known to be a HOOK, AND, or OR node.
* @param name A name that is already known to be global in the current
* scope (e.g. "a" or "a.b.c.d")
* @return The expression's get type, either {@link Ref.Type#DIRECT_GET} or
* {@link Ref.Type#ALIASING_GET}
*/
Ref.Type determineGetTypeForHookOrBooleanExpr(
JSModule module, Scope scope, Node parent, String name) {
Node prev = parent;
for (Node anc : parent.getAncestors()) {
switch (anc.getToken()) {
case INSTANCEOF:
case EXPR_RESULT:
case VAR:
case LET:
case CONST:
case IF:
case WHILE:
case FOR:
case FOR_IN:
case TYPEOF:
case VOID:
case NOT:
case BITNOT:
case POS:
case NEG:
return Ref.Type.DIRECT_GET;
case HOOK:
if (anc.getFirstChild() == prev) {
return Ref.Type.DIRECT_GET;
}
break;
case ASSIGN:
if (!name.equals(anc.getFirstChild().getQualifiedName())) {
return Ref.Type.ALIASING_GET;
}
break;
case NAME: // a variable declaration
if (!name.equals(anc.getString())) {
return Ref.Type.ALIASING_GET;
}
break;
case CALL:
if (anc.getFirstChild() != prev) {
return Ref.Type.ALIASING_GET;
}
break;
case DELPROP:
return Ref.Type.DELETE_PROP;
default:
break;
}
prev = anc;
}
return Ref.Type.ALIASING_GET;
}
/**
* Updates our representation of the global namespace to reflect a read
* of a global name.
*
* @param module The current module
* @param scope The current scope
* @param n The node currently being visited
* @param parent {@code n}'s parent
* @param name The global name (e.g. "a" or "a.b.c.d")
* @param type The reference type
*/
void handleGet(JSModule module, Scope scope, Node n, Node parent,
String name, Ref.Type type) {
Name nameObj = getOrCreateName(name);
// No need to look up additional ancestors, since they won't be used.
nameObj.addRef(
new Ref(module, scope, n, nameObj, type, currentPreOrderIndex++));
}
/**
* Updates our representation of the global namespace to reflect a read
* of a global name's longest prefix before the "prototype" property if the
* name includes the "prototype" property. Does nothing otherwise.
*
* @param module The current module
* @param scope The current scope
* @param n The node currently being visited
* @param parent {@code n}'s parent
* @param name The global name (e.g. "a" or "a.b.c.d")
* @return Whether the name was handled
*/
boolean maybeHandlePrototypePrefix(JSModule module, Scope scope,
Node n, Node parent, String name) {
// We use a string-based approach instead of inspecting the parse tree
// to avoid complexities with object literals, possibly nested, beneath
// assignments.
int numLevelsToRemove;
String prefix;
if (name.endsWith(".prototype")) {
numLevelsToRemove = 1;
prefix = name.substring(0, name.length() - 10);
} else {
int i = name.indexOf(".prototype.");
if (i == -1) {
return false;
}
prefix = name.substring(0, i);
numLevelsToRemove = 2;
i = name.indexOf('.', i + 11);
while (i >= 0) {
numLevelsToRemove++;
i = name.indexOf('.', i + 1);
}
}
if (parent != null && NodeUtil.isObjectLitKey(n)) {
// Object literal keys have no prefix that's referenced directly per
// key, so we're done.
return true;
}
for (int i = 0; i < numLevelsToRemove; i++) {
parent = n;
n = n.getFirstChild();
}
handleGet(module, scope, n, parent, prefix, Ref.Type.PROTOTYPE_GET);
return true;
}
/**
* Determines whether an assignment is nested (i.e. whether its return
* value is used).
*
* @param parent The parent of the current traversal node (not null)
* @return Whether it appears that the return value of the assignment is
* used
*/
boolean isNestedAssign(Node parent) {
return parent.isAssign() && !parent.getParent().isExprResult();
}
/**
* Gets a {@link Name} instance for a global name. Creates it if necessary,
* as well as instances for any of its prefixes that are not yet defined.
