Move the field name out of the FieldInitializer

RELNOTES: None
PiperOrigin-RevId: 156747534

7 files changed, 145 insertions, 175 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializer.java b/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializer.java
index edcc464c18..ff7e9b875e 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializer.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializer.java
@@ -15,7 +15,6 @@ package com.google.devtools.build.android.resources;
 
 import java.io.IOException;
 import java.io.Writer;
-import java.util.Collection;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.commons.InstructionAdapter;
 
@@ -23,27 +22,20 @@ import org.objectweb.asm.commons.InstructionAdapter;
  * Represents a field and its initializer (where initialization is either part of the field
  * definition, or done via code in the static clinit function).
  */
-public interface FieldInitializer extends Comparable<FieldInitializer> {
+public interface FieldInitializer {
   /**
    * Write the bytecode for the field definition.
    *
    * @return true if the initializer is deferred to clinit code.
    */
-  boolean writeFieldDefinition(ClassWriter cw, int accessLevel, boolean isFinal);
+  boolean writeFieldDefinition(String fieldName, ClassWriter cw, int accessLevel, boolean isFinal);
 
   /**
    * Write the bytecode for the clinit portion of initializer.
-   *
    * @return the number of stack slots needed for the code.
    */
-  int writeCLInit(InstructionAdapter insts, String className);
+  int writeCLInit(String fieldName, InstructionAdapter insts, String className);
 
   /** Write the source code for the initializer to the given writer. */
-  void writeInitSource(Writer writer, boolean finalFields) throws IOException;
-
-  /** Tests if the field's name is in the provided collection. */
-  boolean nameIsIn(Collection<String> fieldNames);
-
-  /** Adds fieldName to the provided set. */
-  void addTo(Collection<String> fieldNames);
+  void writeInitSource(String fieldName, Writer writer, boolean finalFields) throws IOException;
 }
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializers.java b/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializers.java
index 45ffadf66d..ae8307ed90 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializers.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/FieldInitializers.java
@@ -16,65 +16,78 @@ package com.google.devtools.build.android.resources;
 import com.android.resources.ResourceType;
 import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.MultimapBuilder;
-import com.google.common.collect.SortedSetMultimap;
+import com.google.common.collect.ImmutableSortedMap;
+import com.google.common.collect.Sets;
 import java.util.Collection;
+import java.util.EnumMap;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.SortedSet;
+import java.util.TreeMap;
 
 /**
  * Represents a collection of resource symbols and values suitable for writing java sources and
  * classes.
  */
 public class FieldInitializers
-    implements Iterable<Entry<ResourceType, Collection<FieldInitializer>>> {
+    implements Iterable<Entry<ResourceType, Map<String, FieldInitializer>>> {
 
-  private final Map<ResourceType, Collection<FieldInitializer>> initializers;
+  private final Map<ResourceType, Map<String, FieldInitializer>> initializers;
 
-  private FieldInitializers(Map<ResourceType, Collection<FieldInitializer>> initializers) {
+  private FieldInitializers(Map<ResourceType, Map<String, FieldInitializer>> initializers) {
     this.initializers = initializers;
   }
 
   /** Creates a {@link FieldInitializers} copying the contents from a {@link Map}. */
   public static FieldInitializers copyOf(
-      Map<ResourceType, Collection<FieldInitializer>> initializers) {
+      Map<ResourceType, Map<String, FieldInitializer>> initializers) {
     return new FieldInitializers(ImmutableMap.copyOf(initializers));
   }
 
