[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 "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)),
+      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) {
+  *consumed_bytes = 0;
+  int bytes_out = 0;
+  // TODO(dschuyler): Perform replacements without accumulation.
+  if (!upstream_end_reached) {
+    // Accumulate.
+    input_.append(input_buffer->data(), input_buffer_size);
+    *consumed_bytes = input_buffer_size;
+  } else if (!input_.empty() && output_.empty()) {
+    // Process.
+    output_ = ui::ReplaceTemplateExpressions(base::StringPiece(input_),
+                                             *replacements_);
+    input_.clear();
+  }
+
+  if (!output_.empty()) {
+    // Drain.
+    bytes_out = std::min(static_cast<int>(output_.size()), output_buffer_size);
+    output_.copy(output_buffer->data(), bytes_out);
+    output_.erase(0, bytes_out);
+  }
+
+  return bytes_out;
+}
+
+}  // namespace content