AmbiguateProperties.java
/*
* Copyright 2008 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.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.base.Joiner;
import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.ImmutableSet;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.graph.AdjacencyGraph;
import com.google.javascript.jscomp.graph.Annotation;
import com.google.javascript.jscomp.graph.GraphColoring;
import com.google.javascript.jscomp.graph.GraphColoring.GreedyGraphColoring;
import com.google.javascript.jscomp.graph.GraphNode;
import com.google.javascript.jscomp.graph.SubGraph;
import com.google.javascript.rhino.FunctionTypeI;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.ObjectTypeI;
import com.google.javascript.rhino.TypeI;
import com.google.javascript.rhino.jstype.JSTypeNative;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Renames unrelated properties to the same name, using type information.
* This allows better compression as more properties can be given short names.
*
* <p>Properties are considered unrelated if they are never referenced from the
* same type or from a subtype of each others' types, thus this pass is only
* effective if type checking is enabled.
*
* Example:
* <code>
* Foo.fooprop = 0;
* Foo.fooprop2 = 0;
* Bar.barprop = 0;
* </code>
*
* becomes:
*
* <code>
* Foo.a = 0;
* Foo.b = 0;
* Bar.a = 0;
* </code>
*
*/
class AmbiguateProperties implements CompilerPass {
private static final Logger logger = Logger.getLogger(
AmbiguateProperties.class.getName());
private final AbstractCompiler compiler;
private final List<Node> stringNodesToRename = new ArrayList<>();
// Can't use these as property names.
private final char[] reservedFirstCharacters;
// Can't use these as property names.
private final char[] reservedNonFirstCharacters;
/** Map from property name to Property object */
private final Map<String, Property> propertyMap = new HashMap<>();
/** Property names that don't get renamed */
private final Set<String> externedNames;
/** Names to which properties shouldn't be renamed, to avoid name conflicts */
private final Set<String> quotedNames = new HashSet<>();
/** Map from original property name to new name. Only used by tests. */
private Map<String, String> renamingMap = null;
/**
* Sorts Property objects by their count, breaking ties alphabetically to
* ensure a deterministic total ordering.
*/
private static final Comparator<Property> FREQUENCY_COMPARATOR =
new Comparator<Property>() {
@Override
public int compare(Property p1, Property p2) {
if (p1.numOccurrences != p2.numOccurrences) {
return p2.numOccurrences - p1.numOccurrences;
}
return p1.oldName.compareTo(p2.oldName);
}
};
/** A map from TypeI to a unique representative Integer. */
private final BiMap<TypeI, Integer> intForType = HashBiMap.create();
/** A map from TypeI to JSTypeBitSet representing the types related to the type. */
private final Map<TypeI, JSTypeBitSet> relatedBitsets = new HashMap<>();
/** A set of types that invalidate properties from ambiguation. */
private final InvalidatingTypes invalidatingTypes;
/**
* Prefix of properties to skip renaming. These should be renamed in the
* RenameProperties pass.
*/
static final String SKIP_PREFIX = "JSAbstractCompiler";
AmbiguateProperties(
AbstractCompiler compiler,
char[] reservedFirstCharacters,
char[] reservedNonFirstCharacters) {
checkState(compiler.getLifeCycleStage().isNormalized());
this.compiler = compiler;
this.reservedFirstCharacters = reservedFirstCharacters;
this.reservedNonFirstCharacters = reservedNonFirstCharacters;
this.invalidatingTypes = new InvalidatingTypes.Builder(compiler.getTypeIRegistry())
.addTypesInvalidForPropertyRenaming()
.addAllTypeMismatches(compiler.getTypeMismatches())
.addAllTypeMismatches(compiler.getImplicitInterfaceUses())
.build();
this.externedNames = compiler.getExternProperties();
}
static AmbiguateProperties makePassForTesting(
AbstractCompiler compiler,
char[] reservedFirstCharacters,
char[] reservedNonFirstCharacters) {
AmbiguateProperties ap =
new AmbiguateProperties(compiler, reservedFirstCharacters, reservedNonFirstCharacters);
ap.renamingMap = new HashMap<>();
return ap;
}
Map<String, String> getRenamingMap() {
checkNotNull(renamingMap);
return renamingMap;
}
/** Returns an integer that uniquely identifies a JSType. */
private int getIntForType(TypeI type) {
// Templatized types don't exist at runtime, so collapse to raw type
if (type != null && type.isGenericObjectType()) {
type = type.toMaybeObjectType().getRawType();
}
if (intForType.containsKey(type)) {
return intForType.get(type).intValue();
}
int newInt = intForType.size() + 1;
intForType.put(type, newInt);
return newInt;
}
@Override
public void process(Node externs, Node root) {
// Find all property references and record the types on which they occur.