-  public Iterable<Entry<ResourceType, Collection<FieldInitializer>>> filter(
-      FieldInitializers fieldsToWrite) {
-    final SortedSetMultimap<ResourceType, FieldInitializer> initializersToWrite =
-        MultimapBuilder.enumKeys(ResourceType.class).treeSetValues().build();
-
-    // Create a map to filter with.
-    final SortedSetMultimap<ResourceType, String> symbolsToWrite =
-        MultimapBuilder.enumKeys(ResourceType.class).treeSetValues().build();
-    for (Entry<ResourceType, Collection<FieldInitializer>> entry :
-        fieldsToWrite.initializers.entrySet()) {
-      for (FieldInitializer initializer : entry.getValue()) {
-        final SortedSet<String> fieldNames = symbolsToWrite.get(entry.getKey());
-        initializer.addTo(fieldNames);
+  public static FieldInitializers mergedFrom(Collection<FieldInitializers> toMerge) {
+    final Map<ResourceType, Map<String, FieldInitializer>> merged =
+        new EnumMap<>(ResourceType.class);
+    for (FieldInitializers mergee : toMerge) {
+      for (Entry<ResourceType, Map<String, FieldInitializer>> entry : mergee) {
+        final Map<String, FieldInitializer> fieldMap =
+            merged.containsKey(entry.getKey())
+                ? merged.get(entry.getKey())
+                : new TreeMap<String, FieldInitializer>();
+        merged.put(entry.getKey(), fieldMap);
+        for (Entry<String, FieldInitializer> field : entry.getValue().entrySet()) {
+          fieldMap.put(field.getKey(), field.getValue());
+        }
       }
     }
+    return copyOf(merged);
+  }
 
-    for (Entry<ResourceType, Collection<String>> entry : symbolsToWrite.asMap().entrySet()) {
-      // Resource type may be missing if resource overriding eliminates resources at the binary
-      // level, which were originally present at the library level.
+  public Iterable<Entry<ResourceType, Map<String, FieldInitializer>>> filter(
+      FieldInitializers fieldsToWrite) {
+    Map<ResourceType, Map<String, FieldInitializer>> initializersToWrite =
+        new EnumMap<>(ResourceType.class);
+
+    for (Entry<ResourceType, Map<String, FieldInitializer>> entry :
+        fieldsToWrite.initializers.entrySet()) {
       if (initializers.containsKey(entry.getKey())) {
-        for (FieldInitializer field : initializers.get(entry.getKey())) {
-          if (field.nameIsIn(entry.getValue())) {
-            initializersToWrite.put(entry.getKey(), field);
-          }
+        final Map<String, FieldInitializer> valueFields = initializers.get(entry.getKey());
+        final ImmutableMap.Builder<String, FieldInitializer> fields =
+            ImmutableSortedMap.naturalOrder();
+        // Resource type may be missing if resource overriding eliminates resources at the binary
+        // level, which were originally present at the library level.
+        for (String fieldName :
+            Sets.intersection(entry.getValue().keySet(), valueFields.keySet())) {
+          fields.put(fieldName, valueFields.get(fieldName));
         }
+        initializersToWrite.put(entry.getKey(), fields.build());
       }
     }
-    return initializersToWrite.asMap().entrySet();
+
+    return initializersToWrite.entrySet();
   }
 
   @Override
-  public Iterator<Entry<ResourceType, Collection<FieldInitializer>>> iterator() {
+  public Iterator<Entry<ResourceType, Map<String, FieldInitializer>>> iterator() {
     return initializers.entrySet().iterator();
   }
 
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/IntArrayFieldInitializer.java b/src/tools/android/java/com/google/devtools/build/android/resources/IntArrayFieldInitializer.java
index 2f595c90f5..140439cd5b 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/IntArrayFieldInitializer.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/IntArrayFieldInitializer.java
@@ -20,53 +20,50 @@ import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import java.io.IOException;
 import java.io.Writer;
-import java.util.Collection;
 import java.util.Objects;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.Type;
 import org.objectweb.asm.commons.InstructionAdapter;
 
-/**
- * Models an int[] field initializer.
- */
+/** Models an int[] field initializer. */
 public final class IntArrayFieldInitializer implements FieldInitializer {
 
   public static final String DESC = "[I";
-  private final String fieldName;
   private final ImmutableCollection<Integer> values;
 
-  public IntArrayFieldInitializer(String fieldName, ImmutableCollection<Integer> values) {
-    this.fieldName = fieldName;
+  private IntArrayFieldInitializer(ImmutableCollection<Integer> values) {
     this.values = values;
   }
 
