aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/tools/android/java/com/google/devtools/build/android/resources/RClassGenerator.java
blob: 2012a989d84fe8e7f1d8f3ba88674eb6a3e0c830 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
// Copyright 2016 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.android.resources;

import static java.nio.file.StandardOpenOption.CREATE_NEW;

import com.android.SdkConstants;
import com.android.resources.ResourceType;
import com.google.common.base.Splitter;
import com.google.common.collect.Iterables;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.LinkedHashMap;
import java.util.Map;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;
import org.objectweb.asm.commons.InstructionAdapter;

/**
 * Writes out bytecode for an R.class directly, rather than go through an R.java and compile. This
 * avoids re-parsing huge R.java files and other time spent in the java compiler (e.g., plugins like
 * ErrorProne). A difference is that this doesn't generate line number tables and other debugging
 * information. Also, the order of the constant pool tends to be different.
 */
public class RClassGenerator {
  private static final int JAVA_VERSION = Opcodes.V1_7;
  private static final String SUPER_CLASS = "java/lang/Object";
  private final Path outFolder;
  private final FieldInitializers initializers;
  private final boolean finalFields;
  private static final Splitter PACKAGE_SPLITTER = Splitter.on('.');

  /**
   * Create an RClassGenerator given a collection of initializers.
   *
   * @param outFolder base folder to place the output R class files.
   * @param initializers the list of initializers to use for each inner class
   * @param finalFields true if the fields should be marked final
   */
  public static RClassGenerator with(
      Path outFolder, FieldInitializers initializers, boolean finalFields) {
    return new RClassGenerator(outFolder, initializers, finalFields);
  }

  private RClassGenerator(Path outFolder, FieldInitializers initializers, boolean finalFields) {
    this.outFolder = outFolder;
    this.finalFields = finalFields;
    this.initializers = initializers;
  }

  /**
   * Builds bytecode and writes out R.class file, and R$inner.class files for provided package and
   * symbols.
   */
  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<Map.Entry<ResourceType, Map<String, FieldInitializer>>> initializersToWrite)
      throws IOException {

    Iterable<String> folders = PACKAGE_SPLITTER.split(packageName);
    Path packageDir = outFolder;
    for (String folder : folders) {
      packageDir = packageDir.resolve(folder);
    }
    // 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("\\.", "/");
    String rClassName = packageWithSlashes.isEmpty() ? "R" : (packageWithSlashes + "/R");
    ClassWriter classWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);
    classWriter.visit(
        JAVA_VERSION,
        Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL | Opcodes.ACC_SUPER,
        rClassName,
        null, /* signature */
        SUPER_CLASS,
        null /* interfaces */);
    classWriter.visitSource(SdkConstants.FN_RESOURCE_CLASS, null);
    writeConstructor(classWriter);
    // Build the R.class w/ the inner classes, then later build the individual R$inner.class.
    for (Map.Entry<ResourceType, Map<String, FieldInitializer>> entry : initializersToWrite) {
      String innerClassName = rClassName + "$" + entry.getKey().toString();
      classWriter.visitInnerClass(
          innerClassName,
          rClassName,
          entry.getKey().toString(),
          Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL | Opcodes.ACC_STATIC);
    }
    classWriter.visitEnd();
    Files.write(rClassFile, classWriter.toByteArray(), CREATE_NEW);
    // Now generate the R$inner.class files.
    for (Map.Entry<ResourceType, Map<String, FieldInitializer>> entry : initializersToWrite) {
      writeInnerClass(entry.getValue(), packageDir, rClassName, entry.getKey().toString());
    }
  }

  private void writeInnerClass(
      Map<String, FieldInitializer> initializers,
      Path packageDir,
      String fullyQualifiedOuterClass,
      String innerClass)
      throws IOException {
    ClassWriter innerClassWriter = new ClassWriter(ClassWriter.COMPUTE_MAXS);
    String fullyQualifiedInnerClass =
        writeInnerClassHeader(fullyQualifiedOuterClass, innerClass, innerClassWriter);

    Map<String, FieldInitializer> deferredInitializers = new LinkedHashMap<>();
    int fieldAccessLevel = Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC;
    if (finalFields) {
      fieldAccessLevel |= Opcodes.ACC_FINAL;
    }
    for (Map.Entry<String, FieldInitializer> entry : initializers.entrySet()) {
      FieldInitializer init = entry.getValue();
      JavaIdentifierValidator.validate(
          entry.getKey(), "in class:", fullyQualifiedInnerClass, "and package:", packageDir);
      if (init.writeFieldDefinition(
          entry.getKey(), innerClassWriter, fieldAccessLevel, finalFields)) {
        deferredInitializers.put(entry.getKey(), init);
      }
    }
    if (!deferredInitializers.isEmpty()) {
      writeStaticClassInit(innerClassWriter, fullyQualifiedInnerClass, deferredInitializers);
    }

    innerClassWriter.visitEnd();
    Path innerFile = packageDir.resolve("R$" + innerClass + ".class");
    Files.write(innerFile, innerClassWriter.toByteArray(), CREATE_NEW);
  }

  private String writeInnerClassHeader(
      String fullyQualifiedOuterClass, String innerClass, ClassWriter innerClassWriter) {
    String fullyQualifiedInnerClass = fullyQualifiedOuterClass + "$" + innerClass;
    innerClassWriter.visit(
        JAVA_VERSION,
        Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL | Opcodes.ACC_SUPER,
        fullyQualifiedInnerClass,
        null, /* signature */
        SUPER_CLASS,
        null /* interfaces */);
    innerClassWriter.visitSource(SdkConstants.FN_RESOURCE_CLASS, null);
    writeConstructor(innerClassWriter);
    innerClassWriter.visitInnerClass(
        fullyQualifiedInnerClass,
        fullyQualifiedOuterClass,
        innerClass,
        Opcodes.ACC_PUBLIC | Opcodes.ACC_FINAL | Opcodes.ACC_STATIC);
    return fullyQualifiedInnerClass;
  }

  private static void writeConstructor(ClassWriter classWriter) {
    MethodVisitor constructor =
        classWriter.visitMethod(
            Opcodes.ACC_PUBLIC, "<init>", "()V", null, /* signature */ null /* exceptions */);
    constructor.visitCode();
    constructor.visitVarInsn(Opcodes.ALOAD, 0);
    constructor.visitMethodInsn(Opcodes.INVOKESPECIAL, SUPER_CLASS, "<init>", "()V", false);
    constructor.visitInsn(Opcodes.RETURN);
    constructor.visitMaxs(1, 1);
    constructor.visitEnd();
  }

  private static void writeStaticClassInit(
      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 (Map.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);
    visitor.visitEnd();
  }
}