// Populate stringNodesToRename, propertyMap, quotedNames.
NodeTraversal.traverseEs6(compiler, root, new ProcessProperties());
ImmutableSet.Builder<String> reservedNames = ImmutableSet.<String>builder()
.addAll(externedNames)
.addAll(quotedNames);
int numRenamedPropertyNames = 0;
int numSkippedPropertyNames = 0;
ArrayList<PropertyGraphNode> nodes = new ArrayList<>(propertyMap.size());
for (Property prop : propertyMap.values()) {
if (prop.skipAmbiguating) {
++numSkippedPropertyNames;
reservedNames.add(prop.oldName);
} else {
++numRenamedPropertyNames;
nodes.add(new PropertyGraphNode(prop));
}
}
PropertyGraph graph = new PropertyGraph(nodes);
GraphColoring<Property, Void> coloring =
new GreedyGraphColoring<>(graph, FREQUENCY_COMPARATOR);
int numNewPropertyNames = coloring.color();
// Generate new names for the properties that will be renamed.
NameGenerator nameGen =
new DefaultNameGenerator(
reservedNames.build(), "", reservedFirstCharacters, reservedNonFirstCharacters);
String[] colorMap = new String[numNewPropertyNames];
for (int i = 0; i < numNewPropertyNames; ++i) {
colorMap[i] = nameGen.generateNextName();
}
// Translate the color of each Property instance to a name.
for (PropertyGraphNode node : graph.getNodes()) {
node.getValue().newName = colorMap[node.getAnnotation().hashCode()];
if (renamingMap != null) {
renamingMap.put(node.getValue().oldName, node.getValue().newName);
}
}
// Actually assign the new names to the relevant STRING nodes in the AST.
for (Node n : stringNodesToRename) {
String oldName = n.getString();
Property p = propertyMap.get(oldName);
if (p != null && p.newName != null) {
checkState(oldName.equals(p.oldName));
if (!p.newName.equals(oldName)) {
n.setString(p.newName);
compiler.reportChangeToEnclosingScope(n);
}
}
}
if (logger.isLoggable(Level.FINE)) {
logger.fine("Collapsed " + numRenamedPropertyNames + " properties into "
+ numNewPropertyNames + " and skipped renaming "
+ numSkippedPropertyNames + " properties.");
}
}
private BitSet getRelatedTypesOnNonUnion(TypeI type) {
// All of the types we encounter should have been added to the
// relatedBitsets via computeRelatedTypes.
if (relatedBitsets.containsKey(type)) {
return relatedBitsets.get(type);
} else {
throw new RuntimeException("Related types should have been computed for"
+ " type: " + type + " but have not been.");
}
}
/**
* Adds subtypes - and implementors, in the case of interfaces - of the type
* to its JSTypeBitSet of related types. Union types are decomposed into their
* alternative types.
*
* <p>The 'is related to' relationship is best understood graphically. Draw an
* arrow from each instance type to the prototype of each of its
* subclass. Draw an arrow from each prototype to its instance type. Draw an
* arrow from each interface to its implementors. A type is related to another
* if there is a directed path in the graph from the type to other. Thus, the
* 'is related to' relationship is reflexive and transitive.
*
* <p>Example with Foo extends Bar which extends Baz and Bar implements I:
* <pre>{@code
* Foo -> Bar.prototype -> Bar -> Baz.prototype -> Baz
* ^
* |
* I
* }</pre>
*
* <p>Note that we don't need to correctly handle the relationships between
* functions, because the function type is invalidating (i.e. its properties
* won't be ambiguated).
*/
private void computeRelatedTypes(TypeI type) {
if (type.isUnionType()) {
type = type.restrictByNotNullOrUndefined();
if (type.isUnionType()) {
for (TypeI alt : type.getUnionMembers()) {
computeRelatedTypes(alt);
}
return;
}
}
if (relatedBitsets.containsKey(type)) {
// We only need to generate the bit set once.
return;
}
JSTypeBitSet related = new JSTypeBitSet(intForType.size());
relatedBitsets.put(type, related);
related.set(getIntForType(type));
// A prototype is related to its instance.
if (type.isPrototypeObject()) {
FunctionTypeI maybeCtor = type.toMaybeObjectType().getOwnerFunction();
if (maybeCtor.isConstructor() || maybeCtor.isInterface()) {
addRelatedInstance(maybeCtor, related);
}
return;
}
// A class/interface is related to its subclasses/implementors.
