Port two completion contributors for use by plugins

pkg/analyzer_plugin/lib/src/utilities/documentation.dart

Index: pkg/analyzer_plugin/lib/src/utilities/documentation.dart
diff --git a/pkg/analyzer_plugin/lib/src/utilities/documentation.dart b/pkg/analyzer_plugin/lib/src/utilities/documentation.dart
new file mode 100644
index 0000000000000000000000000000000000000000..55e67f17e22e454aaa9e5ccb73e42bb43b5d0e6b
--- /dev/null
+++ b/pkg/analyzer_plugin/lib/src/utilities/documentation.dart
@@ -0,0 +1,71 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/**
+ * Return the summary of the given DartDoc [string], which is the content of the
+ * lines before the first blank line.
+ */
+String getDartDocSummary(String string) {
+  if (string == null) {
+    return null;
+  }
+  List<String> lines = string.split('\n');
+  StringBuffer buffer = new StringBuffer();
+  bool firstLine = true;
+  for (String line in lines) {
+    if (buffer.length != 0 && line.isEmpty) {
+      return buffer.toString();
+    }
+    if (!firstLine) {
+      buffer.write('\n');
+    }
+    firstLine = false;
+    buffer.write(line);
+  }
+  return buffer.toString();
+}
+
+/**
+ * Converts [string] from a DartDoc comment with slashes and stars to a plain
+ * text representation of the comment.
+ */
+String removeDartDocDelimiters(String string) {
+  if (string == null) {
+    return null;
+  }
+  // remove /** */
+  if (string.startsWith('/**')) {
+    string = string.substring(3);
+  }
+  if (string.endsWith('*/')) {
+    string = string.substring(0, string.length - 2);
+  }
+  string = string.trim();
+  // remove leading '* ' and '/// '
+  List<String> lines = string.split('\n');
+  StringBuffer buffer = new StringBuffer();
+  bool firstLine = true;
+  for (String line in lines) {
+    line = line.trim();
+    if (line.startsWith('*')) {
+      line = line.substring(1);
+      if (line.startsWith(' ')) {
+        line = line.substring(1);
+      }
+    } else if (line.startsWith('///')) {
+      line = line.substring(3);
+      if (line.startsWith(' ')) {
+        line = line.substring(1);
+      }
+    }
+    if (!firstLine) {
+      buffer.write('\n');
+    }
+    firstLine = false;
+    buffer.write(line);
+  }
+  string = buffer.toString();
+  // done
+  return string;
+}