[MD settings] i18n source stream filtering

content/browser/webui/i18n_source_stream.cc

+// Copyright 2016 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 "content/browser/webui/i18n_source_stream.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/strings/string_piece.h"
+#include "net/base/io_buffer.h"
+
+namespace content {
+
+I18nSourceStream::~I18nSourceStream() {}
+
+std::unique_ptr<I18nSourceStream> I18nSourceStream::Create(
+    std::unique_ptr<SourceStream> upstream,
+    SourceStream::SourceType type,
+    const ui::TemplateReplacements* replacements) {
+  DCHECK(replacements);
+  std::unique_ptr<I18nSourceStream> source(
+      new I18nSourceStream(std::move(upstream), type, replacements));
+  return source;
+}
+
+I18nSourceStream::I18nSourceStream(std::unique_ptr<SourceStream> upstream,
+                                   SourceStream::SourceType type,
+                                   const ui::TemplateReplacements* replacements)
+    : FilterSourceStream(type, std::move(upstream)),
+      drain_offset_(0),
+      replacements_(replacements) {}
+
+std::string I18nSourceStream::GetTypeAsString() const {
+  return "i18n";
+}
+
+int I18nSourceStream::FilterData(net::IOBuffer* output_buffer,
+                                 int output_buffer_size,
+                                 net::IOBuffer* input_buffer,
+                                 int input_buffer_size,
+                                 int* consumed_bytes,
+                                 bool upstream_end_reached) {
+  DCHECK(output_.empty() || (upstream_end_reached && input_buffer_size == 0));
+  *consumed_bytes = input_buffer_size;
+  // TODO(dschuyler): Perform replacements without accumulation.
+  // Accumulate.
+  input_.append(input_buffer->data(), input_buffer_size);
+  if (upstream_end_reached && !drain_offset_ && output_.empty()) {
+    // Process.
+    output_ = ui::ReplaceTemplateExpressions(input_, *replacements_);
+  }
+
+  if (drain_offset_ == output_.size())
+    return 0;
+
+  // Drain.
+  int bytes_out = std::min(output_.size() - drain_offset_,
+                           static_cast<size_t>(output_buffer_size));
+  output_.copy(output_buffer->data(), bytes_out, drain_offset_);
+  drain_offset_ += bytes_out;
+  return bytes_out;
+}
+
+}  // namespace content