FunctionTypeI constructor = type.toMaybeObjectType().getConstructor();
if (constructor != null) {
for (FunctionTypeI subType : constructor.getDirectSubTypes()) {
addRelatedInstance(subType, related);
}
}
}
/**
* Adds the instance of the given constructor, its implicit prototype and all
* its related types to the given bit set.
*/
private void addRelatedInstance(FunctionTypeI constructor, JSTypeBitSet related) {
checkArgument(constructor.hasInstanceType(),
"Constructor %s without instance type.", constructor);
ObjectTypeI instanceType = constructor.getInstanceType();
related.set(getIntForType(instanceType.getPrototypeObject()));
computeRelatedTypes(instanceType);
related.or(relatedBitsets.get(instanceType));
}
class PropertyGraph implements AdjacencyGraph<Property, Void> {
private final ArrayList<PropertyGraphNode> nodes;
PropertyGraph(ArrayList<PropertyGraphNode> nodes) {
this.nodes = nodes;
}
@Override
public List<PropertyGraphNode> getNodes() {
return nodes;
}
@Override
public int getNodeCount() {
return nodes.size();
}
@Override
public GraphNode<Property, Void> getNode(Property property) {
throw new RuntimeException("PropertyGraph#getNode is never called.");
}
@Override
public SubGraph<Property, Void> newSubGraph() {
return new PropertySubGraph();
}
@Override
public void clearNodeAnnotations() {
for (PropertyGraphNode node : nodes) {
node.setAnnotation(null);
}
}
@Override
public int getWeight(Property value) {
return value.numOccurrences;
}
}
/**
* A {@link SubGraph} that represents properties. The related types of
* the properties are used to efficiently calculate adjacency information.
*/
class PropertySubGraph implements SubGraph<Property, Void> {
/** Types related to properties referenced in this subgraph. */
JSTypeBitSet relatedTypes = new JSTypeBitSet(intForType.size());
/**
* Returns true if prop is in an independent set from all properties in this
* sub graph. That is, if none of its related types intersects with the
* related types for this sub graph.
*/
@Override
public boolean isIndependentOf(Property prop) {
return !relatedTypes.intersects(prop.relatedTypes);
}
/**
* Adds the node to the sub graph, adding all its related types to the
* related types for the sub graph.
*/
@Override
public void addNode(Property prop) {
relatedTypes.or(prop.relatedTypes);
}
}
static class PropertyGraphNode implements GraphNode<Property, Void> {
Property property;
protected Annotation annotation;
PropertyGraphNode(Property property) {
this.property = property;
}
@Override
public Property getValue() {
return property;
}
@Override
public Annotation getAnnotation() {
return annotation;
}
@Override
public void setAnnotation(Annotation data) {
annotation = data;
}
}
private void reportInvalidRenameFunction(Node n, String functionName, String message) {
compiler.report(
JSError.make(
n, DisambiguateProperties.Warnings.INVALID_RENAME_FUNCTION, functionName, message));
}
private static final String WRONG_ARGUMENT_COUNT = " Must be called with 1 or 2 arguments.";
private static final String WANT_STRING_LITERAL = " The first argument must be a string literal.";
private static final String DO_NOT_WANT_PATH = " The first argument must not be a property path.";
/** Finds all property references, recording the types on which they occur. */
private class ProcessProperties extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case GETPROP: {
Node propNode = n.getSecondChild();
TypeI type = getTypeI(n.getFirstChild());
maybeMarkCandidate(propNode, type);
return;
}
case CALL: {
Node target = n.getFirstChild();
if (!target.isQualifiedName()) {
return;
}
String renameFunctionName = target.getOriginalQualifiedName();
if (renameFunctionName != null
&& compiler.getCodingConvention().isPropertyRenameFunction(renameFunctionName)) {
int childCount = n.getChildCount();
if (childCount != 2 && childCount != 3) {
reportInvalidRenameFunction(n, renameFunctionName, WRONG_ARGUMENT_COUNT);
return;
}
Node propName = n.getSecondChild();
if (!propName.isString()) {
reportInvalidRenameFunction(n, renameFunctionName, WANT_STRING_LITERAL);
return;
}
if (propName.getString().contains(".")) {
reportInvalidRenameFunction(n, renameFunctionName, DO_NOT_WANT_PATH);
return;
}
maybeMarkCandidate(propName, getTypeI(n.getSecondChild()));
} else if (NodeUtil.isObjectDefinePropertiesDefinition(n)) {
Node typeObj = n.getSecondChild();
TypeI type = getTypeI(typeObj);
Node objectLiteral = typeObj.getNext();
if (!objectLiteral.isObjectLit()) {
return;
}
for (Node key : objectLiteral.children()) {
if (key.isQuotedString()) {
quotedNames.add(key.getString());
} else {
maybeMarkCandidate(key, type);
}
}
}
return;
}
case OBJECTLIT:
// Object.defineProperties literals are handled at the CALL node.
if (n.getParent().isCall()
&& NodeUtil.isObjectDefinePropertiesDefinition(n.getParent())) {
return;
}
// The children of an OBJECTLIT node are keys, where the values
// are the children of the keys.
