Use offset and count to request slices of lists, maps, and typed_data.

runtime/vm/json_stream.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_JSON_STREAM_H_
 #define VM_JSON_STREAM_H_
 
 #include "include/dart_api.h"  // for Dart_Port
 #include "platform/json.h"
 #include "vm/allocation.h"
@@ skipping 91 matching lines @@
   bool HasParam(const char* key) const;
 
   // Returns true if there is an param with key and value, false
   // otherwise.
   bool ParamIs(const char* key, const char* value) const;
 
   const char* method() const { return method_; }
   const char** param_keys() const { return param_keys_; }
   const char** param_values() const { return param_values_; }
 
+  void set_offset(intptr_t value) {
+    ASSERT(value > 0);
+    offset_ = value;
+  }
+
+  void set_count(intptr_t value) {
+    ASSERT(value > 0);
+    count_ = value;
+  }
+
+  void ComputeOffsetAndCount(intptr_t length,
+                             intptr_t* offset,
+                             intptr_t* count);
+
  private:
   void Clear();
   void PostNullReply(Dart_Port port);
 
   void OpenObject(const char* property_name = NULL);
   void CloseObject();
 
   void OpenArray(const char* property_name = NULL);
   void CloseArray();
 
@@ skipping 59 matching lines @@
   TextBuffer buffer_;
   // Default service id zone.
   RingServiceIdZone default_id_zone_;
   ServiceIdZone* id_zone_;
   Dart_Port reply_port_;
   Instance* seq_;
   const char* method_;
   const char** param_keys_;
   const char** param_values_;
   intptr_t num_params_;
+  intptr_t offset_;
+  intptr_t count_;
   int64_t setup_time_micros_;
 
   friend class JSONObject;
   friend class JSONArray;
 };
 
 
 class JSONObject : public ValueObject {
  public:
   explicit JSONObject(JSONStream* stream) : stream_(stream) {
@@ skipping 150 matching lines @@
 
   friend class JSONObject;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(JSONArray);
 };
 
 }  // namespace dart
 
 #endif  // VM_JSON_STREAM_H_