Roll Observatory packages and add a roll script

packages/csslib/example/call_parser.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+
+import 'package:csslib/parser.dart' as css;
+import 'package:csslib/visitor.dart';
+
+const _default = const css.PreprocessorOptions(
+    useColors: false,
+    checked: true,
+    warningsAsErrors: true,
+    inputFile: 'memory');
+
+/**
+ * Spin-up CSS parser in checked mode to detect any problematic CSS.  Normally,
+ * CSS will allow any property/value pairs regardless of validity; all of our
+ * tests (by default) will ensure that the CSS is really valid.
+ */
+StyleSheet parseCss(String cssInput,
+    {List errors, css.PreprocessorOptions opts}) {
+  return css.parse(cssInput,
+      errors: errors, options: opts == null ? _default : opts);
+}
+
+// Pretty printer for CSS.
+var emitCss = new CssPrinter();
+String prettyPrint(StyleSheet ss) =>
+    (emitCss..visitTree(ss, pretty: true)).toString();
+
+main() {
+  var errors = [];
+
+  // Parse a simple stylesheet.
+  print('1. Good CSS, parsed CSS emitted:');
+  print('   =============================');
+  var stylesheet = parseCss(
+      '@import "support/at-charset-019.css"; div { color: red; }'
+      'button[type] { background-color: red; }'
+      '.foo { '
+      'color: red; left: 20px; top: 20px; width: 100px; height:200px'
+      '}'
+      '#div {'
+      'color : #00F578; border-color: #878787;'
+      '}', errors: errors);
+
+  if (!errors.isEmpty) {
+    print("Got ${errors.length} errors.\n");
+    for (var error in errors) {
+      print(error);
+    }
+  } else {
+    print(prettyPrint(stylesheet));
+  }
+
+  // Parse a stylesheet with errors
+  print('2. Catch severe syntax errors:');
+  print('   ===========================');
+  var stylesheetError = parseCss('.foo #%^&*asdf{ '
+      'color: red; left: 20px; top: 20px; width: 100px; height:200px'
+      '}', errors: errors);
+
+  if (!errors.isEmpty) {
+    print("Got ${errors.length} errors.\n");
+    for (var error in errors) {
+      print(error);
+    }
+  } else {
+    print(stylesheetError.toString());
+  }
+
+  // Parse a stylesheet that warns (checks) problematic CSS.
+  print('3. Detect CSS problem with checking on:');
+  print('   ===================================');
+  stylesheetError = parseCss('# div1 { color: red; }', errors: errors);
+
+  if (!errors.isEmpty) {
+    print("Detected ${errors.length} problem in checked mode.\n");
+    for (var error in errors) {
+      print(error);
+    }
+  } else {
+    print(stylesheetError.toString());
+  }
+
+  // Parse a CSS selector.
+  print('4. Parse a selector only:');
+  print('   ======================');
+  var selectorAst = css.selector('#div .foo', errors: errors);
+  if (!errors.isEmpty) {
+    print("Got ${errors.length} errors.\n");
+    for (var error in errors) {
+      print(error);
+    }
+  } else {
+    print(prettyPrint(selectorAst));
+  }
+}