Add validation infrastructure for "pub lish".

utils/pub/utils.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
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Generic utility functions. Stuff that should possibly be in core.
  */
 library utils;
 
 import 'dart:crypto';
 import 'dart:isolate';
 import 'dart:uri';
 
 /** A pair of values. */
 class Pair<E, F> {
   E first;
   F last;
 
   Pair(this.first, this.last);
 
   String toString() => '($first, $last)';
 
   bool operator==(other) {
     if (other is! Pair) return false;
     return other.first == first && other.last == last;
   }
+
+  int get hashCode => first.hashCode ^ last.hashCode;
 }
 
 // TODO(rnystrom): Move into String?
 /** Pads [source] to [length] by adding spaces at the end. */
 String padRight(String source, int length) {
   final result = new StringBuffer();
   result.add(source);
 
   while (result.length < length) {
     result.add(' ');
   }
 
   return result.toString();
 }
 
 /**
  * Runs [fn] after [future] completes, whether it completes successfully or not.
  * Essentially an asynchronous `finally` block.
  */
 always(Future future, fn()) {
   var completer = new Completer();
   future.then((_) => fn());
   future.handleException((_) {
     fn();
     return false;
   });
 }
 
 /**
- * Flattens nested lists into a single list containing only non-list elements.
+ * Flattens nested collections into a single list containing only non-list
+ * elements.
  */
-List flatten(List nested) {
+List flatten(Collection nested) {
   var result = [];
   helper(list) {
     for (var element in list) {
       if (element is List) {
         helper(element);
       } else {
         result.add(element);
       }
     }
   }
@@ skipping 124 matching lines @@
 
 /// Add all key/value pairs from [source] to [destination], overwriting any
 /// pre-existing values.
 void mapAddAll(Map destination, Map source) =>
   source.forEach((key, value) => destination[key] = value);
 
 /// Decodes a URL-encoded string. Unlike [decodeUriComponent], this includes
 /// replacing `+` with ` `.
 String urlDecode(String encoded) =>
   decodeUriComponent(encoded.replaceAll("+", " "));