Move toString() to collection classes.

sdk/lib/_collection_dev/iterable.dart

 // Copyright (c) 2011, 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.
 
 part of dart._collection.dev;
 
 
 // This is a hack to make @deprecated work in dart:io. Don't remove or use this,
 // unless coordinated with either me or the core library team. Thanks!
 // TODO(ajohnsen): Remove at the 11th of Auguest 2013.
@@ skipping 670 matching lines @@
 abstract class BidirectionalIterator<T> implements Iterator<T> {
   bool movePrevious();
 }
 
 /**
  * This class provides default implementations for Iterables (including Lists).
  *
  * The uses of this class will be replaced by mixins.
  */
 class IterableMixinWorkaround {
+  // A list to identify cyclic collections during toString() calls.
+  static List _toStringList = new List();
+
   static bool contains(Iterable iterable, var element) {
     for (final e in iterable) {
       if (e == element) return true;
     }
     return false;
   }
 
   static void forEach(Iterable iterable, void f(o)) {
     for (final e in iterable) {
       f(e);
@@ skipping 173 matching lines @@
     } else {
       buffer.write(list[0]);
       for (int i = 1; i < list.length; i++) {
         buffer.write(separator);
         buffer.write(list[i]);
       }
     }
     return buffer.toString();
   }
 
+  static String toStringIterable(Iterable iterable, String leftDelimiter,
+                                 String rightDelimiter) {
+    for (int i = 0; i < _toStringList.length; i++) {
+      if (identical(_toStringList[i], iterable)) {
+        return '$leftDelimiter...$rightDelimiter';
+        }
+    }
+
+    StringBuffer result = new StringBuffer();
+    try {
+      _toStringList.add(iterable);
+      result.write(leftDelimiter);
+      result.writeAll(iterable, ', ');
+      result.write(rightDelimiter);
+    } finally {
+      assert(identical(_toStringList.last, iterable));
+      _toStringList.removeLast();
+    }
+    return result.toString();
+  }
+
   static Iterable where(Iterable iterable, bool f(var element)) {
     return new WhereIterable(iterable, f);
   }
 
   static Iterable map(Iterable iterable, f(var element)) {
     return new MappedIterable(iterable, f);
   }
 
   static Iterable mapList(List list, f(var element)) {
     return new MappedListIterable(list, f);
@@ skipping 156 matching lines @@
 
   static Set setDifference(Set set, Set other, Set result) {
     for (var element in set) {
       if (!other.contains(element)) {
         result.add(element);
       }
     }
     return result;
   }
 }