1 files changed, 119 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/events/PrintingEventHandler.java b/src/main/java/com/google/devtools/build/lib/events/PrintingEventHandler.java
new file mode 100644
index 0000000000..fa94d95167
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+++ b/src/main/java/com/google/devtools/build/lib/events/PrintingEventHandler.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.lib.events;
+
+import com.google.devtools.build.lib.util.io.OutErr;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Set;
+
+/**
+ * An event handler that prints to an OutErr stream pair in a
+ * canonical format, for example:
+ * <pre>
+ * ERROR: /home/jrluser/src/workspace/x/BUILD:23:1: syntax error.
+ * </pre>
+ * This syntax is parseable by Emacs's compile.el.
+ *
+ * <p>
+ * By default, the output will go to SYSTEM_OUT_ERR,
+ * but this can be changed by calling the setOut() method.
+ *
+ * <p>
+ * This class is used only for tests.
+ */
+public class PrintingEventHandler extends AbstractEventHandler
+    implements EventHandler {
+
+  /**
+   * A convenient event-handler for terminal applications that prints all
+   * errors and warnings it encounters to the error stream.
+   * STDOUT and STDERR events pass their output directly
+   * through to the corresponding streams.
+   */
+  public static final PrintingEventHandler ERRORS_AND_WARNINGS_TO_STDERR =
+      new PrintingEventHandler(EventKind.ERRORS_AND_WARNINGS_AND_OUTPUT);
+
+  /**
+   * A convenient event-handler for terminal applications that prints all
+   * errors it encounters to the error stream.
+   * STDOUT and STDERR events pass their output directly
+   * through to the corresponding streams.
+   */
+  public static final PrintingEventHandler ERRORS_TO_STDERR =
+      new PrintingEventHandler(EventKind.ERRORS_AND_OUTPUT);
+
+  private OutErr outErr = OutErr.SYSTEM_OUT_ERR;
+
+  /**
+   * Setup a printing event handler that will handle events matching the mask.
+   * Events will be printed to the original System.out and System.err
+   * unless/until redirected by a call to setOutErr().
+   */
+  public PrintingEventHandler(Set<EventKind> mask) {
+    super(mask);
+  }
+
+  /**
+   * Redirect all output to the specified OutErr stream pair.
+   * Returns the previous OutErr.
+   */
+  public OutErr setOutErr(OutErr outErr) {
+    OutErr prev = this.outErr;
+    this.outErr = outErr;
+    return prev;
+  }
+
+  /**
+   * Print a description of the specified event to the appropriate
+   * output or error stream.
+   */
+  @Override
+  public void handle(Event event) {
+    if (!getEventMask().contains(event.getKind())) {   
+      return;
+    }
+    try {
+      switch (event.getKind()) {
+        case STDOUT:
+          outErr.getOutputStream().write(event.getMessageBytes());
+          outErr.getOutputStream().flush();
+          break;
+        case STDERR:
+          outErr.getErrorStream().write(event.getMessageBytes());
+          outErr.getErrorStream().flush();
+          break;
+        default:
+          PrintWriter err = new PrintWriter(outErr.getErrorStream());
+          err.print(event.getKind());
+          err.print(": ");
+          if (event.getLocation() != null) {
+            err.print(event.getLocation().print());
+            err.print(": ");
+          }
+          err.println(event.getMessage());
+          err.flush();
+      }
+    } catch (IOException e) {
+      /*
+       * Note: we can't print to System.out or System.err here,
+       * because those will normally be set to streams which
+       * translate I/O to STDOUT and STDERR events,
+       * which would result in infinite recursion.
+       */
+      outErr.printErrLn(e.getMessage());
+    }
+  }
+}