-  public static FieldInitializer of(String name, String value) {
+  public static FieldInitializer of(String value) {
     Preconditions.checkArgument(value.startsWith("{ "), "Expected list starting with { ");
     Preconditions.checkArgument(value.endsWith(" }"), "Expected list ending with } ");
     // Check for an empty list, which is "{ }".
     if (value.length() < 4) {
-      return new IntArrayFieldInitializer(name, ImmutableList.<Integer>of());
+      return of(ImmutableList.<Integer>of());
     }
     ImmutableList.Builder<Integer> intValues = ImmutableList.builder();
     String trimmedValue = value.substring(2, value.length() - 2);
-    Iterable<String> valueStrings = Splitter.on(',')
-        .trimResults()
-        .split(trimmedValue);
+    Iterable<String> valueStrings = Splitter.on(',').trimResults().split(trimmedValue);
     for (String valueString : valueStrings) {
       intValues.add(Integer.decode(valueString));
     }
-    return new IntArrayFieldInitializer(name, intValues.build());
+    return of(intValues.build());
+  }
+
+  public static IntArrayFieldInitializer of(ImmutableCollection<Integer> values) {
+    return new IntArrayFieldInitializer(values);
   }
 
   @Override
-  public boolean writeFieldDefinition(ClassWriter cw, int accessLevel, boolean isFinal) {
-    cw.visitField(accessLevel, fieldName, DESC, null, null)
-        .visitEnd();
+  public boolean writeFieldDefinition(
+      String fieldName, ClassWriter cw, int accessLevel, boolean isFinal) {
+    cw.visitField(accessLevel, fieldName, DESC, null, null).visitEnd();
     return true;
   }
 
   @Override
-  public int writeCLInit(InstructionAdapter insts, String className) {
+  public int writeCLInit(String fieldName, InstructionAdapter insts, String className) {
     insts.iconst(values.size());
     insts.newarray(Type.INT_TYPE);
     int curIndex = 0;
@@ -84,7 +81,8 @@ public final class IntArrayFieldInitializer implements FieldInitializer {
   }
 
   @Override
-  public void writeInitSource(Writer writer, boolean finalFields) throws IOException {
+  public void writeInitSource(String fieldName, Writer writer, boolean finalFields)
+      throws IOException {
     StringBuilder builder = new StringBuilder();
     boolean first = true;
     for (Integer attrId : values) {
@@ -103,43 +101,21 @@ public final class IntArrayFieldInitializer implements FieldInitializer {
   }
 
   @Override
-  public boolean nameIsIn(Collection<String> fieldNames) {
-    return fieldNames.contains(fieldName);
-  }
-  
-  @Override
   public String toString() {
-    return MoreObjects.toStringHelper(getClass())
-        .add("fieldName", fieldName)
-        .add("values", values)
-        .toString();
-  }
-
-  @Override
-  public int compareTo(FieldInitializer other) {
-    if (other instanceof IntArrayFieldInitializer) {
-      return fieldName.compareTo(((IntArrayFieldInitializer) other).fieldName);
-    }
-    // IntArrays will go after IntFields
-    return 1;
+    return MoreObjects.toStringHelper(getClass()).add("values", values).toString();
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(fieldName, values);
+    return values.hashCode();
   }
 
   @Override
   public boolean equals(Object obj) {
     if (obj instanceof IntArrayFieldInitializer) {
       IntArrayFieldInitializer other = (IntArrayFieldInitializer) obj;
-      return Objects.equals(fieldName, other.fieldName) && Objects.equals(values, other.values);
+      return Objects.equals(values, other.values);
     }
     return false;
   }
-
-  @Override
-  public void addTo(Collection<String> fieldNames) {
-    fieldNames.add(fieldName);
-  }
 }
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/IntFieldInitializer.java b/src/tools/android/java/com/google/devtools/build/android/resources/IntFieldInitializer.java
index ffbd64fcda..888e888f0b 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/IntFieldInitializer.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/IntFieldInitializer.java
@@ -16,38 +16,36 @@ package com.google.devtools.build.android.resources;
 import com.google.common.base.MoreObjects;
 import java.io.IOException;
 import java.io.Writer;
-import java.util.Collection;
-import java.util.Objects;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.commons.InstructionAdapter;
 