*
* @param name A global name (e.g. "a", "a.b.c.d")
* @return The {@link Name} instance for {@code name}
*/
Name getOrCreateName(String name) {
Name node = nameMap.get(name);
if (node == null) {
int i = name.lastIndexOf('.');
if (i >= 0) {
String parentName = name.substring(0, i);
Name parent = getOrCreateName(parentName);
node = parent.addProperty(name.substring(i + 1), inExterns);
} else {
node = new Name(name, null, inExterns);
globalNames.add(node);
}
nameMap.put(name, node);
}
return node;
}
}
// -------------------------------------------------------------------------
/**
* A name defined in global scope (e.g. "a" or "a.b.c.d"). These form a tree.
* As the parse tree traversal proceeds, we'll discover that some names
* correspond to JavaScript objects whose properties we should consider
* collapsing.
*/
static class Name implements StaticTypedSlot {
enum Type {
CLASS,
OBJECTLIT,
FUNCTION,
GET,
SET,
OTHER,
}
private final String baseName;
final Name parent;
// The children of this name. Must be null if there are no children.
@Nullable
List props;
/** The first global assignment to a name. */
private Ref declaration;
/** All references to a name. This must contain {@code declaration}. */
private List refs;
Type type;
private boolean declaredType = false;
private boolean isDeclared = false;
int globalSets = 0;
int localSets = 0;
int localSetsWithNoCollapse = 0;
int aliasingGets = 0;
int totalGets = 0;
int callGets = 0;
int deleteProps = 0;
final boolean inExterns;
JSDocInfo docInfo = null;
Name(String name, Name parent, boolean inExterns) {
this.baseName = name;
this.parent = parent;
this.type = Type.OTHER;
this.inExterns = inExterns;
}
Name addProperty(String name, boolean inExterns) {
if (props == null) {
props = new ArrayList<>();
}
Name node = new Name(name, this, inExterns);
props.add(node);
return node;
}
String getBaseName() {
return baseName;
}
@Override
public String getName() {
return getFullName();
}
String getFullName() {
return parent == null ? baseName : parent.getFullName() + '.' + baseName;
}
@Override
public Ref getDeclaration() {
return declaration;
}
@Override
public boolean isTypeInferred() {
return false;
}
@Override
public TypeI getType() {
return null;
}
void addRef(Ref ref) {
addRefInternal(ref);
switch (ref.type) {
case SET_FROM_GLOBAL:
if (declaration == null) {
declaration = ref;
docInfo = getDocInfoForDeclaration(ref);
}
globalSets++;
break;
case SET_FROM_LOCAL:
localSets++;
JSDocInfo info = ref.getNode() == null ? null : NodeUtil.getBestJSDocInfo(ref.getNode());
if (info != null && info.isNoCollapse()) {
localSetsWithNoCollapse++;
}
break;
case PROTOTYPE_GET:
case DIRECT_GET:
Node node = ref.getNode();
if (node != null && node.isGetProp() && node.getParent().isExprResult()) {
docInfo = node.getJSDocInfo();
}
totalGets++;
break;
case ALIASING_GET:
aliasingGets++;
totalGets++;
break;
case CALL_GET:
callGets++;
totalGets++;
break;
case DELETE_PROP:
deleteProps++;
break;
default:
throw new IllegalStateException();
}
}
void removeRef(Ref ref) {
if (refs != null && refs.remove(ref)) {
if (ref == declaration) {
declaration = null;
if (refs != null) {
for (Ref maybeNewDecl : refs) {
if (maybeNewDecl.type == Ref.Type.SET_FROM_GLOBAL) {
declaration = maybeNewDecl;
break;
}
}
}
}
JSDocInfo info;
switch (ref.type) {
case SET_FROM_GLOBAL:
globalSets--;
break;
case SET_FROM_LOCAL:
localSets--;
info = ref.getNode() == null ? null : NodeUtil.getBestJSDocInfo(ref.getNode());
if (info != null && info.isNoCollapse()) {
localSetsWithNoCollapse--;
}
break;
case PROTOTYPE_GET:
case DIRECT_GET:
totalGets--;
break;
case ALIASING_GET:
aliasingGets--;
totalGets--;
break;
case CALL_GET:
callGets--;
totalGets--;
break;
case DELETE_PROP:
deleteProps--;
break;
default:
throw new IllegalStateException();
}
}
}
List getRefs() {
return refs == null ? ImmutableList.of() : refs;
}
void addRefInternal(Ref ref) {
if (refs == null) {
refs = new ArrayList<>();
}
refs.add(ref);
}
boolean canEliminate() {
if (!canCollapseUnannotatedChildNames() || totalGets > 0) {
return false;
}
if (props != null) {
for (Name n : props) {
if (!n.canCollapse()) {
return false;
}
}
}
return true;
}
boolean isSimpleStubDeclaration() {
if (getRefs().size() == 1) {
Ref ref = refs.get(0);
if (ref.node.getParent() != null && ref.node.getParent().isExprResult()) {
return true;
}
}
return false;
}
boolean isCollapsingExplicitlyDenied() {
if (docInfo == null) {
Ref ref = getDeclaration();
if (ref != null) {
docInfo = getDocInfoForDeclaration(ref);
}
}
return docInfo != null && docInfo.isNoCollapse();
}
boolean isInlinableGlobalAlias() {
// Only simple aliases with direct usage are inlinable.
