1 files changed, 201 insertions, 0 deletions
diff --git a/src/tools/android/java/com/google/devtools/build/android/desugar/io/CoreLibraryRewriter.java b/src/tools/android/java/com/google/devtools/build/android/desugar/io/CoreLibraryRewriter.java
new file mode 100644
index 0000000000..f3c546c1c3
--- /dev/null
+++ b/src/tools/android/java/com/google/devtools/build/android/desugar/io/CoreLibraryRewriter.java
@@ -0,0 +1,201 @@
+// Copyright 2017 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.desugar.io;
+
+import java.io.IOException;
+import java.io.InputStream;
+import javax.annotation.Nullable;
+import org.objectweb.asm.Attribute;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassVisitor;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.commons.ClassRemapper;
+import org.objectweb.asm.commons.Remapper;
+
+/** Utility class to prefix or unprefix class names of core library classes */
+public class CoreLibraryRewriter {
+  private final String prefix;
+
+  public CoreLibraryRewriter(String prefix) {
+    this.prefix = prefix;
+  }
+
+  /**
+   * Factory method that returns either a normal ClassReader if prefix is empty, or a ClassReader
+   * with a ClassRemapper that prefixes class names of core library classes if prefix is not empty.
+   */
+  public ClassReader reader(InputStream content) throws IOException {
+    if (prefix.isEmpty()) {
+      return new ClassReader(content);
+    } else {
+      return new PrefixingClassReader(content, prefix);
+    }
+  }
+
+  /**
+   * Factory method that returns a ClassVisitor that delegates to a ClassWriter, removing prefix
+   * from core library class names if it is not empty.
+   */
+  public UnprefixingClassWriter writer(int flags) {
+    return new UnprefixingClassWriter(flags);
+  }
+
+  static boolean shouldPrefix(String typeName) {
+    return (typeName.startsWith("java/") || typeName.startsWith("sun/")) && !except(typeName);
+  }
+
+  private static boolean except(String typeName) {
+    if (typeName.startsWith("java/lang/invoke/")) {
+      return true;
+    }
+
+    switch (typeName) {
+        // Autoboxed types
+      case "java/lang/Boolean":
+      case "java/lang/Byte":
+      case "java/lang/Character":
+      case "java/lang/Double":
+      case "java/lang/Float":
+      case "java/lang/Integer":
+      case "java/lang/Long":
+      case "java/lang/Number":
+      case "java/lang/Short":
+
+        // Special types
+      case "java/lang/Class":
+      case "java/lang/Object":
+      case "java/lang/String":
+      case "java/lang/Throwable":
+        return true;
+
+      default: // fall out
+    }
+
+    return false;
+  }
+
+  public String getPrefix() {
+    return prefix;
+  }
+
+  /** Removes prefix from class names */
+  public String unprefix(String typeName) {
+    if (prefix.isEmpty() || !typeName.startsWith(prefix)) {
+      return typeName;
+    }
+    return typeName.substring(prefix.length());
+  }
+
+  /** ClassReader that prefixes core library class names as they are read */
+  private static class PrefixingClassReader extends ClassReader {
+    private final String prefix;
+
+    PrefixingClassReader(InputStream content, String prefix) throws IOException {
+      super(content);
+      this.prefix = prefix;
+    }
+
+    @Override
+    public void accept(ClassVisitor cv, Attribute[] attrs, int flags) {
+      cv =
+          new ClassRemapper(
+              cv,
+              new Remapper() {
+                @Override
+                public String map(String typeName) {
+                  return prefix(typeName);
+                }
+              });
+      super.accept(cv, attrs, flags);
+    }
+
+    @Override
+    public String getClassName() {
+      return prefix(super.getClassName());
+    }
+
+    @Override
+    public String getSuperName() {
+      String result = super.getSuperName();
+      return result != null ? prefix(result) : null;
+    }
+
+    @Override
+    public String[] getInterfaces() {
+      String[] result = super.getInterfaces();
+      for (int i = 0, len = result.length; i < len; ++i) {
+        result[i] = prefix(result[i]);
+      }
+      return result;
+    }
+
+    /** Prefixes core library class names with prefix. */
+    private String prefix(String typeName) {
+      if (shouldPrefix(typeName)) {
+        return prefix + typeName;
+      }
+      return typeName;
+    }
+  }
+
+  /**
+   * ClassVisitor that delegates to a ClassWriter, but removes a prefix as each class is written.
+   * The unprefixing is optimized out if prefix is empty.
+   */
+  public class UnprefixingClassWriter extends ClassVisitor {
+    private final ClassWriter writer;
+
+    private String finalClassName;
+
+    UnprefixingClassWriter(int flags) {
+      super(Opcodes.ASM6);
+      this.writer = new ClassWriter(flags);
+      this.cv = this.writer;
+      if (!prefix.isEmpty()) {
+        this.cv =
+            new ClassRemapper(
+                this.writer,
+                new Remapper() {
+                  @Override
+                  public String map(String typeName) {
+                    return unprefix(typeName);
+                  }
+                });
+      }
+    }
+
+    /** Returns the (unprefixed) name of the class once written. */
+    @Nullable
+    public String getClassName() {
+      return finalClassName;
+    }
+
+    public byte[] toByteArray() {
+      return writer.toByteArray();
+    }
+
+    @Override
+    public void visit(
+        int version,
+        int access,
+        String name,
+        String signature,
+        String superName,
+        String[] interfaces) {
+      finalClassName = unprefix(name);
+      super.visit(version, access, name, signature, superName, interfaces);
+    }
+  }
+}