-/**
- * Models an int field initializer.
- */
+/** Models an int field initializer. */
 public final class IntFieldInitializer implements FieldInitializer {
 
-  private final String fieldName;
   private final int value;
   private static final String DESC = "I";
 
-  public IntFieldInitializer(String fieldName, int value) {
-    this.fieldName = fieldName;
+  private IntFieldInitializer(int value) {
     this.value = value;
   }
 
-  public static FieldInitializer of(String name, String value) {
-    return new IntFieldInitializer(name, Integer.decode(value));
+  public static FieldInitializer of(String value) {
+    return of(Integer.decode(value));
+  }
+
+  public static IntFieldInitializer of(int value) {
+    return new IntFieldInitializer(value);
   }
 
   @Override
-  public boolean writeFieldDefinition(ClassWriter cw, int accessLevel, boolean isFinal) {
-    cw.visitField(accessLevel, fieldName, DESC, null, isFinal ? value : null)
-        .visitEnd();
+  public boolean writeFieldDefinition(
+      String fieldName, ClassWriter cw, int accessLevel, boolean isFinal) {
+    cw.visitField(accessLevel, fieldName, DESC, null, isFinal ? value : null).visitEnd();
     return !isFinal;
   }
 
   @Override
-  public int writeCLInit(InstructionAdapter insts, String className) {
+  public int writeCLInit(String fieldName, InstructionAdapter insts, String className) {
     insts.iconst(value);
     insts.putstatic(className, fieldName, DESC);
     // Just needs one stack slot for the iconst.
@@ -55,7 +53,8 @@ public final class IntFieldInitializer implements FieldInitializer {
   }
 
   @Override
-  public void writeInitSource(Writer writer, boolean finalFields) throws IOException {
+  public void writeInitSource(String fieldName, Writer writer, boolean finalFields)
+      throws IOException {
     writer.write(
         String.format(
             "        public static %sint %s = 0x%x;\n",
@@ -63,43 +62,21 @@ public final class IntFieldInitializer implements FieldInitializer {
   }
 
   @Override
-  public boolean nameIsIn(Collection<String> fieldNames) {
-    return fieldNames.contains(fieldName);
-  }
-  
-  @Override
   public String toString() {
-    return MoreObjects.toStringHelper(getClass())
-        .add("fieldName", fieldName)
-        .add("value", value)
-        .toString();
-  }
-  
-  @Override
-  public int compareTo(FieldInitializer other) {
-    if (other instanceof IntFieldInitializer) {
-      return fieldName.compareTo(((IntFieldInitializer) other).fieldName);
-    }
-    // IntFields will go before Intarrays
-    return -1;
+    return MoreObjects.toStringHelper(getClass()).add("value", value).toString();
   }
 
   @Override
   public int hashCode() {
-    return Objects.hash(fieldName, value);
+    return value;
   }
 
   @Override
   public boolean equals(Object obj) {
     if (obj instanceof IntFieldInitializer) {
       IntFieldInitializer other = (IntFieldInitializer) obj;
-      return Objects.equals(fieldName, other.fieldName) && value == other.value;
+      return value == other.value;
     }
     return false;
   }
-
-  @Override
-  public void addTo(Collection<String> fieldNames) {
-    fieldNames.add(fieldName);
-  }
 }
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/RClassGenerator.java b/src/tools/android/java/com/google/devtools/build/android/resources/RClassGenerator.java
index 54375fab14..ea09b5bbd3 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/RClassGenerator.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/RClassGenerator.java
@@ -20,9 +20,7 @@ import com.google.common.collect.Iterables;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
+import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import org.objectweb.asm.ClassWriter;
@@ -46,18 +44,6 @@ public class RClassGenerator {
   private static final Splitter PACKAGE_SPLITTER = Splitter.on('.');
 