if (inExterns || globalSets != 1 || localSets != 0 || !canCollapse()) {
return false;
}
// Only allow inlining of simple references.
for (Ref ref : getRefs()) {
switch (ref.type) {
case SET_FROM_GLOBAL:
// Expect one global set
continue;
case SET_FROM_LOCAL:
throw new IllegalStateException();
case ALIASING_GET:
case DIRECT_GET:
case PROTOTYPE_GET:
case CALL_GET:
continue;
case DELETE_PROP:
return false;
default:
throw new IllegalStateException();
}
}
return true;
}
boolean canCollapse() {
return !inExterns
&& !isGetOrSetDefinition()
&& !isCollapsingExplicitlyDenied()
&& (declaredType
|| ((parent == null || parent.canCollapseUnannotatedChildNames())
&& (globalSets > 0 || localSets > 0)
&& localSetsWithNoCollapse == 0
&& deleteProps == 0));
}
boolean isGetOrSetDefinition() {
return this.type == Type.GET || this.type == Type.SET;
}
boolean canCollapseUnannotatedChildNames() {
if (type == Type.OTHER || isGetOrSetDefinition()
|| globalSets != 1 || localSets != 0 || deleteProps != 0) {
return false;
}
// Don't try to collapse if the one global set is a twin reference.
// We could theoretically handle this case in CollapseProperties, but
// it's probably not worth the effort.
Preconditions.checkNotNull(declaration);
if (declaration.getTwin() != null) {
return false;
}
if (isCollapsingExplicitlyDenied()) {
return false;
}
if (declaredType) {
return true;
}
// If this is a key of an aliased object literal, then it will be aliased
// later. So we won't be able to collapse its properties.
if (parent != null && parent.shouldKeepKeys()) {
return false;
}
// If this is aliased, then its properties can't be collapsed either.
if (aliasingGets > 0) {
return false;
}
return (parent == null || parent.canCollapseUnannotatedChildNames());
}
/** Whether this is an object literal that needs to keep its keys. */
boolean shouldKeepKeys() {
return type == Type.OBJECTLIT && (aliasingGets > 0 || isCollapsingExplicitlyDenied());
}
boolean needsToBeStubbed() {
return globalSets == 0
&& localSets > 0
&& localSetsWithNoCollapse == 0
&& !isCollapsingExplicitlyDenied();
}
void setDeclaredType() {
declaredType = true;
for (Name ancestor = parent; ancestor != null;
ancestor = ancestor.parent) {
ancestor.isDeclared = true;
}
}
boolean isDeclaredType() {
return declaredType;
}
boolean isConstructor() {
Node declNode = declaration.node;
Node rvalueNode = NodeUtil.getRValueOfLValue(declNode);
JSDocInfo jsdoc = NodeUtil.getBestJSDocInfo(declNode);
return rvalueNode != null && rvalueNode.isFunction()
&& jsdoc != null && jsdoc.isConstructor();
}
/**
* Determines whether this name is a prefix of at least one class or enum
* name. Because classes and enums are always collapsed, the namespace will
* have different properties in compiled code than in uncompiled code.
*
* For example, if foo.bar.DomHelper is a class, then foo and foo.bar are
* considered namespaces.
*/
boolean isNamespaceObjectLit() {
return isDeclared && type == Type.OBJECTLIT;
}
/**
* Determines whether this is a simple name (as opposed to a qualified
* name).
