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// Copyright (c) 2016, the R8 project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
package com.android.tools.r8.naming;
import com.android.tools.r8.graph.DexAnnotation;
import com.android.tools.r8.graph.DexClass;
import com.android.tools.r8.graph.DexProgramClass;
import com.android.tools.r8.graph.DexString;
import com.android.tools.r8.graph.DexType;
import com.android.tools.r8.graph.DexValue;
import com.android.tools.r8.graph.DexValue.DexValueType;
import com.android.tools.r8.shaking.Enqueuer.AppInfoWithLiveness;
import com.android.tools.r8.shaking.RootSetBuilder.RootSet;
import com.android.tools.r8.utils.DescriptorUtils;
import com.android.tools.r8.utils.StringUtils;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
public class ClassNameMinifier {
private final AppInfoWithLiveness appInfo;
private final RootSet rootSet;
private final String packagePrefix;
private final Set<DexString> usedTypeNames = Sets.newIdentityHashSet();
private final Map<DexType, DexString> renaming = Maps.newIdentityHashMap();
private final Map<String, NamingState> states = new HashMap<>();
private final List<String> dictionary;
private final boolean keepInnerClassStructure;
public ClassNameMinifier(AppInfoWithLiveness appInfo, RootSet rootSet, String packagePrefix,
List<String> dictionary, boolean keepInnerClassStructure) {
this.appInfo = appInfo;
this.rootSet = rootSet;
this.packagePrefix = packagePrefix;
this.dictionary = dictionary;
this.keepInnerClassStructure = keepInnerClassStructure;
}
public Map<DexType, DexString> computeRenaming() {
Iterable<DexProgramClass> classes = appInfo.classes();
// Collect names we have to keep.
for (DexClass clazz : appInfo.classes()) {
if (rootSet.noObfuscation.contains(clazz)) {
assert !renaming.containsKey(clazz.type);
registerClassAsUsed(clazz.type);
}
}
for (DexClass clazz : appInfo.classes()) {
if (!renaming.containsKey(clazz.type)) {
DexString renamed = computeName(clazz);
renaming.put(clazz.type, renamed);
}
}
appInfo.dexItemFactory.forAllTypes(this::renameArrayTypeIfNeeded);
return Collections.unmodifiableMap(renaming);
}
/**
* Registers the given type as used.
* <p>
* When {@link #keepInnerClassStructure} is true, keeping the name of an inner class will
* automatically also keep the name of the outer class, as otherwise the structure would be
* invalidated.
*/
private void registerClassAsUsed(DexType type) {
renaming.put(type, type.descriptor);
usedTypeNames.add(type.descriptor);
if (keepInnerClassStructure) {
DexType outerClass = getOutClassForType(type);
if (outerClass != null) {
if (!renaming.containsKey(outerClass)) {
// The outer class was not previously kept. We have to do this now.
registerClassAsUsed(outerClass);
}
}
}
}
private DexType getOutClassForType(DexType type) {
DexClass clazz = appInfo.definitionFor(type);
if (clazz == null) {
return null;
}
DexAnnotation annotation =
clazz.annotations.getFirstMatching(appInfo.dexItemFactory.annotationEnclosingClass);
if (annotation != null) {
assert annotation.annotation.elements.length == 1;
DexValue value = annotation.annotation.elements[0].value;
return ((DexValueType) value).value;
}
// We do not need to preserve the names for local or anonymous classes, as they do not result
// in a member type declaration and hence cannot be referenced as nested classes in
// method signatures.
// See https://docs.oracle.com/javase/specs/jls/se7/html/jls-8.html#jls-8.5.
return null;
}
private DexString computeName(DexClass clazz) {
NamingState state = null;
if (keepInnerClassStructure) {
// When keeping the nesting structure of inner classes, we have to insert the name
// of the outer class for the $ prefix.
DexType outerClass = getOutClassForType(clazz.type);
if (outerClass != null) {
state = getStateForOuterClass(outerClass);
}
}
if (state == null) {
String packageName = getPackageNameFor(clazz);
state = getStateFor(packageName);
}
return state.nextTypeName();
}
private String getPackageNameFor(DexClass clazz) {
if ((packagePrefix == null) || rootSet.keepPackageName.contains(clazz)) {
return clazz.type.getPackageDescriptor();
} else {
return packagePrefix;
}
}
private NamingState getStateFor(String packageName) {
return states.computeIfAbsent(packageName, NamingState::new);
}
private NamingState getStateForOuterClass(DexType outer) {
String prefix = DescriptorUtils
.getClassBinaryNameFromDescriptor(outer.toDescriptorString());
return states.computeIfAbsent(prefix, k -> {
// Create a naming state with this classes renaming as prefix.
DexString renamed = renaming.get(outer);
if (renamed == null) {
// The outer class has not been renamed yet, so rename the outer class first.
DexClass outerClass = appInfo.definitionFor(outer);
if (outerClass == null) {
renamed = outer.descriptor;
} else {
renamed = computeName(outerClass);
renaming.put(outer, renamed);
}
}
String binaryName = DescriptorUtils.getClassBinaryNameFromDescriptor(renamed.toString());
return new NamingState(binaryName, "$");
});
}
private void renameArrayTypeIfNeeded(DexType type) {
if (type.isArrayType()) {
DexType base = type.toBaseType(appInfo.dexItemFactory);
DexString value = renaming.get(base);
if (value != null) {
int dimensions = type.descriptor.numberOfLeadingSquareBrackets();
StringBuilder builder = new StringBuilder();
for (int i = 0; i < dimensions; i++) {
builder.append('[');
}
builder.append(value.toString());
DexString descriptor = appInfo.dexItemFactory.createString(builder.toString());
renaming.put(type, descriptor);
}
}
}
private class NamingState {
private final char[] packagePrefix;
private final String separator;
private int typeCounter = 1;
private Iterator<String> dictionaryIterator;
NamingState(String packageName) {
this(packageName, "/");
}
NamingState(String packageName, String separator) {
this.packagePrefix = ("L" + packageName + (packageName.isEmpty() ? "" : separator))
.toCharArray();
this.separator = separator;
this.dictionaryIterator = dictionary.iterator();
}
public char[] getPackagePrefix() {
return packagePrefix;
}
protected String nextSuggestedName() {
StringBuilder nextName = new StringBuilder();
if (dictionaryIterator.hasNext()) {
nextName.append(getPackagePrefix()).append(dictionaryIterator.next()).append(';');
return nextName.toString();
} else {
return StringUtils.numberToIdentifier(packagePrefix, typeCounter++, true);
}
}
private DexString nextTypeName() {
DexString candidate;
do {
candidate = appInfo.dexItemFactory.createString(nextSuggestedName());
} while (usedTypeNames.contains(candidate));
return candidate;
}
}
}
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