   /**
-   * Create an RClassGenerator initialized with the ResourceSymbols values.
-   *
-   * @param outFolder base folder to place the output R class files.
-   * @param values the final symbol values
-   * @param finalFields true if the fields should be marked final
-   */
-  public static RClassGenerator fromSymbols(
-      Path outFolder, ResourceSymbols values, boolean finalFields) {
-    return with(outFolder, values.asInitializers(), finalFields);
-  }
- 
-  /**
    * Create an RClassGenerator given a collection of initializers.
    *
    * @param outFolder base folder to place the output R class files.
@@ -82,17 +68,17 @@ public class RClassGenerator {
   public void write(String packageName, FieldInitializers symbolsToWrite) throws IOException {
     writeClasses(packageName, initializers.filter(symbolsToWrite));
   }
-  
+
   /** Builds bytecode and writes out R.class file, and R$inner.class files for provided package. */
   public void write(String packageName) throws IOException {
     writeClasses(packageName, initializers);
   }
-  
+
   private void writeClasses(
       String packageName,
-      Iterable<Entry<ResourceType, Collection<FieldInitializer>>> initializersToWrite)
+      Iterable<Entry<ResourceType, Map<String, FieldInitializer>>> initializersToWrite)
       throws IOException {
-    
+
     Iterable<String> folders = PACKAGE_SPLITTER.split(packageName);
     Path packageDir = outFolder;
     for (String folder : folders) {
@@ -101,11 +87,11 @@ public class RClassGenerator {
     // At least create the outFolder that was requested. However, if there are no symbols, don't
     // create the R.class and inner class files (no need to have an empty class).
     Files.createDirectories(packageDir);
-     
+
     if (Iterables.isEmpty(initializersToWrite)) {
       return;
     }
-    
+
     Path rClassFile = packageDir.resolve(SdkConstants.FN_COMPILED_RESOURCE_CLASS);
 
     String packageWithSlashes = packageName.replaceAll("\\.", "/");
@@ -121,7 +107,7 @@ public class RClassGenerator {
     classWriter.visitSource(SdkConstants.FN_RESOURCE_CLASS, null);
     writeConstructor(classWriter);
     // Build the R.class w/ the inner classes, then later build the individual R$inner.class.
-    for (Entry<ResourceType, Collection<FieldInitializer>> entry : initializersToWrite) {
+    for (Entry<ResourceType, Map<String, FieldInitializer>> entry : initializersToWrite) {
       String innerClassName = rClassName + "$" + entry.getKey().toString();
       classWriter.visitInnerClass(
           innerClassName,
@@ -132,13 +118,13 @@ public class RClassGenerator {
     classWriter.visitEnd();
     Files.write(rClassFile, classWriter.toByteArray());
     // Now generate the R$inner.class files.
-    for (Map.Entry<ResourceType, Collection<FieldInitializer>> entry : initializersToWrite) {
+    for (Map.Entry<ResourceType, Map<String, FieldInitializer>> entry : initializersToWrite) {
       writeInnerClass(entry.getValue(), packageDir, rClassName, entry.getKey().toString());
     }
   }
 
   private void writeInnerClass(
-      Collection<FieldInitializer> initializers,
+      Map<String, FieldInitializer> initializers,
       Path packageDir,
       String fullyQualifiedOuterClass,
       String innerClass)
@@ -147,14 +133,16 @@ public class RClassGenerator {
     String fullyQualifiedInnerClass =
         writeInnerClassHeader(fullyQualifiedOuterClass, innerClass, innerClassWriter);
 