*/
boolean isSimpleName() {
return parent == null;
}
@Override public String toString() {
return getFullName() + " (" + type + "): "
+ Joiner.on(", ").join(
"globalSets=" + globalSets,
"localSets=" + localSets,
"totalGets=" + totalGets,
"aliasingGets=" + aliasingGets,
"callGets=" + callGets);
}
@Override
public JSDocInfo getJSDocInfo() {
return docInfo;
}
/**
* Tries to get the doc info for a given declaration ref.
*/
private static JSDocInfo getDocInfoForDeclaration(Ref ref) {
if (ref.node != null) {
Node refParent = ref.node.getParent();
if (refParent == null) {
// May happen when inlineAliases removes refs from the AST.
return null;
}
switch (refParent.getToken()) {
case FUNCTION:
case ASSIGN:
case CLASS:
return refParent.getJSDocInfo();
case VAR:
case LET:
case CONST:
return ref.node == refParent.getFirstChild()
? refParent.getJSDocInfo()
: ref.node.getJSDocInfo();
case OBJECTLIT:
return ref.node.getJSDocInfo();
default:
break;
}
}
return null;
}
}
// -------------------------------------------------------------------------
/**
* A global name reference. Contains references to the relevant parse tree
* node and its ancestors that may be affected.
*/
static class Ref implements StaticTypedRef {
// Note: we are more aggressive about collapsing @enum and @constructor
// declarations than implied here, see Name#canCollapse
enum Type {
/** Set in the global scope: a.b.c = 0; */
SET_FROM_GLOBAL,
/** Set in a local scope: function f() { a.b.c = 0; } */
SET_FROM_LOCAL,
/** Get a name's prototype: a.b.c.prototype */
PROTOTYPE_GET,
/**
* Includes all uses that prevent a name's properties from being collapsed:
* var x = a.b.c
* f(a.b.c)
* new Foo(a.b.c)
*/
ALIASING_GET,
/**
* Includes all uses that prevent a name from being completely eliminated:
* goog.inherits(anotherName, a.b.c)
* new a.b.c()
* x instanceof a.b.c
* void a.b.c
* if (a.b.c) {}
*/
DIRECT_GET,
/**
* Calling a name: a.b.c();
* Prevents a name from being collapsed if never set.
*/
CALL_GET,
/**
* Deletion of a property: delete a.b.c;
* Prevents a name from being collapsed at all.
*/
DELETE_PROP,
}
Node node;
final JSModule module;
final Name name;
final Type type;
final Scope scope;
final int preOrderIndex;
/**
* Certain types of references are actually double-refs. For example,
* var a = b = 0;
* counts as both a "set" of b and an "alias" of b.
*
* We create two Refs for this node, and mark them as twins of each other.
*/
private Ref twin = null;
/**
* Creates a reference at the current node.
*/
Ref(JSModule module, Scope scope, Node node, Name name, Type type, int index) {
this.node = node;
this.name = name;
this.module = module;
this.type = type;
this.scope = scope;
this.preOrderIndex = index;
}
private Ref(Ref original, Type type, int index) {
this.node = original.node;
this.name = original.name;
this.module = original.module;
this.type = type;
this.scope = original.scope;
this.preOrderIndex = index;
}
private Ref(Type type, int index) {
this.type = type;
this.module = null;
this.scope = null;
this.name = null;
this.preOrderIndex = index;
}
@Override
public Node getNode() {
return node;
}
@Override
public StaticSourceFile getSourceFile() {
return node != null ? node.getStaticSourceFile() : null;
}
@Override
public StaticTypedSlot getSymbol() {
return name;
}
JSModule getModule() {
return module;
}
Ref getTwin() {
return twin;
}
boolean isSet() {
return type == Type.SET_FROM_GLOBAL || type == Type.SET_FROM_LOCAL;
}
static void markTwins(Ref a, Ref b) {
Preconditions.checkArgument(
(a.type == Type.ALIASING_GET || b.type == Type.ALIASING_GET)
&& (a.type == Type.SET_FROM_GLOBAL
|| a.type == Type.SET_FROM_LOCAL
|| b.type == Type.SET_FROM_GLOBAL
|| b.type == Type.SET_FROM_LOCAL));
a.twin = b;
b.twin = a;
}
/**
* Create a new ref that is the same as this one, but of
* a different class.
*/
Ref cloneAndReclassify(Type type) {
return new Ref(this, type, this.preOrderIndex);
}
static Ref createRefForTesting(Type type) {
return new Ref(type, -1);
}
@Override
public String toString() {
return node.toString();
}
}
}