1 files changed, 119 insertions, 0 deletions
diff --git a/src/java_tools/singlejar/java/com/google/devtools/build/singlejar/ZipEntryFilter.java b/src/java_tools/singlejar/java/com/google/devtools/build/singlejar/ZipEntryFilter.java
new file mode 100644
index 0000000000..ab5a24af36
--- /dev/null
+++ b/src/java_tools/singlejar/java/com/google/devtools/build/singlejar/ZipEntryFilter.java
@@ -0,0 +1,119 @@
+// Copyright 2014 Google Inc. 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.singlejar;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.Date;
+
+/**
+ * A custom filter for entries when combining multiple ZIP files (or even just
+ * copying a single ZIP file).
+ *
+ * <p>Implementations of this interface must be thread-safe. The {@link
+ * #accept} method may be called concurrently by multiple threads.
+ */
+public interface ZipEntryFilter {
+
+  /**
+   * Strategy for a custom merge operation. The current file and all additional
+   * file are passed to the strategy object via {@link #merge}, which merges
+   * the files. At the end of the ZIP combination, {@link #finish} is called,
+   * which then writes the merged single entry of that name.
+   *
+   * <p>Implementations of this interface are not required to be thread-safe.
+   * Thread-safety is achieved by creating multiple instances. Each instance
+   * that is separately passed to {@link StrategyCallback#customMerge} is
+   * guaranteed not to be called by two threads at the same time.
+   */
+  interface CustomMergeStrategy {
+
+    /**
+     * Merges another file into the current state. This method is called for
+     * every file entry of the same name.
+     */
+    void merge(InputStream in, OutputStream out) throws IOException;
+
+    /**
+     * Outputs the merged result into the given output stream. This method is
+     * only called once when no further file of the same name is available.
+     */
+    void finish(OutputStream out) throws IOException;
+  }
+
+  /**
+   * A callback interface for the {@link ZipEntryFilter#accept} method. Use
+   * this interface to indicate the type of processing for the given file name.
+   * For every file name, exactly one of the methods must be called once. A
+   * second method call throws {@link IllegalStateException}.
+   *
+   * <p>There is no guarantee that the callback will perform the requested
+   * operation at the time of the invocation. An implementation may choose to
+   * defer the operation to an arbitrary later time.
+   *
+   * <p>IMPORTANT NOTE: Do not implement this interface. It will be modified to
+   * support future extensions, and all implementations in this package will be
+   * updated. If you violate this advice, your code will break.
+   */
+  interface StrategyCallback {
+
+    /**
+     * Skips the current entry and all entries with the same name.
+     */
+    void skip() throws IOException;
+
+    /**
+     * Copies the current entry and skips all further entries with the same
+     * name. If {@code date} is non-null, then the timestamp of the entry is
+     * overwritten with the given value.
+     */
+    void copy(Date date) throws IOException;
+
+    /**
+     * Renames and copies the current entry, and skips all further entries with
+     * the same name. If {@code date} is non-null, then the timestamp of the entry
+     * is overwritten with the given value.
+     */
+    void rename(String filename, Date date) throws IOException;
+
+    /**
+     * Merges this and all further entries with the same name with the given
+     * {@link CustomMergeStrategy}. This method must never be called twice with
+     * the same object. If {@code date} is non-null, then the timestamp of the
+     * generated entry is set to the given value; otherwise, it is set to the
+     * current time.
+     */
+    void customMerge(Date date, CustomMergeStrategy strategy) throws IOException;
+  }
+
+  /**
+   * Determines the policy with which to handle the ZIP file entry with the
+   * given name and calls the appropriate method on the callback interface
+   * {@link StrategyCallback}. For every unique name in the set of all ZIP file
+   * entries, this method is called exactly once and the result is used for all
+   * entries of the same name. Except, if an entry is renamed, the original name
+   * is not considered as having been encountered yet.
+   *
+   * <p>Implementations should use the filename to distinguish the desired
+   * processing, call one method on the callback interface and return
+   * immediately after that call.
+   *
+   * <p>There is no guarantee that the callback will perform the requested
+   * operation at the time of the invocation. An implementation may choose to
+   * defer the operation to an arbitrary later time.
+   */
+  void accept(String filename, StrategyCallback callback) throws IOException;
+}