-    List<FieldInitializer> deferredInitializers = new ArrayList<>();
+    Map<String, FieldInitializer> deferredInitializers = new LinkedHashMap<>();
     int fieldAccessLevel = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC;
     if (finalFields) {
       fieldAccessLevel |= Opcodes.ACC_FINAL;
     }
-    for (FieldInitializer init : initializers) {
-      if (init.writeFieldDefinition(innerClassWriter, fieldAccessLevel, finalFields)) {
-        deferredInitializers.add(init);
+    for (Entry<String, FieldInitializer> entry : initializers.entrySet()) {
+      FieldInitializer init = entry.getValue();
+      if (init.writeFieldDefinition(
+          entry.getKey(), innerClassWriter, fieldAccessLevel, finalFields)) {
+        deferredInitializers.put(entry.getKey(), init);
       }
     }
     if (!deferredInitializers.isEmpty()) {
@@ -199,15 +187,19 @@ public class RClassGenerator {
   }
 
   private static void writeStaticClassInit(
-      ClassWriter classWriter, String className, List<FieldInitializer> initializers) {
+      ClassWriter classWriter,
+      String className,
+      Map<String, FieldInitializer> deferredInitializers) {
     MethodVisitor visitor =
         classWriter.visitMethod(
             Opcodes.ACC_STATIC, "<clinit>", "()V", null, /* signature */ null /* exceptions */);
     visitor.visitCode();
     int stackSlotsNeeded = 0;
     InstructionAdapter insts = new InstructionAdapter(visitor);
-    for (FieldInitializer fieldInit : initializers) {
-      stackSlotsNeeded = Math.max(stackSlotsNeeded, fieldInit.writeCLInit(insts, className));
+    for (Entry<String, FieldInitializer> fieldEntry : deferredInitializers.entrySet()) {
+      final FieldInitializer fieldInit = fieldEntry.getValue();
+      stackSlotsNeeded =
+          Math.max(stackSlotsNeeded, fieldInit.writeCLInit(fieldEntry.getKey(), insts, className));
     }
     insts.areturn(Type.VOID_TYPE);
     visitor.visitMaxs(stackSlotsNeeded, 0);
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/RSourceGenerator.java b/src/tools/android/java/com/google/devtools/build/android/resources/RSourceGenerator.java
index 4c3ef8581f..ffaab026d0 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/RSourceGenerator.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/RSourceGenerator.java
@@ -22,7 +22,7 @@ import java.io.BufferedWriter;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Collection;
+import java.util.Map;
 import java.util.Map.Entry;
 
 /** Writes out an R.java source. */
@@ -62,7 +62,7 @@ public class RSourceGenerator {
 
   private void writeSource(
       String packageName,
-      Iterable<Entry<ResourceType, Collection<FieldInitializer>>> initializersToWrite)
+      Iterable<Entry<ResourceType, Map<String, FieldInitializer>>> initializersToWrite)
       throws IOException {
     String packageDir = packageName.replace('.', '/');
     Path packagePath = outputBasePath.resolve(packageDir);
@@ -82,11 +82,11 @@ public class RSourceGenerator {
       writer.write(" */\n");
       writer.write(String.format("package %s;\n", packageName));
       writer.write("public final class R {\n");
-      for (Entry<ResourceType, Collection<FieldInitializer>> entry : initializersToWrite) {
+      for (Entry<ResourceType, Map<String, FieldInitializer>> entry : initializersToWrite) {
         writer.write(
             String.format("    public static final class %s {\n", entry.getKey().getName()));
-        for (FieldInitializer field : entry.getValue()) {
-          field.writeInitSource(writer, finalFields);
+        for (Entry<String, FieldInitializer> fieldEntry : entry.getValue().entrySet()) {
+          fieldEntry.getValue().writeInitSource(fieldEntry.getKey(), writer, finalFields);
         }
         writer.write("    }\n");
       }
diff --git a/src/tools/android/java/com/google/devtools/build/android/resources/ResourceSymbols.java b/src/tools/android/java/com/google/devtools/build/android/resources/ResourceSymbols.java
index 6b2dbcff7b..b98dfefa64 100644
--- a/src/tools/android/java/com/google/devtools/build/android/resources/ResourceSymbols.java
+++ b/src/tools/android/java/com/google/devtools/build/android/resources/ResourceSymbols.java
@@ -18,8 +18,6 @@ import com.android.builder.dependency.SymbolFileProvider;
 import com.android.resources.ResourceType;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.Multimap;
-import com.google.common.collect.MultimapBuilder;
-import com.google.common.collect.SortedSetMultimap;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import java.io.File;
@@ -27,12 +25,15 @@ import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
+import java.util.TreeMap;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.logging.Logger;
@@ -55,8 +56,8 @@ public class ResourceSymbols {
     public ResourceSymbols call() throws Exception {
       List<String> lines = Files.readAllLines(rTxtSymbols, StandardCharsets.UTF_8);
 
