Add C++ wrappers for output parameters.

ppapi/cpp/array_output.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ppapi/cpp/array_output.h"
+
+#include "ppapi/cpp/logging.h"
+
+namespace pp {
+
+// static
+void* ArrayOutputAdapterBase::GetDataBufferThunk(void* user_data,
+                                                 uint32_t element_count,
+                                                 uint32_t element_size) {
+  return static_cast<ArrayOutputAdapterBase*>(user_data)->
+      GetDataBuffer(element_count, element_size);
+}
+
+VarArrayOutputAdapterWithStorage::VarArrayOutputAdapterWithStorage()
+    : ArrayOutputAdapter<PP_Var>() {
+  set_output(&temp_storage_);
+}
+
+VarArrayOutputAdapterWithStorage::VarArrayOutputAdapterWithStorage(
+    const VarArrayOutputAdapterWithStorage& other)
+    : ArrayOutputAdapter<PP_Var>() {
+  // We can't actually make copies of this adapter once it's been used. But
+  // we need to support copying before it's been used because the completion
+  // callback factory uses this. So ensure that we're empty.

[dmichael (off chromium), 2012/03/09 18:23:27]

Ah. A comment of explanation in the header or a reference to this comment would
be good. Do they all need to support copy? I think most of them are just
providing the compiler defaults, except the WithStorage types. That makes sense,
but a clear explanation somewhere might prevent somebody from coming along and
breaking it by "fixing" it.

Or... we can see if there's a way to make CompletionCallbackFactory not require
the copy (haven't looked at that yet).

+  PP_DCHECK(other.temp_storage_.empty());
+  set_output(&temp_storage_);
+}
+
+VarArrayOutputAdapterWithStorage&
+VarArrayOutputAdapterWithStorage::operator=(
+    const VarArrayOutputAdapterWithStorage& other) {
+  set_output(&temp_storage_);
+  return *this;
+}
+
+std::vector<Var>& VarArrayOutputAdapterWithStorage::output() {
+  PP_DCHECK(output_storage_.empty());
+
+  output_storage_.reserve(temp_storage_.size());
+  for (size_t i = 0; i < temp_storage_.size(); i++)
+    output_storage_.push_back(Var(PASS_REF, temp_storage_[i]));
+  temp_storage_.clear();
+  return output_storage_;
+}
+
+}  // namespace pp