Roll Observatory packages and add a roll script

packages/charted/tool/build_unicode_segmentation_data.dart

+//
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+//
+
+library charted.tool.build_unicode_segmentation_data;
+
+import 'dart:async';
+import 'package:http/http.dart' as http;
+import 'package:charted/core/text_metrics/segmentation_utils.dart';
+
+/// Unicode version
+/// A new version of unicode is available every June.
+const VERSION = '7.0.0';
+
+/// URI for downloading the grapheme properties file.
+const UCD_PROPERTIES_URL =
+    'http://www.unicode.org/Public/${VERSION}/ucd/auxiliary/GraphemeBreakProperty.txt';
+
+const LIBRARY_NAME = 'charted.core.text_metrics.segmentation_data';
+
+/// License header for the generated file.
+const HEADER = """
+//
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+//
+// This is a generated file.
+// Please use tool/build_unicode_segmentation-data.dart to update
+//
+
+/// Code ranges by their types for use with grapheme segmentation
+/// of text in charts.
+library $LIBRARY_NAME;
+
+import "package:charted/core/text_metrics/segmentation_utils.dart";
+
+""";
+
+Future<String> _getPropertiesFile() => http.read(UCD_PROPERTIES_URL);
+
+void _dumpPropertiesData(String data) {
+  StringBuffer buffer = new StringBuffer();
+  RegExp lineRegExp =
+      new RegExp(r'([0-9A-F]{4})..([0-9A-F]{4})?\s+;\s([a-zA-Z]+)\s');
+
+  buffer.write(HEADER);
+  buffer.writeln('const CODE_POINT_BLOCKS = const[');
+
+  List<Iterable> items = [];
+  data.split('\n').forEach((String line) {
+    Match match = lineRegExp.matchAsPrefix(line);
+    if (match == null) return;
+
+    int start = int.parse(match.group(1), radix:16);
+    int end =
+        match.group(2) == null ? start : int.parse(match.group(2), radix:16);
+
+    items.add([start, end, CodeUnitCategory[match.group(3)]]);
+    items.sort((a, b) => a.first.compareTo(b.first));
+  });
+
+  buffer.write(items.map((List range) => range.join(', ')).join(',\n  '));
+  buffer.writeln();
+  buffer.writeln('];');
+  print(buffer.toString());
+}
+
+main() {
+  _getPropertiesFile().then((data) => _dumpPropertiesData(data));
+}