-      final SortedSetMultimap<ResourceType, FieldInitializer> initializers =
-          MultimapBuilder.enumKeys(ResourceType.class).treeSetValues().build();
+      Map<ResourceType, Map<String, FieldInitializer>> initializers =
+          new EnumMap<>(ResourceType.class);
 
       for (int lineIndex = 1; lineIndex <= lines.size(); lineIndex++) {
         String line = null;
@@ -74,10 +75,17 @@ public class ResourceSymbols {
           String value = line.substring(pos3 + 1);
 
           final ResourceType resourceType = ResourceType.getEnum(className);
+          final Map<String, FieldInitializer> fields;
+          if (initializers.containsKey(resourceType)) {
+            fields = initializers.get(resourceType);
+          } else {
+            fields = new TreeMap<>();
+            initializers.put(resourceType, fields);
+          }
           if ("int".equals(type)) {
-            initializers.put(resourceType, IntFieldInitializer.of(name, value));
+            fields.put(name, IntFieldInitializer.of(value));
           } else {
-            initializers.put(resourceType, IntArrayFieldInitializer.of(name, value));
+            fields.put(name, IntArrayFieldInitializer.of(value));
           }
         } catch (IndexOutOfBoundsException e) {
           String s =
@@ -88,7 +96,7 @@ public class ResourceSymbols {
           throw new IOException(s, e);
         }
       }
-      return ResourceSymbols.from(FieldInitializers.copyOf(initializers.asMap()));
+      return ResourceSymbols.from(FieldInitializers.copyOf(initializers));
     }
   }
 
@@ -141,15 +149,11 @@ public class ResourceSymbols {
   }
 
   public static ResourceSymbols merge(Collection<ResourceSymbols> symbolTables) {
-    final SortedSetMultimap<ResourceType, FieldInitializer> initializers =
-        MultimapBuilder.enumKeys(ResourceType.class).treeSetValues().build();
+    List<FieldInitializers> fieldInitializers = new ArrayList<>(symbolTables.size());
     for (ResourceSymbols symbolTableProvider : symbolTables) {
-      for (Entry<ResourceType, Collection<FieldInitializer>> entry :
-          symbolTableProvider.asInitializers()) {
-        initializers.putAll(entry.getKey(), entry.getValue());
-      }
+      fieldInitializers.add(symbolTableProvider.asInitializers());
     }
-    return from(FieldInitializers.copyOf(initializers.asMap()));
+    return from(FieldInitializers.mergedFrom(fieldInitializers));
   }
 
   /** Read the symbols from the provided symbol file. */
@@ -173,7 +177,7 @@ public class ResourceSymbols {
    * @param finalFields
    * @throws IOException when encountering an error during writing.
    */
-  public void writeTo(
+  public void writeSourcesTo(
       Path sourceOut,
       String packageName,
       Collection<ResourceSymbols> packageSymbols,
@@ -187,4 +191,20 @@ public class ResourceSymbols {
     return values;
   }
 
+  public void writeClassesTo(
+      Multimap<String, ResourceSymbols> libMap,
+      String appPackageName,
+      Path classesOut,
+      boolean finalFields)
+      throws IOException {
+    RClassGenerator classWriter = RClassGenerator.with(classesOut, values, finalFields);
+    for (String packageName : libMap.keySet()) {
+      classWriter.write(packageName, ResourceSymbols.merge(libMap.get(packageName)).values);
+    }
+    if (appPackageName != null) {
+      // Unlike the R.java generation, we also write the app's R.class file so that the class
+      // jar file can be complete (aapt doesn't generate it for us).
+      classWriter.write(appPackageName);
+    }
+  }
 }