TypeI type = getTypeI(n);
for (Node key = n.getFirstChild(); key != null; key = key.getNext()) {
// We only want keys that were unquoted.
// Keys are STRING, GET, SET
if (key.isQuotedString()) {
// Ensure that we never rename some other property in a way
// that could conflict with this quoted key.
quotedNames.add(key.getString());
} else {
maybeMarkCandidate(key, type);
}
}
return;
case GETELEM:
// If this is a quoted property access (e.g. x['myprop']), we need to
// ensure that we never rename some other property in a way that
// could conflict with this quoted name.
Node child = n.getLastChild();
if (child.isString()) {
quotedNames.add(child.getString());
}
return;
default:
// Nothing to do.
}
}
/**
* If a property node is eligible for renaming, stashes a reference to it
* and increments the property name's access count.
*
* @param n The STRING node for a property
*/
private void maybeMarkCandidate(Node n, TypeI type) {
String name = n.getString();
if (!externedNames.contains(name)) {
stringNodesToRename.add(n);
recordProperty(name, type);
}
}
private Property recordProperty(String name, TypeI type) {
Property prop = getProperty(name);
prop.addType(type);
return prop;
}
}
private Property getProperty(String name) {
Property prop = propertyMap.get(name);
if (prop == null) {
prop = new Property(name);
propertyMap.put(name, prop);
}
return prop;
}
/**
* This method gets the JSType from the Node argument and verifies that it is
* present.
*/
private TypeI getTypeI(Node n) {
if (n == null) {
return compiler.getTypeIRegistry().getNativeType(JSTypeNative.UNKNOWN_TYPE);
}
TypeI type = n.getTypeI();
if (type == null) {
// TODO(user): This branch indicates a compiler bug, not worthy of
// halting the compilation but we should log this and analyze to track
// down why it happens. This is not critical and will be resolved over
// time as the type checker is extended.
return compiler.getTypeIRegistry().getNativeType(JSTypeNative.UNKNOWN_TYPE);
} else {
return type;
}
}
/** Encapsulates the information needed for renaming a property. */
private class Property {
final String oldName;
String newName;
int numOccurrences;
boolean skipAmbiguating;
JSTypeBitSet relatedTypes = new JSTypeBitSet(intForType.size());
Property(String name) {
this.oldName = name;
// Properties with this suffix are handled in RenameProperties.
if (name.startsWith(SKIP_PREFIX)) {
skipAmbiguating = true;
}
}
/** Add this type to this property, calculating */
void addType(TypeI newType) {
if (skipAmbiguating) {
return;
}
++numOccurrences;
if (newType.isUnionType()) {
newType = newType.restrictByNotNullOrUndefined();
if (newType.isUnionType()) {
for (TypeI alt : newType.getUnionMembers()) {
addNonUnionType(alt);
}
return;
}
}
addNonUnionType(newType);
}
private void addNonUnionType(TypeI newType) {
if (skipAmbiguating || invalidatingTypes.isInvalidating(newType)) {
skipAmbiguating = true;
return;
}
ObjectTypeI maybeObj = newType.toMaybeObjectType();
if (maybeObj != null) {
newType = maybeObj.withoutStrayProperties();
}
if (!relatedTypes.get(getIntForType(newType))) {
computeRelatedTypes(newType);
relatedTypes.or(getRelatedTypesOnNonUnion(newType));
}
}
}
// A BitSet that stores type info. Adds pretty-print routines.
private class JSTypeBitSet extends BitSet {
private static final long serialVersionUID = 1L;
private JSTypeBitSet(int size) {
super(size);
}
private JSTypeBitSet() {
super();
}
/**
* Pretty-printing, for diagnostic purposes.
*/
@Override
public String toString() {
int from = 0;
int current = 0;
List<String> types = new ArrayList<>();
while (-1 != (current = nextSetBit(from))) {
types.add(intForType.inverse().get(current).toString());
from = current + 1;
}
return Joiner.on(" && ").join(types);
}
}
}