1 files changed, 93 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java b/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java
new file mode 100644
index 0000000000..66c6d3b4c2
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/util/io/LineWrappingAnsiTerminalWriter.java
@@ -0,0 +1,93 @@
+// 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.lib.util.io;
+
+import java.io.IOException;
+
+/**
+ * Wrap an {@link AnsiTerminalWriter} into one that breaks lines to use
+ * at most a first given number of columns of the terminal. In this way,
+ * all line breaks are predictable, even if we only have a lower bound
+ * on the number of columns of the underlying terminal. To simplify copy
+ * and paste of the terminal output, a continuation character is written
+ * into the last usable column when we break a line. Additionally, newline
+ * characters are translated into calls to the {@link AnsiTerminalWriter#newline()}
+ * method.
+ */
+public class LineWrappingAnsiTerminalWriter implements AnsiTerminalWriter {
+
+  private final AnsiTerminalWriter terminalWriter;
+  private final int width;
+  private final char continuationCharacter;
+  private int position;
+
+  public LineWrappingAnsiTerminalWriter(
+      AnsiTerminalWriter terminalWriter, int width, char continuationCharacter) {
+    this.terminalWriter = terminalWriter;
+    this.width = width;
+    this.continuationCharacter = continuationCharacter;
+    this.position = 0;
+  }
+
+  public LineWrappingAnsiTerminalWriter(AnsiTerminalWriter terminalWriter, int width) {
+    this(terminalWriter, width, '\\');
+  }
+
+  private void appendChar(char c) throws IOException {
+    if (c == '\n') {
+      terminalWriter.newline();
+      position = 0;
+    } else if (position + 2 < width) {
+      terminalWriter.append(Character.toString(c));
+      position++;
+    } else {
+      terminalWriter.append(new String(new char[] {c, continuationCharacter}));
+      terminalWriter.newline();
+      position = 0;
+    }
+  }
+
+  @Override
+  public AnsiTerminalWriter append(String text) throws IOException {
+    for (int i = 0; i < text.length(); i++) {
+      appendChar(text.charAt(i));
+    }
+    return this;
+  }
+
+  @Override
+  public AnsiTerminalWriter newline() throws IOException {
+    terminalWriter.newline();
+    position = 0;
+    return this;
+  }
+
+  @Override
+  public AnsiTerminalWriter okStatus() throws IOException {
+    terminalWriter.okStatus();
+    return this;
+  }
+
+  @Override
+  public AnsiTerminalWriter failStatus() throws IOException {
+    terminalWriter.failStatus();
+    return this;
+  }
+
+  @Override
+  public AnsiTerminalWriter normal() throws IOException {
+    terminalWriter.normal();
+    return this;
+  }
+}